: EHE A ERHEBEN ENGEN, ss MOINE HE a Alls bd i if 7 4; f in ‘aa 1 fiat # I BE e i een er) ie TE, HI KE 4 4 ; H ñ A i ; - ACTE G PEST ers Seats eet es 3; Re RARES are bie ur ; pri i oe NON =) | Bar LE Fr rl jie - tal wd vr 1 Paleontological Research QE ISSN 1342-8144 Formerly Transactions and Proceedings of the Palaeontological Society of Japan Vol. 3 No.1 April 1999 The Palaeontological Society of Japan ; Co-Editors Kazushige Tanabe and Tomoki Kase Language Editor Martin Janal (New York, USA) Associate Editors Jan Bergström (Swedish Museum of Natural History, Stockholm, Sweden), Alan G. Beu (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Satoru Chiba (Tohoku University, Sendai, Japan), Yoichi Ezaki (Osaka City University, Osaka, Japan), James C. Ingle, Jr. (Stanford University, Stanford, USA), Kunio Kaiho (Tohoku University, Sendai, Japan), Susan M. Kidwell (University of Chicago, Chicago, USA), Hiroshi Kitazato (Shizuoka University, Shizuoka, Japan), Naoki Kohno (National Science Museum, Tokyo, Japan), Neil H. Landman (Amemican Museum of Natural History, New York, USA), Haruyoshi Maeda (Kyoto University, Kyoto, Japan), Atsushi Matsuoka (Niigata University, Niigata, Japan), Rihito Morita (Natural History Museum and Institute, Chiba, Japan), Harufumi Nishida (Chuo University, Tokyo, Japan), Kenshiro Ogasawara (University of Tsukuba, Tsukuba, Japan), Tatsuo Oji (University of Tokyo, Tokyo, Japan), Andrew B. Smith (Natural History Museum, London, Great Britain), Roger D.K. Thomas (Franklin and Marshall College, Lancaster, USA), Katsumi Ueno (Fukuoka University, Fukuoka, Japan), Wang Hongzhen (China University of Geosciences, Beijing, China), Yang Seong Young (Kyungpook National University, Taegu, Korea) Officers for 1999-2000 President : Kei Mori Councillors : Kiyotaka Chinzei, Takashi Hamada, Yoshikazu Hasegawa, ltaru Hayami, Hiromichi Hirano, Noriyuki Ikeya, Junji Itoigawa, Tomoki Kase, Hiroshi Kitazato, Itaru Koizumi, Haruyoshi Maeda, Ryuichi Majima, Makoto Manabe, Hiroshi Noda, Ikuo Obata, Kenshiro Ogasawara, Terufumi Ohno, Tatsuo Oji, Tomowo Ozawa, Yukimitsu Tomida, Tsunemasa Saito, Takeshi Setoguchi, Kazushige Tanabe, Akira Yao Members of Standing Committee : Hiroshi Kitazato (General Affairs), Tatsuo Oji (Laison Officer), Makoto Manabe (Finance), Kazushige Tanabe (Editor in Chief, PR), Tomoki Kase (Co-Editor, PR), Ryuichi Majima (Planning), Hiromichi Hirano (Membership), Kenshiro Ogasawara (Foreign Affairs), Haruyoshi Maeda (Publicity Officer), Noriyuki Ikeya (Editor, “Fossils”), Yukimitsu Tomida (Editor in Chief, Special Papers), Tamiko Ohana (Representative, Union of Natural History Societies), Secretaries : Masanori Shimamoto, Takao Ubukata (General Affairs), Hajime Taru (Planning), Tokuji Mitsugi (Membership), Shuko Adachi (Foreign Affairs), Kazuyoshi Endo, Yasunari Shigeta (Editors of PR), Akira Tsukagoshi (Editor of “Fossils”), Naoki Kohno (Editor of Special Papers) Auditor : Nobuhiro Kotake Notice about photocopying: In order to photocopy any work from this publication, you or your organization must obtain permission from the following organization which has been delegated for copyright for clearance by the copyright owner of this publication. Except in the USA, Japan Academic Association for Copyright Clearance (JAACC), 41-6 Akasaka 9-chome, Minato-ku, Tokyo 107-0052, Japan. Phone: 81-3-3475-5618, Fax: 81-3-3475-5619, E-mail: kammori @msh.biglobe.ac.jp In the USA, Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. Phone : (978) 750-8400, Fax : (978)750-4744, www.copyright.com Cover : Idealized sketch of Nipponites mirabilis Yabe, a Late Cretaceous (Turonian) nostoceratid ammonite. Various reconstructions of the mode of life of this species have been proposed, because of its curiously meandering shell form (after T. Okamoto, 1988). All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN c/o Business Center for Academic Societies, Honkomagome 5-16-9, Bunkyo-ku, Tokyo 113-8622, Japan Paleontological Research, vol. 3, no. 1, pp. 1-17, 6 Figs., April 30, 1999 © by the Palaeontological Society of Japan Permian bivalves from West Spitsbergen, Svalbard Islands, Norway KEWUI NAKAZAWA 28-2, Koyama Shimouchikawara-cho, Kita-ku, Kyoto 603-8132, Japan Received 6 June 1998; Revised manuscript accepted 27 December 1998 Abstract. The bivalve fossils collected by Japanese-Norwegian research groups from the Kapp Starostin Formation in west Spitsbergen are described. They comprise fourteen species belonging to the Pterioida and two species of the Arcoida. Among them, six species, including two that are indeterminate, are newly described. They are Grammatodon (Cosmetodon) ? suzuki, G. (C.)? sp. ind., Streblochondria win- snesi, Vorkutopecten svalbardensis, Deltopecten sp. ind., and Palaeolima nakamurai. The fauna belongs to the Boreal bioprovince, but a single species, Cassianoides sexcostatus (Stuckenberg) has also been reported from the Central Rocky Mountains of the United States. The bivalve fauna suggests an Artinskian-Kungurian age for the Kapp Starostin Formation. This is somewhat earlier than the age deduced from brachiopods and bryozoans, but it is not decisive because the materials are poor. The Kapp Starostin Formation is conformably overlain by the Otoceras-bearing, earliest Triassic Vardebukta Formation, so a time-gap corresponding at least to the Dorashamian and Dzhulfian (= Tatarian) is inferred between the two formations. Key words: Kapp Starostin Formation, Permian bivalves, Spitsbergen Introduction The study materials were collected by Nakamura et al. in 1984 and 1990, and by Nakazawa et al. in 1986 from the Permian Kapp Starostin Formation of west Spitsbergen, in the Svalbard Islands, Norway. Brachiopods and bryozoans are most abundant among the macrofossils. Many species of brachiopods have been described by various authors, notably, Frebold (1937) and Gobbet (1963). Bivalves are found rather rarely and the descriptive studies are few. Toula (1873, 1875a, b) first described the following species, collected from “Carboniferous-Permian” strata on Sdérkapp Island off the southerntip of Spitsbergen, and Axel Island in Bellsund and on Hornsund, on the west coast of Spitsber- gen: Pecten (Aviculopecten) bouei Verneuil, Pecten (Aviculopecten) kokscharofi Verneuil, Pecten (Aviculopecten) cf. ellipticus Phillips, Pecten (Aviculopecten) cf. dissimilis Fleming, Pecten (Aviculopecten) wilczeki Toula, Gervillia cf. antiqua Münster, Aviculopecten draschei Toula and Gervillia sp. Frebold (1937) described the following species, mostly from the upper part of the Kapp Starostin Formation in the Festningen section, located on the southern coast of Spits- bergen at the entrance to Isfjorden and from Sorkapp Island : Aviculopecten (Deltopecten) cf. mutabilis Licharew and A. (D.) cf. hiemalis Salter, Aviculopecten? sp. indet., Pecten (Aequipecten) ? keyserlingiformis Licharew, Pecten (Aequi- pecten) keyserlingi Stuckenberg, Pecten (Pseudamusium) cf. ufaensis Tschernyschew, Pecten (Pseudamusium) ex aff. sericeus Verneuil, Parallelodon sp. ind, genus | =Paral- lelodon ?] et sp. ind., Clidophorus ? sp. ind., Pecten wilc- zeki Toula, and Leda sp. ind. Among the species described by Toula, Aviculopecten bouei was referred to Aviculopecten (Deltopecten) mutabilis by Licharew (1927). Pecten cf. ellipticus was identified as Pecten (Pseudamusium) ex aff. sericeus Verneuil, and Pecten (Aviculopecten) cf. dissimilis was compared to Aviculopecten netschajewi Licharew and reported as Aviculopecten ? sp. ind. by Frebold (1937). Aviculopecten kokscharofi reported by Toula (1873) is probably identical with Aviculopecten cf. hiemalis illustrated by Licharew (1927, especially pl. 5, fig. 20), and is referred to Etheripecten cf. mutabilis Licharew in the present paper. Among the species reported by Frebold, Aequipecten keyserlingi was considered to belong to the genus Mor- rispecten Muromtseva and Guskov by Muromtseva (1984, p. 75). Morrispecten is, however, a junior synonym of Undo- pecten Waterhouse, 1982 (Newell and Boyd, 1995). Pecten (Aequipecten) ? keyserlingiformis and Aviculopecten (Deltopecten) cf. mutabilis and A. (D.) cf. hiemalis of Frebold are referred to Etheripecten keyserlingiformis and E. ci. mutabilis ?, respectively. Pseudamusium cf. ufaensis and Parallelodon sp. ind. are identified as Streblochondria win- snesi sp. nov. and Grammatodon (Cosmetodon) ? suzuki sp. i) nov., respectively, in the present paper. Sixteen species including four new species and two indeterminable ones are described. All the materials are kept at the Department of Geology and Mineralogy, Faculty of Science, Kyoto Univer- sity. Stratigraphy The fossils were collected at four localities in west Spits- bergen, namely, the Festningen section along the southern coast of the entrance to Isfjorden, the Skansbukta section at Billfiorden, and the Reinodden and Ahlstrandodden sections along the southern coast near the entrance of Van Keulenf- jorden, in Bellsund (Figure 1). Faunas from the first and second localities were collected on Nakamura’s expedition in 1984 and in 1990. The stratigraphy of these sections was published by Nakamura et al. in 1990 and, in more detail, by the Japanese-Norwegian Research Group (1992). The other two localities were examined by Nakazawa's party in 1986 and the results were published by Nakazawa et al. (1990). All the materials are from the Permian Kapp Staros- tin Formation which was defined by Cutbill and Challinor (1965). The formation corresponds to the Brachiopod Cherts (including the Spirifer Limestone at the base) of previous authors (e.g., Gee et al., 1953). At the type locality, Festnin- gen, the formation is divided into three members, the Vo- ringen, Svenskeegga, and Hovtinden Members in ascending order (Cutbill and Challinor, 1965). (1) Festningen section (Figure 2A) At Festningen the Kapp Starostin Formation is 385 m in thickness and divided into twelve units (Nakamura et al. 1990 ; Japanese-Norwegian Research Group, 1992). Unit 1, about 20 m thick, is represented by brachiopod-rich, bioclas- tic limestone beds corresponding to the Voringen Member. Units 2 to 5, about 140 m thick, constitute the Svenskeegga Member, each represented mainly by siliceous shale, spicularite, spicularite and shale, and bioclastic limestone, respectively. rt D Ay rms for \>2°___/ Longyearbyen Bellsund \~_ En A Hornsund ~ 2 Figure 1. Map of southern Spitsbergen showing fossil localities. a: Skansbukta, b: Festningen, c: Reinodden, d: Ahlstrandodden. Keiji Nakazawa The Hovtinden Member, about 225 m thick, consists of seven units, 6 to 12, each composed mainly of spicularite, alternation of spicularite and spicularitic shale, bioclastic limestone, spicularite, bioclastic limestone (partly silicified), alternation of siltstone and paper shales, and quartzose sandy shale or siltstone, respectively, in ascending order. Bivalve fossils have been obtained from Units 5, 7, 8,9 and ats (2) Reinodden section (Figure 2B) At Reinodden the formation reaches more than 300 m in thickness. It is classified into eight units, A to H, in ascend- ing order (Nakazawa et al., 1990). Unit A, less than 5m thick, is the Voringen Member consisting of fossiliferous bioclastic limestone. Units B and C are referred to the Svenskeegga Member. Unit B, about 40 m thick, is sub- divided into three beds or subunits, 2 to 4. Beds 2 and 4 are represented by nodular or irregularly bedded, alternating spicularitic chert and thin mudstone. Bed3 consists of black laminated shale and siltstone. Unit C, about 80m thick, includes bedded black shale (Bed 5), and alternations of calcareous sandstone and limestone (Beds 6 and 7). The Hovtinden Member (Units D to H), about 180 m thick, is characterized by coarse-grained sandstone and spicula- rite. It is subdivided into fourteen beds, Beds 8 to 21, as shown in Figure 2B. Glauconite is commonly found in the sandstones. Macrofossils have been collected from ten horizons (RP 1~10) in the Kapp Starostin Formation, among which RP 3, 7 and 9 contain bivalve fossils. (3) Ahlstrandodden section (Figure 2C) At Ahlstrandodden the formation is about 250 m thick. It is divided into eight units, 1 to 8 (Nakazawa et al., 1990). Unit1, 7.6m thick, consists of brachiopod-rich bioclastic wackestone of the Voringen Member. Units 2 and 3, which are 40 m and 58 m thick, respectively, are correlated to the Svenskeegga Member. Units4 to 8, about 140m thick altogether, correspond to the Hovtinden Member. They are composed mainly of spicularitic chert or spicularite, siliceous shale and a minor amount of limestone. Glauconite grains are commonly found in siliceous sandstones throughout the Hovtinden Member. Among nine fossiliferous horizons (AP 1~9) within the formation, five horizons, AP 1,2,6,7 and 8, yield bivalve shells. The fossiliferous horizons AP 8 and 9 of the upper part of the Hovtinden Member can be correlated with hori- zons RP 9 and 10 in the Reinodden section. They are considered to correspond to horizon F 8 of the Festningen section. Fossil occurrence and age assignment Sixteen species in nine genera are identified from three sections mentioned above, plus one species, Acanthopecten licharewi (Fredericks), from Skansbukta (SA 7), as shown in Figures 3. The localities and stratigraphic horizons are shown in Figure 2. Nakamura et al. (1987, 1992) distinguished five brachiopod assemblage zones in the Kapp Starostin Formation of the Isfiorden area. They compared these faunas to those of Russia, Arctic Canada, Greenland, and Alaska, all belonging Permian bivalves from West Spitsbergen 3 A, FESTNINGEN 400 350 ERS B. REINODDEN 300 250 & = = = > fo) [e] | = = 200 E [o} mw 150 Starostin Kapp Svenskeegga Member 100 on [=] Bi H FE —— MN Her 10 6 RP fees C, AHLSTRANDODDEN es (OF She D ID OO DIAOlODEIENO 1 AP 1(9,10) Figure 2. Geological columnar sections of the Kapp Starostin Formation at three localities showing horizons of macrofossils. a: chert or spicularite, b: shale or mudstone, b’: siliceous or spicularitic, c: sandstone, Cc’ : siliceous, d: limestone, d’: siliceous, e: dolostone, e’ : dolostone nodule, f: calcareous, g: muddy. Numbers in parentheses correspond to those of bivalve species in Figure3. A: simplified from Japanese-Norwegian Research Group (1992, fig. 2), B and C: from Nakazawa et al. (1990, fig. 2). to the Boreal bioprovince. From the correlation of these faunas, they concluded that the Kapp Starostin Formation ranges in age from Kungurian up to Midian or early Dzhulfian (Tatarian). Sakagami (1992) studied the bryozoans and pointed out the similarity of the fauna from the Voringen Member with the Kungurian fauna in the Timan-Pechora region. Faunas of the Svenskeegga and Hovtinden Mem- bers resemble Ufimian faunas of Arctic Canada and the Russian Far East, the Kazanian fauna of the southern Urals, and the Late Permian fauna of British Columbia. These comparisons are consistent with the age range inferred from the brachiopods, except that there is no positive evidence, from the bryozoans, of the presence of Dzhulfian strata. These observations support previous views on the age of the Kapp Starostin Formation, for example, Forbes et al. (1958) and Flood et al. (1971). The ranges of the bivalve species are shown in Figure 3. Only two species, Vorkutopecten svalbardensis and V. aff. svalbardensis have been found in the Voringen Member. The overlying Svenskeegga Member is also poor in bivalves. Five species have been collected there, namely, Ether- ipecten cf. mutabilis, Etheripecten wilczeki, Vorkutopecten svalbardensis, Acanthopecten licharewi, and Deltopecten sp. All infrequently occur and their ranges extend up into the Hovtinden Member. Accordingly, the fauna is not essen- tially different from that of the Hovtinden Member. Eight and ten species could be identified from the lower and upper parts of the Hovtinden Member, respectively. In addition to species ranging up from the Svenskeegga Member, Streblopteria cf. eichwaldi, Streblopteria ? sp. and Palaeolima nakamurai appear from the lower part, but they have not been found from the upper part. The upper part is relatively rich in bivalve fossils. Grammatodon (Cos- metodon) ? suzukii, G. (C.) ? sp., Etheripecten keyserlingi- formis, E. aff. sichuanensis, E.? alatus, Streblochondria winsnesi and Cassianoides sexcostatus appear here. The intimate relationship of the Spitsbergen fauna with that of the Russian Arctic region (Ural, Pechora, Russian Platform, Verkhoyansk) is shown by the occurrence of the following species : ety . Grammatodon (Cosmetodon)? sp. ind. . Acanthopecten licharewt (Fredericks) . Etheripecten cf. mutabilis (Licharew) . Etheripecten wilezeki (Toula) Vorkutopecten svalbardensts sp. nov. 2 3 4 5 6. a 8. 9% 0. 1 Rone . Streblochondria winsnest sp. nov. wo . Deltopecten sp. ind. PAs wn . Streblopteria? sp. ind. N a . Palaeolima nakamurat sp. nov. Figure 3. Compiled range-chart of bivalve fossils. Skansbukta. Acanthopecten licharewi (Asselian-Artinskian of the Urals, Kungurian of Pechora, Lower Permian of Verkhoyansk), Etheripecten keyserlingiformis (Upper Carboniferous ?-Lower Permian of the Urals and Pechora), E. cf. mutabilis (Upper Carboniferous-Lower Permian of the Urals, Timan, Siberia), E.? alatus (Lower Permian of Pai Khoi in Siberia), Streblopteria cf. eichwaldi (Artinskian of the Urals and Russian Platform), and Cassianoides sexcostatus (Artinskian of the Urals and Russian Platform). Cassianoides sexcostatus is also report- ed from the Guadalupian of the United States (Branson, 1930 ; Ciriacks, 1963) and Etheripecten sichuanensis occurs in the Upper Permian of South China (Cheng et al., 1974). The stratigraphic occurrences of these species suggest that the Kapp Starostin Formation ranges in age from Artinskian to Kungurian. This is somewhat earlier than the age range inferred from the brachiopods and bryozoans, but the materials are poor and the conclusion is not definitive. The Kapp Starostin Formation is conformably overlain by the Lower Triassic Vardebukta Formation of the Sassendalen Group (Nakazawa et al., 1990 ; Nakamura et al., 1990). The earliest Triassic age of the basal part of this formation is indicated by the occurrence of Otoceras boreale Spath together with Claraia stachei (Bittner) (Kortshinskaya, 1986 ; Nakazawa et al., 1987). Hence, a time-gap corresponding at least to Dzhulfian-Dorashamian ages is indicated between the Permian and the Triassic beds. . Cassianoides sexcostatus (Stuckenberg) *: Festningen, Keiji Nakazawa Hovtinden Svenkeegga Member Member Vèringen . Grammatodon (Cosmetodon)? suzukii sp. nov. . Etheripecten keyserlingiformis (Licharew) Ethertpecten aff. sichuanensis (Chen et al.) Etheripecten? cf. alatus (Lyutkevich and Lobanova) Vorkutopecten aff. svalbardensis sp. nov. . Streblopterta cf. eichwaldi (Stuckenberg) “: Reinodden, *: Ahlstrandodden, ~ : Acknowledgments | am very grateful to T.S. Winsnes, formerly of the Norsk Polarinstitutt, for his critical reading of the manuscript. V. Kotlyar (VSEGEI) and B.A. Muromtseva (VNIGRI) in Russia, T. Ishibashi of Kyushu University, and J. Tazawa of Niigata University, Japan gave me useful information and valuable references to the literature. K.Nakamura of Hokkaido University kindly made his collection available for study. H. Suzuki of Doshisha University, F. Kumon of Shinshu Univer- sity and E.H. Siggerud from Norway cooperated with me in the field. T.Setoguchi, F. Masuda, and T.lrino of Kyoto University made various facilities available for preparation of the manuscript. | wish to thank all these people very much. Systematic description Order Arcoida Stoliczka, 1871 Family Parallelodontidae Dall, 1890 Subfamily Grammatodontinae Branson, 1942 Genus Grammatodon Meek and Hayden, 1861 Subgenus Cosmetodon Branson, 1942 Grammatodon (Cosmetodon) ? suzukii sp. nov. Figures 4-1a, b Parallelodon sp. ind. Frebold, 1937, p. 55, pl. 1, figs. 8, 9. Materials —A pair of left and right external molds. Permian bivalves from West Spitsbergen Holotype, Reg. no. HP 100050. Etymology.—Dedicated to Dr. Hiroyuki Suzuki of Doshisha University, who worked in the field with the author. Diagnosis.—Permian Grammatodon characterized by well developed, fine radial ribs and a little arcuate ventral margin. Description.—Shell moderate in size, a little inflated, elon- gated subquadrate with subparallel dorsal and ventral mar- gins, rounded anterior and truncated posterior margins ; ventral margin slightly arcuate ; 41 mm long and 19 mm high ; umbo broad and low, raised above the hinge margin, situated at anterior one-fifth of shell length ; bluntly rounded umbonal ridge running from the umbo to the posteroventral extremity ; surface covered by numerous, weak radial striae, wider than the interstices, approximately fifteen per centimetre width on the medial surface of the shell, one centimetre from the umbo ; densely spaced concentric growth lines form cancel- late sculpture with the radials (Figure 4-1b) ; hinge and inter- nal characters not observable. Comparison.—Two incomplete specimens illustrated by Frebold (1937) from near the same horizon at Festung (= Festningen) are identical with the present species. Based on Permian material from Malaysia, Yancey (1985) pointed out the possibility that most of the Paleozoic species de- scribed as Parallelodon should be referred to Grammatodon (Cosmetodon). Although the present species does not show its hinge characters, it is identified with that genus on the basis of its external shape and ornament. It is similar to the Guadalupian Cosmetodon multistriatus (Girty, 1908, p. 423, pl. 31, figs. 13, 14) in its shape and weak radial ornament, but it differs from that species in having less numerous radial striae, a little arcuate ventral margin and a larger size. Occurrence.—Rare in black shale of the uppermost fossil horizon, in the Hovtinden Member (F11) at Festningen. Grammatodon (Cosmetodon) ? sp. ind. Figures 4-2a, b Genus (Parallelodon) ? et sp. ind. Frebold, 1937, p. 56, pl. 2, fig. 4. Material—One incomplete, right external cast. Reg. no. HP 100051. Description.—Posterodorsal marginal part is missing. Preserved part of the specimen is 30 mm long and 18.5 mm high. His twice as long as high judging from the growth line. Surface is covered by numerous, close-set radial striae and Table 1. Measurements of Acanthopecten licharewi (Fredericks). in growth lines which are very weak, but visible under the magnifying glass. The radials reach about forty per centimetre width on the medial part of the shell, one centimetre from the umbo (Figure 4-2b). Discussion.—The present material most probably belongs to the species doubtfully referred to Parallelodon by Frebold (1937) from Festningen. It is similar to G. (C.)? suzuki in shape, but differs from it in more densely spaced and more irregular radial ornament. In its numerous radial striae it is similar to Grammatodon multistriatus (Girty), but it has a different shape with a more convex ventral margin than the latter species. Evidence is not adequate to support a new species for this specimen. Occurrence.—Locality and horizon are identical with those for the preceding species. Order Pterioida Newell, 1965 Superfamily Pectinacea Rafinesque, 1815 Family Aviculopectinidae Meek and Hayden, 1864 Subfamily Aviculopectininae Meek and Hayden, 1864 Genus Acanthopecten Girty, 1903 Acanthopecten licharewi (Fredericks, 1915) Figures 4-3—5 Pterinopecten Licharewi Fredericks, 1915, p. 28, pl. 1, fig. 14. Aviculopecten (Acanthopecten ?) licharewi (Fredericks). Lichar- ew, 1927, p. 91, pl. 6, fig. 24. Acanthopecten licharewi (Fredericks). Muromtseva, 1984, p. 66, pl. 25, fig. 26; pl. 28, figs. 7, 8, 11, 12. Materials.—One nearly complete and one incomplete external cast of left valves, an incomplete external mold of a left ? valve, and an incomplete external mold of a right valve. Reg. nos. HP 100052~55. Description.—All the specimens are incomplete internal molds or somewhat abraded external casts, and the details of the ornament are imperfectly preserved. Shell small, subequivalve, subcircular in shape ; left valve a little inflated ; right valve nearly flat ; anterior auricle of left valve trigonal and sharply defined ; posterior auricle relative- ly large, flat, alate and protruding posterodorsally, but not sharply defined from the disc. Shape variable, probably due to secondary deformation; one left valve of nearly equal height and length, with an apical angle of 100° (Figure 4-3) and another left valve more elongate (L/H ratio of 1.34) with Abbreviations and notation of Tables 1-8. L: length, H: height, U: distance of umbo from the anterior end of the shell, |: hinge length, r: total number of radial ribs, r,, : number of primary and secondary radials, respectively, ro_, : secondary to fourth-order radials between primary radials, r3., : number of number of third- and fourth-order radials between primary and secondary radials, c: number of comarginal lamellae or costae, a: apical angle (in degrees), V: valve (R: right, L: left), *: estimated value, linear dimensions in mm, Hor. : horizon. Reg. no. L H H/L a r c V Hor. HP 100052 23.0 19.5* 0.85 100 13 11 L AP 6 HP 100055 20.5. — — 120 17 94 R AP 6 HP 100054 28.5 22, — — 14, 6. R AP 6 HP 100053 14. 14.8 = = 8, 7 L SA 7 Keiji Nakazawa Permian bivalves from West Spitsbergen 7 a larger apical angle, 120°; radial ribs narrow and widely spaced varying in number from 13 to 17; interspaces between radials slightly concave or nearly flat; lamellose comarginal sculpture widely disposed, becoming wider later in growth stage with distally oriented spines in the middle of the interspaces of the radial ribs (Figure 4-5). Discussion.—This species is similar to the Lower Permian Acanthopecten licharewi (Fredericks, 1915) from the Urals, Pechora and Verkhoyansk, and to the Upper Carboniferous Acanthopecten carbonarius (Stevens) reported from the United States (e.g., Newell, 1938), China (Chao, 1927), and the Donetz Basin (Jakowlew, 1903) in its small size and relatively small number of radial ribs. According to Muromtseva (1984), A. licharewi is distinguished from A. carbonarius in having less numerous radial ribs and completely flat interspaces between the radials. In these respects, the present material is identical with A. licharewi. Occurrence.—Rare in calcareous shale or muddy siliceous limestone of Unit5 (lower part of Hovtinden Member) at Ahlstrandodden (AP 6), and in black shale of Unit 7 (upper part of Svenskeegga Member) at Skansbukta (SA 7). According to Thore S.Winsnes (personal communication, 1995) it also occurs in Permian strata in the valley north of Stensiöfjellet, inner Sassendalen. Subfamily Etheripectininae Waterhouse, 1982 Genus Etheripecten Waterhouse, 1963 Discussion. —This genus was introduced by Waterhouse (1963) based on Etheripecten striatura Waterhouse from the Upper Permian of New Zealand. The ornament of the left valve resembles that of “Aviculopecten” with radial ribs increasing in number by insertion and differentiated into more than two orders. The radial ribs of the right valve of this species also increase in number by insertion, but are usually weaker and less differentiated than those of the left valve. In “Aviculopecten”, the number of radial ribs of the right valve increases by bifurcation or ramification. In this respect, Etheripecten is similar to Limipecten, but according to Waterhouse (1969) the concentric lamellae between radial ribs of Etheripecten point dorsally, while those of Limipecten point ventrally as in the case of Aviculopecten planoradiatus M'Coy, the type species. Recently, Newell and Boyd (1995) reexamined the Late Paleozoic pectinoids. They defined Aviculopecten and Aviculopectinidae as bivalves with equiconvex shells, provided with simple plicae in both valves. On the other hand, the family Etheripectinidae is character- ized by inequiconvex and paradiscordant shells, with multi- costate ornament. Newell and Boyd stressed the variability of multiplicated ribbing and concentric sculpture in this family, treating the genera Aviculopecten and Deltopecten of authors, Etheripecten Waterhouse, Paradoxipecten Zhang, Corrugopecten Waterhouse, Fletcheripecten Waterhouse and Squamuliferipecten Waterhouse as synonyms of Heter- opecten Kegel and Costa. In this case, Heteropecten contains a vast number of species with various kinds of ornamentation. In this paper, Etheripecten is treated as a distinct genus from Heteropecten, the type species of which, Aviculopecten catharinae Reed, has broad and bifurcated radial ribs in the right valve. Fletcheripecten and Paradox- ipecten are here considered to be synonyms of Etheripecten. Etheripecten keyserlingiformis (Licharew, 1927) Figures 4-6, 7a, b Pecten (Aequipecten) ? keyserlingiformis Licharew, 1927, p. 33, pl. 3, figs. 1-3; Frebold, 1937, p. 52, pl. 7, fig. 7. Aviculopecten keyserlingiformis (Licharew). Muromtseva, 1984, p. 60, pl. 28, fig. 10. Materials.—One nearly complete, left semiexternal cast (HP 100056) and one incomplete, left internal mold (HP 100057). Description.—Shell medium in size, pectiniform, a little inflated, prosocline, extended posteroventrally ; disc fan-like in shape with slightly arcuate anterodorsal, nearly straight posterodorsal, and rounded ventral margins ; anterior auricle trigonal with slightly convex anterior margin; posterior auri- cle a little larger than anterior one, sinuated posteriorly ; hinge margin straight, shorter than shelllength ; ligament area narrow, nearly smooth, provided with a trigonal alivin- cular ligament pit beneath the umbo (Figure 4-7b) ; umbo not prominent, slightly salient above the hinge margin, situ- ated at about anterior two-fifths of shell length; surface ornamented with nine or ten slender primary radial ribs alternating with secondaries, some of which become as strong as the primaries; two or three radial riblets of third and fourth order inserted in each interspace ; strong con- centric folds developed over the whole surface of the disc, more widely spaced in later growth stage ; three radial ribs observable on anterior auricle, and obsolete ones on poste- rior auricle. Discussion.—These specimens are identical with Pecten (Aequipecten) keyserlingiformis reported by Licharew (1927) and Frebold (1937), in its characteristic ornamentation. Probably due to secondary deformation, one specimen (Fig- Figure 4. 1a,b. Grammatodon (Cosmetodon) ? suzukii sp. nov., 1a: a pair of external molds of left and right valves, holotype (HP 100050), 1b: enlarged figure showing details of sculpture, x 2.5. 2a,b. Grammatodon (Cosmetodon) ? sp. 2a: right external cast (HP 100051), 2b: enlarged figure showing details of sculpture, x4. 3-5. Acanthopecten licharewi (Fredericks), 3,4: left semiexternal casts (HP 100052 and 53), «2 and 1.5, 5: right external mold (HP 100054), «1.5. 6, 7a, b. Etheripecten keyserlingiformis (Licharew), 6: left semiexternal cast (HP 100056), 7a: left semiexternal cast (HP 100057), 7b: enlarged figure showing alivincular ligament pit (arrow), «2.5. 8,9. Etheripecten wilczeki (Toula), 8: gypsum cast of left external mold (HP 100058), «1.5, 9: left external mold (HP 100059), x 2. (Chen et al.), gypsum cast of left external mold (HP 100060). cast of left external mold (HP 100062), 12: left semiexternal cast (HP 100071). indicated. 10. Etheripecten sp. aff. E. sichuanensis 11,12. Etheripecten sp. cf. E. mutabilis (Licharew), 11: gypsum All are in natural size unless otherwise 8 Keiji Nakazawa Table 2. Measurements of Etheripecten keyserlingiformis (Licharew). Reg. no. E H H/L Nee Ia44 a G Hor. HP 100056 45.5 40.0 0.89 18 3 115 15 F11 HP 100057 = 17.6 — 15, 1~2 90 11 F11 ure 4-6) is extended posteroventrally and has a more elon- gated shape than the previously described species, but another (Figure 4-7a) has a shape and ornamentation similar to the type specimen. Although the right valve of this species has not been reported, the shape and ornamentation of its left valve are very similar to those of Etheripecten Striatura Waterhouse, the type species of the genus, so the species is here included in Etheripecten. Occurrence.—Rare in black shale of the uppermost fossil horizon of the Hovtinden Member at Festningen (F11). Etheripecten wilczeki (Toula, 1875) Figures 4-8, 9 Pecten (Aviculopecten) Wilczeki Toula, 1875a, p. 152, pl. 1, fig. 12. Pecten wilczeki Toula. Frebold, 1937, p. 54. Materials. —One nearly complete, left external mold and several fragmental molds of left valves. Reg. nos. HP 100058, 59. Description.—Shell relatively small, pectiniform, a little inflated ; fan-like in shape, with nearly straight anterodorsal, slightly dorsally arcuate posterodorsal, and rounded ventral margins ; prosocline, extended posteroventrally; umbo not prominent, slightly salient above the hinge margin, lying at about anterior two-fifths of shell length; apical angle 95- 110° ; anterior auricle small, trigonal ; posterior auricle a little larger than the posterior one, alate with arcuate posterior margin ; both auricles sharply distinct from disc ; surface of the shell ornamented with nine primary radial ribs; wide, nearly flat interspaces are sculptured by 8-12 weak, radial threads, some a little stronger than the rest referred to as secondary ribs, but not alternating with the primaries ; um- bonal part of the shell, to 16 mm, ornamented with concentric wrinkles, which later fade away; two or three radial striae discernible on both auricles ; ligament unknown. Comparison.—The type specimen described by Toula has seven strong, slender radial ribs, and smooth interspaces without finer radial ribs. Pecten (Aequipecten) ? wilczekifor- mis Licharew (1927, p. 35, pl. 3, figs. 4, 6, 7) is distinguished from E. wilczeki in its development of interstitial radial riblets. According to Frebold (1937) the type specimen of E. wilczeki is not well preserved. He recognized the presence of finer radial ribs in the marginal area of his specimen, where the shell is preserved, and regarded the two species as being conspecific. However, the finer interstitial radial ribs of the specimen described here are very weak, numer- ous and subequal in strength, whereas those of P.(A.) ? wilczekiformis are differentiated into second, third or even fourth orders. Both species are considered to belong to Etheripecten. E. wilczekiformis is more closely allied to E. keyserlingiformis than to E. wilczeki. E. wilczeki is most similar to Euchondria cancellata Gu and Liu (1976, p. 171, pl. 12, figs. 17, 18), from the Lower Permian Kufeng Series of South China, in shape and ornament. It differs only a little from the latter species in its lesser development of concentric folds and greater height relative to length. The genus Euchondria is characterized by a costate left valve, a nearly smooth right valve, and a series of ligament pits perpendicular to the hinge margin, in addition to a large, central ligament pit. In E. cancellata only left valves are known and the hinge character is unknown. Therefore, its generic position is uncertain. Occurrence.—Rare in calcareous shale of the uppermost horizon of the Svenskeegga Member at Festningen (F5); rare in muddy limestone of the upper part of the Hovtinden Member at Ahlstrandodden (AP 7, 8) and Reinodden (RP 9). Etheripecten sp. aff. E. sichuanensis Chen, Zhang and Xu, 1974 Figures 4-10 Resembles.— Etheripecten sichuanensis Chen, Zhang and Xu, 1974, p. 302, pl. 158, figs. 14,17 ; Fang, 1987, p. 373, pl. 2, figs. 1-6. ? Etheripecten sichuanensis Liu, 1976, p.179, pl. 13, figs. 10-13 ; Gan and Yin, 1978, p. 336, pl. 14, figs. 17, 20. Etheripecten hunanensis Zhang, 1981, p. 261, pl. 2, figs. 6-8. Material.—One incomplete left external mold obtained by dissolving away shell material. Reg. no. HP 100060. Description.—Shell relatively large, a little inflated, longer than high, estimated to be 65mm long and 58mm high; disc fan-like in shape with straight antero- and posterodor- sal margins and a broadly rounded ventral margin; hinge margin straight, a little shorter than shell length; anterior auricle small, subtrigonal, a little inlated, clearly separated from the disc by a sulcus; posterior auricle large, flat, sinuated posteriorly, protruding posterodorsally ; umbo sub- dued, slightly salient above hinge margin; apical angle 110° ; surface ornamented with radial ribs of three orders; pri- maries seven in number, strong and round-topped, alternat- ing with weaker secondaries ; five to six, thread-like rdial riblets of third order inserted in each interspace ; auricles with radial and concentric sculpture making a lattice orna- ment ; hinge not preserved. Discussion.—The external shape and the ornamentation indicate a close relationship of this species with Etheripecten sichuanensis Chen, Zhang and Xu (1974) and E. hunanensis Zhang (1981), both from the Upper Permian Luntang Series in South China. The former species was later illustrated as ? E. sichuanensis sp. nov. by Liu (1976) based on the same specimens. Zhang distinguished E. hunanensis from E. si- chuanensis by the presence of striations and spinose pro- jections on the primary ribs. According to Fang (1987), however, these differences represent infraspecific variation. Permian bivalves from West Spitsbergen 9 The specimen described here differs from sichuanensis in its more elongate shape with larger apical angle and larger size. Occurrence.—Arenaceous limestone of the upper part of the Hovtinden Member at Festningen (F8). Etheripecten sp. cf. E. mutabilis (Licharew, 1927) Figures 4-11,12; Figures 5-1—4 Pecten (Aequipecten) Kokscharofi Toula (non Verneuil), 1873, p. 20, pl. 5, fig. 6. Aviculopecten cf. hiemalis Salter. figs. 18-21 ; pl. 6, fig. 1. ? Aviculopecten (Deltopecten) cf. mutabilis Licharew and A. cf. hiemalis Salter. Frebold, 1937, p. 51, pl. 1, figs. 2, 3. Compared with.— Pecten (Aequipecten) Bouei Toula, 1873, p. 19, pl. 5, fig. 8. Aviculopecten mutabilis Licharew, 1927, p. 72, pl. 5, figs. 7-10, 12, 14-17. Aviculopecten (Deltopecten) ? mutabilis Licharew. Lyutkevich and Lobanova, 1960, p. 102, pl. 15, figs. 1-6. Licharew, 1927, p. 76, pl.5, Material.—Eight incomplete left valves, one complete and two incomplete right valves. Reg. nos. HP 100061~68, 100070, 71. Description.—Shell moderate in size, inequivalve, in- equilateral, prosocline, nearly as long as high, apical angle 90-100°. Left valve moderately inflated ; umbo not promi- nent, a little salient above the hinge margin ; beak situated at about anterior one-third of shell length ; disc fan-like in shape with slightly Concave anterodorsal, nearly straight posterodorsal, and well rounded ventral margins ; anterior auricle subtrigonal, with a rounded anterior margin, demar- cated from the disc by a sulcus ; posterior auricle only partly preserved ; surface covered with many radial ribs differ- entiated into three or four orders; primary ribs 7 to 9 in number, strong, round-topped, a little projected at ventral margin ; second- and third- order radials alternating regular- ly with lower-order radials ; some tertiary radials as strong as secondaries ; fourth-order radials very weak, sporadically inserted near the margin; growth lines close-set, curving ventrally on radial ribs and dorsally on interspaces, showing scaly or spinose projections on the primary ribs (Figures 5-1b, 2). Right valve nearly flat; anterior auricle deeply incised below ; posterior auricle subtrigonal, nearly equal in length to the anterior auricle, a little sinuated posteriorly ; numerous radial ribs increasing in number by insertion; first- and second-order radials becoming subequal in strength; a Table 3. Measurements of Etheripecten sp. cf. E. mutabilis (Licharew). radial ribs, #: total number of radial ribs. small number of third-order radials, very weak and thread- like ; total number of radials, 34 ; close-set, weak concen- tric sculpture, making a lattice ornament with the radials ; alivincular ligament pit partly seen in one left internal mold. Remarks and comparison.—In this material, the number of radial ribs increases by insertion in both the left and right valves. The comarginal sculpture curves ventrally on the radial ribs and dorsally on the interspaces. Therefore, these specimens are referred to Etheripecten Waterhosue (1969). In their well differentiated radial ornament and robust primary radial ribs, these shells are identical with Pecten (Ae- quipecten) kokscharofi as described by Toula (1873), Aviculopecten cf. hiemalis Licharew (1927), and probably Aviculopecten (Deltopecten) cf. mutabilis and A. (D.) cf. hiemalis Frebold (1937). They are very similar to Aviculopecten mutabilis Licharew (1927). According to Licharew (1927) the latter species is distinguished from Aviculopecten cf. hiemalis by its more pointed posterior auricle, the sharper restriction of auricles from the disc, the weaker bend of antero- and posterodorsal margins of the disc, and less regularity in the appearence of ribs. These differences, though, are not distinctive, as noted by Licharew himself. A. cf. hiemalis of Licharew has generally more robust primary radials than A. mutabilis. It is clearly distin- guished from the original A. hiemalis reported from the Himalayas (cf. Diener, 1897, p. 9, pl. 5, figs. 10a, b, 11) in taller shape and smaller posterior auricle and is more closely related to A. mutabilis. Lyutkevich and Lobanova (1960) illustrated the right valve of A. mutabilis (pl. 15, figs. 2, 5), which shows inserted radial ribs. Therefore, A. mutabilis is considered to belong to the genus Etheripecten. The right valve of Etheripecten mutabilis has less uniform radial orna- ment than the present species. Occurrence.—Common in the Hovtinden Member at Fest- ningen, Reinodden, and Ahlstrandodden; rare in Svens- keegga Member at Reinodden. Etheripecten ? sp. cf. E. alatus (Lyutkevich and Lobanova, 1960) Figures 5-5 Compared with.— Pseudomonotis alata Lyutkevich and Lobanova, 1960, p. 116, pl. 17, fig. 9. Description.—Only one incomplete, semiexternal cast of a “x : Total number of primary and secondary Reg. no. ik H H/L U U/L ia 1253 a V Hor. HP 100060 60. 58. = = = le 4~6 100 L F9 HP 100062 21.5 22.8 1.06 = = 7 3 85 L RP 3 HP 100063 22.3 21.5 0.96 8.0 0.36 26% 90 R F 11 HP 100064 30. ei). _ _ = 6, 3~4 — E F 9 HP 100065 83.5 35.0 1.04 12.5 0.37 9 3~5 90 E F 11 HP 100066 21.0 — = = = 244 85 R F 11 HP 100067 25.0 25.0 1.00 165 0.30 8 3~4 90 (Es F 11 HP 100071 25.3 257 1.02 10.5 0.42 th 3 90 L F 7p 10 Keiji Nakazawa Permian bivalves from West Spitsbergen 11 left? valve is available (Reg. no. HP 100069). More than posterior one-third of the shell is not preserved. Shell 38 mm high and more than 30 mm long, nearly flat; disc in- ferred to be fan-like in shape ; anterodorsal margin straight ; anterior auricle trigonal, flat, clearly marked off from the disc ; surface ornamented with six strong, round-topped primary radial ribs ; broad, flat or slightly concave interspaces with weak secondary and tertiary radials five to eight in number ; close-set weak concentric striae partly preserved. Discussion.—The present material is quite similar in shape and sculpture to Pseudomonotis alata, described on the basis of a right valve by Lyutkevich and Lobanova (1960) from the Lower Permian at Pai Khoi of the northern coast of Siberia. It differs slightly from that species in taller outline. The well differentiated, straight radial ornament of these Siberian and Spitsbergen species suggests that they belong to Etheri- pecten rather than to Pseudomonotis. Occurrence.—Dark grey calcareous shale of Unit G of the Hovtinden Member at Reinodden (RP 9). Family Streblochondriidae Newell, 1938 Genus Streblochondria Newell, 1938 Streblochondria winsnesi sp. nov. Figures 6-2a, b—4 Pecten (Pseudamusium) cf. ufaensis Tschernyschew. Frebold, 1937, p. 53, pl.1, fig. 3-5. Material —One complete right valve (external and internal molds, holotype, Reg. no. HP 100094a, b) and a nearly complete right valve (internal and external molds, Reg. no. HP100095a, b). Holotype specimen occurs in black shale of Unit 11 of the Hovtinden Member at Festningen. Etymology.—Dedicated to Thore S. Winsnes for his contri- bution to the geological understanding of West Spitsbergen. Diagnosis.—Permian Streblochondria characterized by a broad shape and very fine cancellate ornament composed of numerous radial and concentric striae. Description.—Shell medium in size, a little inflated, and subcircular in shape, with well rounded ventral, slightly convex posterodorsal, and slightly concave anterodorsal margins; as long as high; opisthocline ; umbo subdued, not salient above the hinge margin; apical angle varying from 90° to 110° ; posterior auricle very small, obtuse-triangu- lar, truncated posteriorly; anterior auricle relatively large, rounded trigonal, and marked below by deep slit-like byssal notch ; surface covered with numerous, uniform radial striae increasing in number by insertion, 70 per cm in the medial area 1cm away from the umbo; dense concentric fila Table 4. Measurements of Streblochondria winsnesi sp. nov. Reg. no. EE H H/L | a Hor. HP 100094 33.5 ca33 099 95 90-110 F11 HP 100095 20.0 20.0 1.00 = 90-110 APQ making a cancellate ornament with the radials, slightly raised scales on the radials ; anterior auricle ornamented with five distinct radial ribs and growth lines; hinge characters un- known. Discussion.—Frebold (1937) illustrated three right valves identified as Pecten (Pseudamusium) cf. ufaensis Tscherny- schew from the upper part of the Kapp Starostin Formation at Festningen. One of them shows a distinct sculpture, very similar to that described here, so it is considered to be conspecific with this species. It is similar to Streblochondria sculptilis (Muller), the type of the genus, from the Carbonifer- ous of the United States (cf. Newell, 1938, p. 38, pl. 16, figs. 5a-c, 7, 9a, b). However, the present new species has a larger apical angle, a lower outline, and finer ornament than that species. It is more closely allied to S. ufaensis (Tscher- nyschew) (Licharew, 1927, p. 30, pl. 2, figs. 7,8; Lyutkevich and Lobanova, 1960, p. 131, pl. 21, fig. 1), but differs from that species in the finer radial sculpture as noticed by Frebold and, furthermore, in its longer outline. Occurrence.—Rare in siliceous limestone of the upper part of the Hovtinden Member at Ahlstrandodden (AP 9), and the uppermost horizon of the Hovtinden Member at Festningen (F11). Genus Streblopteria M'Coy, 1851 Streblopteria sp. cf. S. eichwaldi (Stuckenberg, 1898) Figures 6-6, 7a, b, c Pecten (Aviculopecten) cf. ellipticus Toula, 1873, p. 20, pl. 5, fig. 1. Pecten (Pseudamusium) sp. ind. ex aff. sericeus Frebold, 1937, p. 54. Compared with.— Pecten Eichwaldianus Stuckenberg, 1898, p. 208, pl. 1, figs. 25a, b. Materials.—A pair of valves, two internal molds, and two incomplete external molds. Reg. nos. HP 100087~90. Description.—Shell small, nearly equivalve, subcircular in shape, opisthocline, a little extended anteriorly ; left valve gently inflated; right valve slightly less convex than left; anterodorsal margin of the disc a little concave, ventral and posterior margins well rounded ; umbo lying a little posterior to the middle of the shell, not salient above the hinge Figure 5. 1-4. Etheripecten sp. cf. E. mutabilis (Licharew), 1a: gypsum cast of left external mold (HP 100061), 1b: enlarged figure showing details of sculpture, «3, 2: gypsum cast of left external mold (HP 100064), 3: silicon rubber cast of right external mold (HP 100066), 4: gypsum cast of right external mold (HP 100063). (Lyutkevich and Lobanova), left? semiexternal cast (HP 100069). 5. Etheripecten ? sp. cf. E. alatus 6-10. Vorkutopecten svalbardensis sp. nov., 6: gypsum cast of right external mold, holotype (HP 100072), 7 : semiinternal mold of left valve, paratype (HP 100076), 8: gypsum cast of right external mold (HP 100075) «1.2,9: gypsum cast of right external mold (HP 100077), 10: gypsum cast of right external mold (HP 100078), x 1.4. cast of external mold of right valve (HP 100086). 11,12. Deltopecten sp., 11: semiexternal cast of left valve (HP 100085), 1.1. All are natural size unless otherwise indicated. 12: silicon rubber Keiji Nakazawa 12 Permian bivalves from West Spitsbergen 13 margin ; apical angle 90° in umbonal portion and 110-120" in later growth stages ; posterior auricle small, obtuse-triangu- lar; anterior auricle larger, obtuse-triangular in left valve, and deeply incised below in the right valve ; surface almost smooth, weak concentric sculpture discernible in the internal mold and partly preserved external cast ; no radial ornament observed. Discussion and comparison.—The genus Streblopteria was established by McCoy (1851). The Carboniferous Meleagrina laevigata McCoy from Ireland was designated as type species by Meek and Worthen (1866). The genus is char- acterized by smooth shells of acline to opisthocline pectinoid form, and is distinguished from Streblochondria Newell (1938) which has cancellate sculptures. The posterior auricle of the type species is much larger than the anterior auricle, poorly distinguished from the disc. However, the forms with a small, obtuse-triangular, more or less clearly defined posterior auricle are also included in Streblopteria or referred to Pseudamusium Verrill by many authors. According to Cox et al. (1969) Pseudamusium is a junior synonym of the Cenozoic genus, Palliolum Monterosato. Several small Pseudamusium species, such as P. eichwaldi (Stuckenberg), P. pusillus (Schlotheim), and P. ellipticum (Phil- lips), have very weak radial ribs or cancellate ornament on a limited part of the shell. They were doubtfully assigned to Streblochondria by Newell (1938). However, they have a longer shape than Streblochondria and are more similar to smooth forms of Streblopteria or “Pseudamusium”. This hardly warrants recognition as a different genus. In this paper, all these species are treated as Streblopteria, although they differ somewhat from the type species. The species described here is most similar to S. eichwaldi (Stuckenberg, 1898) in shape, but the surface ornament is insufficiently known for specific identification. Pecten cf. ellipticus reported by Toula (1873) from the south point of Spitsbergen was referred to Pecten (Pseudamusium) aff. sericeus Verneuil by Frebold (1937). However, P. sericeus has a more opisthocline shell that is extended more anterior- ly. It is probably identical with the present species. Occurrence.—Siliceous limestone of the lower part of the Hovtinden Member at Ahlstrandodden (AP 6). Streblopteria ? sp. ind. Figures 6-8 Discussion.—One incomplete right internal mold (Reg. no. HP 100092), estimated at 24 mm long and a little more than 24 mm high, is at hand. The shell is subcircular in outline and provided with a concave anterodorsal margin. The surface is covered by a weak concentric sculpture. The auricular part of the shell is not preserved. It probably belongs to Streblopteria, but is too imperfectly preserved to be certain. Occurrence.—Siliceous shale of the lower part of the Hovtinden Member at Ahlstrandodden (AP 6). Family Deltopectinidae Dickins, 1957 Genus Vorkutopecten Guskov, 1984 Vorkutopecten svalbardensis sp. nov. Figures 5-6—10 Material.—Eight right external and internal molds and three left external and internal molds. Reg. nos. HP 10007283 (holotype HP 100072). Holotype from Unit 9 of the Hovtin- den Member at Festningen. Etymology.—Derived from Svalbard Islands, where the species occurs. Diagnosis.—Shell is higher than long ; ornamentation of both left and right valves consists of numerous radial ribs differentiated into three orders, increasing in number by insertion. Concentric costae arch ventrally in the inter- spaces of radial ribs. Description.—Shell inequivalve, inequilateral, suborbicular in shape, a little higher than long ; right valve moderately to weakly inflated ; left valve more inflated than right; umbo situated a little anterior to the middle of shell, nearly acline and slightly salient above the hinge margin in the left valve, but not in the right valve; apical angle about 90°; anterior and posterior auricles nearly equal in length; posterior one trigonal and sinuated posteriorly ; right anterior auricle deep- ly incised below; surface of disc covered with numerous, slender radial ribs narrower than interstices, increasing in Table 5. Measurements of Streblopteria sp. cf. S. eichwaldi (Stuckenberg). Reg. no. [E H H/L | YL U U/L a V Hor. HP 100087a 8.0 TS 0.94 4.0 0.50 4.0 0.50 ~110 L AP 6 HP 100087b 8.0 78 0.98 ST 0.46 4.5 0.56 90-120 R AP 6 HP 100088 12.7 11.6 0.91 5 0.45 7.2 0.56 90-120 R AP 6 HP 100089 13.0* 12.5 0.96 = — 7.5 0.57 ~120 R AP 6 Figure 6. 1. Vorkutopecten sp. aff. V. svalbardensis sp. nov., gypsum cast of right external mold (HP100084). 2-4. Streblochondria winsnesi sp. nov., 2a: right external mold, holotype (HP 100094), «1.4, 2b: gypsum cast, 3: right internal mold of the same, 4: right external mold (HP 100095). 5. Cassianoides sexcostatus (Stuckenberg), left external mold (HP 100093), X 2.4. 6, 7a-c. Streblopteria sp. cf. S. eichwaldi (Stuckenberg), 6 : right internal mold (HP 100088), «1.5, 7a: a pair of internal molds of left (L) and right (R) valves (HP 100087), «2, 7b-c: enlarged figures of right (b) and left (c) valves, <3. 8. Streblopteria ? sp., right external cast (HP 100092). 9,10. Palaeolima nakamurai sp. nov., 9: right external cast, paratype (HP 100097), “1.5, 10: right external cast (R), holotype (HP 100096) and a part of left valve (L), x1.2. All are natural size unless otherwise indicated. 14 Keiji Nakazawa number by insertion; primary radial ribs varying in number from 12 to 17, with two or three radials of second and third orders in each interspace between the primaries ; total number of radials 35 to 50 or more; secondary radials of right valve become as strong as primaries ; lamellose con- centric sculpture developed on the whole surface, curving dorsally on radial ribs and ventrally in interstices; both auricles sculptured by radial ribs and concentric costae; a small, trigonal ligament pit partly preserved in one left internal mold. Remarks and comparison.—The radial ribs of both left and right valves increase in number by insertion, as in Etheri- pecten, Limipecten, and Vorkutopecten. The concentric sculpture swings ventrally between radial ribs as in Limipecten, not Etheripecten. The shell length of Limipecten is usually equal to or larger than the height, and the radial ribs of the right valve are finer and more numerous than those of the left valve. Furthermore, the right valve is nearly flat. The present species has a greater height than length. The ornamentaion is similar in both valves, although secondary ribs of the right valve grow as strong as the primaries. The right valve is more or less inflated. In these respects, it can be identified with Vorkutopecten established by Guskov (in Muromtseva, 1984), based on Aviculopecten giganteus talis Lyutkevich and Lobanova (1960, p. 108, pl. 16, fig. 10; pl.17, fig. 1). Guskov included two species in the genus in addition to the type species, namely, Aviculopecten subclathratus (Keyserling) and A. netschajewi Licharew. However, the type specimen of the latter species has bran- ching radial ribs in the right valve and is excluded from Vorkutopecten. On the other hand, materials described as Vorkutopecten netschajewi by Guskov (Muromutseva, 1984, pl. 29, fig. 8) have inserted radial ribs and cannot be identified with this species, which is more similar to A. subclathratus. The Spitsbergen species is similar to A. subclathratus and A. netschajewi of Guskov, but differs in its more numerous primary radial ribs and larger posterior auricle. Vor- kutopecten, characterized by broad, alivincular ligament pit and a grooved ligament area, is included in Family Deltopectinidae. The present species has a relatively small ligament pit. Occurrence.—Common in siliceous limestones of the Hovtinden Member at Festningen (F 7p, F 8 and 9), rare in limestone of the Voringen Member (AP 1), common in siliceous limestone of the Svenskeegga (AP 2) and the Hovtinden Member (AP 6, 7) at Ahlstrandodden, rare in cal- careous sandstone of the Hovtinden Member at Reinodden (RP 7). Vorkutopecten sp. aff. V. svalbardensis sp. nov. Figures 6-1 Discussion.—The species is represented by a single, large external mold of a right vaive (Reg. no. HP 100084). It is 86 mm long and 91mm high and has an apical angle of 100°. The shell is gently convex and sculptured with as many as 60 radial ribs. The radials are differentiated into three orders, but due to poor preservation distinction between primary and secondary ribs is difficult. This species is very similar to the preceding new species in shape and ornamen- tation, but its size is much larger and its apical angle is a little greater. Occurrence.—Arenaceous limestone of Unit1 (Vgringen Member) at Ahlstrandodden (AP 1). Genus Deltopecten Etheridge, Jr., 1892 Deltopecten sp. ind. Figures 5-11, 12 Material. —One incomplete left semiexternal cast, and one incomplete right valve represented by external and internal molds. Reg. nos. HP 100085, 86. Description.—Shell moderate in size, subcircular in shape, nearly equiconvex and subequilateral ; umbo not prominent, located subcentrally ; apical angle 100-110" ; anterior auricle triangular, with slightly concave anterior margin in the left valve and byssate in the right valve ; left posterior auricle not preserved ; right posterior one partly preserved, obtuse-tri- angular and probably smaller than the anterior one ; surface of the left valve sculptured by relatively slender, rounded primary ribs, 18 in number, separated by wide interspaces and alternating with very weak, secondary radials; right valve ornamented with flat-topped primary radial ribs ; inter- vening flat interspaces of a width nearly equal to that of the radial ribs, with weak secondary radials inserted in the medial part of the shell; surface of both valves covered with close- set concentric fila swinging slightly ventrally, in the inter- spaces ; ligament not preserved. Discussion.—Although the ligament cannot be observed, the present species can be referred to Deltopecten judging from the nearly equiconvex shell and relatively simple, flat- topped radial ribs. This species is somewhat similar to Table 6. Measurements of Vorkutopecten svalbardensis sp. nov. Reg. no. ie H H/L | U/L a r r Vv Hor. HP 100072 SILOF 30.5* 0.98 19. 0.48 88 16 54 R F9 HP 100074 29.0 31.5 1.09 20.0 0.38 90 11? 47 R F 7p HP 100075 35.0 38.0 1.09 35.0 0.46 88 17 46. R F9 HP 100076 24.0* 27.0 113 — 0.46 85 14 30. L AP 1 HP 100077 20.0 22.0 1.10 — 0.50 90 12 42 R F 7p HP 100078 27.0* 28.7 1.06 22.0 0.50 90 12 40 L AP 1 HP 100080 34.3 35.8 1.04 26.0 0.43 90 12 37 R AP 2 HP 100081 26.0* 30.3 dar 13.0 0.49 90 ? 35 R AP 7 Permian bivalves from West Spitsbergen 15 Table 7. Measurements of Deltopecten sp. ind. Reg. no. L H H/L U/L a ri V Hor. HP 100085 35:5 33:5 0.94 16.7 0.47 105 18 [E RP 7 HP 100086 30+ 35.0 — 1725 0.50 110 15? R AP2 Deltopecten Iyonsensis Dickins (1957, p. 41, pl. 7, figs. 1-5 and 9; pl. 8, figs. 11-13; pl.9, fig. 12 ; pl. 10, figs. 3-4) from West Australia, but differs from that species in its less numerous primary radial ribs and the development of secondary radials in the left valve. Occurrence.—Rare in calcareous sandstone of Unit E of the Hovtinden Member at Reinodden (RP 7) and in siliceous limestone of Unit 3 of the Svenskeegga Member at Ahlstran- dodden (AP 2). Family Cassianoididae Newell and Boyd, 1995 Genus Cassianoides Newell and Boyd, 1995 Discussion.—The present family and genus were estab- lished by Newell and Boyd (1995) on the basis of a single species, Cassianoides kingorum Newell and Boyd of the Middle to Late Permian of West Texas. The genus is characterized by small, strongly inequivalve shells ; the left valve is strongly convex, ornamented with a few widely spaced, strong primary costae and a few comarginal, tubular hyote spines on the radial ribs ; the right valve is flat, sculp- tured by spineless, subdued radial ribs. Cyrtorostra sex- radiata Branson (1930, p. 45, pl. 11, figs. 13-15) from the Upper Permian Park City Formation was later shifted to the genus Cassianella of the Family Cassianellidae by Ciriacks (1963). This species was considered to be a junior synonym of Pseudomonotis sexcostatus Stuckenberg (1898, p. 207, pl. 1, fig. 40) from the Permian of Russia and to belong to Aviculopecten by Muromtseva (1984). The species is very similar to Cassianoides kingorum, not only in shell form but also in the characteristic ornamentation of both the left and right valves. It undoubtedly belongs to Cassianoides. Aviculopecten crassispinosus Chronic, reported by Newell et al. (1953, p. 155, pl. 33, figs. 10-13) from the Lower Permian of Peru, is also referred to as a member of this genus. Cassianella rara described by Waterhouse (1987, p. 145, pl 3, figs. 1, 7,10) from the Middle Permian of East Australia is another example. Waterhouse noticed the close relation of this species to C. sexradiata and C. crassispinosus. His figs. 1 and 7, illustrated as a right valve, are quite similar to the left valve of A. crassispinosus (especially fig. 13a of Newell et al., 1953), and are believed to be a left valve. The genus Crassinoides is now known from the Permian of the United States, Peru, Australia, Russia, and Spitsbergen. Cassianoides sexcostatus (Stuckenberg, 1898) Figure 6-5 Pseudomonotis sexcostatus Stuckenberg, 1898, p. 207, pl. 1, fig. 40. Cyrtorostra sexradiata Branson, 1930, p. 45, pl. 2, figs. 13-15. Cassianella sexradiata (Branson). Ciriacks, 1963, p. 45, pl. 5, figs. 5-7. Aviculopecten sexcostatus (Stuckenberg). 61, pl. 27, fig. 6; pl. 33, figs. 10-13. Muromtseva, 1984, p. Material.—Only one external mold of a left valve. HP 100093. Description.—Shell small, 14mm long and 14mm high, strongly inflated ; umbo narrow, orthogyrate, salient above the hinge margin and curving down over the hinge ; anterior auricle rounded-trigonal, a little inflated and marked off from the disc by a deep and wide sulcus ; posterior auricle imper- fectly preserved, relatively small, obtuse-triangular, with its posterior margin weakly sinuated and set off from the disc by a strong, posterior, radial marginal rib ; surface ornamented with nine slender but sharply raised radial ribs, projecting ventrally at ventral margin; interspaces between radials wide, slightly concave; distinct, regular concentric fila, closely spaced, curving dorsally in the interspaces, and with comarginal spinose projections on the radials ; hinge margin straight, shorter than shell length; hinge not preserved. Remarks.—The present specimen differs from the type in its more numerous radial ribs, but this is considered to be due to infraspecific variation. Crassianoides sexcostatus can be distinguished from C. crassispinosus (Chronic) by its weaker radial ribs and less spinose concentric sculpture, and from C. rara (Waterhouse) by the absence of secondary radial riblets. Occurrence.—Black siliceous shale of the uppermost fossil horizon of the Hovtinden Member at Festningen (F1). Reg. no. Superfamily Limacea Rafinesque, 1815 Family Limidae Rafinesque, 1815 Genus Palaeolima Hind, 1903 Palaeolima nakamurai sp. nov. Figures 6-9, 10 Materials.—External casts and molds of a complete right valve and an incomplete left valve, and a nearly complete external cast of a right valve. Reg. nos. HP 100096 (holotype) and 100097. Holotype specimen occurs in shale of Unit 7 of the Hovtinden Member at Festningen. Diagnosis.—Broadly rounded Palaeolima ornamented with wide, rounded, branching radial ribs intercalated with narrow furrows. Etymology.—Dedicated to Dr. K. Nakamura, who surveyed West Spitsbergen several times as a leader of the Japanese Expedition. Description.—Shell equivalve, inequilateral, a little inflated, broad and oblique-oval in shape, opisthocline, extended anteroventrally ; umbo not prominent, a little salient above the hinge margin; apical angle about 110°; umbonal angle about 80°, no umbonal ridge ; umbo situated near the middle of the straight hinge margin; height slightly less than the length; both auricles obtuse-triangular, anterior one Table 8. Measurements of Palaeolima nakamurai sp. nov. longest axis of the shell) Keiji Nakazawa A: umbonal angle (angle between hinge line and Reg. no. [a H H/L U U/L a A r th V Hor. HP 100096 31.0 29.7 0.96 18.8 1.65 80 110 33 15 R F 7-1 HP 100097 24, 24.5 80 110 30 16 R AP 6 depressed, obscurely defined from the main body ; posterior one marked off anteriorly by a steep umbonal slope ; surface ornamented with 15-16 broadly rounded, primary radial ribs wider than interstitials, increasing in number by bifurcation, reaching 30 or more in total; growth lines weak; anterior auricle nearly smooth; posterior one sculptured by weak radial costae ; hinge not preserved. Comparison.—The species is similar in ornament to Palaeolima simplex Hind (1908, p. 39, pl. 39, figs. 24-27) from the Carboniferous of England, P. petaline Zhang (1981, p. 213, pl. 11, figs. 17) and P. fasciculicostata Liu (1976, p. 236, pl. 17, figs. 22, 24, 25), both from the lower Upper Permian of South China. It is distinguished from them by its larger size and more circular outline. Palaeolima krotowi (Stuckenberg, 1898, p. 336, pl.1, fig. 29) from the Upper Carboniferous of Russia has radial ribs narrower than its interstitial furrows and is easily distinguished from the present species. Specimens referred to P. krotowi by Licharew (1927, p. 37, pl. 3, figs. 8-12, 14) and Muromtseva (1984, p. 79, pl. 33, fig. 11), from the Lower Permian of the Urals and Pechora, have broader radials than interstices, so the specific identification is doubtful. These shells are more similar to the present new species than to P. krotowi, but they differ from it being more anteroventrally extended and more oblique in shape. Occurrence.—Rare in black shale of the lower part of the Hovtinden Member at Festningen (F 7-1) and at Ahlstrandod- den (AP 6). References Branson, C.C., 1930: Paleontology and stratigraphy of the Phosphoria formation. Missouri University Studies, vol. 5, p.1-99. Chao, Y., 1927: Fauna of the Taiyuan Formation of North China-Pelecypoda. Palaeontologia Sinica, ser. B, vol. 9, fasc. 3, p. 1-64. (in Chinese) Chen, C.C., Zhang, ZM, and Xu, J.T., 1974: Permian Bivalvia. /n, Nanjing Institute of Geology and Palaeontology ed., A Handbook of Stratigraphy and Palaeontology in Southwest China, p. 302-303. (in Chinese) Ciriacks, K.W., 1963: Permian and Eotriassic bivalves of the Middle Rockies. Bulletin American Museum of Natural History, vol. 125, 100 p., 16 pls. Cox, L.R., 1969: Palliolum (Palliolum). In, Moor, R.C. ed., Treatise on Invertebrate Paleontology, Part N, vol. 1, Mollusca 6. Bivalvia, N354, The University of Kansas Press and the Geological Society of America. Cutbill, J.L. and Challinor, A., 1965: Revision of the strati- graphical scheme for the Carboniferous and Permian rocks of Spitsbergen and Bjorngya. Geological Maga- zine, vol. 102, p. 418-435. Dickins, J.M., 1957: Lower Permian pelecypods and gas- tropods from the Carnavon Basin, Western Australia. Bureau of Mineral Resources, Geology and Geophysics, Commonwealth of Australia, Bulletin, vol. 41, 55 p., 10 pls. Diener, C., 1897: The Permian fossils of the Productus Shales of Kumaon and Gurhwal. Memoir Geological Survey of India, Ser. XV Himalayan Fossils, vol. 1, pt. 4, 54 p., 5 pls. Fang, Z.Z., 1987: Bivalves from the upper part of the Per- mian in Southern Hunan, China. Collection of Post- graduate Theses, Nanjing Institute of Geology and Palaeontology, Academia Sinica, no. 1, p. 349-411, pls. 1- 8. (in Chinese with English abstract) Flood, B., Naggy, J. and Winsnes, T.S., 1971: Geological Map Svalbard 1: 500,000, sheet 1G, Spitsbergen South- ern Part. Norsk Polarinstitutt Skrifter, Nr. 154A. Forbes, C.L., Harland, W.B. and Hughes, N.F., 1958: Palaeontological evidences for the age of the Carbonif- erous and Permian rocks of Central Vestspitsbergen. Geological Magazine, vol. 95, p. 465-489. Frebold, H., 1937 : Das Festungsprofil auf Spitsbergen. IV Die Brachiopoden- und Lamellibranchiaten und die Strati- graphie des Oberkarbons und Unterperms. Skrifter Svalbard og Ishavet, vol. 69, p. 1-94, pls. 1-11. Fredericks, G., 1915: Fauna verkhnepaleozoyskoy tolstshi okrestnosty g. Krasnoufimska Permskoy gubernii (Upper Paleozoic fauna of the environment of Krasnoufimsk). Mémoires du Comité Géologique, n. ser. vol.109, 117 p., 10 pls. (in Russian with French abstract) Gan, X. and Yin, H., 1978: Lamellibranchiata. In, Working Team on Stratigraphy and Palaeontology of Guizhou Province ed., Palaeontological atlas of Southwest China, volume of Guizhou Province, pt. 2, p. 337-396, pls. 109- 126. (in Chinese) Gee, E.R., Harland, W.B. and McWhale, J.R.H., 1953: Geol- ogy of Central Vestspitsbergen, Part Il. Carboniferous to Lower Permian of Billefjorden. Transactions Royal Society of Edinburgh, vol. 62, p. 299-356. Girty, G.H., 1903 : The Carboniferous formations and faunas of Colorado. United States Geological Survey, Profes- sional Paper, vol. 16, 546 p. Girty, G.H., 1908: The Guadalupian fauna. United States Geological Survey, Professional Paper, vol. 58, 626 p., 31 pls. Gobbet, D.J., 1963 : Carboniferous and Permian brachiopods of Svalbard. Norsk Polarinstitutt Skrifter, vol.127, 201 p., 25 pls. Gu, Z.W. and Liu, L., 1976: Euchondria cancellata, sp. nov. In, Nanjing Institute of Geology and Palaeontology, Academia Sinica ed., Monograph of bivalve fossils of China, p.171. Science Press. (in Chinese) Guskov, B.A., 1984: Genus Vorkutopecten. In, Murom- tseva, V.A. ed., Permian marine deposits and bivalve molluscs of the Soviet Arctic, p.65. Ministry of Geol- Permian bivalves from West Spitsbergen ogy, USSR, Lenigrad, (Nedra). (in Russian) Hind, W., 1901-1905 : Monograph of the British Carbonifer- ous Lamellibranchiata, vol.2, 222p., 25 pls. Palaeontological Society of London. Jakowlew, N., 1903: Die Fauna der oberen Abteilung der paleozoischen Ablagerungen im Donetz-Bassin. |. Die Lamellibranchiata. Mémoires du Comité Geologique, n. ser. vol. 4, 44 p., 2 pls. Japanese-Norwegian Research Group, 1992: Investigation on the Upper Carboniferous-Upper Permian succession of West Spitsbergen, 1981-1991, 134 p. Hokkaido Uni- versity. Kortshinskaya, M.V., 1986: Biostratigraphy of Induan Stage of Spitsbergen. In, Krasilstshikov, A.A. and Mirzaev, M. N. eds., Geology of sedimentary cover of Spitsbergen Archipelago, p. 77-93, pls.1-7. Ministry of Geology, USSR, Leningrad. (in Russian) Licharew, B.K., 1927: Upper Carboniferous Pelecypoda of Ural and Timan. Mémoires du Comité Geologique, n. ser., vol.164, 137 p., 4pls. (in Russian with English abstract) Liu, L., 1976: Etheripecten sichuanensis, sp. nov. In, Nan- jing Institue of Geology and Palaeontology, Academia Sinica eds., Monograph of bivalve fossils of China, p. 179. Science Press. (in Chinese) Lyutkevich, E.M. and Lobanova, O.V., 1960: Permian pelecypods from the Soviet sector of the Arctic. Transactions All-Union Petroleum Scientific-Research Geological-Prospecting Institute (VNIGRI), Bulletin, vol. 149, 218 p., 35 pls. (in Russian) McCoy, F., 1851: Aviculopecten. Annals Magazine of Natu- ral History, vol. 2, p. 171. Meek, F.B. and Worthen, A.H., 1866: Description of inverte- brates from the Carboniferous system. Illinois Geologi- cal Survey, vol. 2, Palaeontology, p. 143-411. Muromtseva, A.V. ed., 1984: Permian marine deposits and bivalve molluscs of the Soviet Arctic, 154 p., 53 pls. Ministry of Geology, USSR, Leningrad (Nedra). (in Russian) Nakamura, K., Kimura, G. and Winsnes, T.S., 1987: Bra- chiopod zonation and age of the Permian Kapp Staros- tin Formation (Central Spitsbergen). Polar Research, n. s. vol. 5, p. 207-219. Nakamura, K., Kimura, G., Winsnes, T.S. and Lauritzen, O., 1990 : Permian and Permian-Triassic boundary in Cen- tral Spitsbergen. In, Tatsumi, T. ed., The Japanese Scientific Expedition to Svalbard 1983-1990, p. 137-153. Kyoikusha, Tokyo. Nakamura, K., Tazawa, J. and Kumon, F., 1992: Permian brachiopods of the Kapp Starostin Formation. In, Japanese-Norwegian Research Group, Investigation on the Upper Carboniferous-Upper Permian succession of West Spitsbergen, 1989-1991, p. 77-95, pls. 1-5. Hok- kaido University. Nakazawa, K., Nakamura, K. and Kimura, G., 1987 : Discov- ery of Otoceras boreale from West Spitsbergen. Pro- ceedings of Japan Academy, vol. 63, p. 171-174. Nakazawa, K., Suzuki, H., Kumon, F. and Winsnes, T.S., 1990: Japanese Geological Expedition to Svalbard in the summer of 1986. /n, Tatsumi, T. ed., The Japanese Scientific Expedition to Svalbard 1983-1990, p. 175-214. Kyoikusha, Tokyo. Newell, N.D., 1938: Late Paleozoic pelecypods : Pectinacea. State Geological Survey of Kansas, vol. 10, 123 p., 20 pls. Newell, N.D. and Boyd, D.W., 1995 : Pectinoid bivalves of the Permian-Triassic crisis. Bulletin of the American Museum of Natural History, no. 227, 95 p. Newell, N.D., Chronic, J. and Roberts, T.G., 1953: Upper Paleozoic of Peru. Geological Society of America, Memoirs, vol. 58, 261 p., 34 pls. Sakagami, S., 1992: Notes on the Permian bryozoans from Kapp Starostin Formation at Festningen route, Spitsber- gen. In, Japanese-Norwegian Research Group, Inves- tigation on the Upper Carboniferous-Upper Permian succession of West Spitsbergen, p. 40-57. Hokkaido University. Stuckenberg, A., 1898: Allgemeine geologische Karte von Russland. Blatt 127. Mémoires du Comité Geologi- que, vol. 16, 361 p., 5 pls. Toula, F., 1873: Kohlenkalk-Fossilien von der Sudspitze von Spitzbergen. Sitzungberichte der keyserlichen Akademie der Wissenschaften in Wien, Mathematisch- naturwissenschaftliche KI., vol. 68, pt. 1, p. 267-291. Toula, F., 1875a: Kohlenkalk- und Zechstein-Fossilien aus dem Hornsund am der Süd-Westküste von Spitzbergen. Sitzungbericht der keyserlichen Akademie, Wien, Mathematisch-naturwissenschaftlich KI., vol. 70, pt.1, p. 133-157. Toula, F., 1875b: Permo-Carbon-Fossilien von der West- küste von Spitzbergen. Neues Jahrbuch für Miner- alogie, Geologie und Paläontologie, 1875, p. 225-264, pls. 5-10. Waterhouse, J.B., 1963: Etheripecten, a new Avicul- opectinid genus from the Permian. New Zealand Jour- nal of Geology and Geophysics, vol. 6, p. 193-196. Waterhouse, J.B., 1969: Growth lamellae on the type species of the Upper Paleozoic bivalve Aviculopecten McCoy. Journal of Palaeontology, vol. 43, p. 1179-1183. Waterhouse, J.B., 1982: Permian Pectinacea and Limacea (Bivalvia) from New Zealand. New Zealand Geological Survey, Palaeontological Bulletin, vol. 49, 75 p., 25 pls. Waterhouse, J.B., 1987: Late Palaeozoic Mollusca and correlation from the south-east Bowen Basin, East Australia. Palaeontographica, Pal. A, vol. 198, p. 129- 233, pls. 1-14. Yancey, T.E., 1985: Bivalvia of the H.S. Lee Formation (Permian) of Malaysia. Journal of Palaeontology, vol. 59, p. 1286-1297. Zhang, R., 1977 : Class Bivalvia. In, Hubei Geological Insti- tute ed., Palaeontological Atlas of Central-South-China, Part 2, p. 470-533, pls. 189-202. Geological Press. (in Chinese) Zhang, Y., 1981: Late Permian bivalves from Yunjia of Jahe, Hunan Province. Acta Palaeontologia Sinica, Vol. 20, no. 8, p. 260-265. (in Chinese with English abstract) Paleontological Research, vol. 3, no. 1, pp. 18-28, 6 Figs., April 30, 1999 © by the Palaeontological Society of Japan An early Late Cretaceous mammal from Japan, with reconsideration of the evolution of tribosphenic molars TAKESHI SETOGUCHI', TAKEHISA TSUBAMOTO’, HAJIME HANAMURA?’”’ and KIICHIRO HACHIY A’ ‘Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Kitashirakawaoiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan ‘Department of Anatomy, School of Dentistry, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan Division of Oral Aging, Resarch Institute of Advance Dental Science, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa- ku, Nagoya 464-8650, Japan Received 4 July 1998 ; Revised manuscript accepted 18 March 1999 Abstract. The morphology of a mandibular fragment with a left lower molar discovered in the “Upper Formation” (upper Cenomanian-lower Turonian) of the Mifune Group in central Kyushu, southwestern Japan, suggests that this fossil should be assigned to a new species of Late Cretaceous mammal, Sorlestes mifunensis sp. nov. (Infraclass Eutheria ; Order Proteutheria ; Family Zhelestidae). S. mifunen- sis is the oldest zhelestid yet recorded. Some workers suggest that the Zhelestidae have a close affinity with ungulates. A detailed comparison between the lower molar of the new species and those of ungulates supports this suggestion. The comparison also suggests that the Zhelestidae have a closer affinity with ungulates than the Zalambdalestidae and other contemporary mammals, and that S. mifunen- sis has a relatively primitive character within the Zhelestidae. This comparison leads us to revise the diagnoses of the family Zhelestidae and of the genus Sorlestes. The unique character of the entoconid- hypoconulid twinning seen in the Zhelestidae was probably caused by the movement of the hypoconid (the presumed first single talonid cusp seen in the first therian Kuehneotherium) to the buccal side, far away from the other talonid cusps. This twinning pattern is distinct from the twinning pattern seen in marsupials. Key words: Japan, Late Cretaceous, Mesozoic mammal, Mifune Group, Sorlestes, tribosphenic molar Introduction It is generally believed that tribosphenic mammals first appeared around the Jurassic-Cretaceous boundary (Bown and Kraus, 1979; Kielan-Jaworowska et al, 1979b; Sigogneau-Russell, 1991). They are ancestors of the eu- therian and metatherian mammals which probably differ- entiated during the Neocomian (Early Cretaceous) (Kielan Jaworowska et al., 1979a ; Cifelli, 1993 ; Eaton, 1993 ; Wang et al., 1995). The eutherian orders radiated widely at the beginning of the Tertiary. However, recent fossil finds suggest that the eutherian orders may have originated and differentiated in the Late Cretaceous (Fox and Youzwyshyn, 1994 ; Archibald, 1996 ; Gheerbrant et al., 1996). Until 20 years ago there were only very few reports of tribosphenic mammals from the early Late Cretaceous (Cenomanian-Santonian). This situation has, however, changed and many such fossils are now known from this period (Cifelli and Eaton, 1987 ; Cifelli, 1993; Eaton, 1993 ; Nessov et al. 1994; Nessov et al., 1998). In particular, Nessov et al. (1994) report many early Late Cretaceous tribosphenic mammals from Middle Asia (Uzbekistan, Ka- zakhstan and Tajikistan). In the present study, we document a mammal fossil specimen, which was first reported by Setoguchi (1992), from the “Upper Formation” (upper Cenomanian-lower Turonian ; lower Upper Cretaceous) of the Mifune Group in central Kyushu, southwestern Japan. The specimen is a small mandibular fragment with a tribosphenic lower molar. The new find is significant because it is the only known example of a mammal fossil from the Late Cretaceous eastern coastal lowlands of the Asian Continent. The other Asian Late Cretaceous mammal fossils, in contrast, come from either inland deposits or deposits along the Tethys sea and the Late Cretaceous mammal from Japan 19 Turgai Strait of that time (Clemens et a/., 1979 ; Nessov et al., 1994). The tooth nomenclature used in this contribution is that of Bown and Kraus (1979) and Nessov et al. (1998). Geological setting The present fossil material was discovered in the “Upper Formation” of the Mifune Group, which is distributed in the Mifune Town area of Kumamoto Prefecture, central Kyushu, southwestern Japan (Figure 1). The Mifune Group unconfor- mably overlies green schist associated with serpentinite in the northern area, and the Upper Permian Mizukoshi Forma- tion in the southern area (Matsumoto, 1939). The Mifune Group is, in turn, unconformably overlain by the Upper Cretaceous Gankaizan Formation (Tamura and Tashiro, 1966). The Mifune Group is considered to be early Late Cretaceous in age (see below), and to have formed in a sedimentary basin situated on the east coastal margin of the Late Cretaceous Asian Continent. The Mifune Group has a total thickness of about 1,500 m and consists of “Basal”, “Lower” and “Upper” formations (Matsumoto, 1939). The lowermost or “Basal Formation” is dominated by conglomerate and very coarse-grained sand- stone (Matsumoto, 1939), yielding fresh-water bivalves, such as Trigonioides, (Tamura, 1979; Matsumoto et al., 1982). The middle or “Lower Formation” is dominated by sandstone and sandy mudstone (Matsumoto, 1939), yielding brackish- water and shallow-marine molluscan fossils, such as /nocer- amus concentricus costatus and Eucalycoceras sp. cf. E. spathi of middle Cenomanian age (Tamura and Matsumura, 1974; Tamura, 1979; Matsumoto et al., 1982). The upper- most or “Upper Formation” is dominated by red mudstone (Matsumoto, 1939), yielding non-marine bivalves (Tamura, 1979) and several vertebrate fossils, such as dinosaurs, pterosaur, and the present specimen (Tamura et al., 1991; Setoguchi, 1992 ; Okazaki and Kitamura, 1996). The Gankaizan Formation, which unconformably overlies the Mifune Group, consists of conglomerate, coarse-grained sandstone and red mudstone (Tamura and Tashiro, 1966 ; Matsumoto et al., 1982), yielding Inoceramus (Platyceramus) amakusensis, of lower Santonian age, in its upper part (Tamura and Tashiro, 1966 ; Matsumoto et al., 1982). The present fossil material comes from the upper part of the “Upper Formation” near the Amagimi Dam, Mifune Town (Figure 1). The stratum where the fossil was discovered AU NE OSSI Figure 1. Topographic map showing the fossil locality, near the Amagimi Dam, Mifune Town, Kumamoto Prefecture, Kyushu, southwestern Japan (a part of topographic map “Mifune”, 1 : 25,000 scale, Geographical Survey Institute of Japan). 20 Takeshi Setoguchi et al. Upper Formation (non-marine) Mifune Group (m., partly br.) non-m.) LL 5 a © a Basement Stratigraphy | T.(m)| Lithology Fossils Inoogramus (Platyceramus) amakusenss ———® Lower Santonian Sorlestes (KUJM 95002), Piicatounio, Gyraulus, Pterodactyloidea, fam., gen. and sp. undetermined Siragimelania Nipponicorbula mashikensis Eucalycoceras sp. cf. E. spathh ——?® Middle Cenomanian Acanthotrigonia, Inoceramus, Septifer, Turritella Matsumotoa, Brachidontes, Crassostrea, Eomiodon, Tetoria, Pulsides ?Megalosauridae gen. et sp. indet. Nipponicorbula mashikensis Siragimelania Trigonioides, Plicatounio Figure 2. Stratigraphy of the Cretaceous deposits in the south of Kumamoto City, Kyushu, Japan (modified from Matsumoto, 1939 ; Tamura and Tashiro, 1966 ; Matsumoto et al., 1982 ; Tamura et al., 1991; Hasegawa et al. 1992 ; Okazaki and Kitamura, 1996). ss., sandstone ; cg., conglomerate. consists of coarse-grained sandstone. The age of the “Upper Formation” is considered to be late Cenomanian to early Turonian on the basis of the ages of the Lower Formation and the Gankaizan Formation. A synthetic scheme of the stratigraphy of the Mifune Group is shown in Figure 2. Systematic paleontology Class Mammalia Linnaeus, 1758 Infraclass Eutheria Gill, 1872 Order Proteutheria (Romer, 1966) Butler, 1972 Family Zhelestidae (Nessov, 1985) Nessov, 1990 Revised diagnosis.—The upper and lower molars are typical tribosphenic types. The protocone is large and mesiodistally expanded. The stylar shelf is relatively narrow, but the parastylar region is wide and expanded mesially bearing two cusps. A small paraconid is displaced relatively lingually and relatively close to the metaconid. Compared with other proteutherians, the trigonid height is lower relative to talonid height. The talonid is about as wide as the trigonid and mesiodistally longer and lower than the trigonid. Abbreviations : m., marine; br., brackish; T., thickness ; ms., mudstone ; The talonid basin is deep and open lingually, so that the deepest part of the talonid basin is situated at its lingual margin. The entoconid and hypoconulid are markedly close to one another, and are quite clearly separated from the hypoconid. The upper and lower last premolars are premolariform (sensu Krishtalka, 1976), but the upper one has a incipient metacone. In occlusal view, the upper one is somewhat mesiodistally constricted between the paracone and the protocone. Genus Sorlestes Nessov, 1985 Type species.—Sorlestes budan Nessov, 1985. Included species.—S. budan Nessov, 1985; S. kara Nes- sov, 1993; S. mifunensis sp. nov. Revised diagnosis.—The paraconid is not strongly appres- sed to the metaconid. The protoconid is larger than in Aspanlestes (Zhelestidae). The entoconid is very markedly close to the hypoconulid (entoconid-hypoconulid twinning), and both are located at the distolingual corner of the talonid, opposite the hypoconid which is located at the distobuccal corner. The cristid obliqua extends just below the notch of Late Cretaceous mammal from Japan the protocristid between the protoconid and the metaconid. Sorlestes mifunensis sp. nov. Figure 3 Holotype.—KUJM 95002, a left mandibular fragment with a molar. (KUJM means Kyoto University, Japan, Mesozoic) Hypodigm.—The type specimen only. Etymology.—Named after Mifune Town, where the type specimen was discovered. Repository.—Department of Geology and Mineralogy, Division of Earth and Planetary Sciences, Graduate School of [59] Science, Kyoto University, Japan. Locality.—Lat. 32°44’09” N ; Long. 130°50’32” E: Loc. 1 of Tamura et al. (1991, fig. 1; Figure 1), near the Amagimi Dam, Mifune Town, Kumamoto Prefecture, Kyushu, southwestern Japan. Horizon. —Upper part of the “Upper Formation”, Mifune Group (Figure 2). Age.—Late Cenomanian to early Turonian ; Late Cretaceous. Diagnosis.— The lower molar of S. mifunensis is almost as large as S. budan, and larger than S. kara. Compared to S. budan, the paraconid is less appressed to the metaconid, and the entoconid and hypoconulid are closer together. Figure 3. Sorlestes mifunensis sp. nov., KUJM 95002, holotype. A, A’, occlusal view (stereophotographic pair). B, lingual view. C, buccal view. D, D’, occlusal view of the preserved molar (stereophotographic pair). Scale bars=2 mm (left scale corresponds to A, A’, B, C, right scale corresponds to D, D’). 22 Takeshi Setoguchi et al. Description —The type specimen (KUJM 95002) is a frag- mentary left mandible with a molar. The preserved part of the mandibular ramus is about 8 mm in length, and about 4 mm in height and about 2 mm in width below the preserved molar. Immediately mesial to the molar, there is a broken root, which is circular and not compressed anteroposteriorly in occlusal view (Figures 3-A, A’). Immediately distal to the molar, there is a broken alveolus. Mental foramen could not be identified in KUJM 95002. The protoconid of the preserved molar is much larger and higher than the metaconid, and leans somewhat lingually. The metaconid is situated just lingual to the protoconid. Although badly broken at the base, it is clear that the paraconid is near the anteroposterior midline, and less anteriorly appressed than in S. budan. There is no crest joining the paraconid with the metaconid. A distinct precin- gulid runs downward from the mesiobuccal base of the paracristid notch, disappearing at the buccal base of the protoconid. The posterior trigonid wall is almost vertical, and nearly perpendicular to the mandibular extension. The talonid is longer than wide. It is longer than, as wide as, and roughly half as tall as the trigonid. The hypoconid and entoconid are almost the same height, and somewhat higher than the hypoconulid. The hypoconulid is only very slightly projected posteriorly. The entoconid and hypoconulid are closer together than in S. budan, and are located at the distolingual corner of the talonid. A very weak postcingulid runs down buccally from the hypoconulid, disappearing at the buccal base of the hypoconid. The deepest part of the vi AP > k TALL % TRIL y I TRIW Figure 4. Orientations of the measurements of lower molars (modified from Nessov et a/., 1994). Buccal to top of page ; anterior to right. Abbreviations are shown in Table 1. Table 1. sp. nov. talonid basin is situated at its lingual margin, so that the deep talonid basin is open lingually, and inclined lingually as a whole. The cristid obliqua originates directly below the notch between the protoconid and the metaconid, and is much higher than the entocristid. The hypoflexid is well- formed and deep. Wear facets can be observed from the tip of the protoconid to the tip of the metaconid through the proto- cristid. The tips of the hypoconid, hypoconulid and entoconid are slightly worn. The talonid basin is also worn (although the effects of secondary erosion are difficult to assess), which forms a U-shaped “wear facet”. Dental measurements are given in Table 1 and Figure 4. Discussion Identification of the present lower molar The tooth class of the molar preserved in KUJM 95002 can be identified as M., because the trigonid is as wide as the talonid which is the same as on M, of S. budan. The possibility that it should be identified as M, cannot, however, be immediately excluded. As Lillegraven (1976) pointed out, it is a usual therian condition that the paraconid is most buccally set on M, and becomes progressively more lingual on M.-M;. Furthermore, Cretaceous eutherians character- istically have a protoconid that leans somewhat more lin- gually on M, than that on M,, so the distance between the tip of the protoconid and that of the metaconid in occlusal view is shorter on M, than that on M,. These characters are also observed in the zhelestid Aspanlestes (Nessov et al., 1994, pl. 4, fig. 1). KUJM 95002 shows a combination of these M, characters. In either case, KUJM 95002 and S. budan clearly have distinct lower molar structures (see diagnosis of S. mifunen- sis). S. kara, another species of Sorlestes, has much smaller molar size than KUJM 95002. We, therefore, consider KUJM 95002 to be a new species of Sorlestes. Phyletic position of Sorlestes mifunensis Phylogenetic relationships of the Zhelestidae have been discussed by various workers (Figure 5). Lillegraven (1976) described Gallolestes, which was subsequently classified as belonging to the Zhelestidae by Nessov et al. (1994), based on the lower molar morphology. Lillegraven (1976) favors eutherian affinities for Gallolestes, and points out the similar- ities between Gallolestes and hyopsodontid condylarths. Butler (1977), however, points out that Gallolestes shares some derived characters of the lower molars with Zalamb- dalestes (Proteutheria; Zalambdalestidae) and with Pur- gatorius (Primatomorpha), and he doesn't exclude the possi- Measurements (in mm) of the preserved molars of the type specimens of Sorlestes mifunensis The measurements are oriented as shown in Nessov et al. (1994, fig.1; see Figure 4). Abbreviations : AP, anteroposterior length; TRIL, trigonid length; TALL, talonid length; TRIW, trigonid widt! ; TALW, talonid width. PTS Er [mm] AP TRIL TALL TRIW TALW KUJM 95002 (S. mifunensis) left lower molar (M, or M.) 1.15 1.45 1.75 | 1.70 | | | Late Cretaceous mammal from Japan 23 Nessov (1985) Butler (1990) : based on the|/based on the Pt EME Kennalestidae Kennalestes Sorlestes Zhelestes Zhelestes Aspanlestes Taslestes Mixotheridia Gallolestes Pe Coreundulates’) close to ungulates Family u Sorlestes Aspanlestes close to Taslestes Zalambdalestidae ? Gallolestes Zalambdalestidae Nessov et al. (1994) Archibald (1996) & Nessov et al. (1998) mainly based on the morphology of the lower molars mainly based on the morphology of Proteutheria the upper molars Kennalestidae Mixotheridia Kennalestidae ("preungulates") Zalambdalestidae Zhelestidae Zhelestes Sorlestes Ungulato! Aspanlestes Zhelestidae Taslestes Ungulata Gallolestes Zalambdalestidae Figure 5. The classifications and phylogenetic relationships used in recent studies for the Zhelestidae. bility of a relationship between Gallolestes and Protun- gulatum (Condylarthra). Clemens (1980) concludes that Gallolestes is possibly a representative of another lineage of metatherian-eutherian grade of dental evolution that cannot be assigned to either the Eutheria and Metatheria. Based on the lower molar morphology, Nessov (1985) suggests that Tas/estes, Aspanlestes, Sorlestes and Gal- lolestes should be combined in the same taxonomic group, a group which was subsequently classified as belonging to the Zhelestidae in Nessov et al. (1994). Nessov (1985) proposed a new suborder Mixotheridia (Proteutheria) includ- ing both the above genera and the Zalambdalestidae, and suggested that this suborder was related to condylarths. In the same paper, he described a new genus Zhelestes, based on the upper dentition. He classified it into the new sub- family Zhelestinae (Proteutheria ; Kennalestidae), and at this time didn't include it in the Mixotheridia. Later, he raised this subfamily to the family level (Nessov, 1990). Butler (1990) points out that the zalambdalestids differ from Aspan- lestes, Sorlestes and Gallolestes in some molar features, suggesting that relationships of these genera to zalamb- dalestids is not impossible, but it needs to be substantiated. He also considers that Zhelestes might be an earlier repre- sentative of condylarths. According to Nessov et al. (1994), the Zhelestidae include Gallolestes, Taslestes, Aspanlestes and Sorlestes, and these are all included in the suborder Mixotheridia along with the Zalambdalestidae. They con- sider the Mixotheridia (both the Zhelestidae and the Zalamb- dalestidae) to be “preungulates”. In contrast, based mainly on the upper molars morphology, Archibald (1996) and Nessov et al. (1998) consider that the Zhelestidae are sister groups of ungulates, and the Zalambdalestidae are only distantly related to them. In this paper, we follow the suggestions of Archibald (1996) and Nessov et al. (1998). The reasons for our preference are briefly summarized below. On the basis of the lower molar structure, Nessov et dl. (1994) claimed that both the Zhelestidae and the Zalamb- dalestidae are closely related to ungulates. However, the two families show the following differences: (1) The Zhe- lestidae have more low-crowned lower molars with a trigonid that is less elevated to the talonid (Butler, 1990). (2) The paraconid and metaconid in the Zhelestidae are less closely appressed than in the Zalambdalestidae. (3) The Zhe- lestidae have a lingually open talonid, whereas the talonid is lingually closed in the Zalambdalestidae (see Kielan-Jawor- owska, 1984, pl. 14,15). In these features, the Zhelestidae are morphologically more similar to early ungulates than to the Zalambdalestidae. Most early ungulates (for instance, Protungulatum, Diacodexis, and so on) share the diagnostic characteristics of zhelestids, that is, the high, large, wide and lingually open talonid with the hypoconulid situated markedly close to the entoconid, and the rather lingually displaced paraconid with some appression to the metaconid (see McKenna, 1960, figs. 52, 53, 56, 57 ; Archibald, 1982, figs. 56, 60; Estravis and Russell, 1989, pl.1; Rose, 1996, fig. 1). This combination of characteristics is not seen in any other contemporary mammal. For example, in Purgatorius, an early primatomorphan, the talonid is large, wide and high, but is Closed lingually with the hypoconulid situated centrally (see Clemens, 1974, fig.2; Buckley, 1997, fig.1). In Gypsonictops, a Late Cretaceous insectivore, the talonid is large, wide and somewhat lingually open. However, the hypoconulid is centrally situated, and the paraconid is situ- ated rather centrally than lingually (see Clemens, 1973, figs. 1,4; Cifelli, 1990, fig. 2). Based mainly on an analysis of upper molar morphology, Archibald (1996) and Nessov et al. (1998) suggest that the Zalambdalestidae does not have a close affinity with un- gulates. Similarly, a study of lower molar morphology indi- cates that the Zhelestidae most closely resemble early ungulates. The lingually closed talonid in the Zalambaa- 24 Takeshi Setoguchi et al. lestidae, which is shared by many other eutherians, may be an apomorphic character which zhelestids and early un- gulates do not posses (see below). This would imply that the Zalambdalestidae should be excluded from a very close relationship with ungulates. In support of this idea, some workers (Van Valen, 1964; McKenna, 1975; Stucky and McKenna, 1993; Archibald, 1996) consider the Zalambda- lestidae to be more closely related to Anagale and rabbits. Compared with the Zhelestidae, early ungulates have a relatively high talonid with robust cusps on the lower molars. Compared to the other representatives of the Zhelestidae, Sorlestes mifunensis shows a primitive characteristic in that the paraconid is less appressed to the metaconid. Nessov (1993) created a new family Kulbeckiidae (consist- ing of a single new genus Kulbeckia) within the Mixotheridia. In the Kulbeckiidae, the hypoconulid is markedly close to the entoconid, and the paraconid is lingually situated with appression to the metaconid, similar to the Zhelestidae. Unfortunately, it is not clear whether the talonid is open or not in the Kulbeckiidae, so it is difficult to discuss any possible relationship between the Zhelestidae, Kulbeckiidae and other mammals. Evolution of tribosphenic molars The most characteristic feature of Sorlestes mifunensis is the lower molar with the hypoconulid situated markedly close to the entoconid, quite clearly opposed to the hypoconid. This twinning pattern is rarely seen in other Cretaceous eutherians, in which the hypoconulid is centrally-located between the hypoconid and the entoconid. The recognition of this character prompted us to reconsider the evolution of the talonid cusps. It seems that the talonid cusps devel- oped along with the occluding upper tooth and the adjacent lower tooth. 1. First cusp formed in the talonid of Kuehneotherium, the first therian mammal: The earliest therian mammal, Kuehneotherium, had already appeared by the Norian (Late Triassic) (Fraser et al., 1985). In the lower molars of Kueh- neotherium, the tallest and largest Cusp can be recognized as homologous with the protoconid of the later tribosphenic molars. The other two cusps, which are situated mesiolin- gually and distolingually from the protoconid, can likewise be identified as equivalents of the paraconid and metaconid, respectively (Kermack et a/., 1968). These homologies of the trigonid Cusps are now not really in debate (Slaughter, 1971). In the lower molars of Kuehneotherium, there is, however, a unicuspid distal heel or talonid, posterior to the trigonid (Kermack et al., 1968, fig. 3). The homology of this cusp has been discussed by several workers (Slaughter, 1971; Clemens and Lillegraven, 1986), and the two main opinions are that it corresponds to either the hypoconid or hypoconulid. Mills (1967) used the occlusal relationship between the upper and lower molars to propose that the single talonid cusp of Jurassic pantotheres corresponds to the hypoconid on the basis of the occlusal relationship between the upper and lower molars. The same conclusion was also reached by Freeman (1979) and Prothero (1981). In contrast, Kermack (1967) interpreted the single talonid cusp in Welsh pantothere (Kuehneotherium) as the hypoconulid on the basis of the relationship between the talonid and its following tooth. Crompton (1971), Slaughter (1971) and Butler (1978) also correlated this cusp with the hypoconulid, although the latter didn't completely exclude the possibility that it could repre- sent the hypoconid. The next stage in evolution toward the tribosphenic molar is seen in Amphitherium or Palaeoxonodon, whose talonid extends distobuccally from the base of the metaconid and bears a large single cusp at its distobuccal margin (Simpson, 1928, fig. 38 ; Freeman, 1979, pls. 16,17). In Palaeoxonodon, there is a small cuspule at the approximate median point of the oblique crest which links the metaconid and a large single talonid cusp (Freeman, 1979). Further development is seen in Peramus. In this genus the talonid bears two or three cusps, identified as the hypoconid, hypoconulid and entoconid of the tribosphenic molar (Clemens and Mills, 1971; Clemens and Lillegraven, 1986). The talonid basin is not fully basined and is open lingually (Clemens and Mills, 1971, pl. 3). By comparing the molar morphology of the animal mentioned above with later tribosphenic mammals, we consider that the single talonid cusp seen in Kuehneother- jum corresponds to the hypoconid, as proposed by Mills (1967). This suggestion is also supported by the following arguments. (1) We would like to stress the occlusal relation- ship between the upper main cusp (paracone) and the first talonid cusp. The paracone is the largest cusp in the upper molar and is functionally very important for masticating foods. We, therefore, propose that the occlusal relationship between the paracone and the single talonid cusp, as well as between the paracone and the protoconid, is likely to be maintained in the therians. (2) In Amphitherium or Palae- oxonodon, the talonid extends distobuccally from the base of the metaconid and bears a large single cusp at its distobuc- cal margin, where the hypoconid of the tribosphenic molar is situated. (3) We propose, furthermore, that the groove separating the hypoconid and the hypoconulid in tribos- phenic molars is also significant. This groove is deeper and stronger than the groove separating the hypoconulid and the entoconid, so the hypoconulid and entoconid are likely to be related more closely to each other than to the hypoconid. (4) Freeman (1979) stated that in certain specimens of Palaeoxonodon there is an incipient development of the entoconid and hypoconulid in addition to the large talonid cusp situated distobuccally. We, therefore, propose the following sequential develop- ment. The first talonid cusp seen in Kuehneotherium corre- sponds to the hypoconid, and the entoconid and hypoconulid appeared at some later stage, being more closely related to each other than to the hypoconid. 2. Entoconid-hypoconulid twinning: The primitive talonid for a tribosphenic molar envisaged by most workers is basined and lingually opened with a relatively large hypoconid, smaller hypoconulid and in some cases also an entoconid (Clemens and Lillegraven, 1986; Szalay, 1994). Examination of Early Cretaceous tribosphenic mammals suggests that the roughly centrally-placed hypoconulid Late Cretaceous mammal from Japan between the hypoconid and the entoconid may also be a primitive Characteristic. In Late Cretaceous mammals, the lower molars of many eutherians have a centrally-placed hypoconulid. In con- trast, the molars of contemporary marsupials have a hypoconulid twinned with an entoconid. In this respect the molars of the eutherian Zhelestidae resemble those of marsupials. However, the twinning in the Zhelestidae is clearly distinct from that in marsupials (Figure 6). In marsupials, the hypoconulid is distolingually displaced compared to the Zhelestidae. The twinning pattern seen in the Zhelestidae is associated with a primitive-type talonid as seen in the tribosphenic pattern. This association suggests that the twinning seen in the Zhelestidae is more primitive than in marsupials. The twinning pattern seen in the Zhelestidae is likely to have been caused by the movement of the hypoconid to the buccal side far away from the other talonid cusps, corresponding to the expansion of the protocone of the upper molars (Archibald, 1996 ; Nessov et al., 1998). The twinning pattern seen in marsupials is more likely to be a secondary feature (Cifelli, 1993), and could be functionally related to the early trend of the enlargement of the metacone and reduction of the paracone in this group (Clemens and Lillegraven, 1986). The entoconid-hypoconulid twinning is also related to the position of the paraconid of the posterior molar. This is because the paraconid fits into the groove between the hypoconulid and the entoconid of the anterior tooth. In many eutherians, the paraconid is situated centrally, Zhelestidae Other eutherians and ungulates sone hypoconulid Nw Nn because the hypoconulid of the anterior tooth is centrally- placed between the hypoconid and the entoconid, and the groove between the hypoconulid and the entoconid is situated more buccally. In the Zhelestidae, the paraconid is situated more lingually than centrally, because the hypoconulid is situated lingually and twinned with the entoconid, and the groove between the two cusps is situated more lingually than centrally. In marsupials, the paraconid is situated more mesiolingually than in eutherians (include the Zhelestidae), because the hypoconulid of the anterior tooth is situated more distolingually and twinned with the entoconid, and the groove between the two cusps is situated far more distolingually. As mentioned above, the lingually open talonid with a hypoconulid markedly close to the entoconid as seen in the Zhelestidae is probably a reflection of the primitive state. This condition is also seen in early eutherian like Proken- nalestes (Kielan-Jaworowska and Dashzeveg, 1989, figs. 26, 27), but not seen in early metatherian, Kokopellia (Cifelli, 1998, fig. 1). Co-evolution of mammals and plants The age from the Albian to the Cenomanian was a very important period for the mammalian evolution. At this time the flora underwent a change from one dominated by ferns and gymnosperms to one with abundant angiosperms. Flowering angiosperms appeared at the beginning of the Cretaceous, and very rapidly became a major plant group (Crane, 1987 ; Collinson, 1990). Angiosperms have leaves, Marsupials protoconid entoconid paraconid metaconid deepest part of the talonid basin Primitive tribosphenic pattern buccal distal Eu mesial lingual O O ee) Figure 6. Comparisons of the lower molar patterns of tribosphenic mammals (occlusal view of the left lower molars). 26 Takeshi Setoguchi et al. flowers, fruit, pollen and honey. In other words, these plants have foods with high nutritive value. It was for this reason that insects began to evolve explosively at this time. It follows, therefore, that insectivorous mammals, whose staple foods were insects and/or larvae of insects, also began to increase in numbers and diversity. The mammals who began to diversify and radiate in this way are the Cretaceous tribosphenic mammals. The period when the Mifune Group was deposited is the very period when angiosperms had become a major plant group, and when insectivorous mam- mals like Sorlestes evolved rapidly. Conclusions Morphological studies of the mammalian remain discov- ered from the lower Upper Cretaceous Mifune Group in central Kyushu, southwestern Japan suggest that it should be assigned to a new species of the genus Sorlestes (Order Proteutheria ; Family Zhelestidae), and is here named S. mifunensis. The lower molars of the Zhelestidae exhibit a series of ungulate-like characteristics. It suggests that the Zhe- lestidae and early ungulates are far more closely related to each other than to the Zalambdalestidae and other mam- mals. The twinning pattern of the hypoconulid and entoconid in the Zhelestidae, including Sorlestes mifunensis, shows a more primitive state than that of metatherians and most of the other eutherians. Sorlestes mifunensis is the oldest known zhelestid yet recorded, and suggests that the origin of ungulates perhaps goes back even further to the early Late Cretaceous, or at least, that mammals having ungulate-like characters had already been differentiated by the late Cenomanian to early Turonian. The find of Sorlestes mifunensis also indicates that zhelestid existed not only in western Asia but also on the coastal plain of eastern Asia. Acknowledgments We are grateful to Kazuhiro Koyasu of Aichi-Gakuin University, who donated the specimen to Kyoto University. Our thanks also go to Naoki Ikegami of Mifune Board of Education, who gave us facilities in our field work. Thanks are also due to Hidetoshi Kamiya of Kyoto University, who gave the specimen number to the present material. We would like to express our sincere gratitude to Masanaru Takai of Kyoto University Primate Research Institute for his critical reading of the manuscript and taking the photographs of the specimen, to Naoki Kohno of National Science Museum and Simon R. Wallis of Kyoto University for their critical reading of the manuscript, and to Haruyoshi Maeda of Kyoto University for his advice about the construction of the manuscript. This manuscript was improved following con- structive reviews by two anonymous referees. This research was partly supported by Grant-in-Aid for JSPS Fellows from the Ministry of Education, Science, Sports and Culture of Japan to Takehisa Tsubamoto (No. 9714). References Archibald, J.D., 1982: A study of Mammalia and geology across the Cretaceous-Tertiary boundary in Garfield County, Montana. University of California Publications in Geological Sciences, vol. 122, xvi+286 p. Archibald, J.D., 1996 : Fossil evidence for a Late Cretaceous origin of “hoofed” mammals. 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Paleontological Research, vol. 3, no. 1, pp. 29-35, 3 Figs., April 30, 1999 © by the Palaeontological Society of Japan A new cheirolepidiaceous conifer from the Lower Cretaceous (Albian) of Hokkaido, Japan KEN'ICHI SAIKI Department of Plant Science, Natural History Museum and Institute, Chiba 955-2, Aoba, Chuo-ku, Chiba 260-8682, Japan Received 8 August 1998 ; Revised manuscript accepted 28 November 1998 Abstract. A new fossil conifer, Pseudofrenelopsis glabra sp. nov., (Cheirolepidiaceae) is described based on a single specimen obtained from the Lower Cretaceous Yezo Group (Albian) of Hokkaido, Japan. The new species is characterized by cuticle possessing thin periclinal walls, a well-developed hypodermis, and absence of trichomes on internode and outer leaf surface. Recently, the author described Frenelopsis pombetsuensis from the Lower Cretaceous Yezo Group (Albian) of Hokkaido. The family Cheiro- lepidiaceae is a diagnostic taxon of the Ryoseki-type element that is reported only from the Ryoseki- and the Mixed-type floras. Thus Pseudofrenelopsis glabrais the second evidence of the Ryoseki-type element from Hokkaido. Key words: Albian, conifer, Hokkaido, Middle Yezo Group, Pseudofrenelopsis glabra, Ryoseki-type floras. Introduction Jurassic and Early Cretaceous floras in eastern Eurasia have been classified by Kimura (1980, 1987) and Ohana and Kimura (1995) into three characteristic floras, the Ryoseki- and the Tetori-type floras, and the Mixed-type floras com- prising elements of both the Ryoseki- and the Tetori-type floras. According to these authors, the Ryoseki-type floras grew under tropical to subtropical conditions with an annual long arid season, while the Tetori-type floras grew under temperate and moderately humid conditions. The genus Pseudofrenelopsis belongs to the extinct conifer family Cheirolepidiaceae. Although this family is a dominant group of Mesozoic conifers, its closer affinity remain equivocal. The members of the family have various kinds of shoot morphology ranging from Brachyphyllum- Pagiophyllum-type shoots bearing scale leaves to Frenelop- sis-Pseudofrenelopsis-type cylindrical segmented shoots bearing minute leaves. The single most reliable character of this family is possession of the pollen of the genus Classopollis Pflug (Watson, 1988). Although the plants yield- ing fossil remains attributed to the genus Pseudofrenelopsis were widely distributed during the Early Cretaceous (Ber- riasian-Albian) of North America, Europe, North Africa and Asia, they were apparently restricted to the Cretaceous (Table 1). The frenelopsids, which include the genus Pseudo- frenelopsis and the closely related genus Frenelopsis, have been used as indicator taxa of tropical to subtropical arid climate (Alvin, 1982). In east Asia the occurrence of the frenelopsids in fossil floras is restricted to the Ryoseki- and the Mixed-type floras. Although Frenelopsis is known from the Ryoseki-type floras of the Upper Jurassic to Lower Cretaceous in Japan, fossil remains assigned to Pseudo- frenelopsis have not been reported yet. In the present paper, the remains of shoot and associated cuticular fea- tures of Pseudofrenelopsis from Japan are described. Mikasa City Museum Katsurazawa Lake Xn | Figure 1. Map of Hokkaido, Japan showing the location of the Pombetsu Valley. Ken'ichi Saiki 30 Cheirolepidiaceous conifer from Lower Cretaceous of Hokkaido 31 Material and Methods Material—A compressed conifer shoot was found in the Pombetsu Valley about 60 km northeast of Sapporo (Figure 1). The specimen was obtained from the mudstone bed of the so-called “Main part of Middle Yezo Group”. The locality is situated between Matsumoto's outcrops Ik 2025 and 2031, from where the Albian ammonite Ammonoceratites yezoensis Yabe has been reported (Matsumoto, 1965, fig. 3). Methods.—Fossil remains were immersed in Schulze’s solution followed by diluted NaOH. The cuticle was mounted in Eukitt for light microscopy. For SEM observa- tion, cuticles were coated with Pt-Pd in a Hitachi E-1030 ion sputter and photographed with Hitachi S-800. All specimens used in this study are deposited in the Mikasa City Museum (MCM), Ikushumbets-nishikicho, Mi- kasa, Hokkaido. Systematic description Order Coniferales Family Cheirolepidiaceae Takhtajan, 1963 Genus Pseudofrenelopsis Nathorst, 1893 Remarks of the genus.—The diagnosis originally based only on the type species was emended by Watson (1977) after studying specimens of Frenelopsis varians Fontaine, which is now placed in this genus. Recently, Srinivasan (1995) emended the diagnosis of Pseudofrenelopsis based on new morphological characters of Puddledock material. Srinivasan's concept is followed here. Pseudofrenelopsis glabra sp. nov. Figures 2A-H, 3A-I Material.—Holotype, MCM-PO30 Horizon.—Main part of the Middle Yezo Group (Albian). Type locality —Pombetsu Valley, Mikasa, Hokkaido (Figure 1; ca. 4316°31”N, 141°59'20”E). The locality is about 80 m south of Matsumoto’s (1965) outcrop Ik 2031. Diagnosis.—Segmented shoot bears a simple spiral of leaves, each leaf encircling the stem. Leaf margin having hairs ; outer surface of both abaxial and adaxial leaf cuticle smooth, without trichomes. Internode cuticle well devel- oped. Outer surface of cuticle smooth, nonpapillate. Stomata arranged in longitudinal rows. Stomatal complex consisting of a pair of guard cells and 7-9 subsidiary cells. Guard cells sunken below a ring of subsidiary cells with irregularly oriented apertures. Stomatal pit rounded in sur- face view. Outer surface of subsidiary cells forming a raised rim bounded by a deep groove around stomatal pit. A well developed cutinized hypodermis of thin-walled cells cover- ing most of the internal surface of the cuticle. Description.—A single compressed shoot was obtained (Figures 2A, B). The shoot is segmented, bearing a simple spiral of leaves. Each of the leaves encircles the stem. The internode is 6-9 mm long and 4 mm wide (Figures 2A, B). Triangular part of the leaf is up to 1.5 mm high at a node (Figures 2B, C; 3A). The leaf margin has hairs up to 40 um long (Figures 2E ; 3B, C). Outer surface of both abaxial and adaxial leaf cuticle is smooth, without trichomes (Figures 3B- D). The internode cuticle is well developed, about 8 um in total thickness. The cuticle consists of outer periclinal epidermal wall about 3 «m thick, anticlinal wall and thinly cutinized hypodermis (Figure 3E). No dorsiventrality is ob- served (Figure 2F). Stomata are about the same optical density as the rest of cuticle and are arranged in well marked longitudinal rows in 7-9 rows per mm. Each row of stomata is a single stoma wide. 70-100 per mm? in density. (Figures 2F, G; 3F, G). The bands of epidermal cells between the rows of stomata are 20-70 um (1-3 cells) wide, consist of longitudinally arranged epidermal cells. The epidermal cells are elongated rectangular to polygonal in shape, 25-50 um long and 10-25 um wide (Figures 2F,G; 3G). Outer surface of the cuticle is smooth, nonpapillate (Figure 3F). The stomatal complex is 80-120 um in diameter, consists of a pair of guard cells and 7-9 subsidiary cells (Figure 3G). The guard cells are 40-70 uum long and 10 ~m wide and are sunken below a ring of subsidiary cells. The aperture of the stoma is irregularly oriented (Figure 3G). The stomatal pit is about 30 um in diameter and is rounded in surface view (Figures 3F, H). Outer surface of the subsidiary cells forms a raised rim bounded by a deep groove around stomatal pit. Each of the subsidiary cells has a single papilla projecting into the stomatal pit (Figures 2H ; SF, H, |). A well developed cutinized hypodermis of thin-walled cells cover most of the internal surface of the cuticle except for the region immediately beneath each stomatal apparatus. The hypodermal cells are rectangular or polygonal under the stomatal zone and are axially elongate rectangular under the nonstomatal zone (Figures 3E, G). Discussion.—Due to the fragmentary nature of the fossil specimen the arrangement of the branch system of Pseudo- frenelopsis glabra is uncertain. External and cuticular observations of the specimen clearly indicate the absence of a groove or suture separating the basal cushions, as seen in living species of the Cupressaceae. Although the epidermal cells are clearly visible with light microscopy (Figure 2G), SEM microscopy of the inner surface of cuticle shows only hypodermis and stomatal complexes, Figure 2. Pseudofrenelopsis glabra sp. nov. (MCM-P030). holotype showing leaf margins (I). A: Holotype (MCM-P030). B: Middle region of the C, D: Opposite sides of the same shoot fragment showing the margin of a single leaf (I). E: Light microscope image of the leaf margin showing short hairs. region showing fold represented by central dark line, and cuticles of both sides of the compressed specimen. of stomata and epidermal cells show no siginificant difference on both sides of the cuticles. of cuticle from the internodal region showing longitudinally arranged stomata, light microscope. of stomata, focused through the stomatal pit showing the papillae. F: Light microscope image of cuticle from internodal Arrangement G: Light microscope image H: Light microscope image Scale bars=5 mm in A-D; 100 um in E-H. 10} D Ken’ichi Saiki Figure 3. SEM micrographs of Pseudofrenelopsis glabra sp. nov. cuticle (MCM-P0O30). A: Triangular free part of leaf. B: Edge of a leaf, showing marginal hairs and outer surface of abaxial leaf cuticle. C: Enlarged photo of 3B showing the short marginal hairs and smooth outer surface of the abaxial (ab) and adaxial (ad) leaf cuticle. D: Surface view of adaxial leaf cuticle (ad) and inner view of cuticle from the internodal region (i). E: Section of cuticle showing cutinized epidermis (c) and hypodermis (h). F: Outer view of cuticle from the internodal region showing mouth of stomatal pit. G: Cuticle from the internodal region showing longitudinally arranged stomatal complexes. Inner view of stomatal complexes showing the guard cells (g), and subsidiary cells (s). H: Outer view of a stoma showing the rounded mouth of the stomatal pit with papillae. 1: Section of stoma showing guard cells (g), and papillae in throat of stoma (p). Scale bars=500 um in A, B; 50 um in C, D, F-H; 10 um in E, I. 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ARSOU euou w7/ 002 0} dn wr QOL sawoyol} ur O’GpL 0} dn surey WW Q'} SoA wu 0'2-0'1 wu 67-01 ‘aou “ds eıgey6 ‘d euensioyjeu ‘q SIsuaueysiay ‘qd — SMOJ PSUIJEP [JOM 9u0U auou wit G-€ sırey Jnoyym sırey NOUJIM ww z euou WW ÿ-G'e ww 9-G SMOJ pauyap |jem euou ee||ided ete] um wr/(gZ-)01-9'1(-9) surey 1noyym Ajjeuwlou sirey 1NOyuMm ww Z auou WLU g'g-& WLW OL-G'G sisuazjejep ‘d SMOJ jeulpnyBuo| euou jussaud Ajjensn wi! G'2-G juesaid sirey uw” O8 0} dn sie WLU GL auou WWW G'/-€ wu LLG esoyided ‘d SMOJ peuljep [JOM paziulynd em surey Buo Alan 0} euou ur (€ juasaid surey uw” 08 0} dn sırey WW Z UO} ‚uedo, SOS UI > WLU | esoweJsao4ed ‘4 PES, ul peueyeos suolysno sseq-jes| ,uado,, ul uw” 08 0} dn ur” OLL-OS juasaid suey uw” 09 0} dn surey WW G'| auou ww J-¢ wu /1-Gl SUBLIEA ‘d ‘saioads payejaı pue ‘aou ‘ds eiqe{6 sIsdojauaopnesd Jo saorawoydiow antpereduio9 Loge. jueusBueie |eYEWO}S sıwlspodAy paziuijing SI89 jewıopıdo uo SIIEU JO SAWOYOH | SSaUMOIU} a|o1n9 apouss}u| jee] JO aoeNs jeixepe uo siley JO SAWOYOU | ulBuew yea yes] 99 jo u}Bus] WNWIXeIN def 10 aunyns Jo aouasald UIPIM SpouIsqu] u}Bus| apousa}u| saloadg/ SiJoBIeUN 34 Ken'ichi Saiki because the epidermal cells are covered by cutinized hypodermis (Figure 3G). Comparison.—Although the present specimen is fragmen- tary, both external and cuticular features of the specimen correspond well with the diagnosis of Pseudofrenelopsis Nathorst emended by Srinivasan (1995) in its segmented shoot bearing a simple spiral of leaves, smooth cylindrical internode, and guard cells sunken below ring of subsidiary cells. Among the species of Pseudofrenelopsis previously de- scribed, the European P. varians (Fontaine) Watson and American P. parceramosa (Fontaine) Watson differ from P. glabra in possessing an extremely thick cuticle and having trichomes on the adaxial surface of the leaf cuticle (Watson, 1977). Although various species of Pseudofrenelopsis have been reported from China, most are provided with brief descrip- tions (Zhou, 1995). Recently, Zhou (1995) reexamined and combined the Chinese Pseudofrenelopsis into the following three species : P. papillosa (Chow et Tsao) Zhou, P. dalatzen- sis (Chow et Tsao) Zhou, and P. heishanensis Zhou (Table 1). Pseudofrenelopsis glabra is similar to these Chinese species in possessing a thinner internode cuticle than the European and American species. Pseudofrenelopsis dalatzensis and P. heishanensis can be distinguished from P. glabra by the stellate rim of the stomatal pit and absence of hairs on their leaf margins. The shape of the cells, smooth periclinal walls, and thin anticlinal walls of the hypodermis of Pseudofrenelopsis glabra (Figures 3G, E) are very similar to the “epidermal cells” of Pseudofrenelopsis heishanensis described by Zhou (1995). However, detailed light and SEM microscopy of P. hei- shanensis is required prior to meaningful comparison of P. heishanensis and P. glabra. Pseudofrenelopsis papillosa, redescribed in detail by Zhou (1995), possesses the most similar cuticle to that of P. glabra in having hairs on the margin of the leaf, round stomatal pits, and a thin cuticle. These resemblances may indicate a close phylogenetic relationship between these two species. Pseudofrenelopsis glabra is however, clearly distinguished from P. papillosa by a smaller number of subsidiary cells and absence of trichomes on the outer surface of the leaf adaxial cuticle. Paleophytogeography.—Since Kimura (1961,1975) has divided the Late Jurassic-Early Cretaceous floras of Japan and its adjacent areas into the Ryoseki-type and the Tetori type floras, this paleophytogeographical distinction has been extended to East Asia with some modification, and the Mixed-type flora that consist predominantly of the Ryoseki type element and subordinate Tetori-type element was added (Kimura, 1980, 1987 ; Kimura and Ohana, 1992 ; Cao, 1994 ; Ohana and Kimura, 1995). Although the Mesozoic flora of Hokkaido is famous for its well preserved permineralized materials, the stratigraphic range of these materials is restricted to the Upper Cretaceous (Nishida, 1991). So far, the absence of Jurassic and Lower Cretaceous fossil plants from Hokkaido had prevented comparison of the Early Cretaceous flora of Hokkaido with the Ryoseki- and the Tetori-type floras. Recently, Saiki (1997) described Frenelopsis pombetsuensis, from the Lower Cretaceous Yezo Group (Albian) of Hokkaido. The family Cheirolepidiaceae is a diagnostic taxon of the Ryoseki-type element reported only from the Ryoseki- and the Mixed-type floras (Ohana and Kimura, 1995). Thus, Pseudofrenelopsis glabra is the second evidence of the presence of Ryoseki-type element from Hokkaido. Ohana and Kimura (1995) estimated that the Ryoseki-type floras flourished under tropical or subtropical conditions with an annual long arid season. Their idea is consistent with the thermophilous nature of frenelopsids proposed by Alvin (1982) based on the distribution of frenelopsids of the world and their possession of a thick cuticle. However, the two frenelopsids species from Hokkaido lack two of the xeromor- phic features observed in many other frenelopsids, namely, a thick cuticle and trichomes on the internode surface. The cuticle thickness of eight species listed in Alvin (1982) are 8- 110 um thick in their periclinal wall rather than 3 um and 3- 4 um thick as in Frenelopsis pombetsuensis and Pseudo- frenelopsis glabra respectively. The cuticular features of Frenelopsis pombetsuensis and Pseudofrenelopsis glabra may reflect the rather humid condition inferred for the Albian of Pombetsu, rather than the xeric conditions from other regions of the world where frenelopsids were distributed (Alvin, 1982). This assumption is consistent with recent palynological data indicating that the group inhabited a variety of ecological niches (Watson, 1988). Acknowledgments The author thanks T. Kimura, director of the Institute of Natural History, Tokyo, for his critical reading the manuscript and his helpful suggestions ; M. Futakami, |. Obata, M. Ma- tsukawa, Y. Taketani, M. Ito and H. Nagata for their encour- agement and helpful suggestions. Thanks are also extended to Ben A. LePage, University of Pennsylvania, for his kindness in critically reading the manuscript. This study was supported by the Ishikari River Local Head Office, Hokkaido Development Bureau. References cited Alvin, K.L., 1977 : The conifer Frenelopsis and Manica in the Cretaceous of Portugal. Palaeontology, vol. 20, p. 387- 404. Alvin, K.L., 1982 : Cheirolepidiaceae : Biology, structure and paleoecology, Review of Palaeobotany and Palynology, vol. 37, p. 71-98. Alvin, K.L., Spicer, R.A. and Watson, J., 1978: A Classopol- lis-containing male cone associated with Pseudo- frenelopsis. Palaeontology, vol. 21, p. 847-856. Cao, Z., 1994: Early Cretaceous floras in Circum-Pacific region of China. Cretaceous Research, vol. 15, p. 317- 332. Chow, T.Y. and Tsao, C.Y. 1977: On eight new species of conifers from the Cretaceous of East China with refer- ence to their taxonomic positiion and phylogenetic relationship. Acta Palaeontologica Sinica, vol. 16, no. 2, p. 165-181. (in Chinese with English summary) Kimura, T., 1961: Mesozoic plants from the Itoshiro Sub- Cheirolepidiaceous conifer from Lower Cretaceous of Hokkaido group, the Tetori Group, Central Honshu, Japan. part 2. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 41, p. 21-32. Kimura, T., 1975: Notes on the Early Cretaceous floras of Japan. Bulletin of the Tokyo Gakugei University, Series 4, vol. 27, p. 217-257. Kimura, T., 1980: The present status of the Mesozoic land floras of Japan. Professor Saburo Kanno Memorial Volume, p. 379-413. Tsukuba University. Kimura, T., 1987: Geographical distribution of Palaeozoic and Mesozoic plants in East and Southeast Asia. In, Taira, A. and Tashiro, M. eds., Historical Biogeography and Plate Tectonic Evolution of Japan and Eastern Asia, p. 135-200. Terrapub, Tokyo. Kimura, T. and Ohana, T., 1992: Cretaceous palaeobotany and phytogeography in Eastern Eurasia. Palaeontological Society of Korea, Special Publication, no. 1, p. 27-34. Matsumoto, T., 1965: A monograph of the Collignoni- ceratidae from Hokkaido, part1. Memoirs of the Fac- ulty of Science, Kyushu University, Series D, no. 16, p. 1-80. Nishida, H., 1991: Diversity and significance of Late Cretaceous permineralized plant remains from Hok- kaido, Japan. Botanical Magazine Tokyo, vol. 104, p. 253-273. Ohana, T. and Kimura, T., 1995: Late Mesozoic phytoge- ography in eastern Eurasia, with special reference to the ww in origin of angiosperms in time and site. Proceedings of 15th International Symposium of Kyungpook National University, p. 293-328. Saiki, K., 1997 : Frenelopsis pombetsuensis : a new cheiro- lepidiaceous conifer from the Lower Cretaceous (Albian) of Hokkaido, Japan. Paleontological Research, vol. 1, no. 2, p. 126-131. Srinivasan, V., 1995: Conifers from the Puddledock locality (Potomac Group, Early Cretaceous) in eastern North America. Review of Palaeobotany and Palynology, vol. 89, p. 257-286. Watson, J., 1977: Some lower Cretaceous conifers of the Cheirolepidiaceae from the U.S.A. and England. Palaeontology, vol. 19, p. 715-749. Watson, J., 1988: The Cheirolepidiaceae. In, Beck, C.B. ed., Origin and Evolution of Gymnosperms, p. 382-447. Columbia University Press, New York. Zhou, Z., 1995: On some Cretaceous pseudofrenelopsids with a brief review of cheirolepidiaceous conifers in China. Review of Palaeobotany and Palynology, vol. 84, p. 419-438. Zhou, Z. and Cao, Z., 1979: Some Cretaceous conifers from southern China and their stratigraphical significances. In, Institute of Vertebrate Palaeontology and Palaeoanthropology, and Nanjing Institute of Geology and Palaeontology, Academia Sinica eds, Mesozoic and Cenozoic Red Beds of Southern China, p. 218-222. Science Press, Beijing. Ikushumbets-nishikicho #4 5/$#H), Mikasa =*, Pombetsu #1] Paleontological Research, vol. 3, no. 1, pp. 36-40, 3 Figs., April 30, 1999 © by the Palaeontological Society of Japan The first record of Mesoturrilites (Ammonoidea) from Hokkaido (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin — LXXxXill) TATSURO MATSUMOTO and AKITOSHI INOMA c/o Faculty of Science, Kyushu University, Fukuoka 812-8581, Japan 6-29-19 Daida, Setagaya, Tokyo 155-0033, Japan Received September 3 1998 ; Revised manuscript accepted 22 November 1998 Abstract. Several small specimens collected years ago by A.l. from a locality in the Soeushinai area of Hokkaido are now identified as Mesoturrilites boerssumensis (Schlüter, 1876). The species has been reported from the Lower Cenomanian of western and central Europe and western Asia. Our material is also referred to the Lower Cenomanian on the biostratigraphic evidence. This may be the first record of Mesoturrilites in the northern Pacific region. Key words : Cenomanian, geographic distribution, Hokkaido, Mesoturrilites, Pacific region, Turrilitidae Introduction A number of species belonging to Mariella, Pseud- helicoceras, Ostlingoceras, Neostlingoceras, Turrilites and Hypoturrilites of the family Turrilitidae [Ammonoidea] show worldwide distribution. Some of them occur fairly commonly in the Upper Albian and Cenomanian strata in Japan, although many of them are waiting for complete descriptions. In this paper a species of Mesoturrilites from Hokkaido is described. Stratigraphic setting The area concerned, called “Soeushinai’, was geologically mapped by Hashimoto et al. (1965) and has been recently reinvestigated by Nishida et al. (1996, 1997, 1998a, b). According to these authors, a thick series of strata called the Middle Yezo Subgroup of late Albian through Turonian age, is extensively exposed in this area. The subgroup is sub- divided into Members My1 to My8 in a revised scheme of Nishida et al. (1996, fig. 10). The specimens described below were contained in a transported nodule obtained by A.l. in 1959. That nodule was collected in the upper reaches of the Sanjussen-zawa, a tributary of the River Uryu. The nodule is interpreted as a derivative from Member Mys. This member consists primarily of mudstones which have sometimes fine-grained sands or sandy laminae and contain commonly calcareous nodules. Ammonoids occur fairly abundantly in Member My3 together with inoceramids and other mollusks. Some of them were described by Matsu- moto and Inoma (1975, 1991) and Inoma (1980) and also amply listed by Nishida et a/. (1996, 1997). The fauna forms the Assemblage Zone of Graysonites adkinsi, indicating the lower part of the Lower Cenomanian. The overlying Member My4 is composed of ill-sorted conglomerates in some parts and predominant sandstones with some mudstones and conglomerates in other parts. It is poor in fossils. The succeeding Member My5 consists mainly of mudstones which contain numerous inoceramids with some associated ammonoids, representing the rest of the Cenomanian. The Inoma’s locality, numbered Al-72803, is concisely indicated in a map by Matsumoto and Inoma (1975, fig. 2) and more precisely in Figure1. A fossiliferous nodule contains small specimens of Algericeras proratum (Coquand) and Euhystrichoceras cf. nicaisei (Coquand) besides those of Mesoturrilites described herein. At another locality, R7239p, about 70m NEE of AI-72803, Y. Kawashita and N. Egashira obtained another ammonite which is identified by T.M. with Gabbioceras yezoense Shigeta. The three ammonite species indicate an early Cenomanian age and the mud- stones around the above localities are referable to Member My3. Incidentally, as a result of Y. Inoue’s examination of foraminifera, the strata exposed in the source area of the Sanjussen-zawa, including localities R7238, R7231, R7232, R7233 and R7234, have proved to be Member My5 (middle to upper part of the Cenomanian) (for details see Nishida et al., 1998a). The two members My3 and My5 are probably in fault contact (Figure 1). Repository The specimens described below have numbers with the prefix TKD, which is the abbreviation of “Tokyo Kyoiku Daigaku [Tokyo University of Education|”, where A.l. was a student. Since this university was closed, As collection of ammonoids from the Soeushinai area under TKD numbers has been temporarily stored in the Department of Geology, Mesoturrilites from Hokkaido 37 i # My3 ara AI-72803 i VER) re ’ FH 45° S - 100m S| Figure 1. Route map along the upper course of the Sanjussen-zawa, cited from Nishida et al., 1998a by permission. Inset is a map of Hokkaido in which the Soeushinai area is indicated by an arrow. Small solid circle : megafossil (in situ), cross : ditto (trantported nodule), solid square : microfossil sample, empty square: rock sample, tiny empty circle: conglomerate, dots: sandstone, grass: no outcrop, blank along the route: mudstone, broken line: fault (inferred), chain : boundary of lithostratigraphic units (members). All the locality numbers should have prefix R, except for Al-72803. Kyushu University in Fukuoka, but they should be eventually returned to the Deparrtment of Geosciences, Tsukuba University, Tsukuba, 305-0006 Japan, which is the new guise of the TKD. Morphological terms For the morphological terms used to describe the turrilitid ammonoids, we follow those of Wright and Kennedy (1996). Setting the apex of the turrical shell at the top, the terms upper and lower or adapical and adapertural | =adoral| are defined and the rows of tubercles or ribs on the face of each whorl are described in descending order as the first, the second and so on. Palaeontological description Order Ammonoidea Zittel, 1884 Suborder Ancyloceratina, Wiedmann, 1966 Family Turrilitidae Gill, 1871 Genus Mesoturrilites Breistroffer, 1953 Type species.—Turrilites aumalensis Coquand (1862, p. 323, pl. 35, fig. 5), by original designation of Breistroffer (1953, p. 1351). Diagnosis.— Turrilitid ammonoid with four rows of tubercles or ribs ; the upper row made up of ribs or rounded tubercles, the second and the third rows spirally elongated tubercles on semicontinuous, narrow ridges separated by a groove ; the fourth row of weak tubercles at the outer edge of the lower whorl surface ; faint ribs may be elongated from the fourth row of tubercles toward a narrow umbilicus. Remarks.—The lectotype and paralectotypes of the type species have been photographically illustrated by Wright and Kennedy (1996, text-fig. 146A-G). At present five species are known in Mesoturrilites. The distinction between species is based on the size of the apical angle, mode of ribbing and/or tuberculation, whorl shape etc. Atabekian (1985, p.75) referred Turrilites col- canapi Boule, Lemoine and Thevenin, 1907 to Mesoturrilites. However, we agree with Spath (1937, p. 523) and also Wright and Kennedy (1996, p. 323) on their assignment of T. col- canapi to Ostlingoceras. The phylogenetic origin of Mesoturrilites is uncertain, but it can likely be sought in some form of Mariella. A sulcate variety of Mariella oehlerti (Pervinquiere) may be a candidate, as Pervinquiére (1910, p.55, pl.5, fig.17) has already mentioned its affinity to Mesoturrilites aumalensis. Wright and Kennedy (1996, p. 346) have suggested Mariella bicar- inata (Kner) as another allied form. The type species and some other species of Mesoturrilites have been recorded from the Lower Cenomanian of both ine 38 Tatsuro Matsumoto and Akitoshi Inoma Tethys and Boreal provinces. Mesoturrilites boerssumensis (Schlüter, 1876) Figures 2 and 3 Turrilites börssumensis Schlüter, 1876, p. 129, pl. 38, figs, 6, 7. Turrilites (Mesoturrilites) boerssumensis Schlüter. Immel, 1979, p. 636, pl. 4, fig. 4; Hiss, 1982, p. 190, pl. 7, figs. 11, 12 ; Atabekian, 1985, p. 75, pl. 27, figs. 3, 4. Mesoturrilites boerssumensis (Schlüter). Wright and Ken- Figure 2. Mesoturrilites boerssumensis (Schlüter). 1. TKD30089A, two lateral (a,b) and basal (c) views. 2. TKD30089B, two lateral (a, b) views. 3. TKD30089C, two lateral (a, b) views. All x 2. Figure 3. Mesoturrilites boerssumensis (Schlüter). Suture of TKD30089C, showing relative position of the ribs and tubercles by dotted lines. Approximately x 8. nedy, 1996, p. 347, pl. 105, figs. 4, 20 (with full synonymy) ; Lehmann, 1998, p. 36, pl. 5, fig. 5. Lectotype.—The original of Schlüter, 1876, pl. 38, figs. 6, 7, from the Cenomanian Planer near Borssum, Germany, by subsequent designation of Juignet and Kennedy (1976, p. 67). Material—Four specimens, TKD30089A (Figure 2-1), TKD30089B (Figure 2-2), TKD30089C (Figure 2-3 ; Figure 3) and TKD30089D (unillustrated). They were removed by Al. from a transported nodule at locality Al-72803 in the upper reaches of the Sanjussen-zawa of the Soeushinai area, northwestern Hokkaido (Figure 1). Description.—TKD30089A consists of four whorls with estimated tower height 28.8 mm, apical angle about 19°, height and diameter of the preserved last whorl 5.4 mm and 11.2mm respectively. Other three are smaller than the above and incomplete, representing younger stages. The main part of the exposed whorl face is flattened or slightly convex and the interwhorl junction is feebly im- pressed. The ornament is typical for Mesoturrilites. On the upper half of the exposed whorl face there are slightly prorsiradiate ribs of moderate breadth and density (Figure 2- 1). They number 21 per whorl at diameter of 11mm in TKD30089A and 16 or 15 at diameter 7 or 6mm in TKD30089B or TKD30089C. At about the middle of the whorl face the ribs terminate at tubercles of the first row. These tubercles are subrounded at the base and pointed at the top, as far as the test is well preserved. The tubercles of the second row are narrowly clavate and rest on a blunt spiral ridge. They correspond in number to the tubercles of the first row but are displaced adaperturally. The space between the first and the second rows of tubercles forms a smooth band and may appear to be slightly concave on the internal mould. The tubercles of the third row are narrowly clavate and aligned along the narrow ridge along the lower seam of the whorl. The narrow interspace between the second and the third rows of clavi is distinctly sulcate. As is shown by TKD30089A, the spiral groove between the second and third rows of semi-continuous ridges is immedi- ately above the interwhorl junction in early growth stages, but later it is covered by the shell layer of the succeeding whorl (Figure 2-1). The tubercles of the fourth row are close to those of the third row, but they are aligned on the outer margin of the lower whorl face. Weak ribs run from them toward a narrow umbilicus, showing slightly rursiradiate Curvature (Figure 2-1c). A septal suture of a young stage is exposed on the whorl face of TKD30089C. As is shown in Figure 3, the saddle E/L is much broader than L/U. The relative disposition of the tubercles with respect to the sutural elements in shown is the same figure. Discussion.—The specimens described above are un- doubtedly identified with Mesoturrilites boerssumensis (Schluter, 1876), redefined by Wright and Kennedy (1996, p. 347). In view of the variation of the rib density with growth and between individuals, the 17 ribs to a whorl specified in Schlüter's (1876, p. 636) description may not be incorrect. Hiss (1982, p.190) counted 20 ribs on an example from Westphalia. Wright and Kennedy (1996, p. 347) estimated Mesoturrilites from Hokkaido 39 as many as 24-26 ribs per whorl in a specimen from England, but 9 or 10 ribs are shown on its illustrated face of slightly less than half a whorl (op. cit., pl. 105, fig. 4) as in our TKD30089A (Figure 2-1). Hitherto described specimens, comprising those from Hokkaido, are more or less small, with diameters of the preserved last whorl less than 25mm. The small size may be, therefore, a diagnostic character of this species. How- ever, further investigation is required to search out a com- pletely preserved specimen with a rostrate peristome and also to examine the problem of dimorphism. Occurrence.—As for material. M. boerssumensis has been reported from the Lower Cenomanian of Germany (Westphalia and Bavaria), England, Poland and southern Turkmenistan (see synonymy list). Now its distribution is extended to Hokkaido. This may be the first record of Mesoturrilites from the northern Pacific region. Acknowledgements We are much indebted to C.W. Wright and W.J. Kennedy for their kind help during this study. Thanks are extended to Tamio Nishida, Seiichi Toshimitsu and Kazuko Mori for practical support. References cited Atabekian, A.A., 1985: Turrilitids of the late Albian and Cenomanian of the southern part of the USSR. Acad- emy of Sciences of the USSR, Ministry of Geology of the USSR. Interdepartmental Stratigraphic Committee of the USSR, Transactions, vol. 14, p. 1-112, pls. 1-34. (in Russian) Boule, M., Lemoine, P. and Thevenin, A., 1907 : Cepha- lopode crétacés des environs de Diego-Suarez. An- nales de Paléontologie, vol. 2, p. 1-56, pls. 1-8. Breistroffer, M., 1953: L’evolution des Turrilitides albiens et cenomaniens. Comptes Rendus Hebdomadaires des Sciences de l'Académie des Sciences, vol. 237, p. 1349-1351. Coquand, H., 1862: Géologie et paléontologie de la region sud de la Province de Constantine. Mémoires de la Société d’Emulation de la Provence, Marseille, vol. 2, p. 1-320, 321-341 (supplement), pls. 1-35. Hashimoto, W., Nagao, S. and Kanno, S., 1965 Soeushinai. Explanatory Text of the Geological Map of Japan, scale 1: 50,000, p.1-92, quadrangle map. Geological Sur- vey of Hokkaido. (in Japanese with English abstract) Hiss, M., 1982 : Ammoniten des Cenomans von Südrand der westfälischen Kreide zwischen Unna und Möhnesee. Paläontologische Zeitschrift, vol. 56, p. 177-208, pls. 7- 9. Immel, H., 1979: Cenoman-Ammoniten aus den Losen- steiner Schichten der Bayerischen-Alpen. In, Wied- mann, |. ed., Aspekte der Kreide Europas. International Union of Geological Sciences, Ser. A, vol. 6, p. 607-644, 4 pls. Inoma, A., 1980: Mid-Cretaceous ammonites from the Shumarinai-Soeushinai area, Hokkaido. Part2. Pro- fessor Saburo Kanno Memorial Volume, Tsukuba, p. 167-183, pls. 21-22. Juignet, P. and Kennedy, W.J., 1976: Faunes d’ammonites et biostratigraphie comparee du Cenomanien du nord ouest de la France (Normandie) et du sud de l’Angleter- re. Bulletin trimestriel, Société Geologique Normandie Amis Muséum Havre, vol. 63, p. 1-193, pls. 1-34. Lehmann, J., 1998: Systematic palaeontology of the ammo- nites of the Cenomanian-Lower Turonian (Upper Cretaceous) of northern Westphalia, north Germany. Tubingen Geowissenschaftliche Arbeiten (TGA), Reihe A, vol. 37, p. 1-58, pls. 1-5. Matsumoto, T. and Inoma, A., 1975 : Mid-Cretaceous ammo- nites from the Shumarinai-Soeushinai area, Hokkaido. Part |. Memoirs of the Faculty of Science, Kyushu University, Series D, Geology, vol. 23, no. 2, p. 263-293, pls. 38-42. Matsumoto, T. and Inoma, A., 1991: The mid-Cretaceous ammonites of the family Kossmaticeratidae from Japan. Part 3. Descriptions of the species from the Shuma- rinai-Soeushinai area of Hokkaido. Palaeontological Society of Japan, Special Papers, no. 33, p. 103-122, pls. 25-30. Nishida, T., Matsumoto, T. and Inoue, Y., 1998a: For- aminifera from the Cretaceous System in the Shuma- rinai Valley of Hokkaido. Journal of the Faculoy of Culture and Education, Saga University, vol. 3, no.1, p. 301-331. (in Japanese with English abstract) Nishida, T., Matsumoto, T., Kawashita, Y., Egashira, N., Aizawa, J. and Ikuji, Y., 1997: Biostratigraphy of the middle part of the Cretaceous Yezo Group in the Soeushinai area of Hokkaido—with special reference to the transitional part from Lower to Upper Cretaceous : supplement—. Journal of the Faculty of Culture and Education, Saga University, vol.1, no.1, p. 237-279. (in Japanese with English abstract) Nishida, T., Matsumoto, T., Kawashita, Y., Egashira, N. and Aizawa, J., 1998b: Characteristics of the Cretaceous stratigraphy in the Shumarinai Valley of Hokkaido. Journal of the Faculty of Culture and Education, Saga University, vol.1, no. 2, p. 143-181. (in Japanese with English abstract) Nishida, T., Matsumoto, T., Yokoi, K., Kawashita, Y., Kyuma, Y., Egashira, N., Aizawa, J., Maiya, S., Ikuji, Y. and Yao, A., 1996: Biostratigraphy of the Cretaceous Middle Yezo Group in the Soeushinai area of Hokkaido—with special reference to the transitional part from Lower to Upper Cretaceous—. Journal of the Faculty of Educa- tion, Saga University, vol.44, no.1, p.65-149. (in Japanese with English abstract) Pervinquière, L., 1910: Sur quelques ammonites du Crétacé algérien. Mémoires de la Société Geologique de France, Paléontologie 17, memoir 42, p. 1-86, pls. 1-7. Schlüter, C., 1876: Cephalopoden der oberen deutschen Kreide. Palaeontographica, vol. 24, p. 121-264, pls. 36- 55. Spath, L.F., 1937 : A monograph of the Ammonoidea of the Gault, part 12. Monograph of the Palaeontographical Society, London, p. 49-540, pls. 57-58. Wright, C.W. and Kennedy, W.J. 1996 : The Ammonoidea of the Lower Chalk, part 5. Monograph of the Palaeonto- graphical Society, London, no. 601, p. 320-403, pls. 95 124. 40 Tatsuro Matsumoto and Akitoshi Inoma Hokkaido 4b#i8, Sanjussen-zawa =-+-# Ri, Shumarinai K##N, Soeushinai EN, Uryu N, Yezo thas Paleontological Research, vol. 3, no. 1, pp. 41-48, 5 Figs., April 30, 1999 © by the Palaeontological Society of Japan Early Silurian actinocerid and orthocerid cephalopods from the Kerman area, East-Central Iran SHUJI NIKO’, YOSHITAKA KAKUWA’, DAISUKE WATANABE’ and RYO MATSUMOTO’ ‘Department of Environmental Studies, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashihiroshima 739-8521, Japan "Department of Earth Science and Astronomy, College of Arts and Sciences, University of Tokyo, Komaba 153-0041, Japan “Geological Institute, University of Tokyo, Hongo 113-0033, Japan Received 23 September 1998 ; Revised manuscript accepted 22 February 1999 Abstract. Six species of uncoiled cephalopod, including the actinocerids Actinoceratidae, gen. and sp. indet., Armenoceras banestanense sp. nov., A. sp., Elrodoceras sp. and Huroniella iranica sp. nov., and an orthocerid Proteoceratidae ?, gen. and sp. indet., are present in collections made recently from an unnamed formation near Banestan village in the Kerman area of southern East-Central Iran. The cephalopod fauna contains forms closely related with those from Laurentia, and is considered to be of Early Silurian age. This discovery reveals that the geologic age of these cephalopod-bearing horizons should be revised from a vague late Ordovician or early Silurian one. These horizons are correlative with the Niur Formation in the Shirgesht area of northern East-Central Iran. Key words: Actinocerida, cephalopods, Early Silurian, Iran, Orthocerida Introduction and geologic setting During the course of field work in February, 1996, several uncoiled cephalopods were discovered by two of us (Y.K. and D.W.) at three localities near Banestan village in the Kerman area of southern East-Central Iran (Figure 1). The purpose of this paper is to document the fauna and to discuss its implications. The specimens are deposited in the University Museum of the University of Tokyo (UMUT). Until its separation and northward drifting at or near the Permian-Triassic boundary, the Iran terrane belonged to the Gondwana continent, and the Kerman area was part of a carbonate platform around the margin of Gondwana (e.g., Lensch et al., 1984). The geology of the Kerman area has been described by Huckriede et al. (1962), Zohrenbakhsh and Vahdati Daneshmand (1992) and Richards et al. (1994). These investigatiors discerned three units in the Lower to Middle Paleozoic strata: Upper Cambrian to Lower Or- dovician carbonates of the Mila Formation, the Arenig (upper Lower Ordovician) graptolite shale of the Katkoyeh Forma- tion, and an unnamed formation probably ranging from Upper Ordovician to Middle Devonian that mainly consists of clastics with subordinate carbonates. The cephalopods described herein occur in argillaceous and/or bioclastic limestone of the unnamed formation (Figure 2). The cephalopod-bearing horizons have been described as “orthoceras limestone” by Huckriede et al. (1962), and regard- ed as being of late Ordovician or early Silurian age. How- ever, the exact biostratigraphic range of the cephalopod- bearing horizons has so far been a matter of debate. Detailed analysis of morphologic features of the present cephalopods resulted in the identification of five Early Silurian actinocerid and one orthocerid species that provide insights into the precise age and paleobiogeographic affin- ities of the fauna. This is the first modern taxonomic treat- ment of Silurian cephalopods from the Iran terrane. Systematic paleontology Subclass Actinoceratoidea Teichert, 1933 Order Actinocerida Teichert, 1933 Family Actinoceratidae Saemann, 1853 Genus and species indeterminate Figures 3-7, 5-5, 6 Discussion.—A single incomplete specimen of a gently cyrtoconic (?) phragmocone is assigned to the Actinocer- atidae, genus and species indeterminate, based on its rela- tively long and normal cyrtochoanitic septal necks and the high ratio (at least 3.2) of maximum diameter/length of its siphuncular segments. The restricted development of the annulosiphonate 42 Shuji Niko et al. = N \ \ \ 2 ~ by) © ise) Figure 1. Index map of fossil localities (1-3) in the Ker- man area (Small arrow in inset), southern East-Central Iran. deposits on the ventral siphuncular wall and the straight radial canals projecting to the vicinity of brims are an unusual diagnosis for the family and indicate a possibility that the species represents a new genus. Unfortunately the ventral shell is not preserved in the only specimen available. Until additional material is found, the present material is consid- ered too poor to justify naming it to the generic level. Material and occurrence.—UMUT PM 27332, 72 mm in length, from locality 3. Family Armenoceratidae Troedsson, 1926 Genus Armenoceras Foerste, 1924a Type species.—Actinoceras hearsti Parks, 1913. shale & siltstone [= © Do Oosr0 = conglomerate E Di 5 == = limestone T ® E 2 dolostone € 3 pillow lava & volcanic breccia Inne ale | LI Tun | [hi] Katkoyeh Formation If | ; el is à 0 [0] al D le Al . oll: | 200m (part) Oo Formation Mila Figure 2. Generalized stratigraphic section of the Lower to Middle Paleozoic rocks near Banestan village in the Ker- man area. Stratigraphic horizons of each locality are indicat- ed. Armenoceras banestanense sp. nov. Figures 3-1—6 Diagnosis.— Armenoceras with smaller ratio of maximum siphuncular diameter to shell diameter (approximately 0.3- 0.4), very narrow adnation areas in dorsal siphuncular wall ; cameral deposits well developed ; central canal situated on dorsal margin. Description.—Orthoconic shells with circular cross sec- tions, moderate shell expansion for the genus, lacking Figure 3. 1-6. Armenoceras banestanense sp. nov., 1-4,6: holotype, UMUT PM 27328, 1, dorsoventral thin section, venter on left, x2, 2, dorsoventral thin section, showing details of ventral wall of siphuncle, 14, 3, dorsoventral thin section, showing details of dorsal wall of siphuncle, note very narrow adnation area, 14, 4, dorsoventral thin section, showing details of ventral shell, x5, 6, transverse thin section of adoral end, venter down, x2, 5: paratype, UMUT PM 27327, weathered surface of dorsal side, coated with ammonium chloride, x2. 7. Actinoceratidae, gen. and sp. indet., UMUT PM 27332, dorsoventral thin section, venter on right, x 2. Early Silurian cephalopods from Iran 44 conspicuous surface ornamentation ; adoral end of imper- fect phragmocone of holotype attains approximately 25 mm (slightly deformed) in diameter. Septa closely spaced, moderately shallow; siphuncle large, ratio of maximum siphuncular diameter to shell diameter is small for genus, approximately 0.3-0.4, submarginal in position ; septal necks very short, 0.15-0.21 mm in length, strongly recurved cyrto- choanitic ; brims short for genus, 0.44 mm in well preserved dorsal brim of holotype, in contact with apical surface of septa; diameter of septal foramen 5.9-8.9 mm in holotype ; connecting rings broadly expanded ; adnation areas moder- ate to relatively narrow (their length in dorsoventral section approximately 0.9 mm) in ventral siphuncular wall, and very narrow (do. approximately 0.3 mm) in dorsal siphuncular wall ; maximum diameter/length ratio of siphuncular segments 3.5-4.0. Cameral deposits well developed, episeptal-mural and forming circumsiphuncular ridges, additional hyposeptal deposits recognized in ventral side of camerae; ventral endosiphuncular deposits fusing to form thick lining on siphuncular wall, differentiated into outer annuli and inner lining deposits ; profile of outer annuli laterally elongated elliptical in longitudinal section; development of endosi- phuncular deposits on dorsal siphuncular wall weak, sepa- rated annuli with semicircular profile in longitudinal section. Central canal situated on dorsal margin, branching off narrow radial canals, of which distal parts are curved adorally ; perispatia small, situated near adoral end of each connecting ring. Discussion.—Armenoceras banestanense sp. nov. is most similar to A. hearsti (Parks, 1913 ; 1915, pl. 6, fig. 5; Foerste, 1924a, pl. 13, fig. 4) which has a siphuncular position and a form ratio of the siphuncular segments like the new species. Armenoceras hearsti was reported from “Limestone Rapids” on the Severn River, Ontario, Canada, and derived from the Ekwan River or Attawapiskat Formation of late Llandovery (Early Silurian) age (Jin et al., 1993). However the former is distinguishable from the latter by its smaller siphuncle (ratio of maximum siphuncular diameter to shell diameter approxi- mately 0.45 in A. hearsti versus 0.3-0.4 in A. banestanense), its somewhat weaker inflation of the connecting rings with the narrower adnation area, and the marginal position of its central canal. The brims of Armenoceras banestanense and the cooc- curring A. sp. (this report) are frequently missing or obscured by diagenesis, thus they are apt to be incorrectly described as “achoanitic”. Material and occurrence.—Holotype, UMUT PM 27328, an incomplete phragmocone, 51 mm in length ; paratype, UMUT PM 27327, an incomplete phragmocone, 42 mm in length. Both from locality 3. Etymology.—The specific name is derived from the village Shuji Niko et al. named Banestan near the type locality. Armenoceras sp. Figures 4-5,7,8 Description.—Orthoconic shells with gradual shell expan- sion, shell diameter reaches 20 mm at adoral end of largest specimen (UMUT PM 27329). Siphuncle subcentral in position, consisting of strongly recurved cyrtochoanitic septal necks and expanded connecting rings with relatively wide adnation area; brims in contact with septa; maximum diameter/length ratio of siphuncular segments approximately 2.5. Cameral deposits episeptal-mural and hyposeptal ; endosiphuncular deposits of annuli have elliptical profile in longitudinal section. Nearly straight radial canals connect with prespatia in apical shell. Discussion.—This species is easily distinguished from Armenoceras banestanense sp. nov. by its subcentral siphun- cular position and the smaller form ratio of the siphuncular segments. Material and occurrence.—Two incomplete phragmocones, UMUT PM 27329, 62 mm in length, and 27330, 61 mm in length, from locality 3. Genus Elrodoceras Foerste, 1924b Type species.—Cyrtoceras indianense Miller, 1892. Elrodoceras sp. Figures 5-1—3 Description.—Siphuncle gently curved (?) and large, attains at least 15.5 mm in maximum diameter, with relatively low ratio of maximum diameter/length in siphuncular segment for armenoceratids, at approximately 2.5-2.7 ; siphuncular posi- tion submarginal (?). Septal necks bend adapically, thus septal foramen is funnel-shaped ; brims strongly recurved cyrtochoanitic, in contact with septa; connecting rings form very wide adnation area and moderately inflated free parts. Cameral deposits episeptal-mural and hyposeptal ; endosi- phuncular deposits well developed, annulosiphonate. Cen- tral canal surrounded by lining deposits that are darker in color than annulosiphonate deposits ; radial canal arched with branches. Discussion.—Except for the deposit-filled siphuncle, the shell of this only known specimen is broken and weathered on the dorsum, thus accurate shell shape and siphuncular position can not be determined in the present material. Nevertheless, this species appears most similar to Elrodocer- as in its siphuncular morphology such as the funnel-shaped Figure 4. venter on left, of ventral wall of siphuncle, 1-4, 6. Huroniella iranica sp. nov., holotype, UMUT PM 27326, isolated siphuncle, 1, dorsoventral thin section, <2, 2, transverse thin section of apical end, venter down, <2, 3, dorsoventral thin section, showing details <5, 4, dorsoventral thin section, showing details of dorsal wall of siphuncle, <5, 6, dor- soventral thin section, showing details of septal neck and radial canal in ventral wall of siphuncle, note contact layer and depression on apical surface of septum, section, venter on right, <14. 5,7,8. Armenoceras sp., 5,7: UMUT PM 27330, 5, dorsoventral thin <2, 7, dorsoventral thin section, showing details of ventral wall of siphuncle, x14, 8: UMUT PM 27329, weathered surface of ventral side, coated with ammonium chloride, x 2. Early Silurian cephalopods from Iran 46 Shuji Niko et al. septal foramen, arched radial canals and relatively low form ratio of the siphuncular segments. Material and occurrence.—UMUT PM 27331, 55 mm in length, from locality 3. Family Huroniidae Foerste and Teichert, 1930 Genus Huroniella Foerste, 1924a Type species.—Huronia inflecta Parks, 1915. Huroniella iranica sp. nov. Figures 4-1—4, 6 Diagnosis.—Huroniella with asymmetrical connecting rings ; siphuncular segments short ; adoral bending of septa lacking; width of septal foramen/distance of neighboring septal necks 2.3-3.0; perispatia wide, attain distal end of brim. Description.—Large straight siphuncle, 20.5 mm in lateral diameter of apical end of holotype; septal necks short, approximately 0.5mm in length, strongly recurved cyrto- choanitic ; brims 0.63-0.68 mm in length, in contact with apical surface of septa; diameter of septal foramen 12.5-14. O mm; shape of connecting rings asymmetrical in dor- soventral section, ventral connecting rings strongly inflated, bluntly pointed arcs with obliquely adoral direction in longitu- dinal section ; adnation area in adoral surface of septa very wide, forming contact layer by thickening of connecting ring ; in contrast to adoral surface of septa, relatively narrow in apical surface, contact layer also recognized where septa are weakly depressed ; dorsal connecting rings semicircular with narrow adnation area lacking evident contact layer ; siphuncular segments short for huroniids, width of septal foramen/distance of neighboring septal necks 2.3-3.0. Endosiphuncular deposits of annuli well developed leaving large central canal in a position slightly shifted from axis ; radial canals curving adapically and branching, to join wide perispatia, which attain distal end of brim. Discussion.—Huroniella iranica sp. nov. appears to be most like H. persiphonata (Billings, 1857 ; Foerste, 1927, pl. 44, fig. 1; Teichert, 1933, figs. 4, 20) from the upper Llandovery Jupiter Formation of Anticosti Island, Canada. The Lau- rentian species shares the asymmetrical profile of its con- necting rings with the present new species. The most obvious difference between these species is the septal morphology, i.e., a strong adoral bending of the septum is recognized in Huroniella persiphonata, but only a weak depression on the adoral septal surface is representative of H. iranica. In addition, the width of septal foramen/ distance of neighboring septal necks ratio (approximately 2 in H. persiphonata versus 2.3-3.0 in H. iranica) is also a diagnostic feature. Huroniella inflecta (Parks, 1915, pl. 6, fig. 4 ; Foerste, 1924a, pl. 16, figs. 2a, b; Teichert, 1933, fig.12), known from the “Limestone Rapids” in Ontario, is distinguished from the present species by having more strongly inflated dorsal connecting rings with a nearly symmetrical profile in dor- soventral section. Material and occurrence.—Holotype, UMUT PM 27326, an isolated and incomplete siphuncle 65 mm in length, from locality 1. Etymology.—The specific name in derived from Iran. Subclass Nautiloidea Agassiz, 1847 Order Orthocerida Kuhn, 1940 Superfamily Pseudorthocerataceae Flower and Caster, 1935 ? Family Proteoceratidae Flower, 1962 Genus and species indeterminate Figures 5-4, 7 Discussion.—The poorly preserved specimen consists of a gradually expanding orthoconic shell with relatively short camerae, subcentral siphuncle consisting of short cyrto- choanitic septal necks and inflated connecting rings. Its maximum diameter/length ratio of siphuncular segments is approximately 1.5, and cameral deposits are episeptal. This species probably belongs to the Proteoceratidae, and its large siphuncular segment ratio for an orthocerid suggests a possible relationship with Ephippiorthoceras, although the material is insufficiently preserved to identify any further. Material and occurrence.—Single incomplete phrag- mocone, UMUT PM 27333, 74 mm in length, from locality 2. Stratigraphic and paleobiogeographic implications The cephalopod species recognized at each locality are as follows : locality 1, Huroniella iranica sp. nov.; locality 2, Proteoceratidae ?, gen. and sp. indet.; and locality 3, Actinoceratidae, gen. and sp. indet., Armenoceras banes- tanense sp. nov., A. sp. and Elrodoceras sp. The most useful taxon for correlation is Huroniella, whose range is known with certainty from late Llandovery to early Wenlock strata in Laurentia and Baltica. Species similar to Huroniella iranica are found in the Anticosti Island and Hudson Bay areas and are of late Llandovery age. Flrodoceras is the only Silurian cephalopod previously known from Laurentia, Avalonia, Baltica and Siberia. Armenoceras banestanense sp. nov. is related to the late Llandovery species A. hearsti from the Hudson Bay area, and the genus is cosmopolitan Figure 5. 1-3. Elrodoceras sp., UMUT PM 27331, 1, dorsoventral thin section, venter on right, x2, 2, dorsoventral thin section, showing details of ventral wall of siphuncle, 5, 3, dorsoventral thin section, showing details of septal necks, radial canal and connecting ring in ventral wall of siphuncle, note adapical bending of septal necks, «14. 4, 7. Proteoceratidae ?, gen. and sp. indet., UMUT PM 27333, 4, longitudinal thin section, x2, 7, longitudinal thin section, showing details of siphuncle, <8. 5,6. Actinoceratidae, gen. and sp. indet., UMUT PM 27332, 5, dorsoventral thin section, showing details of ventral wall of siphuncle, arrows indicate septal necks, of siphuncle, 14. <14, 6, dorsoventral thin section, showing details of dorsal wall 47 Early Silurian cephalopods from Iran 48 Shuji Niko et al. and ranges from Middle Ordovician to Late Silurian in age. Besides cephalopods, the Wenlockian bryozoan species Trematopora beikhemensis is identified by S. Sakagami (per- sonal communication) from locality 1. Although locality 2 lacks a clear age indicator, lithologically the three horizons may belong to a stratigraphic unit without notable breaks. On the basis of this evidence, we infer that at least the cephalopod-bearing horizons in the unnamed formation indicate a late Llandovery (or early Wenlock) age, and are lithologically and chronostratigraphically correlative with the Niur Formation (Ruttner et al., 1968) in the Shirgesht area of northern East-Central Iran. On the other hand, the affinity of the cephalopod fauna is apparently with northeastern Laurentia. This new material suggests a faunal connection between Gondwana and Laurentia during Early Silurian times. Acknowledgments We with to thank Sumio Sakagami for providing unpub- lished data on a bryozoan associated with the present cephalopods. This research was supported by grant 0704194 from the Japanese Ministry of Education. References Billings, E., 1857: Report for the year 1856, of E. Billings Esq., palaeontologist, addressed to Sir William E. Logan, provincial geologist. Geological Survey of Canada. Report of Progress, for the years 1853-54-55-56, p. 247-345. Flower, R.H., 1962 : Notes on the Michelinoceratida. New Mexico Bureau of Mines and Mineral Resources, Mem- oir 10, p. 21-42, pls. 1-6. Flower, R.H. and Caster, K.E., 1985: The stratigraphy and paleontology of northwestern Pennsylvania. Part Il: Paleontology. Section A: The cephalopod fauna of the Conewango Series of the Upper Devonian in New York and Pennsylvania. Bulletins of American Paleontology, vol. 22, p. 199-271. Foerste, A.F., 1924a: Silurian cephalopods of northern Michigan. Contributions from the Museum of Geology, University of Michigan, vol. 2, p. 19-86, pls. 1-17. Foerste, A.F., 1924b: Notes on American Paleozoic cephalopods. Denison University Bulletin, Journal of the Scientific Laboratories, vol. 20, p. 193-268, pls. 21 42. Foerste, A.F., 1927 : Cephalopoda. In, Twenhofel, W.H. ed, Geology of Anticosti Island, p. 257-321, pls. 27-58. Canada Geological Survey, Memoir 154. Foerste, A.F. and Teichert, C., 1930: The actinoceroids of “ East-Central North America. Denison University Bulle- tin, Journal of the Scientific Laboratories, vol. 25, p. 201- 296, pls. 27-59. Huckriede, R., Kürsten, M. and Venzlaff, H., 1962. Zur Geologie des Gebietes zwischen Kerman und Sagand (Iran). Beihefte zum Geologischen Jahrbuch, no. 51, p. 1-197. Jin, J., Caldwell, W.G.E. and Norford, B.S., 1993: Early Silurian brachiopods and biostratigraphy of the Hudson Bay Lowlands, Manitoba, Ontario, and Quebec. Geo- logical Survey of Canada, Bulletin, vol. 457, p. 1-221. Lensch, G., Schmidt, K. and Davoudzadeh, M., 1984 : Intro- duction to the geology of Iran. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, vol. 168, p. 155-164. Miller, S.A., 1892 : Palaeontology. Annual report of Depart- ment of Geology and Natural Resources, Indiana, vol. 17, p. 611-705, pls. 1-20. Parks, W.A., 1913: Notes on fossils. In, Tyrrell, J.B., Hudson Bay Exploring Expedition, 1912. Twenty-second Annual Report of the Ontario Bureau of Mines, part 1, p. 161-209. Parks, W.A., 1915: Palaeozoic fossils from a region south- west of Hudson Bay. Transactions of the Royal Canadian Institute, vol. 11, p. 1-95, pls. 1-7. Rickards, R.B., Hamedi, M.A. and Wright, A.J., 1994: A new Arenig (Ordovician) graptolite fauna from the Kerman district, East-Central Iran. Geological Magazine, vol. 131, p. 35-42. Ruttner, A., Nabavi, M.H. and Hajian, J., 1968: Geology of the Shirgesht area (Tabas area, East Iran). Geological Survey of Iran, Report 4, p. 1-133. Saemann, L., 1853: Ueber die Nautiliden. Palaeontogra- phica, vol. 3, p. 121-167, pls. 18-21. Teichert, C., 1933: Der Bau der actinoceroiden Cephalopoden. Palaeontographica, Abteilung A, vol. 78, p. 111-230, pls. 8-15. Troedsson, G.T., 1926 : On the Middle and Upper Ordovician faunas of northern Greenland, 1. Cephalopods. Med- delelser om Gronland, vol. 71, p. 1-157, pls. 1-65. Zohrehbakhsh, A. and Vahdati Daneshmand, F., 1992: Geological Quadrangle Map of Iran 1: 250.000, sheet Rafsanjan. Geological Survey of Iran, Tehran. Paleontological Research, vol. 3, no. 1, pp.49-56, 3 Figs., April 30, 1999 © by the Palaeontological Society of Japan Occurrence of Carboniferous corals from the Geumcheon Formation of Danyang area, Korea JEONG- YUL KIM’, HYO-NYONG LEE’ and CHANG- HI CHEONG’ ‘Department of Earth Science Education, Korea National University of Education, Cheongwon, Chungbuk 363-791, Korea "Department of Geological Sciences, Seoul National University, Seoul 151-749, Korea Received 2 October 1998 ; Revised manuscript accepted 5 February 1999 Abstract. Two species of Carboniferous coral, Arachnastraea manchurica and Diphyphyllum delicatum, are described for the first time from the upper part of the Geumcheon Formation of the Danyang area, Korea. They were previously reported as Devonian corals, Disphyllum sp. and Phillipsastraea sp. Associated fossils are fusulinids, including Beedeina schellwieni, B. siviniensis, B. samarica, B. sp., Fusulina cylindrica, F. sp., Fusulinella mosquensis, Fusulinella provecta, Neostaffella sphaeroidea, and Ozawainella turgida. Occurrence of these corals and fusulinids suggests that the upper part of the Geumcheon Formation is middle Moscovian in age. Key words: Carboniferous, coral, Danyang area, Korea Introduction Yabe and Suzuki (1955) first reported specimens of corals from a limestone bed in Danyang area, Korea. They as- signed them in open nomenclature to colonial corals of Devonian type as Disphyllum sp. and Phillipsastraea sp. and suggested that Devonian deposits existed in Danyang area. Unfortunately, their specimens were lost. Furthermore, they figured only one weathered surface and one polished-slab figure of Disphyllum sp. and offered no systematic descrip- tions. On the basis of a second discovery of coral specimens of Phacellophyllum sp.? (Disphyllum sp.) associated with fusulinids including Fusulina sp., Fusulinella sp., and Neostaf- fella sp. from nearly the same horizon as that of Yabe and Suzuki (1955), Cheong (1972) saw a problem in the Danyang area, with a Devonian dating. He mentioned that the lime- stone containing the coral is not Devonian but Moscovian (Late Carboniferous) in age and surmised that this coral, which had been known as a Devonian type, probably sur- vived into the Carboniferous. Several months after Cheong’s report, Kato (1972) reex- amined the figures of Yabe and Suzuki (1955) and briefly documented that Disphyllum sp. and Phillipsastraea sp. re- ported from the Danyang area by Yabe and Suzuki (1955) are Diphyphyllum sp. and Arachnastraea sp. respectively. Recently well preserved coral specimens, which are close- ly associated with abundant fusulinids, were discovered from a limestone bed of the Geumcheon Formation by the present authors. The purpose of this paper is to report an additional occurrence of Carboniferous coral specimens, which are described here as Diphyphyllum delicatum and Arachnastraea manchurica, and to compare these with the Devonian corals Disphyllum sp. and Phillipsastraea sp. illustrated by Yabe and Suzuki (1955). Geologic setting and fossil locality General geological studies in the Danyang area have previously been carried out by many investigators (Kobatake, 1942 ; Brill, 1957; Lee and Kim, 1966; Son et al, 1967; Park and Cheong, 1975 ; Park et al., 1975; Kim, 1981). Kim (1971) studied the Paleozoic and Mesozoic paleocurrents of the Danyang Coalfield on the basis of sedimentary struc- tures. Structural analysis and tectonic studies of the Danyang area have been recently carried out by Cho et dl. (1986), Kim and Koh (1992), Kim et al. (1992a), Kim et al. (1992b), and Kim et al. (1994). The Permo-Carboniferous sedimentary strata, the Pyeon- gan Supergroup, in southern Korea are widely distributed in the Danyang, Taebaeg, Yeongweol, Jeongseon, and Gang- neung areas. The sediments are shallow marine to fluvial in origin and consist predominantly of sandstone and shale with small amounts of carbonate. Cheong (1973) subdivided the Pyeongan Supergroup into the Carboniferous Manhang and Geumcheon formations, the Permian Bamchi, Jangseong, Hambaegsan, Dosagok and Kohan formations, and Triassic Donggo Formation in ascending order. In Danyang area, the Carboniferous strata disconformably cover the Ordovician strata and are divided into two forma- tions, namely, the Manhang and Geumcheon formations (Cheong, 1971) and are inturn unconformably overlain by the Jurassic deposits (Figure 1). Cheong (1971) firstly carried out 50 Jeong-Yul Kim et al. biostratigraphic research on fusulinids in the Danyang area overlies the Ordovician strata. The formation, about 175 m and described 37 fusulinid species belonging to 11 genera. thick, is characterized by red to purple shale and greenish The Carboniferous Manhang Formation unconformably coarse sandstone, with the intercalation of nine white and PO00000000. 7090000008 0099900008 9200099208 RAC 2222227 Ct. = EA CCLOLLO0E. 36° 59' 30" N Cece, Greene 228 2202 Sindanyang 128°22' 30" E Geumcheon Bansong Fm. Em: @ Fossil locality Dosagog Fm. Manhang Fm. Thrust fault | Hambaegsan : Goseong Ls. A Geological boundary GQ” INEmM: sss—- Local road number RE = Jangseong Fm. EF Om Maggol Fm. Figure 1. Geological map and fossil localities of study area. (After Son et al., 1967 ; Lee and Kim, 1995) Carboniferous corals from the Geumcheon Formation, Korea 5] 24 Arachnastraea manchurica Diphyphyllum delicatum Fusulina cylindrica Fusulina sp. Fusulinella mosquensis Fusulinella provecta Ozawainella turgida nN nN Beedeina schellwieni edeina siviniensis Beedeina samarica Beedeina sp. Neostaffella sphaeroidea Geumcheon Formation Manhang Formation CARBONIFEROUS (Moscovian) CARBONIFEROUS (Moscovian) Limestone Chert - bearing limestone Quartz porphyry Soil-coverd Fossil horizon Fault Manhang Formation 125 Unconformity OR. Figure 2. Measured stratigraphic section of study area. light gray limestone beds or lenses in the measured section The Geumcheon Formation from which the coral speci- (Figure 2). In the upper part, the formation contains gray to mens were collected is about 70 m thick and comformably bluish-gray limestone which bears white chert. covers the Manhang Formation. The formation comprises a Jeong-Yul Kim et al. 52 WHOL. ur RN oe N N “ < A TOY we, hy ae ¢ fh, N i ) Carboniferous corals from the Geumcheon Formation, Korea variety of terrigenous sediments intercalated with dark gray limestone lenses (Figure 2). The upper part of the formation is characterized by black shale and greenish sandstone. Abundant and diverse corals and fusulinids were only recor- ded from the limestone units in the formation. Lee and Kim (1995) also described Beedeina schellwieni, Fusulina sp. Neostaffella sphaeroidea, and Ozawainella turgida from the Geumcheon Formation near Gosu Pass in the Danyang area. All of the specimens considered here were collected from a measured section of the Geumcheon Formation exposed in Gosu Pass along the local road 595, Danyang area (Figure 1). The fossil locality 1 is exposed near the top of Gosu Pass, about 1.2km north of the Sindanyang Bridge. The limestone bed of locality 1, which is 2m in thickness, is composed of abundant fusulinids and coral fragments which can not be used in the description. Many kinds of bioclasts, foraminifera, conodonts, brachiopods, and crinoids, were also found from the limestone bed. The fossil locality 2 is about 800m northwest from the Sindanyang Bridge. Fossil specimens were collected from a 5m thick chert-bearing limestone bed which is stratigra- phically nearly 40m above the base of the Geumcheon Formation. The limestone is characterized by gray to dark gray color (Figure 2). Abundant corals together with fusulinids, brachiopods, bryozoa, and crinoid stems are cleary shown on the weathered surface of limestone bed. Systematic description The conventional treatment has been followed in the taxonomic hierarchy above the species level. The mor- phologic terminology used for systematic description fol- lowed is that of Hill (1935, 1956, 1981), the terminology of microstructural elements is that of Kato (1963, 1968). Speci- mens collected for the present study and described herein are housed in the Department of Earth Science Education, Korea National University of Education. Phylum Cnidaria Hatschek, 1888 Class Anthozoa Ehrenberg, 1834 Order Rugosa Milne-Edwards and Haime, 1850 Suborder Streptelasmatina Wedekind, 1927 Family Lithostrotionidae d’Orbigny, 1851 Genus Arachnastraea Yabe and Hayasaka, 1916 Arachnastraea Yabe and Hayasaka, 1916, p. 69. Type species.—Arachnastraea manchurica Yabe and Hayasaka, 1916, from the Lower Permian of South Manchur- ia. Diagnosis.—Corallum compound, massive, typically cerioid or astraeoid. Septa numerous, of two orders. Septa thin, usually extending across tabularium to columella but partly Nn LU) discontinuous in dissepimentarium. Both major and minor septa are well developed. Tabulae conical, complete or incomplete, regular dissepimentarium (slightly modified after Hill, 1956). Remarks.—In the typical species of the Devonian Phillips- astraea d'Orbigny, the septa never extend to the center of the corallites with horse-shoe dissepiments. The septa are dilated, especially at inner margin of dissepimentarium, and there is always a conspicuous inner wall formed by the abrupt thickening of all the septa. These characteristic features are not visible in Arachnastraea (Yabe and Hayasa- ka, 1916). Kato (1972) concluded that Yabe and Sugiyama (1940) misdescribed Arachnastraea as Phillipsastraea in an occurrence from Cheonseongri, Suncheongun, Pyeongan- namdo, Northwest Korea. Arachnastraea manchurica Yabe and Hayasaka, 1916 Figures 3-1; 3-2 Arachnastraea manchurica Yabe and Hayasaka, 1916, p. 69. Material.—KNUE 96201-96216 (KNUEDY Locality 2). Four specimens for this study were collected by the present authors from the measured stratigraphic section (see Figure 2). Description.— Transverse section description : Corallum is astraeoid and composed of nearly equal-sized polygonal corallites which are 4.1-6.6 mm in diameter and have 9-11 major septa. Septa are thin, straight, alternately long and short, and fibronormal in terms of microstructure. Major septa reach the center of the corallite. Corallite walls are almost indistinguishable from septa and dissepiments. In most corallites, the major septa are 2.0-3.5 mm long and minor septa are 0.8-2.4mm long. Minor septa typically extend about 2/3 length of major septa to tabularium wall. Dissepimentarium is formed by 3-5 rows and is 0.3-2.7 mm. Tabularium has a diameter of on average 2.3 mm. Longitudinal section description: Dissepiments are well developed in the peripheral part, elongate in form and not much inclined. Dissepimentarium rather wide, occupying about 2/3 of the diameter of the corallites and consisting of 3-5 rows of dissepiments which are an average of 2mm long. Axial tabellae and periaxial tabellae are similarly in- clined. Diameter of the tabularium varies around the aver- age of 2.2mm, from 1.8 to 3.0mm. In the tabularium, the tabulae adjacent to the dissepimentarium have a slope of 25°-40°. Remarks.—One of the so-called ‘Devonian type corals’ from Cheonseongri described by Yabe and Sugiyama (1940) was reidentified by Kato (1972) as Arachnastraea kaipingensis (Grabau). It was the first record of occurrence of Arachna- straea in Korea. Arachnastraea manchurica differs from Arachnastraea kaipingensis in corallite walls, columella and Figure 3. 1,2. Arachnastraea manchurica Yabe and Hayasaka ; 1, transverse section (7, KNUE 96201), 2, Longitudi- nal section (x 7.5, KNUE 96215). 3-5. Diphyphyllum delicatum Minato and Kato ; 3, transverse section showing both the early and mature stages («8, KNUE 96219), 4, slightly obliquely cut logitudinal section (x7, KNUE 96229), 5, slightly obliquely cut transverse section (X 7, KNUE 96217). KNUE 96199). 6. association of Arachnastraea manchurica and Fusulinella sp. (10, 54 Jeong-Yul Kim et al. dissepimentarium. In the latter the corallum is cerioid- astraeoid and corallite walls are well developed, sharply zigzag and partially depressed. The dissepimentarium of the latter consists of 3-4 rows of regular dissepiments. Family Lithostrotionidae d’Orbigny, 1851 Subfamily Diphyphyllininae Dybowski, 1873 Genus Diphyphyllum Lonsdale, 1845 Diphyphyllum Lonsdale, Hill, 1956, p. 283 ; Hill, 1981, p. 383. Type species.—Diphyphyllum concinnum Lonsdale, 1845. Diagnosis.—Fasiculate corallum, typically without colum- ella. Septa short, continuous in dissepimentarium and amplexoid in tabularium. Columella absent or impersistent. Tabulae convex or flat, with downturned edges. Dis- sepimentarium narrow, composed of one or more rows of small dissepiments (slightly modified after Hill, 1956). Remarks.—The species of Diphyphyllum may have a wide range of variability in terms of the structure, shape and mode of the tabulae. This genus has inner tabulae which are strongly arched, and each arch rests upon the arch below. In addition, Sando and Bamber (1985) mentioned that this genus is very similar to Siphonodenaron, from which it differs by having flat or convex tabulae and by lacking a columella or having a thin, vertically discontinuous one. Armstrong (1970) regarded a smaller group of species, such as Diphyphyllum venosum, Diphyphyllum nasorakensis and Diphyphyllum klawockensis, as having complete tabulae with broad flat tops and downturned edges that extend to the dissepimentarium without touching the lower tabulae. The majority of the descibed species of Diphyphyllum indicated a late Early Carboniferous age (Minato and Kato, 1975). This genus is common in North America and is found exclusively in the shallow-water carbonate lithofacies (Sando and Bamber, 1985). Diphyphyllum delicatum Minato and Kato, 1957 Figures 3-3—3-5 Diphyphyllum delicatum Minato and Kato, 1957, p. 137, text-figs. A-C; Minato and Kato, 1974, p. 56-60. Material.—KNUE 96217-96245 (KNUEDY Locality 2). Only two specimens for this study were collected by the present authors from the measured stratigraphic section (see Figure 2). Description.— Transverse section description : Corallum is compound, fasciculate and dendritic rather than phaceloid. Corallites are circular to subcircular. Corallites are closely adjacent, and are often in contact. Mature corallites range from about 6.7 to 11.4 mm in diameter and possess 18 to 25 major septa. Both major and minor septa are thin, fibronor- mal in terms of microstructure. Major septa are 1.5-2.2 mm in length, protruding 0.2-0.9mm in tabularium, except for some major septa which are 0.9-1.1mm in length. Minor septa are usually confined to adaxial first row of dissepi- ments, rarely protruding into second row of dissepiments, and are 0.25 to 0.38mm in length. Dissepimentarium ranges from 1.1 to 2.2 mm in width and consists of one to three rows of regular dissepiments. Tabularium varies from 41 to 6.4 mm in width and is open without any axial structure. Longitudinal section description : Corallites are cylindrical and rather closely disposed. Dissepimentarium is 0.5 to 1.9 mm wide and consists of one to three rows of inclined, inflated to globose dissepiments. Tabulae are mostly com- plete, slightly concave in central part of the corallite, 4 to 9 in a vertical distance of 5mm. However, they turn down- ward at an average angle of 32° before joining the dissepi- ments. Remarks.—Our specimens differ slightly from Minato and Kato's (1975, pl. 9, figs. 2-6, pl. 10, figs. 1-4) species Diphy- phyllum delicatum, which was described from the Upper Carboniferous Nagaiwa Series of northeast Japan, by having more numerous major septa, a wider dissepimentarium, and a more strongly developed row of dissepiments. Igo and Kobayashi (1980) described a new subspecies, Diphyphyllum delicatum nishitamensis, from the Itsukaichi District, Tokyo, Japan, which is similar to, but not conspecific with Diphy- phyllum delicatum illustrated by Minato and Kato (1975). Igo and Kobayashi (1980) noted that Diphyphyllum delicatum and Diphyphyllum delicatum nishitamensis differ noticeably in the length of major and minor septa. The former is character- ized by short major and minor septa, while the subspecies has longer septa compared with the size of the corallite. As Minato and Kato (1957) mentioned, Diphyphyllum has a long stratigraphic range from the Lower Carboniferous to Permian, but this particular species is confined to the upper part of the Upper Carboniferous Geumcheon Formation in the Danyang area. Discussion One of the purposes of this study is to reexamine the Devonian corals mentioned by Yabe and Suzuki (1955). According to Kato (1972), Suzuki earlier collected several coral specimens in Gosuri, Danyang in 1944, but these materials are lost. Yabe and Suzuki (1955) reported the occurrence of the Devonian corals Disphyllum sp. and Phillipsastraea sp. Their figures 1 and 2 are index maps of the fossil locality, while figures 3 and 4 show the corals on the weathered surface of the limestone near Gosu Pass in Danyang area. The figures are not clear, but colony type and internal structure of corals were, however, distinguished. On the basis of their figure 3, several clues to identification of the corals were found by the present authors. First of all, the corallites in figure 3 are compound, fasciculate and dendritic rather than phaceloid. Although Yabe and Suzuki (1955) identified them as Disphyllum sp., the branches of their coral specimens are too irregular to be those of Disphyllum. The second is that the septa are very short and the dis- sepimentarium are very narrow with one or two rows of small dissepiments. In longitudinal view, the tabulae are convex with downturned edges without columella. These are typi- cal characters of Diphyphyllum. It is considered that the coral specimens described by Yabe and Suzuki (1955) are not of the Devonian genus Disphyllum, but the Carboniferous Diphyphyllum. Disphyllum sp. is illustrated only in figure 3 of Carboniferous corals from the Geumcheon Formation, Korea Yabe and Suzuki (1955), but they did not provide any illustra- tions of Phillipsastraea sp. Furthermore, fusulinids and conodonts occur abundantly from the Geumcheon Formation. A number of fusulinids are observed together with corals in the same thin sections (Figure 3-6). Because the Carboniferous corals have long ranges, both fusulinids and conodonts may provide a useful criteria for understanding the paleoecology and determining the geologic age of the Geumcheon Formation. Conclusion Two species of rugose corals from the Geumcheon For- mation in the Danyang area, Korea are described as Arach- nastraea manchurica and Diphyphyllum delicatum. The corals indicate that the age of the Geumcheon Formation is middle Moscovian, Late Carboniferous. Coral specimens from the Danyang area once illustrated as the Devonian corals Disphyllum sp. and Phillipsastraea sp. (Yabe and Suzuki, 1955), are considered Carboniferous corals, Diphyphyllum sp. and Arachnastraea sp. respectively. Acknowledgments We wish to sincerely thank Makoto Kato, Professor Emeritus of Hokkaido University, and Hisayoshi Igo, Professor Emeritus of the University of Tsukuba for sending useful references and giving comments. We wish to express our thanks to E.W. Bamber, Geological Survey of Canada, Lin Baoyu, Institute of Geology, Chinese Academy of Geological Sciences, Lin Ying Dang, Changchum College of Geology, and Wang Xun Lian, China University of Geosciences, for kindly offering helpful comments and sending many copies of valuable references. Special thanks are given to two anonymous referees for critically reviewing the original manuscript and suggesting numerous useful comments and constructive revisions. References Armstrong, A.K., 1970: Mississippian rugose corals, Per- atrovich Formation, west coast, Prince of Wales Island, southeastern Alaska. U.S. Geological Survey Profes- sional Paper, no. 534, 44 p. Brill, G., 1957 : Geology of Tanyang Coalfield of the Republic of Korea. Geological Report on Coalfields of Korea, vol. 1, p. 75-98. Cheong, C.H., 1971: Stratigraphy and paleontology of the Danyang Coalfield, North Chungcheong-do, Korea. Journal of Geological Society of Korea, vol. 7, p. 63-88. Cheong, C.H., 1972: On the Devonian problem in Korea. Journal of Geological Society of Korea, vol.8, p. 53-54. Cheong, C.H., 1973: A paleontological study of the fusulinids from the Samcheog Coalfield, Korea. Jour- nal of Geological Society of Korea, vol. 9, p. 47-82. Cho, M.J., Choi, Y.S., Kang, P.C. and Choi, K.H., 1986: A study on structural analysis for the southern part of Taebaegsan region. Researches on Coal Resources vol. 5 (KR-86-2-10), p. 239-279. Hill, D., 1935: British terminology for rugose corals. Geo- Un in logical Magazine, vol. 72, p. 481-519. Hill, D., 1956: Rugosa. In, Moore, R.C. ed., Treatise on Invertebrate Paleontology, Part F, Coelenterata, p. 233 324. Geological Society of America and University of Kansas Press, Lawrence. Hill, D., 1981: Rugosa and Tabulata. In, Teichert, C. ed., Treatise on Invertebrate Paleontology, Part F, Coelen- terata, Supplement 1, 762p. Geological Society of America and University of Kansas Press, Lawrence. Igo, H. and Kobayashi F., 1980: Carboniferous corals from the Itsukaichi district, Tokyo, Japan. Science Report, Institute of Geoscience, University of Tsukuba, Section B, vol.1, p. 149-162. Kato, M., 1963: Fine skeletal structures in Rugosa. Journal of Faculty of Science, Hokkaido University, Series 4, vol. 11, p. 571-630. Kato, M., 1968: Note on the fine skeletal structures in Scleractinia and Tabulata. Journal of the Faculty of Science, Hokkaido University, Series 4, vol. 14, p. 45-50. Kato, M., 1972: Devonian of Korea. Journal of Geological Society of Japan, vol. 78, p. 541-544. Kim, H.M., 1971: Paleozoic and Mesozoic paleocurrents of the Danyang Coalfield, Korea. Journal of Geological Society of Korea, vol. 7, p. 257-276. Kim, J.H. and Koh, H.J., 1992: Structural analysis of the Danyang area, Danyang Coalfield, Korea. Journal of Korean Institute of Mining Geology, vol. 25, p. 61-73. 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Journal of Korean Earth Science Society, vol. 16, p. 144-151. Lee, D.W. and Kim, D.S., 1966: Geology of northern part of Danyang Coalfield. Geological Report on Coalfield of Korea, vol. 7, p. 5-32. Minato, M., 1975: Upper Carboniferous corals from the Nagaiwa Series, southern Kitakami Mountains, N.E. Japan. Journal of Faculty of Science, Hokkaido Uni- versity, vol. 16, p. 43-119. Minato, M. and Kato, M., 1957: Two Carboniferous corals from the Kitakami Mountains, northeast Honshu, Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 28, p. 137-142. Park, S.I. and Cheong, CH, 1975: A study on the Jurassic Sapyeongri Conglomerate in the vicinity of Danyang, N. Chungcheongdo, Korea. Journal of Geological Society of Korea, vol. 11, p. 24-37. Park, J.S., Shin, M.S., Chung, C.S., Lee, M.H., Yoon, Y.D., Nn a Kim, S.H. and Hwang, H.S., 1975 : Geological investiga- tion report of Danyang Coalfield. p. 54. Sando, W.J. and Bamber, E.W., 1985: Coral zonation of the Mississippian System in the western interior province of North America. U.S. Geological Survey Professional Paper, no. 1334, 55 p. Son, C.M., Cheong, C.H., Kim, B.K., Lee, S.M. and Kim, S.J., 1967 : Geology of the Danyang Coalfield. Geological Report on Coalfields of Korea, vol. 8, p. 73-94. Jeong-Yul Kim et al. Yabe, H. and Hayasaka, I, 1916: Paleozoic corals from Japan, Korea and China. Journal of Geological Society of Tokyo, vol. 23, p. 9-22. Yabe, H. and Sugiyama, T., 1940: Discovery of corals of Devonian types from Tyosen (Korea). Proceedings of the Japan Academy, vol. 15, p. 305-310. Yabe, H. and Suzuki, A., 1955: Second occurrence of colonial coral of Devonian type in Tyosen (Korea). Proceedings of the Japan Academy, vol. 31, p. 355-359. Cheonseongri KEH, Danyang Fi, Donggo Formation # Gangneung {1 {%, Geumcheon Formation 27)! |/e, Jangseong Formation EE, Jeongseon fig#=, Kohan Formation HE, Manhang Formation Hé Gosu 5 tf}, Dosagok Formation 78-4 Hambaegsan Formation Jak All le EI TES, Pyeongan Supergroup FASIEÉ£, Sindanyang #1}, Taebaeg KH, Yeongweol Fk Paleontological Research, vol. 3, no. 1, pp. 57-64, 6 Figs., April 30, 1999 © by the Palaeontological Society of Japan Relation of growth rings to reproductive cycle in Cryptopecten vesiculosus, a dimorphic pectinid bivalve NAOKO TAKENAKA Shinagawa Joshi Gakuin, 3-3-12 Kitashinagawa, Shinagawa-ku, Tokyo 140-8707, Japan Received 30 October 1998 ; Revised manuscript accepted 23 February 1999 Abstract. The relation between growth rings and reproductive cycle in a dimorphic pectinid bivalve, Cryptopecten vesiculosus (Dunker, 1877) was examined histologically on the basis of semi-regularly collected samples from Sagami Bay. This pectinid is hermaphroditic. Male and female gonads ripen between June and September, and spawning occurs during July to November. A strong growth ring is formed just before spawning, and the first ring indicates that the specimens has reached the stage of sexual maturity. This means that growth rings are formed once a year after the individual reaches sexual maturity. No visual difference was detected in the gonad development between the two phenotypes ; their gonadal weight indices are statistically identical throughout the year. Therefore the previous interpretation that the dimorphism represents discontinous intrapopulational variation is upheld. The results of this study are applicable to life history analysis in extant and fossil populations. Key words: Dimorphism, growth rings, life history, pectinid bivalve, reproductive cycle Introduction The pectinid bivalve, Cryptopecten vesiculosus (Dunker, 1877) is characterized by a few prominent commarginal growth rings, which consist of periodic changes in the convexity of the disc surface. It has been judged that the growth rings are caused by a growth pause during the reproductive season. Furthermore, C. vesiculosus has been considered a dimorphic species, because two discrete phenotypes exist in every population. One phenotype has highly elevated and generally quadrate radial ribs, while the other has low and generally rounded radial ribs. They have been called “Phenotype Q” and “Phenotype R”, respectively. These two phenotypes are strictly sympatric, and their allozyme patterns show no statistical difference. Conse- quently it has been believed that the dimorphism is due to discontinous intrapopulational variation (Hayami, 1984 ; Sar- ashina, 1995). Histological observations on the development of gonads through the year is vital to prove the assumptions mentioned above, as well as to trace a clear relation between growth rings and the reproductive cycle. The relation, if clarified, would become fundamental to analyses of life history (espe- cially, age, lifespan, growth rate and mortality rate) not only in extant but also in fossil populations. Material and method Cryptopecten vesiculosus (Dunker, 1877) is distributed from the central part of Japan to the East and South China Sea. It is a lower sublittoral species, living Commonly on sandy bottoms at the depth of 50-200 m (Hayami, 1984). Fossils of this species are also found abundantly in Early Pliocene and later marine deposits of Japan. Living individuals of C. vesiculosus were collected monthly to bimonthly between March 1997 and February 1998 almost at one and the same station, about 2 km west of the western end of Jögashima Islet in the eastern part of Sagami Bay [35°08’N, 139°35’E, 80-85 m]. Table1 shows the dates of dredging and the number of collected living individuals. The integrated rela- tive frequency of the two phenotypes is almost identical with the ratio indicated by Hayami (1984) in samples Jg (1-26) collected during 1974-1983 at nearby stations in Sagami Bay, and statistically there is no significant difference. To clarify the reproductive cycle and the shell size at sexual maturity, | observed the process of gametogenesis and determined the gonad developmental phase for many individuals in each phenotype. Collected specimens were anesthetized with 0.01% 2-phenoxyethanol methylene glycol diluted with sea water, and then fixed for 48 hours in a solution of 10% formaldehyde. The dissected gonadal tis- sue of each specimen was excised and weighed after rinsing in water. It was dehydrated through a graded series of ethanol and benzol, and then embedded in paraffin (melting 58 Table 1. Collecting dates and the number of individuals of Cryptopecten vesiculosus. Date Na Nea N P Op Mar. 25, 1997 9 14 23 0.61 0.10 May 1, 1997 42 30 72 0.42 0.06 Jun 4, 1997 26 25 51 0.49 0.07 Jul. 29, 1997 54 30 84 0.36 0.05 Sep. 30, 1997 79 67 146 0.46 0.04 Nov. 19, 1997 35 28 63 0.44 0.06 Dec. 18, 1997 44 31 75 0.41 0.06 Feb. 16, 1998 36 36 72 0.50 0.06 Total 325 261 586 0.45 0.02 N: Total number of individuals ; No: Number of individuals belonging to Phenotype Q; Nr: Number of individuals belonging to Phenotype R; P=Nr/N; op: Standard error. point: 56~58'C). Thin transverse sections of the gonadal tissue were prepared at intervals of 8 um and stained with Lillie-Mayer's hematoxylin-eosin. The stained thin sections were observed and photographed using an Olympus model BX50 optical microscope. Based on histological examina- tion of the thin-sectioned gonadal tissue, each specimen was assigned to a specific gonad developmental phase : early active phase (EA), late active phase (LA), ripe phase (R), partially spawned phase (PS), or spent phase (S). Further, the mean gonad index [(gonad weight 100)/soft body weight] was calculated for sexually mature individuals to analyze the annual reproductive cycle of the population. The results were analysed to determine whether or not growth rings can be used as an index of age. Shell height from the umbo to each growth ring, normal to the hinge line, was measured in all the samples with a digimatic caliper (accuracy+0.02 mm). In addition, the numbers of growth rings was counted, and the mean shell height at each growth ring was calculated for individuals with more than three growth rings. The fit of these mean values to von Bertalanf- fy, Gompertz and logistic curves was examined. These Curves are expressed by the following formulae : H(B)=K(1— expla—Rt)) (von Bertalanffy curve) H(G)= Kexp(— aexpfRt) (Gompertz curve) H())=K /(1+ exp(a— Rt)) (logistic Curve) where H is the size of the animal (Shell height in this case) at age t, K is the upper limit of the curve, R is the specific growth rate, and a is a constant defined by the initial size (=H,) at t=0. Naoko Takenaka Results 1. The reproductive cycle of Cryptopecten vesiculosus Spermatozoa were observed in the milky white proximal part of the crescentic gonad and oocytes in the orange distal part. In consequence, it was confirmed that Cryptopecten vesiculosus is hermaphroditic and that the shell dimorphism is never sexual. Histological examination of gonadal tissue revealed that gametogenesis in C. vesiculosus is essentially similar to that in the commercial scallop Azumapecten farreri nipponensis, which was analyzed by Kanno and Tanita (1961), though that species is dioecious. Following the general classification of gametogenetic phases in bivalves proposed by Ropes (1968) and Sato (1995), the reproductive cycle of C. vesiculosus is described below. Early active phase (Figure 1A, B) In the male gonad of this phase, many spermatogoniums about 8 um in diameter, each of which consists of a nucleus and thin nucleoplasm, appear along the inner periphery of the alveolar walls. Further, spermatocytes about 5 um in diameter proliferate towards the lumina from the alveolar walls. Oogoniums and oocytes which protrude inside the alveolar walls are seen in the female gonad. The oogoniums range from 15 to 20 um and the oocytes range from 20 to 30 um in diameter. Each oocyte has a nucleus about 15-20 4m, which contains a nucleolus approximately 4 um in diameter. Late active phase (Figure 1C, D) Many spermatocytes are seen in the male gonad of this phase. Spermatids about 4.5 um in diameter also are seen, and they form dense masses near the center of the alveoli. A transformation of the spermatids results in the appearance of sperm. They form weak columns toward the center of the alveoli. Oocytes in the late active phase are mostly rounded and larger than in the early active phase. Some oocytes are attached to the basement membrane of the alveoli, but most are free in the lumina. In this phase oogoniums and ripe oocytes coexist within one and the same female gonad. Ripe phase (Figure 1E, F) In this phase, spermatozoa or free oocytes occupy the major space in the gonadal tissue. The head of each sperm is corn-shaped and about 2 wm in length. Oocytes are free in the lumina of the alveoli. Each oocyte about 60 um in diameter contains a round or oval nucleus ranging from 30 to 35 um, and each nucleus possesses one small opaque basophilic nucleolus about 5 um in diameter. Ripe gonads typically have a dense appearance because the alveoli are crowded together and are filled with large oocytes or numer- Figure 1. Optical photomicrographs of sections of male and female gonadal tissues in Cryptopecten vesiculosus in each phase of the reproductive cycle. The scale bar in A pertains as well to B-J. All specimens were collected from Sagami Bay. A: Early active phase of a male collected on 16 February 1998. B: Early active phase of a female collected on 16 February 1998. C: Late active phase of a male collected on 25 March 1997. D: Late active phase of a female collected on 25 March 1997. E: Ripe phase of a male collected on 29 July 1997. F: Ripe phase of a female collected on 29 July 1997. G: Partially spawned phase of a male collected on 19 November 1997. H: Partially spawned phase of a female collected on 19 November 1997. a female collected on 18 December 1997. 1: Spent phase of a male collected on 18 December 1997. J: Spent phase of Relation of growth rings to reproductive cycle in Cryptopecten vesiculosus 59 60 Naoko Takenaka ous spermatozoa. Partially spawned phase (Figure 1G, H) In the male gonad of this phase, spermatozoa are still present near the center of alveoli, but they are substantially less numerous than in the ripe phase. A few large ripe oocytes remain free in the lumina of some alveoli of the female gonad. Spent phase (Figure Il, J) In this phase the alveoli of male and female gonads contain few or no spermatozoa or oocytes. Their lumina characteristically are open. Seasonal change in the relative frequency of the five gametogenetic phases in the samples of Cryptopecten vesiculosus from Sagami Bay in 1997-1998 is shown in Figure 2. Individuals belonging to the late active phase amount to than 80% of the population between March and May, while ripe-phase individuals become dominant between June and September. Some individuals begin to spawn in July, and almost all individuals reach the spent phase in December. After that, the proportion of individuals in the early active phase increases gradually. The mean Phenotype Q 100 90 80 70 60 50 Frequency (%) Phenotype R 100 90 80 70 60 50 Frequency (%) MSASMEU UN AS SN ONNEDAURENM Month Figure 2. Diagram showing the change of relative fre- quency (%) of gonad development stages through a year (1997-1998) in the two phenotypes of C. vesiculosus. EA: Early active phase, LA: Late active phase, R: Ripe phase, PS: Partially spawned phase, S: Spent phase. pO mm ————— Fee 30 % Phenotype Q 25 % Phenotype R i ‘ | ait $ 0 Mean gonad index (%) MONA MS JA JEANS 0) IN Si Dia eel Month Figure 3. Seasonal changes in mean gonad _ index |(gonad weight x 100)/soft body weight]. The mean and the range of one standard deviation (vertical bar) are indicated. No statistical difference was detected between the two phenotypes. gonad index increases from March to June, scarcely changes from June to September, and decreases significant- ly after September (Figure 3). Therefore, the reproductive season of C. vesiculosus is considered to be a relatively long period between early June and late September. Neither visual nor statistical difference was detected between the two phenotypes in their reproductive cycles and seasonal changes of gonad indices. 2. The size at sexual maturity Table 2 indicates the frequencies of juvenile, semimature and mature specimens and their relation to shell height in the samples collected during the reproductive season. Repro- ductive cells were not observed at all in individuals smaller than 10 mm in shell height, and gonadal tissue, if present, was so small that they are regarded as juvenile. Individuals larger than 14 mm in shell height can be regarded as mature. Most individuals between 10 and 14 mm possess only a few reproductive cells. They are regarded here as semimature, and spawn like mature individuals. It is, therefore, consid- ered that individuals of C. vesiculosus reach sexual maturity at about 10 mm in shell height. 3. Formation of growth rings The position of growth rings was observed, and the follow- ing four states are discriminated by the relation between the last growth ring and the ventral margin (Figure 4). State A (Figure 4-1a, 1b) Individuals with swelling of the marginal area State B (Figure 4-2a, 2b) Individuals with a growth ring just on the ventral margin State C (Figure 4-3a, 3b) Individuals with slight new shell growth (<5 mm) after the formation of last ring State D (Figure 4-4a, 4b) Individuals without swelling of the marginal area The seasonal change in the relative frequency of these states is shown in Figure 5. In spring, many individuals in Relation of growth rings to reproductive cycle in Cryptopecten vesiculosus Table 2. Distribution of the stages of sexual maturation in relation to shell height in the samples of Cryptopecten vesiculosus collected from Sagami Bay during the reproductive season. Shell Sampling date height May 1 June 4 July 29 Sept. 30 Nov. 19 (mm) A B Gc A B C B C A B C A B C 6- 8 8-10 1 10-12 1 12-14 1 2 12 14-16 16-18 6 18-20 9 1 20-22 11 22-24 2 24-26 1 26-28 A: Juveniles, B: Semimature individuals, C: Mature individuals A 1 1 1 SO ORONUI— — — Woah © @ N © Figure 4. Extant sample of Cryptopecten vesiculosus collected from Sagami Bay. 1: Individual of Phenotype Q with swelling of marginal area (State A) collected on 1 May 1997, (a) right view, (b) anterior view ; 2: Individual of Phenotype R with a growth ring just on ventral margin (State B) collected on 30 September 1997, (a) right view, (b) anterior view; 3: Individual of Phenotype Q with slight new growth (<5 mm) after the formation of the last growth ring (State C) collected on 16 February 1997, (a) right view, (b) anterior view ; 4: Individual of Phenotype Q without swelling of marginal area (State D) collected on 25 March 1997, (a) right view, (b) anterior view. All figures magnified about 1.9 times. 61 62 Naoko Takenaka Frequency (%) M A M J J AS O N D JS F M Month Figure 5. Diagram showing the relative frequency (%) of four states of shell growth. State A : Individuals with a swelling of the marginal area, State B: Individuals with a growth ring just on the ventral margin, State C : Individuals with slight new growth (<5 mm) after the formation of the last growth ring, State D: Individuals without swelling of the marginal area. state A appear simultaneously with the early development of the gonads. Individuals in state B become most abundant in July. This produces a temporary cessation of shell growth. On the other hand, the proportion of individuals in state C gradually increases from June and becomes almost 100% in November. The result indicates that the growth rings are formed once a year and can be used as an index of age. The shell height at each growth ring was measured in all individuals (Figure 6). The first growth ring is formed at a height of 9-11 mm in most individuals. Using individuals with more than three growth rings, | calculated the mean shell height at each growth ring. | then examined how the data adapt to the von Bertalanffy, Gompertz and logistic growth curves. The results of Computation show that the shell growth of this species fits well to all of the three curves, especially to the Gompertz curve (Table 3). 90 | _ 80 @ Ist growth ring © 2 70 O 2nd growth ring 2 60 03rd growth ring = 50 & 4th growth ring © Sa © 30 5 20 zZ ei hile 0 Domo. =. n®»oor un» Do Fr ® OO or NO STM OR el ll reereerer NNNNNNAN LOSC UE et: 12! RUMI CL anes Clee TE RER Ne ite ne Ope eNO Sh ON OEM DO EO MEN Oot ste 10 DO ete ler N) peg se NNNNNNANWN Shell height at the growth ring (mm) Figure 6. Frequency distribution of shell height at each growth ring in the samples of Cryptopecten vesiculosus col- lected during March 1997-February 1998. Table 3. Mean shell height at each growth ring and its adaptability to three theoretical growth curves of the extant sample of Cryptopecten vesiculosus collected from Sagami Bay. Age (years) 1 2 3 4 Mean shell height (mm) Standard deviation Number of individuals 337 176 47 5 Calculated values (mm) von Bertalanffy curve 10.20 1750 21.80 24.35 Gompertz curve 10.20 1743 21.98 24.30 logistic Curve 10.20 17.41 2216 2416 Calculated formula curve von Bertalanffy curve H(B)= 28.02 (1 — exp (—0.453—0.527t)) r=0.999 Gompertz curve H(G)= 26.24 exp (— 2.180 exp 0.8371) r=1.000 logistic Curve H(l) = 25.16/(1 + exp (1.574—1.192t) r=0.998 Discussion The spawning season of Cryptopecten vesiculosus begins in early June and extends to late September, continuing for a comparatively long period. No visual difference was detected in the gonad development between the two phenotypes ; seasonal changes of weight indices of the gonads show very similar patterns (Figure 3). Therefore, the previous interpretation that the dimorphism is due to dis- continous intrapopulational variation is upheld. Growth rings are formed clearly on the shell surface in many bivalves and are often useful in determining the age of individuals and their growth rate. Kennish (1980) called the strong internal growth lines of bivalves growth breaks. The growth breaks reflect various enviromental or physiological stresses such as freeze shocks (in winter), heat shocks (in summer), thermal shocks, shell-margin abrasions, spawning, neap tides, and storms. There is often a direct relationship between internal growth breaks and external growth rings (Dillon and Clark, 1980). Therefore, growth rings are consid- ered to be formed by the same factors as internal growth breaks. Among various bivalves, growth rings are produced by freeze-shock breaks (e.g., Pecten maximus, Mason, 1957 ; Tivela stultorum, Hall et al., 1974; Modiolus modiolus, Seed and Brown, 1978; Aequipecten opercularis, Broom and Mason, 1978; Mya arenaria, Goshima, 1982; Phacosoma japonicum, Tanabe, 1988) or heat-shock breaks (e.g., Mer- cenaria campechiensis, Jones et al., 1990 ; Chamelea gallina, Ramon and Richardson, 1992). Spawning breaks are also used to assess annual growth increment in some species (e. g., Spisula solidisima, Jones et al., 1978; Arctica islandica, Thompson et al., 1980). Generally, a growth ring is formed by an interruption of the shell growth. Because various states of the ventral margin are observed within each simultaneous sample of C. vesiculosus, it is unlikely that growth cessation due to ther- mal stress or any other such instantaneous events. Relation of growth rings to reproductive cycle in Cryptopecten vesiculosus 63 The cause of ring formation may be better understood, if gametogensis and spawning are taken into consideration. Some individuals of C. vesiculosus begin to spawn in July, but the spawning season extends until the end of September (Figure 2). Moreover, the number of individuals with newly grown shell after the formation of the last growth ring gradually increases from June on (Figure 5). Consequently, it is obvious that a growth ring is formed just before spawn- ing, when the gonad is still filled with sperm and free oocytes. On the other hand, the gonad index becomes much smaller in individuals with newly grown shell. Reproduction is one of the most energy-consuming physiological activities ; it is therefore likely that gametogenesis exerts a great influence on shell formation. In this connection Gutsell (1930) discussed the formation of growth rings in Argopecten irradians. He believed that a decline of metabolic activity, which is related to the develop- ment of eggs and sperm rather than spawning, must be responsible for the growth cessation. It is considered that the growth ring of C. vesiculosus is also formed by growth cessation in relation to energy consumed in gametogenesis. The surface swelling before the formation of a growth ring may be caused by the retardation of shell growth. The growth rings of C. vesiculosus must be produced just before spawning. The present interpretation is in agreement with the trade-off relationship between somatic and reproductive cells. Since mature reproductive cells were observed in the individuals larger than 10 mm in shell height, sexual maturity may be attained at this size. The first growth ring is com- paratively weak and is formed at 9-11 mm in shell height in most individuals (Figure 6). This is consistent with the sexual maturity size. Therefore, the growth rings of C. vesiculosus are considered to be formed once a year after the individual has reached sexual maturity. The growth rings are thus useful for determining the age of extant specimens and can presumably be applied to fossils as well. The shell growth pattern fits well with the von Bertalanffy, Gompertz and logistic curves. The shell height indicates a decrease in specific growth rate as the shell size approaches its upper limit of 26-28mm. The number of growth rings indicates that the maximum lifespan of C. vesiculosus is four or five years. The absolute growth pattern, however, may change geo- graphically and chronologically within one and the same species. In fact, the growth rate and ultimate size in the samples from Sagami Bay are significantly smaller than those of some other extant and fossil samples, as shown by Hayami (1984, fig. 7). The exact age distribution and mortal- ity rate are difficult to obtain from the present samples, because juvenile individuals smaller than 10 mm in height are not present in most samples and may have passed through the mesh of the dredging gear. It is also not clear whether the first ring is formed during the first year. However, the relation between growth rings and the reproductive cycle has been made very clearer through the present study. Such prominent growth rings occur in some other pectinids ; e.g. Swiftopecten swiftii, Chlamys cosibensis (a fossil species), and Decatopecten striatus. Although more detailed study is necessary for each species, the mode and periodicity of growth rings are very similar in these species to those of C. vesiculosus. It is likely that gametogenesis is related to the formation of growth rings in those species also. It is expected that applying the knowledge about growth rings will clarify the life history of fossil populations and their evolution. On the other hand, in many other pectinids periodical growth breaks, if present, are scarcely accompanied by surface swelling. Even in C. vesiculosus, Pleistocene fossil populations generally show weaker surface convexity between growth rings than the extant populations. The most plausible explanation in my mind is that the degree of trade-off between the gametogenesis and body growth actually varies among the pectinids species. In other words, the prominent growth rings in the extant populations of C. vesiculosus may be the product of more exhaustive trade-off than in many other pectinids and in the fossil populations of this species. Acknowledgments | express my sincere thanks to Itaru Hayami, Kanagawa University for his valuable advice and reading of the manu- script. | am grateful to Shinichi Sato, National Science Museum, Tokyo for his valuable suggestions throughout this study. | also thank staff members of the Geological Institute and Misaki Marine Biological Laboratory of the University of Tokyo for collecting samples. References Broom, M.J. and Mason, J., 1978: Growth and spawning in the pectinid Chlamys opercularis in relation to tempera- ture and phytoplankton concentration. Marine Biology, vol. 47, p. 277-285. Dillon, J.F. and Clark, G.R.ll, 1980 : Growth-line analysis as a test for contemporaneity in populations. /n, Rhoads, D.C. and Lutz, R.A. eds., Skeletal Growth of Aquatic Organisms, p. 395-415. Plenum Press, New York. Dunker, W., 1877 : Mollusca nonnulla nova maris japonici. Malacozoologische Blatter, Bd. 24, p. 67-75. Goshima, S., 1982: Population dynamics of the soft shell clam, Mya arenaria L., with special reference to its life history pattern. Publication of the Amakusa Marine Biological Laboratory, vol. 6, p. 119-165. Gutsell, J.S., 1930 : Natural history of the bay scallop (Pecten irradians). Bulletin of the United States Bureau of Fisheries, vol. 46, p. 569-632. Hall, C.A.Jr., Dollase, W.A. and Corbato, C.E., 1974: Shell growth in Tivela stultorum (Mawe, 1823) and Callista chione (Linnaeus, 1758) (Bivalvia): annual periodicity, latitudinal differences, and diminution with age. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 15, p. 33-61. Hayami, |, 1984: Natural history and evolution of Cryptopecten (a Cenozoic-Recent pectinid genus). University Museum, University of Tokyo, Bulletin, no. 24, p. 1-149. Jones, D.S., Quitmyer, LR., Arnold, W.S. and Marelli, D.C., 64 Naoko Takenaka 1990: Annual shell banding, age, and growth rate of hard clams (Mercenaria spp.) from Florida. Journal of Shellfish Research, vol. 9, p. 215-225. Jones, D.S., Thompson, |. and Ambrose, W., 1978: Age and growth rate determinations for the Atlantic surf clam Spisula solidissima (Bivalvia: Mactracea), based on internal growth lines in shell cross-sections. Marine Biology, vol. 47, p. 63-70. Kanno, H. and Tanita, S., 1961: Studies on Chlamys farreri nipponensis Kuroda. ll. Seasonal change of the gonads. Bulletin of Tohoku Regional Fishery Labora- tory, no. 19, p. 135-141. Kennish, M.J., 1980: Shell microgrowth analysis. Mer- cenaria mercenaria as a type example for research in population dynamics. In, Rhoads, D.C. and Lutz, R.A. eds., Skeletal Growth of Aquatic Organisms, p. 255-294. Plenum Press, New York. Mason, J., 1957 : The age and growth of the scallop, Pecten maximus (L.), in Manx waters. Journal of the Marine Biological Association of the United Kingdom, vol. 36, p. 473-492. Ramon, M. and Richardson, C.A., 1992 : Age determination and shell growth of Chamelea gallina (Bivalvia: Vener- idae) in the western Mediterranean. Marine Ecology. Progress Series, vol. 89, p. 15-23. Ropes, J., 1968: Reproductive cycle of the surf clam, Spisula solidissima, in offshore New Jersey. Biological Bulletin, vol. 135, p. 349-365. Sarashina, |., 1995: Genetic variation within a dimorphic species, Cryptopecten vesiculosus (Bivalvia, Pectinidae). Transactions and Proceedings of the Palaeontological Society of Japan, N.S., no. 180, p. 203- 207. Sato, S., 1995: Spawning periodicity and shell microgrowth pattern of the venerid bivalve Phacosoma japonicum (Reeve, 1850). The Veliger, vol. 38, p. 61-72. Seed, R. and Brown, R.A., 1978: Growth as a strategy for survival in two marine bivalves, Cerastoderma edule and Modiolus modiolus. Journal of Animal Ecology, vol. 47, p. 283-292. Tanabe, K., 1988: Age and growth rate determination of an intertidal bivalve, Phacosoma japonicum, using internal shell increments. Lethaia, vol. 21, p. 231-241. Thompson, D.S., Jones, D.S. and Dreibelbis, D., 1980: Annual internal growth banding and life history of the ocean quahog Arctica islandica (Mollusca: Bivalvia). Marine Biology, vol. 57, p. 25-34. a Le ee om \ Os 148 EIAlZ1&, 1999 Æ 6 A 26H (£68 27 A (A) iz, [KREANTACHADEMEE T BRS EST. SRSRHOM LAS 5 A7 ACT. 6A 2 AY Y RY IL [AKON I 0 De, tr: NEBEN TECS, AMPOROMRDREL WHAM DS OED, HDLErÉREN2ELAHESNI HIER ARS (http:// N ammo.kueps.kyoto-u.ac.jp/palaeont) DERAZDON—- PIED-HIHERKÄANTOET, i ©2000 FREI, 2000441 28H SJ-1AS0H (A) ce SAS CHHÉSNET, YO Den It 1009 EIQA BA, YU RYT ADAP LA AUX 1999 Æ az ı O58 149 IPS (FARE T ERA : 2000 FO 6 AREA) ıcık, [ZAR YORE | 7» 5 Bee FA LAADE D ELE, | Of ERST, 2001 FS OER + RL PAO PRIOR DUE SE Lic, PR HE ; SILO A FADS 7 AOMOHA HEOPISOMEED), BIS 1 A PADS 2 ADMD ER + ‘ + % + FOES RZOFERHN) BHÉ&NET, RR TES NCO SRS) LAS, BAL AA Fat, ARBOR LIASSE: T240-0067 ker EHRE 79-2 BEENTA SAR AREA ARE FIRE (TEA) AeGt5e FAIBME—: TEL 045-339-3349 [83H FAX 045-339-3264 FHREREZ E-mail majima@ed.ynu.ac.jp HDA01631 @nifty.ne.jp BE À| (TEARS): T250-0031 / HET A EH 499 HSS) [WRT AR AO aE + HERE ORE TEL 0465-21-1515 FAX 0465-23-8846 E-mail taru @ pat-net.or.jp rer Tr ee EEE OOOO OS OO OS OF OO OE SOOO SL SO OE SOOO OL OL OOOO OO OOS AEEOFAT ICES SAAS, SRDRÉADUHE, SEEMS OAS S 5 NEN ZA DZAMBZATONTOET HEDENZALTEDEN CT. YEAY ST BRASH Ballen RENTE EAN Ae fe wMARMMBRARAH FA rı vv NL R FE eR Ks H ÉEYXLÉROBMEÉS Sa-VY7LN- IRRE (74 7 TT IB) 4 A Ft OMREE SHAM HARRAH) Ick 2, Je ccs, ea eS 19994 4A 27H El hil 113-8622 SEH ABICHK ABSA 5-16-9 1999E4A30H % fr HAMARB LY I-A eas On 3 — 58: A558 ff À À NE - kh - 1 À kB eee Bm - £ - BHR kK an ÉD Al 4 T984-001 (ATK T © Era 8-45 2,500 F fEACAREU MISH ER SEF Att 022-288-5555 HEHE 03- 3455-4415 ISSN 1342-8144 Paleontological Research Paleontological Research Vol. 3 No. 1 April 30, 1999 CONTENTS Keiji Nakazawa: Permian bivalves from West Spitsbergen, Svalbard Islands, Norway .............- Takeshi Setoguchi, Takehisa Tsubamoto, Hajime Hanamura and Kiichiro Hachiya: An early Late Cretaceous mammal from Japan, with reconsideration of the evolution of tribosphenic molars .. .. Kenichi Saiki: A new cheirolepidiaceous conifer from the Lower Cretaceous (Albian) of Hokkaido, Japan ce se kbc sn ee Shwe. ads ale heim ale ae Gallas ee Ser erty cu He dog A Oe Tatsuro Matsumoto and Akitoshi Inoma: The first record of Mesoturrilites (Ammonoidea) from Hokkaido (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXxIll) .. .. ..... .. Shuji Niko, Yoshitaka Kakuwa, Daisuke Watanabe and Ryo Matsumoto: Early Silurian actinocerid and orthocerid cephalopods from the Kerman area, East-Central Iran Jeong-Yul Kim, Hyonyong Lee and Chang-Hi Cheong: Occurrence of Carboniferous corals from the Geumcheon Formation of Danyang area, Korea .. .. .. ke 22 22 ce ee ee ce en ee an en en en an en te en ee Naoko Takenaka: Relation of growth rings to reproductive cycle in Cryptopecten vesiculosus, a dimorphic pectinidibiIVAIVE: faux u. on esse ee Gales 40) SR oe oa eee 18 29 36 ai 49 57 Paleontological Research Por ISSN 1342-8144 E: u Formerly Y254 : 3 Transactions and Proceedings Va of the Palaeontological Society of Japan Vol. 3 No.2 June 1999 The Palaeontological Society of Japan Co-Editors Kazushige Tanabe and Tomoki Kase Language Editor Martin Janal (New York, USA) Associate Editors Jan Bergstrom (Swedish Museum of Natural History, Stockholm, Sweden), Alan G. Beu (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Satoru Chiba (Tohoku University, Sendai, Japan), Yoichi Ezaki (Osaka City University, Osaka, Japan), James C. Ingle, Jr. (Stanford University, Stanford, USA), Kunio Kaiho (Tohoku University, Sendai, Japan), Susan M. Kidwell (University of Chicago, Chicago, USA), Hiroshi Kitazato (Shizuoka University, Shizuoka, Japan), Naoki Kohno (National Science Museum, Tokyo, Japan), Neil H. Landman (Amemican Museum of Natural History, New York, USA), Haruyoshi Maeda (Kyoto University, Kyoto, Japan), Atsushi Matsuoka (Niigata University, Niigata, Japan), Rihito Morita (Natural History Museum and Institute, Chiba, Japan), Harufumi Nishida (Chuo University, Tokyo, Japan), Kenshiro Ogasawara (University of Tsukuba, Tsukuba, Japan), Tatsuo Oji (University of Tokyo, Tokyo, Japan), Andrew B. Smith (Natural History Museum, London, Great Britain), Roger D.K. Thomas (Franklin and Marshall College, Lancaster, USA), Katsumi Ueno (Fukuoka University, Fukuoka, Japan), Wang Hongzhen (China University of Geosciences, Beijing, China), Yang Seong Young (Kyungpook National University, Taegu, Korea) Officers for 1999-2000 President : Kei Mori Councillors : Kiyotaka Chinzei, Takashi Hamada, Yoshikazu Hasegawa, Itaru Hayami, Hiromichi Hirano, Noriyuki Ikeya, Junji Itoigawa, Tomoki Kase, Hiroshi Kitazato, ltaru Koizumi, Haruyoshi Maeda, Ryuichi Majima, Makoto Manabe, Hiroshi Noda, Ikuo Obata, Kenshiro Ogasawara, Terufumi Ohno, Tatsuo Oji, Tomowo Ozawa, Yukimitsu Tomida, Tsunemasa Saito, Takeshi Setoguchi, Kazushige Tanabe, Akira Yao Members of Standing Committee : Hiroshi Kitazato (General Affairs), Tatsuo Oji (Laison Officer, Makoto Manabe (Finance), Kazushige Tanabe (Editor in Chief, PR), Tomoki Kase (Co-Editor, PR), Ryuichi Majima (Planning), Hiromichi Hirano (Membership), Kenshiro Ogasawara (Foreign Affairs), Haruyoshi Maeda (Publicity Officer), Noriyuki Ikeya (Editor, “Fossils”), Yukimitsu Tomida (Editor in Chief, Special Papers), Tamiko Ohana (Representative, Union of Natural History Societies). 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Phone : (978)750-8400, Fax : (978)750-4744, www.copyright.com Cover: Idealized sketch of Nipponites mirabilis Yabe, a Late Cretaceous (Turonian) nostoceratid ammonite. Various reconstructions of the mode of life of this species have been proposed, because of its Curiously meandering shell form (after T. Okamoto, 1988). All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN c/o Business Center for Academic Societies, Honkomagome 5-16-9, Bunkyo-ku, Tokyo 113-8622, Japan Paleontological Research, vol. 3, no. 2, pp. 65-80, 8 Figs., June 30, 1999 © by the Palaeontological Society of Japan Three Ordovician cephalopods from the Jigunsan Formation of Korea CHEOL-SOO YUN Geological Institute Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan Current adaress. Taegu 702-701, Korea Department of Earth Science, Teacher's College, Kyungpook National University, Received 24 June 1998 ; Revised manuscript accepted 10 February 1999 Abstract. Cephalopod species previously described from the Middle Ordovician Jigunsan Formation of Duwibong type Joseon Supergroup of Baegunsan Syncline, Kangweondo in Korea were re-examined taxonomically based on the type and figured specimens and newly collected ones. Three species, Holmiceras coreanicum (Kobayashi, 1927), Sactorthoceras makkolense (Kobayashi, 1927), and Kotoceras grabaui (Kobayashi, 1927) are described. Each species was restudied and compared with closely related species described by Kobayashi (1927, 1934) ; respective lectotypes are also designated herein. In this study, Sigmorthoceras coreanicum, based on its sigmoidally curved conch, was identified as belonging to Holmiceras which is characterized by the early loosely gyroceraconic shell portion. Sinuitopsis kochirien- sis, previously identified as an Ordovician gastropod, is a juvenile shell of H. coreanicum, judging by the number of the volutions and prominent shell surface. Three species belonging to Sactorthoceras and also Cycloceras taihakuense were regarded, based on the existence or nonexistence of the preserved shell and the imploded internal structure, as junior synonyms of Sactorthoceras makkolense in a broad sense. Kotoceras frechi was rejected as an invalid taxon, since its septal angulation, broader siphuncle and rapid expansion of the conch are characteristics caused by secondary deformation. Key words: cephalopods, gyroceraconic, lectotype, Middle Ordovician, secondary deformation, synonym Introduction Paleontological study of the invertebrate fauna from the Cambro-Ordovician formations in Kangweondo, Korea was initiated by Kobayashi (1927). At that time, he identified three units (fossil beds 13, 14, and 15) as the “Chikunsan fossil beds”. From these beds, he described 16 nautiloid species belonging to 8 genera from the Maggol, Hwarari and Hwang- jiri areas. He mentioned that the cephalopods from the “Jigunsan fossil beds” show an affinity with the Chazyan of North America, while the trilobites and brachiopods show European affinity. Kobayashi (1934) subsequently described a great number of cephalopod fossils which belong to 58 species of 29 genera, revising 11 hitherto described species, and stated that the Jigunsan cephalopod fauna is diagnosed by the age of orthoceroidal divergence in cephalopod macroevolutionary history. Later, Kobayashi (1966) made a comprehensive compilation of the Cambro-Ordovician for- mations and faunas of South Korea and divided the Middle Ordovician sequence of the Duwibong type Joseon Super- group into five cephalopod assemblage zones i.e., Manchuro- ceras, Polydesmia, Sigmorthoceras, orthoceroid, and actinoceroid Zones in ascending order. The Korean Ordovician cephalopods have been studied both taxonomically and biostratigraphically by Kobayashi (1927, 1934, 1966, 1969, 1977a, 1977b, 1978) and have not been revised by any subsequent researcher. The series of Kobayashi's works provides important phylogenetic clues and insight into the Asiatic and worldwide Ordovician paleogeography of fossil cephalopods. However, some Korean cephalopod specimens described by Kobayashi require additional restudy in view of the current knowledge of cephalopod taxonomy. This paper aims to re-examine the systematics and taxon- omy of three Ordovician cephalopod species from Korea on the basis of Kobayashi's (1927, 1934) type specimens and newly collected specimens from the type localities and other new localities. Geological setting The Cambro-Ordovician deposits are widely distributed in Kangweon-do, Korea. They have been divided into five types, based on the lithology and fauna; viz., Duwibong, Yeongweol, Jeongseon, Pyeongchang, and Mungyeong types (Kobayashi et al., 1942). The cephalopod specimens 66 Cheol-Soo Yun LEGEND Ordovician Odj Fault National road e Jikdong SANGDONG 10 km Duwibong Formation Jigunsan Formation Maggol Formation Dumugol Formation Dongjeom Quartzite Geologic boundary Provincial road Fossil localities aia de Gürae "Sodo © | 6 GD : Maggol (MG) er : Sesong (SS) GI : Manhangjae (MH) 127 Ee TAEBAEG e : Sanaegol (SN) : Sorogol (SR) : Dongjeom (DJ) Oo U1 B CO PO — Figure 1. Geologic map of the study area, showing the cephalopod localities. used in this study were collected from the Jigunsan Forma- tion, Upper Joseon Supergroup which extends from east to west in the southern limb region of the Duwibong type Joseon Supergroup of the Baegunsan Syncline (Figure 1). The Jigunsan Formation originally named as the “Chikun- san Shale” by Yamanari (1926), is about 50 m thick, confor- mably covers the Maggol Formation and grades into the overlying Duwibong Formation (Figure 2) This formation can be traced from east and west in the Taebaeg region. The Jigunsan Formation is lithostratigrahically divided into the lower, middle, and upper members. The lower member is essentially non-fossiliferous and consists mainly of black shale containing a little calcareous material; the middle member is composed of “worm-eaten” bioturbated limestone and vermicular shale intercalated by three or four limestone beds, each about 50 cm thick, and has yielded a large number of trilobites ; the upper member consists of lime- stone and bioclastic grainstone with intercalating calcareous shale. The amount of carbonate gradually increases toward the top of the sequence and ultimately grades into the limestone of the Duwibong Formation; this member has yielded a rich cephalopod fauna. The Jigunsan Formation is especially well exposed in the Sanaegol section (Figures 1, 2). It consists mainly of black shales and thin beds of calcareous nodules, in which ortho- cerid and lituitid nautiloids occur. The lower member is almost barren of fossils ; the middle member is characterized by the abundant occurrence of Holmiceras ; the upper member is represented by bioclastic grainstone with inter- calating calcareous shale and contains abundant ormocer- oid cephalopods. According to Kobayashi (1934, 1966), the Jigunsan Forma- tion is correlated with the Llandeilo in the European succes- sion and the Chazy in the American sequence. Shimizu and Obata (1935b) described three graptolite species from the formation and correlated it with the Lower Llandeilian Diplograptus teretiusculus and Nemagraptus gracilis Zones in the Glenklin Shale, England and Pingliang Shale of Gansu Province in North China. Shikama and Ozaki (1969) distin- guished three assemblage zones in the Jigunsan Formation in the Dongjeom area, namely, the Orthis nipponica, Basilicus deltacaudus, and Basilicus yokusensis Zones in ascending order, based on the macrofossils collected by a member of the Yokohama Geologists Club in 1967 (Ozaki and Ogino, 1968). The Jigunsan trilobite fauna has been studied in detail by Lee et al. (1980), who described 15 species belonging to 5 genera and correlated the formation with the Llandeilo to Ordovician cephalopods from Korea 67 Duwibong Fm. Sanaegol Section Sorogol Section Dongjeom Section Upper Member c € = I) mo SI o| € T 3 a © o| = Middle Member ce alle 3| § EE sed ey S| 7 _ Lower Member Maggol Section Sesong Section Manghangjae Section Maggol Fm. = Limestone TS Limestone to bioclastic grainstone 1 CAC ZI=I=] with partings calcareous shale Legend = Shale-parted limestone Varnicularehale = Alternation of shale and ao calcareous nodular bed Warm-eaten limestone =| Shale << No exposure Figure 2. Geological columns of the Jigunsan Formation in the study area, showing the horizons of the cephalopod localities. lower Caradoc interval in Europe. Lee and Lee (1986) established a conodont biozone in the middle and upper parts of the Jigunsan Formation, namely, the Eoplacognathus suecicus-Eoplacognathus jigunsanensis Assemblage Zone. These authors correlated the conodont fauna with the Eoplacognathus suecicus-Acontiodus ? linxiensis Zone of the lower Upper Majiagou Formation in North China and with the Lower to Middle Llanvirn in the European type section. They also suggested that the Jigunsan Formation was deposited in a deep shelf environ- ment, based on the conodont fauna. Materials Most cephalopod specimens described by Kobayashi were collected from Maggol in Korea, where strata indicative of the western part of the Duwibong type Joseon Supergroup are exposed (Loc. 1 in Figure 1). The list of type specimens re-examined in this study is shown in Table1. The ce- phalopod type specimens in Table1 are housed in the University Museum, University of Tokyo (UMUT). Fifty-seven specimens listed in Table2 were used for comparison with Kobayashi's type specimens. These new and unstudied specimens were collected by the present author and K. Tanabe on three occasions during May to August, 1997. All of them were discovered from the Middle Ordovician Jigunsan Formation in Kangweondo, Korea. They are deposited in the Department of Earth Science, Teacher's College, Kyungpook National University (KPE prefix), Taegu, Korea. 68 Table 1. List of cephalopod type specimens which were described by Kobayashi (1927, Cheol-Soo Yun 1934) from the Jigunsan Formation and are re-examined in this study. Registered no. Scientific name Locality Type UMUT PM 8 Sigmorthoceras coreanicum Maggol Syntype UMUT PM 9 Sigmorthoceras coreanicum Maggol Syntype UMUT PM 651 Sigmorthoceras coreanicum Maggol Syntype UMUT PM 6 Sactorthoceras makkolense Maggol Syntype UMUT PM 7 Sactorthoceras makkolense Maggol Syntype UMUT PM 660 Cycloceras sp. Hwangji Syntype UMUT PM 570 Sinuitopsis kochiriensis Hwangji Syntype UMUT PM 571 Sinuitopsis kochiriensis Hwangji Syntype UMUT PM 634 Kawasakiceras densistriatum Maggol Holotype UMUT PM 652 Sigmorthoceras sigmoidale Maggol Holotype UMUT PM 657 Cycloceras taihakuense Maggol Paratype UMUT PM 658 Cycloceras taihakuense Maggol Paratype UMUT PM 659 Cycloceras taihakuense Maggol Holotype UMUT PM 650 Sactorthoceras gonioseptum Maggol Holotype UMUT PM 643 Sactorthoceras shimamurai Maggol Holotype Table 2. List of cephalopod specimens from the Middle Ordovician Jigunsan Formation, Kangweondo, Korea. Species | Locality No. of specimens Holmiceras coreanicum | SN801, SN802, SN809, SN835, DJ500, MH201 32 Sactorthoceras makkolense SN802, SN809, SN835, DJ500 15 Kotoceras grabaui | SR900, SS663, MG343, MG350, MG357 10 Systematic paleontology Subclass Nautiloidea Order Tarphycerida Family Lituitidae Genus Holmiceras Hyatt, 1894 Type species.—Lituites praecurrens Holm, 1891 from the Lower Ordovician (Kundan Stage) of Oland, Sweden. Generic diagnosis.—Lituiticonic with adapically one-volut- ed gyroceraconic and adorally sigmoidal curved shell por- tion; septal necks orthochoanitic ; surface ornamented with growth lines and annulations, forming ventral sinus and lateral salient in the earlier coiled stage and transverse or slightly undulating ones in the later stage. Remarks.—Hyatt (1894) recognized that this genus is characterized by having distinct ventral and dorsal lobes in the ephebic stage, with low, broad, almost staight, lateral saddles. Ancistroceras is most closely allied to Holmiceras, but differs from the latter in having small, tightly coiled whorls and a much more rapidly expanding conch. Sweet (1958) emphasized the sigmoid profile of the shell which is missing in Ancistroceras. Holmiceras has long been an all-but-forgotten genus. However, Flower (1975) added Holmiceras benetti from the Middle Ordovician Table Head Formation in Newfoundland to the two previously known Holmiceras species. Presently, only four species in the world can be referred to Holmiceras ; Holmiceras praecurrens (Holm, 1891), Holmiceras kjerulfi (Brögger, 1882), Holmiceras benetti Flower, 1975 and Hol- miceras coreanicum (Kobayashi, 1927) which is described below. Holmiceras coreanicum from the Jigunsan Formation is a first reliable record of this genus from Asia. Holmiceras coreanicum (Kobayashi, 1927) Figures 3-1a, b, 2a, b; 4-1—10. Orthoceras coreanicum Kobayashi, 1927, p. 181, pl. 18, fig. 6; pl. 19, figs. 3a-c. Orthoceras makkolense Kobayashi, 1927, p. 181, pl. 19, figs. 2a-c. Sigmorthoceras coreanicum (Kobayashi). Kobayashi, 1934, p. 413, pl. 22, fig. 7. Sactorthoceras makkolense (Kobayashi). Kobayashi, 1934, p. 408, pl. 15, fig. 9. Cycloceras sp. Kobayashi, 1934, p. 421, pl. 29, figs. 12, 13. Sinuitopsis kochiriensis Kobayashi, 1934, p. 360, pl. 5, figs. 1-4. aff. Trilacinoceras sp. Ozaki and Ogino, 1968, pl. 3, fig. 3. Holmiceras coreanicum (Kobayashi). Yun, 1998, p. 78, figs. 1c-h. Types.—A sigmoidally curved phragmocone figured by Kobayashi (1927, p. 181, pl. 19, figs. 2a-c) from the Jigunsan Formation of Maggol, Kangweondo, Korea, UMUT PMS9, is here designated as the lectotype (see also Figures 3-1a, b). A slightly curved phragmocone specimen from the same locality, UMUT PMB is also designated as the lectoparatype. Material.—In addition to the above two type specimens, newly collected specimens from the Jigunsan Formation including 9 figured (KPE20001, KPE20002, KPE20003, KPE20004, KPE20005, KPE20006, KPE20007, KPE20020, KPE20026-1, KPE20302) and 23 other specimens were Ordovician cephalopods from Korea 69 examined. Specific diagnosis ——Sigmoidally curved conch with early loosely coiled portion ; body chamber long; circular in cross section ; siphuncular segments somewhat expanded within camera; septal necks orthochoanitic ; no cameral deposits detected ; surface ornamented with prominent annulations and very fine growth lines. Description. —Conch large-sized lituiticone, composed of two different continuous shell portions, namely, early loosely coiled juvenile shell portion (Figures 4-1a-c—4) and later sigmoidally curved adult shell portion (Figures 4-6a, 7, 8). The best preserved specimen, KPE20001 (Figures 4-1a— c), is broken into two portions, but when put together is about 63 mm long; the early juvenile shell portion is loosely coiled, its umbilical opening being 3.2mm across, first Camera pointed anterolaterally, constricted to 1mm at a height of 1.5 mm from the adapical apex, forming a subquadrate outline ; internal structure unknown owing to recrystallization ; septa moderately concave and closely spaced with septal spacing 0.7 mm on the dorsum and 1mm on the venter, gradually increasing adorally ; slightly curved later shell portion, 58 mm long, circular in cross section, its diameter expanding from 7 mm at the adapical end to 15.7 mm at the broken upper end ; siphuncle central, narrow, its width one-eighth of the conch diameter ; siphuncular segments tubular to slightly inflated within camerae ; transverse septal suture and surface an- nulations crossing each other; septal depth smaller than one cameral height on the concave side and larger than that on the convex side; cameral height gradually increasing towards the top from 1.3 mm to 2.9 mm, five camerae equal in length to the conch diameter of 15.9 mm measured at the uppermost camera; septal necks orthochoanitic, attaining 0.5mm at the 3rd septum from the adoral end, occupying about one-third of the cameral height, distinguishable from the connecting ring by means of their thickness, septal suture transverse, but intersecting with annulations ; camera filled with crystalline calcite, no organic deposits detected ; siphuncle lined by endosiphuncular nonsegmental material along the inner siphuncular wall and leaving central narrow siphotube ; surface ornamented with low, narrow annula- tions separated by much broader intergrooves, both of which are covered with very fine transverse growth lines, showing different features during ontogeny, ventral sinus and lateral salients in juvenile coiled stage and then adorally run parallel to transverse axis, 7 annulations in a length equal to the conch diameter at the preserved adoral end, annulation density slightly larger than that of septal one, i.e., 8 growth lines occurring between two annulations. KPE20002 (Figure 4-4) represents a young, possibly embryonic or early postembryonic shell with 10 camerae consisting of endogastrically curved gyroconic phragmocone and subsequent straight body chamber, small, 15.5 mm long, conch diameter rapidly enlarging from 2.2mm near the adapical end to 4.9mm at the base of the living chamber ; siphuncle central, its segments expanded within camerae, constricted at the septal necks ; septal depth corresponding to one cameral height ; siphuncle filled with imported matrix, camera filled with crystalline calcite; surface annulated in longitudinal section, being arranged at intervals of 0.8 mm. KPE20003 (Figure 4-2) judging from the silicone rubber cast, is the external mould of an early coiled shell portion, 17.5 mm long, composed of a loosely coiled embryonic shell portion, its umbilical opening about 3mm across, conch expanding at a rate of 1mm per 4mm; surface ornamented with prominent annulations and transverse fine growth lines, forming ventral and dorsal sinuses, and ventrolateral salients. KPE 20004 (Figure 4-7), a sigmoidally curved phrag- mocone, 85.2mm in length, conch diameter expanding moderately rapidly in the earlier stage from 3.8 mm to 10 mm at a distance of 21mm and more slowly afterwards, conch circular in cross section; siphuncle narrow, central; septal necks orthochoanitic ; cameral height ranging from 1.7 mm to 3mm; septal depth slightly larger than one cameral height ; surface ornamented with primary annulations and very fine growth lines. KPE20005 (Figure 4-5) is a sigmoidally cuved fragmentary phragmocone, 76mm in length, conch diameter gently expanding from 10.2 mm at the adapical end to 22.9 mm at the adoral end; siphuncle subcentral, narrow, occupying one-seventh of the conch diameter ; siphuncular segments slightly inflated within camera, dimensions 2.6 mm in length and 3mm in maximum diameter at the midportion of the segment in the adoral end, constricted to 2.2mm at the septal foramina ; septal necks suborthochoanitic, septa rela- tively deep, exhibiting one and a half of the cameral height ; septal distance varying from 19mm to 2.8mm; nonseg- mental endosiphonal linings along the siphuncular wall, leaving a central tube; surface ornamented with distinct annulations and growth lines. KPE20006 (Figure 4-10) is an external mould retaining well preserved surface ornamentation, consisting of annulations very closely spaced at intervals of approximately 1mm, with ventral sinus formed by each annulus about 2.6 mm in width and about 1.3 mm in length in earlier shell portion, and of much more widely spaced, more prominent transverse an- nulations in later shell and further annulations again becom- ing narrower in gerontic shell, annulations and intergrooves both covered with very fine growth lines. KPE20007 (Figures 4-6a, b) represented by a moderately curved, large-sized adult shell lacking an early coiled por- tion, is 162 mm long of which the body chamber is 57 mm long, adoral portion of phragmocone and body chamber secondarily depressed during fossilization, conch circular in cross section ; its diameter gently enlarging from 19.7 mm at the adapical end to 33.3 mm at a point 74 mm farther up; siphuncle central, narrow, a little more than one-seventh of the conch diameter ; siphuncular segment as long as broad ; surface ornamentation on body chamber partly preserved, comprising annulations and growth lines. KPE20302 (Figure 4-8), 53.5 mm in length, consists of a loosely coiled early shell portion and succeeding sigmoidally curved conch, but an initial chamber is not preserved ; umbilical opening about 2.8 mm across ; moderately expan- ding at a rate of 1mm per 5mm. Remarks.—Sigmorthoceras coreanicum from the Jigunsan Formation of Maggol (Kobayashi, 1927, pl. 18, fig. 6; pl. 19, figs. 3a-c ; 1934, p. 413, pl. 22, fig. 7) is the type species of Sigmorthoceras which has been regarded as a doubtful 70 Cheol-Soo Yun taxon for a long time. Externally, the slightly curved conch was regarded as the diagnostic character by Kobayashi (1934). However, Shimizu and Obata (1935a) regarded the sigmoidal conch shape of specimens of Sigmorthoceras described by Kobayashi as a secondarily deformed Sactor- thoceras makkolense. Such secondary deformation is com- mon in other nautiloid fossils from this region. Flower (1946) stated that Sigmorthoceras is an erratic form deviation, perhaps not worthy of generic status. However, the internal morphology of the sigmoidally curved conch of the present species is identical with that of the type specimens of Sigmorthoceras coreanicum. Based on the identical curvature of all the specimens, the secon- dary deformation conjecture by Shimizu and Obata, (1935a) can be rejected. Thus, Holmiceras coreanicum is revealed to possess a loosely coiled early shell portion and slightly sigmoidal more mature conch. It is well known that secondary deformation and dissolu- tion of shelly matter during fossilization sometimes cause misidentification of fossil taxa. Kobayashi (1934) described Cycloceras sp. from the Jigunsan Formation of Homyeong (p. 421, pl. 29, figs. 12,13), based on the annulated ornamenta- tion. The annulations observed on the ventral portion near the adapical end of the specimen are more broadly spaced than those on the dorsal one. Accordingly, the specimen represents a portion of the shell shifting from the early coiled stage to the sigmoidally curved phragmocone in Holmiceras coreanicum. Furthermore, all the features observed in the longitudinal section agree well with those of Holmiceras coreanicum, although the state of preservation of the internal structure is rather poor. Meanwhile, Kobayashi (1934) described a sinuitid gas- tropod, Sinuitopsis kochiriensis from the Jigunsan Formation of Homyeong, based on two incomplete external moulds (Kobayashi, 1934, p.360, pl.5, figs.1-4). In general, the genus Sinuitopsis consists of a tightly coiled shell with 3 to 4 volutions (Knight et al., 1960, pl. 176, fig. 93-7a, b) and its surface is sculptured by fine growth lines without more raised primary annulations. However, the specimens described by Kobayashi (1934) as “Sinuitopsis” have loosely coiled shells having one volution and lacking the characteristic surface sculpture of true Sinuitopsis. In addition, its surface orna- mentation consisting of ventral sinus and lateral salients is strong evidence to support the contention that the two external moulds belong to Holmiceras. Sactorthoceras makkolense (Kobayashi, 1927) was proposed based on two individuals. One of them (UMUT PM7 ; Figures 3-2a, b), illustrated in Kobayashi (1927, pl. 19, figs. 2a-c) differs from the other specimen (UMUT PM6; Kobayashi, 1927, pl. 18, fig.5; see also Figures 3-4a, b) in having more crowded septa and a narrower siphuncle. Accordingly, the former specimen (UMUT PM7) is dissimilar to the lectotype but has a cameral height of no more than two-thirds the diameter of the siphuncle. Moreover, the conch of the specimen has a slightly curved form, although its siphuncular position is more or less eccentric due to secondary deformation. In these respects, this specimen must also be assigned to Holmiceras coreanicum. Ozaki and Ogino (1968, pl.3, fig.3) figured a single nautiloid, aff. Trilacinoceras sp. from the Jigunsan Forma- tion of Dongjeom. It is represented by an early coiled phragmocone. However, its generic identification may be incorrect because of the less loosely coiled portion of the conch than those in the species of the genus Trilacinoceras. Based on the mode of coiling in the early portion of the conch and the surface ornamentation, this nautiloid is assigned with reservation to Holmiceras coreanicum. Comparison.—In view of the external morphology, this species is closely allied to Holmiceras kjerulfi (Brogger) from the Orthoceras Limestone of the Oslo region, Norway (Brgger, 1882, p. 54, pl. 12, fig. 16), but differs from the latter species by its loosely gyroceraconic volution, somewhat curved cyrtoconic or sigmoidal adoral portion, circular section of the conch and slightly more crowded septa. This species is distinguished from Holmiceras benetti Flower from the Middle Ordovician Lower Table Head Limestone, Newfoundland (Flower, 1975, p. 151, pl. 4, figs. 1-6), which has a more rapidly expanding conch and lacks a sigmoidal adoral shell portion. This species is similar to the Middle Ordovician species Ancistroceras undulatum Boll, 1857 recovered from erratic boulders in northern Germany (Foerste, 1929, p. 272, pl. 41, figs. 3,4) and the Ampyx Limestone in Oslo-Asker district, Norway (Sweet, 1958, p.129, pl. 13, figs. 2,3, 5) in that the early coiled portion and the mode of surface ornamentation are similar to H. coreanicum, but this taxon is quite distinct from the latter in its more slowly expanding conch. Like- wise, Ancistroceras subcurvatum Qi, 1980 from the upper Taiwan Formation, Lower Ordovician, Wuwei, Anhui, China (Qi, 1980, p. 256, pl.1, figs. 1, 2) is similar to this species in general features but also differs from it by its own somewhat more rapidly expanding conch. Occurrence.—This species is known to occur from various localities (SN801, SN802, SN809, SN835, DJ500 and MH201) in the Middle Ordovician Jigunsan Formation. Order Orthocerida Family Sactorthoceratidae Genus Sactorthoceras Kobayashi, 1934 Type species.—Sactorthoceras gonioseptum Kobayashi, 1934 from the Jigunsan Formation of Maggol, Kangweondo, Korea. ~ Figure3. 1a,b, 2a,b. Holmiceras coreanicum (Kobayashi, 1927). 1a,b. A sigmoidally curved phragmocone, lectotype (UMUT PMS9), x 1, 1a: lateral view, 1b: longitudinal section. which is here assigned to Holmiceras coreanicum (Kobayashi), 2a, b. “Sactorthoceras makkolense (Kobayashi)”, UMUT PM7, <1, 2a: lateral view, 2b: longitudinal section. 3a, b. Kotoceras grabaui (Kobayashi, 1927). The best preserved partial phragmocone, lectotype (UMUT PM631), <1, 3a: ventral wew, 3b. adoral view of the septa and siphuncle, venter down. 4a, b. Sactorthoceras makkolense (Kobayashi, 1927). An adoral phragmocone, lectotype (UMUT PM6), 4a: longitudinal section, x1, 4b: enlargement of the same section, x 2. Ordovician cephalopods from Korea 71 72 Cheol-Soo Yun Generic diagnosis.—Straight or slightly Curved longiconic orthoceracone with subcentral siphuncle ; siphuncular seg- ments tubular or slightly expanded within camerae ; cameral height nearly equal to or a little more than siphuncular diameter; no discernible cameral and endosiphuncular deposits; surface smooth or ornamented with closely spaced annulations and very fine transverse growth lines. Remarks.—The genus Sactorthoceras is known from the Middle Ordovician formations in East Asia, Norway and northeastern America. Flower (1941) considered Sactor- thoceras as the ancestor of the ascocerid nautiloids that make up a specialized group having siphuncular segments from orthochoanitic to cyrtochoanitic. Indeed, Sactorthoceras may be not distinguished from Holmiceras when any specimen is found as an adoral broken phragmocone without an early coiled shell portion. How- ever, the longitudinal section through the center of the siphuncle reveals that the siphuncle of Sactorthoceras is always broader and its septal distance is higher than in Holmiceras. The generic assignment of Cycloceras M'Coy is based mainly on the surface ornamentation and not on internal structure. The Group1 of Cycloceras which was divided artificially by Kobayashi (1934) is regarded as belonging to either Sactorthoceras or Holmiceras, because its internal structure and surface ornamentation agree well with the latter genera. Moreover, Sweet (1964) mentioned that “no species other than the type species should be referred to Cycloceras until its type is better known”. Based on present knowledge, the genus Cycloceras may be superseded by Wennanoceras, which was proposed by Chen (1976) for shells having a strongly annulated surface and a central siphuncle. Sactorthoceras makkolense (Kobayashi, 1927) Figures 3-4a, b; 5-1—6; 6-1—4 Orthoceras makkolense Kobayashi, 1927, p. 181, pl. 18, fig. 5; not pl. 19, figs. 2a-c. Sigmothoceras sigmoidale Kobayashi, 1934, p. 414, pl. 21, figs. 1 3. Sactorthoceras gonioseptum Kobayashi, 1934, p. 412, pl. 16, fig. 6 ; pl. 18, figs. 1-3; pl. 20, fig. 9. Sactorthoceras shimamurai Kobayashi, 1934, p. 408, pl. 19, figs. 1 3: Kawasakiceras densistriatum Kobayashi, 1934, p. 397, pl. 14, figs. EXT Cycloceras taihakuense Kobayashi, 1934, p. 420, pl. 22, figs. 1,2; pl. 23, figs. 1-5; pl. 24, figs. 4-6. Sactorthoceras makkolense (Kobayashi). pl. 6, figs. 1, 2. Kim et al., 1986, p. 26, Type.—The type specimen, UMUT PM6, from the Jigun- san Formation of Maggol, Kangweondo, Korea is here designated as the lectotype (Figures 3-4a, b). Material.—15 specimens including seven figured ones (KPE20030, KPE20031, KPE20032, KPE20033, KPE20036, KPE20037, UMUT PM634). Specific diagnosis.—Longiconic orthoceracone ; siphun- cular segments tubular; septal necks orthochoanitic to suborthochoanitic ; cameral height nearly equal to siphun- cular diameter; surface ornamented with low annulations and very fine transverse growth lines. Description.—Conch large-sized longiconic orthocer- acone, enlarging at a rate of 1mm per 8 to 10 mm in conch length ; cross sections of conch and siphuncle subcircular ; ratio of the siphuncular diameter versus conch diameter being 1:9 in KPE20030 (Figure 5-3); siphuncle subcentral, tubular ; septa moderately concave forwards, septal depth nearly two to three times the cameral height, septal distance ranging from 3.3 mm to 5.4 mm, in other words, a little more than or equal to the siphuncular diameter, septal necks orthochoanitic, relatively long, approximately 2mm in KPE20037 (Figure 5-6), bending smoothly toward adapical end and then forming a right angle with septa, septal suture directly transverse ; connecting ring thin, distinguishable from septal neck by its thickness ; in KPE20037 camerae comparatively high, ranging from 3.5mm to 4mm, 7 to 8 camerae in a distance corresponding to the conch diameter ; no cameral or siphuncular deposits detected; surface marked with low, narrow annulations, separated by broader interspaces, both covered with very fine numerous trans- verse growth lines, 7 to 8 per 1mm length, annulations being arranged at intervals of about 2 mm, but fluctuating within a narrow range. Remarks.—Kobayashi (1927) described the present species as follows: “In the middle part of the polished specimen (pl. XVIII, fig. 5) the segmentation is quite abnormal, the double — Figure 4. Holmiceras coreanicum (Kobayashi, 1927). 1a-c. Partial phragmocone steinkern (KPE20001) from SN801, 1a: ventrolateral view, showing the septal suture crossing annulations, 1, 1b: dorsoventral section of coiled embryonic conch, *1.8, 1c : longitudinal section of partial phragmocone made by an acetate peel, showing the details of siphuncle and septa, <1.5. 2. Silicon rubber cast of external mould (KPE20003) from DJ500, showing loosely coiled embryonic shell portion with annulated surface ornamentation, x3. 3. Juvenile shell (KPE20026-1) from MG343, dorsoventral section of the early coiled septated shell portion, x3. 4. Possibly embryonic conch (KPE20002) from SN801, dorsoventral section, showing the phragmocone and subsequent body chamber, 3. 5. Partial phragmocone (KPE20005) from DJ500, longitudinal section, showing details of siphuncule and septa, <1. 6a, b. Moderately curved conch (KPE20007) from SN801, <1. 6a: lateral view. Surface ornamentation is partly preserved on body chamber. 6b: apical view, showing the position of the siphuncle. 7. Longitudinal section of partial phragmocone (KPE20004) from SN801 made by an acetate peel, showing the sigmoidally cuved conch and details of siphuncle and septa, <2. 8. Early coiled and later sigmoidally curved conch (KPE20302) from SN802, 1.5. 9a, b. Partial phragmocone (KPE20020) from SN801, x1, 9a: lateral view, 9b: apical view of septum and siphuncle, showing the position of siphuncle. 10. Partial phragmocone (KPE20006) from DJ500, ventral view, silicon rubber cast of external mould, showing the well developed surface ornamentation, especially ventral sinus of annulations on earlier portion, x 2.5. Ordovician cephalopods from Korea 13 74 Cheol-Soo Yun camerae on one side of the siphuncle corresponding to a single camera on the other....... It may be possibly be due to a pathological state”. However, in the type speci- mens of this species (Figures 3-4a, b), the septa in the adoral portion of the phragmocone are distributed disorderedly here and there. This peculiar shell feature is considered to be an artifact created by recrystallization. As the result of restora- tion, the septa on each side in the each longitudinal section of the lectotype (UMUT PM6) correspond well one to one. This phenomenon is easily found in many cephalopods. For example, Actinoceras bellefontense Foerste and Teichert, 1930 shows a disagreement between septa on both sides owing to the diagenesis of internal components (Foerste and Teichert, 1930, p. 227, pl. 38, fig. 2B). Stridsberg (1990) sug- gested that internal destruction of septa may be caused by implosion due to increasing water pressure during post- mortem sinking. Accordingly, the abnormal camerae obser- ved in the lectotype of Sactorthoceras makkolense may not represent a pathological state during life, but were formed secondarily by taphonomic processes. Taphonomic damage gave rise to other taxonomic prob- lems too. Kobayashi (1934, p. 408, pl. 19, figs. 1-3) proposed Sactorthoceras shimamurai for a specimen with very rapid expansion of the conch, namely, at the rate of 1mm per conch length of 4mm. However, this specimen (UMUT PM643), which is represented by a fragmentary phrag- mocone with the last six camerae being closely spaced and a strongly compressed, large-sized body chamber, does not reflect the real expansion rate of the shell owing to secon- dary deformation of the body chamber and erosion of one side. Furthermore, since the last six camerae indicate the gerontic stage, more widely spaced camerae would be present in the adolescent stage. Consequently, Sactor- thoceras shimamurai is regarded as a junior synonym of Sactorthoceras makkolense. Sactorthoceras gonioseptum from the Jigunsan Formation of Maggol was described by Kobayashi (1934) as having a narrower siphuncle and more crowded septa than Sactor- thoceras makkolense. He also emphasized the angulation of the septa shown in the holotype (UMUT PM650) as a diagnostic character of this species. However, this feature can not be observed in the specimen because of the crushed and distorted condition of the septa along the outer part of the cameral portion. Shell breakage during fossiliza- tion resulted in a pinched septal foramen with curiously angulated septal necks. Apart from the aberrant feature of septal angulation, Sactorthoceras gonioseptum can be regard- ed as a junior synonym of Sactorthoceras makkolense. Kobayashi (1934) established Sigmorthoceras sigmoidale on the basis of a single sigmoidally curved specimen (UMUT PM652). He stated that this species is characterized by more broadly spaced septa and a broader siphuncle than in Sigmorthoceras coreanicum. (Kobayashi (1934) described the shell surface of this specimen as smooth, but reanalysis of the same specimen revealed that it is actually sculptured by weak annulations and very fine transverse growth lines. Kobayashi (1934) emphasized that this species is closely similar to Sactorthoceras makkolense, except for the sig- moidal curvature of the conch. However, as Shimizu and Obata (1935a) pointed out, the sigmoidal mode of nautiloids from the Jigunsan Formation including Sigmocycloceras kogenense (Kobayashi), presumably originated by secondary deformation rather than from biological causes. Re-analy- sis of this specimen in longitudinal section indicates that over half of the right cameral portion is abraded and worn away and subsequently the chambers were filled with sedi- ment. Therefore, this specimen probably suffered some secondary deformation from one side. It seems likely that this force together with compactional load changed this specimen to a sigmoidal form. Thus, the original mor- phological features of the type specimen of Kobayashis Sigmorthoceras sigmoidale are identified with those of Sactorthoceras makkolense, indicating that the former species is a junior synonym of the latter. Meanwhile, Kobayashi (1934) established Kawasakiceras densistriatum on the basis of its characteristic annulated and striated ornamentation on the surface. In the holotype (UMUT PM634), the large-sized ventral endosiphuncle which is a primary morphologic feature for the endoceroid nautiloids such as Kotoceras can not be detected. Re- examination of the specimen strongly suggests that Kobaya- shi mistakenly interpreted the fracture line through the center as holochoanitic septal necks in his retouched figure in longitudinal section with a body chamber (Kobayashi, 1934, pl. 14, fig. 7; see also Figure 6). The right-half portion of the logitudinally sectioned type specimen may have been regarded as a ventral siphuncle. Also, the endocone which is the vacant space formed by the last endosheath is not observed in the portion that was considered by Kobayashi (1934) as the siphuncle. Therefore the septa are extended to the ventral margin and continue to the right-half portion. This fact is revealed not only by the preserved successive septa in longitudinal section but also by the camerae exposed on the lateral side of the specimen. In this way, this longitudinally sectioned specimen appears to represent a remaining part through which the siphuncle does not pass. Unfortunately, the other half is missing. It is evident that Kawasakiceras densistriatum does not possess a large ven- tral siphuncle as in the species of Kotoceras, but has a centrally located narrow siphuncle. In addition, the surface + Figure 5. Sactorthoceras makkolense (Kobayashi, 1927). ta, b. Partial phragmocone (KPE20036) from SN835, 1a: lateral view, <1, 1b: details of surface ornamentation, showing the annulations and fine growth lines, x5. 2a, b. Fragmen- tary phragmocone (KPE20032) from DJ500, 2a: longitudinal section, showing the siphuncle and septa, <1, 2b: septal view, venter down, showing the position of the siphuncle, x1. longitudinally polished section, 1. showing the phragmocone and subsequent body chamber, » section, showing the slightly inflated siphuncular segments, 1. nal section, showing the internal cameral structure, x1. 3. Naturally weathered phragmocone (KPE20030) from DJ500, 4. Incomplete large conch (KPE20033) from SN835, lateral view of partial conch, 5. Partial phragmocone (KPE20031) from DJ500, longitudinal 6. Partial phragmocone (KPE20037) from SN809, longitudi- Ordovician cephalopods from Korea 75 76 Cheol-Soo Yun Figure 6. “Kawasakiceras densistriatum Kobayashi”, UMUT PM634, which is here assigned to Sactorthoceras makkolense (Kobayashi). 1. Lateral view, *0.5. 2. Longitu- dinal section, x0.5. 3. Sketch based on Kobayashi's view, showing the broad ventral siphuncle. 4. Sketch based on reexamination of the holotype, showing the septa instead of siphuncle. Longitudinal (upper) and cross (lower) sections are shown in 3 and 4. ornamentation agrees well with the pattern of the species of Sactorthoceras. Accordingly, this species is attributed to Sactorthoceras makkolense (Kobayashi, 1927), based on the moderately concave septa, probably central narrow siphun- cle and annulated surface ornamentation with a fine trans- verse striation. Comparison.—This species is similar to Sactorthoceras wongiforme Kobayashi from the Jigunsan Formation of Maggol and Hwangjiri (Kobayashi, 1934, p. 410, pl. 20, fig. 10 ; pl. 31, figs. 1, 2) in its tubular siphuncle and moderately con- cave septa, but differs from the latter in its broader siphuncle and higher camera. Sactorthoceras tenuicurvatum Kobayashi from the Jigun- san Formation of Homyeong and Sanaegol (Kobayashi, 1934, p. 409, pl.16, figs.1,2; pl.17, figs.9,10) is readily distin- guished from this species by its gentle curvature and ellipti- cal section of the compressed conch. This species resembles Sactorthoceras sp. from the Ce- phalopod Shale at Hovindsholm, Helggya, Oslo region, Norway (Sweet, 1958, p. 60, pl. 3, fig. 12; pl. 4, figs. 1, 7), but its septal concavity is nearly three times of cameral height, while that of the latter species is less than half the length of a camera. Occurrence.—Rarely occurs at the localities SN802, SN809, SN835, and DJ500 in the Middle Ordovician Jigunsan Formation. Subclass Endoceratoidea Order Endocerida Family Endoceratidae Genus Kotoceras Kobayashi, 1934 Type species.—Kotoceras typicum Kobayashi, 1934 from the Jigunsan Formation of Maggol. Generic diagnosis.—Longiconic or somewhat curved ortho- ceracone, subcircular to ovate in cross section; siphuncle marginal, broad, nearly a half of the dosoventral conch diameter or less, in actual contact with slightly flattened ventral wall; endocones extending much farther forward ventrally than on dorsal side, apical end slightly closer to the dorsal side than the ventral one; septal necks holo- choanitic ; suture disconnected at ventral flattening ; sur- face smooth. Remarks.—Kotoceras is one of the Asiatic endemic genera from the Jigunsan Formation, Korea, and several species of the genus are known from China and Siberia. The diagnos- tic generic characters are the asymmetric endosiphocone and the disconnected septal suture on the ventral side. Kobayashi (1934) emphasized that Kotoceras is easily distin- guished from other related genera, Endoceras, Vaginoceras, and Cameroceras in having the marginal siphuncle in actual contact with the shell wall on the broadly flattened venter. Flower (1958) recognized that his Lamottoceras is very similar to the Asiatic Kotoceras, in which holochoanitic septal necks are present. However, the genus Lamottoceras differs from Kotoceras in having aneuchoanitic septal necks and thick connecting rings. Kotoceras grabaui (Kobayashi, 1927) Figures 3-3a, b; 7-1—4; 8-1—4 Vaginoceras grabaui Kobayashi, 1927, p. 79, pl. 18, figs. 1a-c, 2. Vaginoceras frechi Kobabyashi, 1927, p. 179, pl. 18, figs. 2a-c. Kotoceras grabaui (Kobayashi). Kobayashi, 1934, p. 395, pl. 11, figs. 5-8; pl. 12, fig. 6; pl. 14, figs. 5-8. Kotoceras frechi (Kobayashi). Kobayashi, 1934, p. 395 (not fig- ured). Type.—The best preserved and largest specimen (UMUT PM631) is designated here as the lectotype of Kotoceras grabaui (Kobayashi) (Figures 3-3a, b). Material.—Eleven specimens including the five figured ones (KPE20042, KPE20043, KPE20044, KPE20045, UMUT PM3). Specific diagnosis.—Subcircular to elliptical in cross sec- Ordovician cephalopods from Korea 77 Figure 7. Kotoceras grabaui (Kobayashi, 1927). 1a-c. Partial phragmocone (KPE20042) from SS663, <1, 1a: ventral view, showing the disconnected septal suture, 1b: dorsoventral section, venter on left, showing the large siphuncle with endosiphuncular deposits and closely spaced septa, 1c: lateral view, venter on left side, showing the transverse septal suture. 2. Strongly compressed phragmocone (KPE20043) from MG350, dorsolateral view, venter on right, showing the septal neck impressions on ventral side of the siphuncle, x1. Sa, b. Partial phragmocone (KPE20044) from MG357, x1, 3a: ventral view, showing the siphuncle-septal neck portion, 3b: apical view of septum and siphuncle, showing the nearly circular conch cross section and slightly depressed siphuncle. 4. Partial phragmocone (KPE20045) from MG357, ventral view, showing the somewhat flattened ventral side, <1. tion ; septal suture transverse, but gradually bends adapical- Description.—Conch medium-sized longiconic orthocera- ly and then turns into longitudinal section; septal impres- cone, represented by several fragmentary phragmocones, its sions sloping from venter to dorsal; siphuncle large, nearly diameter gently enlarging at a rate of 1 mm per conch length half or a little less than half the dorsoventral conch diameter ; of 9mm in KPE20045 (Figure 7-4); conch elliptically ovate camerae crowded. to subcircular in cross section, slightly dorsoventrally 78 Cheol-Soo Yun Figure 8. which is here assigned to Kotoceras grabaui (Kobayashi). 1. “Kotoceras frechi (Kobayashi)’, UMUT PM3, Longitudinal section shown by an acetate peel, X2. 2. Cross section by the same method, x2. 3,4. Sketches of longitudinal section and cross section, respectively, showing the strongly depressed cameral portion and broken septa. Arrows indicate the direction of compaction. depressed, ratio of the dorsoventral to lateral diameter of the conch near the adoral portion being 7:8 in KPE20042 (Figure 7-1); siphuncle marginal, in actual contact with the ventral wall, its cross section elliptical to subcircular, ventrally more flattened, expansion rate of the siphuncle commensu- rate with that of the conch; septal impression on the si- phuncle running obliquely down from ventral to dorsal, its distance being about 2 mm or more in KPE20043 (Figure 7- 2); Camerae crowded, averaging 11 in the distance of the dorsoventral diameter of the conch, tending to broaden adorally in the middle part of the phragmocone, but finally attaining a height of 1.5 mm in KPE20042 (Figure 7-1); septal necks holochoanitic ; septa moderately concave adorally, their depth corresponding to one and a half times the cameral height, increasing adorally where attaining a little more than twice the cameral height; septal ridge on the siphuncle running obliquely from ventral to dorsal; septal suture laterally transverse, but dorsally abruptly inclined backward, gradually bending posteriorly on the ventral side, and then becoming parallel to vertical axis ; no endocone observed; camera filled with clastic sediments; surface apparently smooth. Remarks.—Kobayashi (1927) proposed Vaginoceras frechi from the Jigunsan Formation of Maggol, based on a single specimen (p.179, pl. 18, figs. 2a-c; UMUT PMS; Figure 8). Kobayashi (1934) subsequently reassigned this species to Kotoceras. According to his description, the characteristics of this species are summarized as follows: “The septum is gently inclined near the siphuncle but very steeply near the shell wall and is subangulated at a point where the septum bends from a gentle to a sharp angle”. Kobayashi (1934) mentioned that this species is distinguished from Kotoceras typicum by having a more rapidly expanded conch, broader siphuncle and more concave septa. However, the monotype of this species, UMUT PMB, is secondarily deformed along the dorsal margin, so that the above features may not fairly represent the specific diagno- sis (Figure 8). Firstly, in the longitudinal section, septa of the dorsal portion are crushed by depression and then three or four septa are duplicated so as to be obliquely parallel with the shell wall. Most of the septa on the dorsal margin are irregularly arranged and broken. Because the clusters of broken septa are piled up longitudinally along the dorsal wall, the degree of convexity of each septum appears to change abruptly at a point midway on the septa. Secondly, the siphuncle has an unusually large diameter as compared with the conch diameter. In every species of Kotoceras, the siphuncle generally takes up one-third to a half of the conch diameter. The cameral portion in Kotoceras frechi is only one-third. The appearance must have been deformed by the effect suffered from sediments outside the dorsal portion. Thus, the diagnostic features of the specimen described as Kotoceras frechi by Kobayashi (1927, 1934) may be the result of diagenetic deformation, and therefore this taxon can be reassigned as a junior synonym of Kotoceras grabaui (Kobayashi, 1927). In the meantime, Chen and Zou (1984, p. 80, pl. 16, fig. 6) identified a longitudinally sectioned specimen from the Lower Ordovician Yaoxian Formation of Shaanxi, North China as Kotoceras frechi. However, this specimen is assignable to Kotoceras multiseptum Kobayashi from the Jigunsan Formation of Maggol in having crowded and deeply con- caved septa and a broad siphuncle. Comparison.—This species is comparable to Kotoceras stolbovense Balashov from the Middle Ordovician Krivoluts- ky Formation of the Siberian Platform (Balashov, 1962, p. 32, pl. 26, figs. 1a-d) ; however, the present species has a much shallower septal concavity and slightly larger siphuncle. Kotoceras typicum Kobayashi from the Jigunsan Formation of Maggol (Kobayashi, 1934, p. 392, pl. 11, figs. 1-4) is distin- guished from K. grabaui by its more broadly spaced septa, nearly circular cross section of the conch in juvenile shell, Ordovician cephalopods from Korea 79 and shell surface with fine growth lines. In the septal distance and the shape of the cross section, Kotoceras multiseptum Kobayashi from the Jigunsan Forma- tion of Maggol (Kobayashi, 1934, p. 394, pl. 12, figs. 1,2; pl. 13, figs.1-3) is closely allied to K. grabaui, but its conch expansion rate is much more rapid than that of the latter. Kotoceras cylindricum Kobayashi from the Jigunsan Forma- tions of Maggol and Homyeong (Kobayashi, 1934, p. 393, pl. 12, figs. 7-9; pl. 18, figs. 8, 9) is easily distinguished from K. grabaui by its circular cross section with a depressed siphun- cle and more crowded septa. Occurrence.—Middle Ordovician Jigunsan Formation, localities ; SR900, SS663, MG343, MG350 and MG357. Acknowledgments | express my thanks to Kazushige Tanabe (University of Tokyo) for his critical reading of the manuscript and valuable suggestions. | am grateful to Takeo Ichikawa (Tokyo Univer- sity Museum) for access to the late Prof. Kobayashi’s collec- tions under his care. | am indebted to Seong-Young Yang (Kyungpook National University) in Korea for his kind advice and encouragement. Thanks are also extended to Yasunari Shigeta and Shin'ichi Sato (both National Science Museum) for their kind assistance in the field and providing specimens. Special thanks are due to to Royal H. Mapes (Ohio University) for his thoughtful review and going over the language of the present paper. References cited Balashov, Z. G., 1962: Ordovician nautiloids of the Siberia Platform. 131p, 52pls. Leningrad University Press, Leningrad. (in Russian) Boll, E., 1857: Beitrage zur Kenntniss des silurischen Ce- phalopoden im norddeutschen Diluvium und den anste- henden Lagern Schwedens. 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Paleontological Research, vol. 3, no. 2, pp. 81-87, 2 Figs., June 30, 1999 © by the Palaeontological Society of Japan Esgueiria futabensis sp. nov., a new angiosperm flower from the Upper Cretaceous (lower Coniacian) of northeastern Honshu, Japan MASAMICHI TAKAHASHI’, PETER R. CRANE’ and HISAO ANDO* ‘Department of Bioscience, Kagawa University, Takamatsu, 760-8522, Japan "Department of Geology, The Field Museum, Chicago, Illinois, 60605-2496, U.S.A. “Department of Environmental Sciences, Faculty of Science, Ibaraki University, Mito 310-8512, Japan Received 12 December 1998, Revised manuscript accepted 12 March 1999 Abstract. Bulk sieving of samples from the Ashizawa Formation, Futaba Group (lower Coniacian) of northeastern Honshu, Japan, has yielded a well-preserved plant mesofossil assemblage comparable to those recently described from eastern North America, Europe and central Asia. The most distinctive component of the assemblage is a new species of the genus Esgueiria (Esgueiria futabensis sp. nov.), a fossil flower known previously only from the Upper Cretaceous (Campanian-Maastrichtian) of Portugal. A possible additional species of the genus has also been recovered from a second mesofossil assemblage in the Tamayama Formation (lower Santonian). The occurrence of Esgueiria in Europe and eastern Asia during the Late Cretaceous indicates that despite the vegetational differences between these areas inferred from fossil pollen, some elements were widespread across middle paleolatitudes, presaging the strong floristic similarities among mid- and high latitude regions of the Northern Hemisphere during the early Tertiary. Key words: Angiosperm flower, Ashizawa Formation, Coniacian, Esgueiria futabensis sp. nov., Santonian, Tamayama Formation Introduction Studies of the early fossil history of flowering plants (an- giosperms) have been revolutionized over the last 15 years by the discovery of abundant, small, well-preserved and sys- tematically informative fossil flowers in assemblages of Cretaceous plant mesofossils from Europe and eastern North America (e.g., Friis and Skarby, 1982 ; Friis, 1983 ; Knobloch and Mai, 1984 ; Friis et al., 1994 ; Crane et al., 1994). These specimens have yielded important information relating to the early diversification of many lineages of extant angiosperms and the evolution of their pollination and dispersal biology (eg. Crane et al, 1995). Only recently have similar mesofossil assemblages been recognized in central Asia (Frumina et al., 1995, Frumin and Friis, 1996, 1999), and we now report that they also occur in eastern Asia. In this paper we describe the most characteristic of several fossil flowers in newly discovered plant mesofossil assemblages from the Futaba Group (lower Coniacian-lower Santonian) of Northeast Japan. Materials and methods Plant fossils were isolated from two sets of bulk samples collected at two different levels in the Futaba Group exposed in Fukushima Prefecture, northeastern Honshu, Japan. The fossils are small, three-dimensional and charcoalified or lignitized mesofossils. The Kamikitaba plant mesofossil asssemblage (sample F16) was isolated from a poorly sorted, carbonaceous, black, sandy siltstone collected along a tributary of the Kitaba River in Kamikitaba, Hirono-machi (Study Route B of Ando et al. 1995; 3712’N, 140°57’E). These samples were from the Asamigawa Member of the Ashizawa Formation, which is interpreted as alluvial fan sediments (Ando, 1997). The Kohisa plant mesofossil assemblage (sample F11), comprised a poorly sorted, beige, sandy siltstone with scattered carbonaceous flecks. It was collected along the Kohisa River, Kohisa, Ouhisa-machi northeast of Iwaki City (Study Route N of Ando et al., 1995 ; 37 10'N, 140°57’E). These samples were from the middle part of the Tamayama Formation, which is interpreted as braided river flood plain sediments with lagoonal facies in the uppermost part (Ando, 1997). The Futaba Group comprises fluvial to shallow marine 82 Masamichi Takahashi et al. sediments in the southern Abukuma Belt of Northeast Japan (Ando et al., 1995). The Ashizawa Formation is the lower- most formation in the Futaba Group, and is overlain by the Kasamatsu Formation, which itself is overlain by the Tamayama Formation. Based on the occurrence of lower Coniacian ammonites and inoceramids in the middle of the Ashizama Formation, and a lower Santonian inoceramid (Inoceramus amakusensis) in the upper part of the Tamayama Formation, the Futaba Group is thought to range in age from early Coniacian to early Santonian. The age of the plant- bearing sediments in the Asamigawa Member is probably early Coniacian (ca. 89 million years before present; Grad- stein et al., 1995), whereas the age of the plant-bearing sediments in the Tamayama Formation is probably early Santonian (ca. 85 million years before present; Gradstein et al., 1995). Bulk samples of ca. 500 kg of carbonaceous, black, poorly sorted sandy siltstone were dried in the laboratory, disag- gregated in water and sieved through a 0.8mm mesh. Recovered carbonaceous debris was then cleaned in hydro- fluoric and hydrochloric acids, thoroughly rinsed in water, and dried in air. Individual specimens selected for scanning electron micrsocopy were mounted on scanning electron microscope stubs, sputter coated with platinum-palladium and examined in a Hitachi S-800 field emission scanning electron microscope. All specimens are deposited in the paleobotanical collections of the Field Museum of Natural History, Chicago (PP). Systematic description Class Magnoliopsida (angiosperms) Genus Esgueiria Friis, Pedersen and Crane, 1992 The genus was established by Friis, Pedersen and Crane (1992) based on material from two localities of Campanian- Maastrichtian age in the northern part of the Western Portuguese Basin, Beira Litoral, Portugal. Two species were distinguished : Esgueiria adenocarpa from the Esgueira locality (the type species), and Esgueiria miraensis from the Mira locality. Esgueiria futabensis sp. nov. Figures 1-1—1-8, 2-1, 2-2, 2-4, 2-5 Material— PP45389 (holotype). 45390-PP45417. Type Locality and Horizon.—Kamikitaba plant mesofossil assemblage (sample F16), along a tributary of the Kitaba River in Kamikitaba, Hirono-machi, (Study Route B of Ando et al. 1995; 37°12’N, 140°57’E). Etymology.—Named after the Futaba Group, the geologi- cal unit from which the specimens were recovered. Specific Diagnosis.—Ovary and fruit narrowly elongate, rounded at the base. Peltate (glandular) trichomes on the base of the styles, and also in rows, often of ten or more, on the hypanthium. Simple trichomes densely spaced on the surface of the ovary, calyx and styles. Prominent recep- tacular mounds present between the stamens and the perianth. Dimensions.—All specimens lacking a well-preserved corolla: length of ovary: (1.85-) 2.76 (—3.3) mm; breadth of ovary: (0.7—) 1.12 (—1.5)mm; length of sepals: unknown; breadth of sepals: (0.3-) 3.62 (—0.4)mm: 25 specimens measured. Pollen not identified. Description and Remarks.—The species is known from 29 complete or fragmentary flowers from the Kamikitaba assemblage preserved mainly as charcoalified specimens. Similar material from the Kohisa assemblage is not referred to E. futabensis, and probably represents a different species of Esgueiria (see below). Many of the specimens are broken or abraded fragments of the inferior ovary, but almost all show either the distinctive peltate glands, or the remains of the glands and their secretion in one or more longitudinal grooves in the ovary wall. None of the specimens is a bud and most of the material probably represents mature fruits with a partially persistent perianth and androecium. None of the specimens has yielded information on inflorescence structure, anthers, pollen or ovules. Flower : Flowers are epigynous (Figure 1-1) and the calyx is visible in most specimens. Remains of filament and styles bases are also commonly preserved. Unequivocal remains of the petals are rarely present. None of the specimens have a pedicel or prophyll preserved. Perianth : The calyx consists of five free sepals (Figure 1- 2). In all specimens the calyx lobes are broken and their shape cannot be established reliably (Figures 1-2, 1-6, 2-5). Other specimens ; PP > Figurei. Esgueiria futabensis sp. nov., Kamikitaba assemblage, Asamigawa Member, Ashizawa Formation (lower Coniacian), Futaba Group, Fukushima Prefecture, northeastern Honshu, Japan. 1. Holotype, lateral view of well-preserved epigynous flower showing peltate and simple trichomes on the ovary wall, note remains of sepals and three styles at flower apex, as well as the protruding hemispherical glands in the outer tissues of the ovary wall, PP45389, x35. 2. Holotype, apex of flower showing sepals, possible remains of corolla, receptacular mounds, stamen filaments and three styles, PP45389, “73. 3. Holotype, detail of small, peltate, trichome from base of style, note also thick wall of broken trichome, PP45389, 930. 4. Lateral view of abraded specimen showing ovary with longitudinal ribs denuded of trichomes, note remains of sepals and stout style base at the apex of the flower, PP45403, «35. 5. Holotype, detail of peltate and simple trichomes from ovary wall, note also the opening of a hemispherical gland in the ovary wall, PP45389, «100. 6. Detail of apical portion of specimen in Figure 1-4 showing sepals, receptacular mounds, filament bases and stout base of style, PP45403, x72. 7. Holotype, detail of simple trichome from ovary wall, note verrucate surface, PP45389, «920. 8. Detail of apex of flower in Figure 1-4 showing remains of sepals, ten prominent receptacular mounds, eight (possibly nine) filament bases and stout base of style, PP45403, x 72. Cretaceous angiosperm flower Masamichi Takahashi et a/. Figure 2. Esgueiria futabenis sp. nov. and Esgueiria sp., Futaba Group, Fukushima Prefecture, northeastern Honshu, Japan. 1, 2, 4,5, Esgueiria futabensis sp. nov., Kamikitaba assemblage, Asamigawa Member, Ashizawa Formation (lower Coniacian). 3,6, Esgueiria sp., Kohisa assemblage, middle part of the Tamayama Formation (lower Santonian). 1. Lateral view of abraded specimen showing numerous peltate trichomes in two grooves in the ovary wall, PP45391, x32. 2. Lateral view of abraded specimen showing remains of peltate trichomes in two grooves in the ovary wall, note remains of sepals and stout base of style at the floral apex, PP45393, «30. 3. Lateral view of compressed specimen showing three prominent peltate trichomes on the ovary wall, note that the peltate trichomes are larger and fewer than in E. futabensis, PP45419, «17. 4. Detail of specimen in Figure 2-1 showing remains of peltate trichomes and unabraded portion of ovary wall, PP45391, «90. 5. Apex of specimen in Figure 2-2 showing sepals, bases of two filaments and stout base of style, PP45393, «67. 6. Apex of specimen in Figure 2-3 showing stamen filament surrounding stout base of style, note remains of receptacular mounds between the sepals and stamen bases, PP45419, x 27. Cretaceous angiosperm flower 85 However, there are sufficient specimens in which parts of the calyx are preserved to infer that it was persistent through fruit development. The corolla is not clearly visible in any of the specimens, although a few show fragments of tissue that may represent the bases of petals. The rare presence of the corolla in more than 1,000 specimens of E. adenocarpa led to the conclusion that the corolla was probably caducous (Friis et a/., 1992), and this may also have been the case in E. futabensis. Receptacular mounds : Most specimens show prominent, more or less ellipsoidal mounds of tissue, ca. 0.2 mm broad and ca. 0.1mm deep, on the receptacle between the filament bases and the calyx (Figures 1-6, 1-8). In one specimen there are ten mounds that alternate with the stamen bases (Figure 1-8). The nature of these mounds is uncertain, but judging from their position and swollen structure (Figures 1-2, 1-6) it is possible that they are nectary lobes. A possible nectary was observed in E. adenocarpa, but in the more usual postion for a disc nectary, between the stamens and the style bases (Friis et al., 1992). In E. futabensis it is clear that the receptacular mounds are outside the androecium between the sepals and the stamens (Figure 1-8). Androecium: None of the specimens has a complete stamen preserved and we have been unable to detect pollen on any of the flowers. However, the position of the stamen filaments indicates stamens were both opposite to, and alternate with, the sepals (Figure 1-8). Based on this pattern an androecium of ten stamens would be inferred. However, the best preserved androecium (Figure 1-8) shows the remains of only eight (or possibly nine) filaments. It is uncertain whether this indicates incomplete preservation, or whether less than ten stamens developed as in E. adenocar- pa (Friis et al., 1992). There is no clear indication that stamens were arranged in more than one whorl (Figure 1-8). Gynoecium: The ovary is inferior and unilocular. The holotype clearly shows that there were three free styles, at least distally (Figure 1-2). Proximally, however the styles appear to have been fused into a single, stout, style base (Figures 1-6, 2-5). The ovary is narrowly elongated, more or less parallel-sided and with a rounded base (Figures 1-1, 1-4, 2-1,2-2). The ovary wall is pleated into five longitudinal grooves that alternate with sepals, and five longitudinal ridges that are on the same radius as the sepals. The ovary wall is about 0.05 mm thick. In several specimens there are protruding hemispherical glands, ca. 0.1mm in diameter, in the outer tissues of the ovary wall. In abraded specimens that lack the epidermis the inner layers of the ovary wall are seen to be composed of small equiaxial sclerenchyma cells ca. 0.01 mm in diameter. Lining the locule there is a inner epidermis of larger cuboidal cells. Trichomes: Two different types of trichomes have been Observed on the specimens. They are best developed and most easily Observed on the surface of the ovary but also occur on the stout style base. Simple trichomes: Simple hairs are scattered all over the Ovary and other floral organs. The hairs may be up to ca. 0.2 mm long, are more or less parallel-sided for much of their length, and appear to be unicellular (Figure1-7). At the apex they have an acute point. Broken specimens show that the trichomes are thick-walled (Figure 1-3). The tri- chome wall close to the point of attachment seems to be thinner and somewhat collapsed (Figure 1-7). In well- preserved specimens the trichome wall is ornamented with distinctive elongated verrucae (Figures 1-3, 1-7). Peltate trichomes: Peltate trichomes (inferred to have been glandular) are arranged in a single row in the grooves in the ovary wall (Figures 1-5, 2-4). The peltate trichomes never occur side-by-side. Smaller peltate trichomes also occur on the style bases (Figure 1-3). On the ovary wall the peltate trichomes are typically more or less circular, 0.12-0.18 mm in diameter, and appear to consist of a central stalk and a shieldlike head. A clear radiating structure among the cells comprising the head has not been seen. The number of peltate trichomes in a single row varies, but it is often between 10 and 20 (Figure 1-1, 2-1). Frequently, under the light microscope, the peltate trichomes appear to be embed- ded in a black shiny substance, which is often present even when the trichomes themselves are not clearly visible (Figure 2-2). We infer that this represents the remains of a secre- tion associated with the glandular trichomes. Peltate tri- chomes also occur on the style-bases of well-preserved specimens scattered among the simple hairs. These tri- chomes are generally smaller (ca. 0.06 mm in diameter) and less prominent than those on the ovary wall but are similar in structure (Figure 1-3). Comparison Esgueiria futabensis clearly shows the diagnostic features of the genus (Friis et al. 1992). The flowers are small, epigynous and bisexual with the perianth and androecium organized on a basically pentamerous plan. There is a Calyx of five free sepals and an androecium with more than five stamens. The ovary is unilocular with three styles. The indumentum consists of simple stiff hairs and the characteristic multicellular, peltate trichomes. Esgueiria futabensis is clearly distinguished from the two other species of the genus. It differs from the type species, E. adenocarpa, in being generally larger : (1.85-) 2.76 (—3.3) mm rather than (1.5-) 1.88 (2.2) mm long. The shape of the ovary is also more or less parallel-sided, rather than obovate, and the base of the ovary is rounded rather than pointed (compare Figures 1-1, 1-4, 2-1, 2-2 with Friis, Pedersen and Crane, 1992, Plate1). The peltate trichomes are smaller (0.12-0.18 mm in diameter) in E. futabensis than in E. adenocarpa (0.2-0.3 mm in diameter). Also significant is the number of peltate glands in a single groove on the ovary wall, which is often 10-20 in E. futabensis, compared with a maximum of five or six in E. adenocarpa. The occurrence of peltate glands on the style bases (Figure 1-3) is a further difference between E. futabensis and E. adenocarpa, but a similarity with E. miraensis. However, compared to E. miraensis, E. futabensis is larger: length of ovary (1.85-) 2.76 (—3.3)mm compared to 0.8-0.95 mm. The ovary of E. futabensis is also long and narrow, rather than campanulate as in E. miraensis. Other Esguieria flowers are known from the Kohisa plant mesofossil assemblage, which is younger (early Santonian) 86 Masamichi Takahashi et a/. than the Kamikitaba assemblage that yielded E. futabensis. However, the Kohisa specimens are larger than those from Kamikitaba (length of ovary [2.75-] 3.5 [—4] mm), are more obovate in shape with a more pointed base, and also have significantly larger peltate trichomes (Figures 2-3, 2-6). These specimens may represent a fourth species of Esgueir- ia, but because only eight specimens are known (PP45418- PP45425), they are here left unassigned as Esgueiria sp. Discussion In terms of systematic affinities, E. futabensis does not add to previous discussions of a relationship between Esgueiria and the extant angiosperm family Combretaceae. .. However, this new species is important in several respects. It docu- ments the occurrence of mesofossil assemblages with well- preserved angiosperm flowers in the Upper Cretaceous of Japan that are comparable in their quality of preservation to those recently described from eastern North America, Europe and central Asia. It adds a new species to the very small number of fossil angiosperm reproductive structures so far described from the Upper Cretaceous of Japan (Stopes and Fujii, 1910; Ohana and Kimura, 1987 ; Nishida, 1985, 1991, 1994 ; Nishida and Nishida 1988; Nishida et a/., 1996). It also provides the first evidence of botanically informative plant fossil assemblages (other than palynofloras ; Miki, 1977 ; Takahashi, 1988) in the Futaba Group. The discovery of Esgueiria futabensis also has interesting biogeographic implications and extends substantially the range of a genus previously known only from the Campanian-Maastrichtian of Portugal. Based on pollen and spore assemblages Portugal was part of the Nor- mapolles Province during the Late Cretaceous. Japan is generally included in the Aquilapollenites Province (Hern- green et al., 1996) based on the first appearance of tripro- jectate grains in Late Cretaceous sediments younger than those of the Futaba Group (Miki, 1977). The occurrence of Esgueiria in both eastern Asia and southern Europe docu- ments that some Late Cretaceous floristic elements had very broad geographic distributions, presaging the strong floristic similarities evident at middle and high latitudes of the Northern Hemisphere during the early Tertiary. Acknowledgments This work was supported by Grant-in-Aids (08640891 and 09640827) from the Ministry of Education, Science, Sports and Culture of Japan to MT., and by fellowships from the Japan Society for the Promotion of Science in 1997 (S-97128) and 1998 (S-98106) to PRC. This work was also supported in part by U.S. National Science Foundation Grant EAR- 9614672 to PRC. PRC is also grateful to Kagawa University for its hospitality during completion of this research. References cited Ando, H., Seishi, M., Oshima, M. and Matsumaru, T., 1995: Fluvial-shallow marine depositional systems of the Futaba Group (Upper Cretaceous): Depositional facies and sequences. Journal of Geography, vol.104, p. 284-303. (in Japanese) Ando, H., 1997: Apparent stacking patterns of depositional sequences in the Upper Cretaceous shallow-marine to fluvial successions, northeast Japan. Memoirs of the Geological Society of Japan, vol. 48, p. 43-59. Crane, P. R., Friis, E. M. and Pedersen, K. 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Philosophical Transactions of the Royal Society, B, vol. 201, p. 1-90. Takahashi, K., 1988: Palynology of the Upper Cretaceous Futaba Group. Bulletin of the Faculty of Liberal Arts, Nagasaki University (Natural Science), vol. 28, p. 67-183. Paleontological Research, vol. 3, no. 2, pp. 88-94, 3 Figs., June 30, 1999 © by the Palaeontological Society of Japan Boreal-type brachiopod Yakovlevia from the Middle Permian of Japan JUN-ICHI TAZAWA Department of Geology, Faculty of Science, Niigata University, Niigata, 950-2181, Japan Received 15 April 1998 ; Revised manuscript accepted 25 March 1999 Abstract. The following three species of the Boreal-type brachiopod genus Yakovlevia are described from the Middle Permian (Kungurian to Ufimian) of the Hida Gaien (=Hida Marginal) and South Kitakami Belts, Japan: Y. kaluzinensis Fredericks, Y. mammata (Keyserling) and Y. mammatiformis (Fredericks). The occurrence of Yakovlevia together with various Boreal- and Tethyan-type brachiopods in the Middle Permian of the two belts suggests that these regions were probably a continental shelf at the eastern margin of the Sino-Korean block in Middle Permian time. Key words: Boreal-type brachiopod, Hida Gaien Belt, Middle Permian, Sino-Korean block, South Kitakami Belt, Yakovlevia Introduction Brachiopods are important and useful for Permian global palaeobiogeography as the predominant element in the benthic fauna at that time (Stehli, 1973; Waterhouse and Bonham-Carter, 1975 ; Grunt, 1995 ; Shi et al., 1995 ; Jin and Shang, 1997). Yakovlevia is a typical Boreal-type, Middle Carboniferous to Middle Permian productoid genus belong- ing to the family Yakovleviidae Waterhouse, 1975. This genus was established by Fredericks in 1925, with Chonetes (Yakovlevia) kaluzinensis Fredericks, 1925 from the Middle Permian Chandalaz Formation of Cape Kalouzin in the Vladivostok area, South Primorye as the type species. The morphology and classification of Yakovlevia and related genera have been fully discussed by Licharew (1947), Muir- Wood and Cooper (1960), Kotljar (1961), Muir-Wood (1965), Cooper and Grant (1975), Waterhouse (1975), and Shi (1995). Concerning the relationship of Yakovlevia with Muirwoodia Licharew, 1947, | follow Kotljar (1961), Cooper and Grant (1975), and Shi (1995), all of whom considered Muirwoodia as a junior synonym of Yakovlevia. The purpose of this paper is to describe three Yakovlevia species, Y.kaluzinensis Fredericks, 1925, Y. mammata (Keyserling, 1846), and Y. mammatiformis (Fredericks, 1926), from the Middle Permian (Kungurian to Ufimian) of the Hida Gaien and South Kitakami Belts, Japan, discussing their palaeobiogeographical significance. The material utilized is: eight specimens of Y. kaluzinensis from the lower part of the Moribu Formation in the Moribu area, Hida Mountains (Hida Gaien Belt), central Japan; two specimens of Y. mammata from the lower Kanokura Formation in the Kesen- numa area, southern Kitakami Mountains (South Kitakami Belt), northeast Japan; and the single specimen of Y. mammatiformis from the upper Iriishikura Formation in the Takakurayama area, Abukuma Mountains (South Kitakami Belt), northeast Japan (Figure1). These specimens are housed in the Department of Geology, Faculty of Science, Niigata University, Niigata (NU-B) and the Institute of Geology and Palaeontology, Tohoku University, Sendai (IGPS). Palaeobiogeographical significance of Yakovlevia Recently Shi (1995) summarized the stratigraphical and geographical distribution of Yakovlevia using 45 species of this genus. According to him, the genus is distributed from the Middle Carboniferous to Middle Permian of the Boreal Realm and the transitional zone between the Boreal and Tethyan Realms, namely, the Northern Transitional Zone (Sino-Mongolian Province) and the Cordilleran Province (see Shi, 1995, figs. 2, 8, table 1). The former transitional zone is almost equal to the Inner Mongolian-Japanese Transition Zone of Tazawa (1991). As shown in Figure 2, the three Yakovlevia species de- scribed below clearly indicate a Boreal distribution. Y. kaluzinensis has been known from the Middle Permian (Kungurian to Ufimian) of South Primorye, eastern Russia, and the Hida Mountains, central Japan (Fredericks, 1925 ; Muir-Wood and Cooper, 1960; Kotljar, 1961 ; Licharew and Kotljar, 1978; Horikoshi et al. 1987; Tazawa, 1987). Y. mammata has been known from the Lower Permian (Artins- kian) to Middle Permian (Guadalupian) of Spitsbergen ; Timan and Pechora, northern Russia; Upper Yukon River, Yukon Territory; Grinnell Peninsula, Devon Island, Arctic Canada; Tien Shan, West China; Ekenalsileng, Jisu (Zhesi), Dong Ujimgin, Xi Ujimgin and Horgin Youyi Qiangi, Inner Mongolia, North China; South Primorye, eastern Russia ; Yakovlevia from Japan 89 138° KESENNUMA KAKURAYAMA Pacific Ocean Figure1. Map showing the fossil localities. southern Kitakami Mountains, northeast Japan (Keyserling, 1846 ; Koninck, 1847 ; Tschernyschew, 1902 ; Keidel, 1906 ; Chao, 1927; Grabau, 1931; Stepanov, 1937 ; Muir-Wood and Cooper, 1960; Harker in Harker and Thorsteinsson, 1960 ; Kotljar, 1961; Gobbett, 1963; Brabb and Grant, 1971; fanova, 1972 ; Lee and Gu, 1976; Licharew and Kotljar, 1978; Lee and Gu in Lee et a/., 1980 ; Liu and Waterhouse, 1985; Tazawa, 1987; Malkowski, 1988; Zhang, 1990; Nakamura et al., 1992 ; Kalashnikov, 1993). Y. mammatifor- mis is distributed in the Lower Permian (Sakmarian) to Middle Permian (Kungurian) of the northern Urals, Timan, Pechora Basin and Novaya Zemlya, northern Russia ; Omolon Massif, northeastern Russia ; South Primorye, eastern Russia ; Abu- kuma Mountains, northeast Japan (Fredericks, 1926 ; Kotljar, 1961 ; Mironova, 1964; Yanagisawa, 1967 ; Zavodowsky and Stepanov in Zavodowsky et al. 1970; Ifanova, 1972; Kulikov, 1974 ; Kalashnikov, 1983, 1993). The Middle Permian brachiopod faunas of the Hida Gaien and South Kitakami Belts are characterized by a mixture of Boreal and Tethyan elements, e.g., Yakovlevia, Cancrinella, Waagenoconcha, Megousia, Stenoscisma, and Spiriferella as the Boreal-type genera, and Leptodus, Enteletes, Transen- natia, Permundaria, and Urushtenoidea as Tethyan-type genera (Tazawa, 1987, 1991,1992; Nakamura and Tazawa, 1990), and closely resemble those of South Primorye, North- east China and Inner Mongolia (Tazawa, 1987, 1991, 1992). The occurrence of Yakovlevia together with various Boreal- and Tethyan-type brachiopods in the Middle Permian of the Hida Gaien and South Kitakami Belts supports the opinion of Tazawa (1991,1992), who considered that 1) the above regions belonged to the Southern Subzone of the Inner Mongolian-Japanese Transition Zone, and that 2) this sub- zone was being probably a piece of continental shelf border- ing the eastern margin of the Sino-Korean block, which was situated at a middle northern palaeolatitude in Middle Per- mian time (Figure 2). Systematic descriptions Order Productida Waagen, 1883 Suborder Productidina Waagen, 1883 Superfamily Linoproductoidea Stehli, 1954 Family Yakovleviidae Waterhouse, 1975 Genus Yakovlevia Fredericks, 1925 Type species— Chonetes (Yakovlevia) kaluzinensis Fredericks, 1925. 90 Jun-ichi Tazawa RES © Y. kaluzinensis A Y. mammata A Y. mammatiformis Inner Mongolian-Japanese Transition Zone Figure 2. Geographical distribution of Yakovlevia kaluzinensis Fredericks, Yakovlevia mammata (Keyserling) and Yakovlevia mammatiformis (Fredericks) in Middle Permian. (Palaeogeographic map after Ziegler et al., 1996). 1. Yukon Territory, 2. Devon Island, 3. Spitsbergen, 4. Omolon Massif, 5. Novaya Zemlya, 6. Pechora Basin, 7. Timan, 8. northern Urals, 9. Tien Shan, 10. Inner Mongolia, 11. South Primorye, 12. Moribu, Hida Mountains, 13. Kesennuma, southern Kitakami Mountains, 14. Takakurayama, Abukuma Mountains. AF: Africa, AN: Antar- ctica, AR: Arabia, AU: Australia, E: Eurasia, G: Greenland, IC: Indochina, IN: India, L: Lhasa, M: Mongolia, NA: North America, Q: Qangtang, SA: South America, SI: Sibumasu, SK: Sino-Korea, T: Tarim, Y : Yangtze. Yakovlevia kaluzinensis Fredericks, 1925 Figures 3-7—15 Chonetes (Yakovlevia) kaluzinensis Fredericks, 1925, p. 7, pl. 2, figs. 64-66. Yakovlevia kaluzinensis Fredericks. Muir-Wood and Cooper, 1960, pl. 133, figs. 5,6; Kotljar, 1961, text-figs. 1-3; Licha- rew and Kotljar, 1978, pl. 14, figs. 1, 2. Yakovlevia sp. Horikoshi et a/., 1987, text-figs. 3A, B; Tazawa, 1987, text-fig. 1.7. Material.—Eight specimens, from the lower Moribu Forma- tion in the Moribu area, Hida Mountains (Hida Gaien Belt), central Japan: (1) external and internal moulds of a pedicle valve, NU-B157 ; (2) internal moulds of three pedicle valves, NU-B158-160 ; (3) external and internal moulds of two bra- chial valves, NU-B161, 162; (4) external moulds of two brachial valves, NU-B163, 164. Description.—Shell large for genus, transversely sub- rectangular in outline, with greatest width at hinge line; length about 37 mm, width about 44mm in the smaller pedicle valve specimen (NU-B157); length 38mm, width about 60 mm in the largest and best preserved brachial valve specimen (NU-B163). Pedicle valve gently convex on venter, strongly genicu- lated, and followed by a long trail. Umbo small. Ears large, prominent, but not clearly differentiated from visceral part. Sulcus narrow and shallow, originating near umbo, and extending to anterior margin. External ornament of pedicle valve invisible except for a row of oblique spines just anterior to the posterior margin. Brachial valve nearly flat on vis- ceral disc, strongly geniculated, and followed by a short trail. Fold narrow and low on anterior half of valve. External surface of brachial valve ornamented by numerous fine costellae and several weak, irregular concentric rugae on visceral disc, costellae only on trail; costellae often bifurcat- ing and intercalating, numbering 11-13 costellae in 5mm at midvalve. Pedicle valve interior with a pair of small, elongate subtrigonal adductor scars and two large diductor scars. Diductor scars striated anteriorly and encircled by a strong ridge posterolaterally. Internal structure of brachial valve obscure in the present material. Comparison.—The Moribu specimens are referred to Yakovlevia kaluzinensis Fredericks, 1925, originally described by Fredericks (1925) from the Middle Permian in size and shape of the shells, especially in the transversely subrectan- gular outline. Yakovlevia impressa (Toula, 1875, p. 236, pl. 5, figs. 1a-c) from the Middle Permian of Spitsbergen differs from Y. kaluzinensis in having larger and more prominent ears. Yakovlevia mammata (Keyserling, 1846) Figures 3-1—5 Productus mammatus Keyserling, 1846, p. 206, pl. 4, figs. 5-5b ; Koninck, 1847, p. 49, pl. 7, figs. 4a-e ; Tschernyschew, 1902, p. 295, pl. 35, figs. 4-6; Keidel, 1906, p. 367, pl. 12, figs. 5a, Yakovlevia from Japan 91 14 Figure 3. 1-5. Yakovlevia mammata (Keyserling). 1,2. External mould of a brachial valve and the latex cast, NU-B166. 3-5. latex cast of a pedicle valve exterior, external mould of a brachial valve and the latex cast, NU- B165. 6. Yakovlevia mammatiformis (Fredericks), external mould of a brachial valve, IGPS coll. cat. no. 86649. 7 —15. Yakovlevia kaluzinensis Fredericks. 7—9. internal moulds of pedicle valve specimens, 7. NU-B158, 8. NU- B160, 9. NU-B159. 10,11. external mould of a pedicle valve and the latex cast, NU-B157 ; 12. external mould of a brachial valve, NU-B162 ; 13,14. external mould of a brachial valve and the latex cast, NU-B163. 15. external mould of a brachial valve, NU-B161. (All figures in natural size) b. Muirwoodia mammata (Keyserling). Muir-Wood and Cooper, Linoproductus ? mammatus (Keyserling). Chao, 1927, p. 146, pl. 1960, pl. 120, figs. 9-11 ; Harker in Harker and Thorsteinsson, 15, figs. 10-14. 1960, p. 58, pl. 16, figs. 1-5 ; Gobbett, 1963, p. 112, pl. 18, figs. Productus (Linoproductus ?) mammatus Keyserling. Grabau, 23-28 ; Lee and Gu, 1976, p. 263, pl. 159, figs. 7-9; pl. 163, 1931, p. 288, pl. 29, figs. 10-14. figs. 2a,b; pl.164, figs. 3-4; pl.170, figs. 6,7; Licharew Productus (Thomasina) mammatus Keyserling. Stepanov, 1937, and Kotljar, 1978, pl. 14, figs. 3-5 ; Liu and Waterhouse, 1985, p. 127,177, pl. 2, figs. 5-7. p. 17, pl. 4, figs. 4-6 ; Nakamura et al., 1992, pl. 1, figs. 4a, b ; 92 Jun-ichi Tazawa Kalashnikov, 1993, p. 63, pl. 19, figs. 1-3. Yakovlevia mammatus Keyserling. Kotljar, 1961, text-figs. 4-6. Yakovlevia mammata (Keyserling). Brabb and Grant, 1971, p. 16, pl. 1, figs. 9-12, 33-36 ; Ifanova, 1972, p. 121, pl. 7, figs. 4-5; Malkowski, 1988, p. 40, pl. 5, fig. 6; Zhang, 1990, pl. 2, figs. 4,7,9. Yakovlevia paragreenlandica Lee and Gu in Lee et al., 1980, p. 382, pl. 171, figs. 5-7. Muirwoodia sp. Tazawa, 1987, text-fig. 1.6. Material—Two specimens, from the lower Kanokura For- mation of Kamiyasse and Omotematsukawa in the Kesen- numa area, southern Kitakami Mountains (South Kitakami Belt), northeast Japan : (1) external and internal moulds of a pedicle valve, NU-B165 ; (2) an external mould of a brachial valve, NU-B166. Description.—Shell small for genus, transversely subtrap- ezoidal in outline, with greatest width at hinge line ; length 13 mm-+, width 28mm in the pedicle valve specimen (NU- B165); length 16mm, width 29mm in the brachial valve specimen (NU-B166). Pedicle valve moderately and unevenly convex in lateral profile, slightly convex on venter, strongly geniculated, and followed by a short trail. Cardinal extremities acute. Ears large, not clearly demarcated from visceral part. Sulcus narrow and shallow on venter, becoming wide and deep on trail. Brachial valve nearly flat on visceral disc, strongly geniculated, and followed by a short trail. Fold originating at about midvalve, narrow and low on visceral disc, but wide and distinct on trail. External surfaces of both valves ornamented by numerous fine capillae and several weak, irregular, concentric rugae on visceral disc, capillae only on trail; capillae often bifurcated and intercalated, numbering 14-15 capillae in 5mm at midvalve. Pedicle valve interior with large, flabellate diductor scars, occupying posterior half of valve, deeply depressed and bounded by marginal ridges posterolaterally. Other internal structures not observed. Comparison.—The specimen numbered NU-B166, from the lower Kanokura Formation of the southern Kitakami Mountains, was first figured by Tazawa (1987, text-fig. 1.6) as Muirwoodia sp., but is now referred to Yakovlevia mammata (Keyserling, 1846), originally described by Keyserling in 1846 from the Lower Permian (possibly Sakmarian) of the Pechora Land, northern Russia, on the basis of similarities in size, outline and external ornament. Yakovlevia paragreenlandica Lee and Gu (in Lee et al. 1980), from the Middle Permian Dashizhai Formation of Horqin Youyi Qianqi, eastern Inner Mongolia may be con- specific with the present species. The shells described and figured by Grabau (1936, p. 107, pl.6, figs.5-6; pl. 11, figs. 4-6) as Productus mammatus Keyserling from the Maping Limestone in the Guangxi and Guizhou Provinces, South China differ from Y. mammata in having smaller ears and coarser costellae. Both species, Yakovlevia artiensis (Tschernyschew, 1889, p. 279, pl. 7, figs. 29-31) from the Artinskian of the Central Urals and Yakovlevia greenlandica (Dunbar, 1955, p. 108, pl. 16, figs.1-17) from the Middle Permian (Guadalupian) of Central East Greenland are distinguished from the present species by their fewer and coarser costellae. Yakovlevia mammatiformis (Fredericks, 1926) Figure 3-6 Productus mammatiformis Fredericks, 1926, p. 87, pl. 3, figs. 4-6. Yakovlevia mammatiformis Fredericks. Kotljar, 1961, text-figs. 7, 8. Yakovlevia mammatiformis (Fredericks). Mironova, 1964, p. 97, pl., figs. 14a-v ; Zavodowsky and Stepanov in Zavodowsky et al., 1970, p. 114, pl. 35, figs. 8-10 ; Ifanova, 1972, p. 119, pl. 6, figs. 15-16 ; pl. 7, figs. 1-2; Kalashnikov, 1983, p. 210, pl. 49, figs. 5, 6,9; Kalashnikov, 1993, p. 61, pl. 16, figs. 1-4. Linoproductus cf. mammatus (Keyserling). Yanagisawa, 1967, p. 88, pl. 2, fig. 7. Muirwoodia mammatiformis (Fredericks). 3, figs. 6a-v. Kulikov, 1974, p. 89, pl. Material —One specimen, an external mould of a brachial valve, IGPS coll. cat. no. 86649, from the upper Iriishikura Formation in the Takakurayama area, Abukuma Mountains (South Kitakami Belt), northeast Japan. Description.—Shell medium for genus, transverse, subtrap- ezoidal in outline, with greatest width at hinge line ; length 22 mm, width 42 mm in the brachial valve specimen. Brachial valve gently concave on visceral disc, strongly geniculated at anterior margin of visceral disc, and followed by a short trail. Ears large, flat and prominent, obscurely demarcated from visceral disc. Fold moderately high, originating at about midvalve, and rapidly widening anteriorly. External surface of brachial valve ornamented by numerous fine costellae ; costellae rounded, with narrow interspaces, numbering 10-11 costellae in 5mm at midvalve. No spines or spine bases observed. Comparison.—The single specimen from the Abukuma Mountains was first described by Yanagisawa (1967, p. 88) as Linoproductus cf. mammatus (Keyserling), but this specimen is referred to Yakovlevia mammatiformis (Fredericks, 1926) on the basis of its size, shape and surface ornament of the brachial valve. Yakovlevia mammata (Keyserling, 1846) differs from Y. mammatiformis in its smaller and less transverse shell, ornamented by more numerous, fine capillae. Yakovlevia transversa (Cooper, 1957, p. 39, pl. 5, figs. 1-13) from the Middle Permian of Oregon resembles Y. mam- matiformis in general appearance, but the former is distin- guished from the latter by its smaller dimensions, more developed fold commencing a little below the umbo, and fewer and coarser costellae on the brachial valve. The shells described as Y. mammatiformis from the Middle Permian of Gansu, Northwest China (Ding and Qi in Zhang et al., 1983, p. 292, pl. 99, figs. 9a, b), Inner Mongolia, North China (Lee and Gu, 1976, p. 264, pl. 164, figs. 6,8; pl. 165, figs. 1,5) and Heilongjiang, Northeast China (Lee et al., 1980, p. 383, pl. 165, figs. 25a, b; pl. 172, fig. 3) are distinguished from the present species by their much larger size. Acknowledgements | thank Guang R. Shi of Deakin University, Melbourne, Yakovlevia from Japan 93 Australia for critical reading of the manuscript ; Ei Horikoshi of Toyama University, Yukio Miyake of Miya-mura, Gifu Prefecture and Hiroyuki Ohta of Adachi-ku, Tokyo for providing some of the brachiopod specimens. References cited Brabb, E.E. and Grant, R.E., 1971: Stratigraphy and paleontology of the revised type section for the Tahkan- dit Limestone (Permian) in east-central Alaska. U.S. Geological Survey Professional Paper, no. 703, p. 1-26, pls. 1, 2. Chao, Y.T., 1927: Productidae of China, Pt. 1. Producti. Palaeontologia Sinica, Ser. B, vol. 5, fasc. 2, p. 1-244, pls. 1-16. Cooper, G.A., 1957: Permian brachiopods from central Oregon. Smithsonian Miscellaneous Collections, vol. 134, no. 12, p. 1-79, pls. 1-12. Cooper, G. A. and Grant, R. E., 1975: Permian brachiopods of West Texas, 3. Smithsonian Contributions to Paleobiology, no. 19, p. 795-1921, pls. 192-502. 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In, Xian Institute of Geology and Mineral Resources, ed., Palaeontological atlas of Northwest China; Shaanxi, Gansu and Ningxia volume, Pt. 2. Upper Palaeozoic, p. 244-425, pls. 88-143, Geological Publishing House, Beijing. (in Chinese) Ziegler, A. M., Hulver, M.L. and Rowley, D.B., 1996: Per- mian world topography and climate. In, Martini, |. P., ed., Late glacial and postglacial environmental changes Quaternary, Carboniferous-Permian and Proterozoic, p. 1-37, Oxford University Press, New York. Paleontological Research, vol. 3, no. 2, pp. 95-105, 7 Figs., June 30, 1999 © by the Palaeontological Society of Japan Taxonomy and distribution of Macoma (Rexithaerus) (Bivalvia: Tellinidae) in the northwestern Pacific KAZUTAKA AMANO’, KONSTANTIN A. LUTAENKO’ and TAKASHI MATSUBARA’ ‘Department of Geoscience, Joetsu University of Education, 1 Yamayashiki, Joetsu, Niigata 943-8512, Japan “Institute of Marine Biology, Far East Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia “Division of Earth Sciences, Museum of Nature and Human Activities, Hyogo, 6 Yayoigaoka, Sanda, Hyogo 669-1546, Japan Received 9 March 1999 ; Revised manuscript accepted 30 March 1999 Abstract. Fossil and Recent Macoma (Rexithaerus) of the northwestern Pacific consist of the following three species: Macoma (Rexithaerus) hokkaidoensis sp. nov., M. (R.) sectior Oyama and M. (R.) shiratori- ensis (Matsubara). Among them, the first species, which is new, is characterized by an elongate shell shape and a low pallial sinus, and is now living in the sea around Hokkaido, Kunashiri Island, Aniva Bay of Sakhalin, Peter the Great Bay and Ussuri Bay of Primorye. The oldest species, M. (R.) shiratoriensis appeared in subtropical waters in the late early Miocene. The Recent and allied species, M. (R.) sectior and M. (R.) cf. hokkaidoensis first occurred in middle Miocene deposits. From the middle Miocene to early Pleistocene, the subgenus was confined to the mild- to cool-temperate realm. In the Holocene, M. (R.) sectior has extended its range to subtropical waters, while M. (R.) hokkaidoensis now inhabits the cool-temperate to subarctic waters. Key words: Distribution, Macoma, Rexithaerus, Macoma (Rexithaerus) hokkaidoensis sp. nov., taxonomy Introduction Rexithaerus Tryon, 1869 is a subgenus of Macoma Leach, 1819 and is characterized by a ridge running from beak to posteroventral corner, a bluntly truncated posterior end, a short, rather strong ligamental ridge, and upwardly elevated posterodorsal margin behind ligament. Two Recent species of the subgenus, Macoma (Rexithae- rus) secta (Conrad) and M. (R.) indentata Carpenter, are known from the northeastern Pacific (Coan, 1971). Macoma expansa Carpenter was also included in the subgenus Rexithaerus by Coan (1971). However, M. expansa Carpen- ter and a related species, M. dexioptera Baxter, 1977 do not belong to the subgenus Rexithaerus because they do not have the posterodorsal margin set off as a flange. On the other hand, only one Recent form in this subgenus, “M. (R.) sectior" Oyama, has been recorded from around the Japanese Islands, Korea and Far East Russia in the north- western Pacific (Habe, 1977; Kwon et al., 1993; Kafanov and Lutaenko, 1996). As a result of our review of the both living and fossil specimens from Japan and adjacent areas, we found a new living species of Macoma (Rexithaerus) from southern Hok- kaido, Aniva Bay of Sakhalin and Primorye in Far East Russia, and Kunashiri Island. Macoma (Rexithaerus) originated in northwestern North America in late Oligocene time and migrated westward into Far East Asia during the late early Miocene (Matsubara, 1994). Recently it has been revealed that many molluscan groups show such a pattern of migration (Amano et al., 1993 ; Amano and Vermeij, 1998). However, little is known of the details of the process of climatological adaptation in these groups because most of the westward-spreading species have scattered fossil records owing to their rocky shore habitat. As the subgenus Rexithaerus lives in muddy bot- toms, it is well suited for examining the above biogeographic invasion. In this paper, we discuss the taxonomy of Macoma (Rexi- thaerus) in the northwestern Pacific in addition to the description of the new species. Based on the temporal and spatial distributions of Macoma (Rexithaerus), we will review the climatological adaptation of this genus after its migration to the Northwest Pacific. Materials and methods We have examined specimens of fossil and Recent species stored at Joetsu University of Education (JUE), Museum of Natural History, Tohoku University (IGPS), Sendai, Museum of Nature and Human Activities, Hyogo (MNHAH), Museum of Institute of Marine Biology (MIMB), and Zoologi- cal Museum, Far East State University (ZMFU), Vladivostok. 96 Kazutaka Amano et al. @M. (R-) hokkaidoensis T: type locality AM. (R.) sectior Figure 1. Recent specimens of Macoma (Rexithaerus). Locality map of the treated or illustrated Concerning the new species, we have examined twenty- one right valves and seventeen left valves from the beach of Oshamanbe and Yufutsu along Funka Bay, Hokkaido, one specimen from the Pleistocene Narita Formation in Chiba Prefecture, and two fossil specimens from the upper middle Miocene Shibiutan Formation of Hokkaido (Figure 1). These specimens are all stored in JUE other than one Narita specimen, which is stored in IGPS. In addition, we also have examined seven right valves and eight left valves of the new form collected from the beach of Peter the Great Bay in Primorye (Figure 1). These are housed in ZMFU. Unfortu- nately, all materials were empty shells ; we could not exam- ine the soft parts. For comparison with the above specimens, many Recent specimens of Macoma (Rexithaerus) sectior Oyama were examined from the following localities at hand and stored in IGPS and MNHAH: Katsuori (Ibaraki Pref.) ; Kagamigaura and Kazusa-Onjuku (Chiba Pref.); Kamakura and Zushi (Kanagawa Pref.); Mikawa-Isshiki (Aichi Pref.); Ise (Mie Pref.); Kushimoto and Shionomisaki (Wakayama Pref.) ; Ashiya (Fukuoka Pref.) ; Oga (Akita Pref.) ; Kakizaki (Niigata Pref.) ; and Pohang City and Kallam Village (South Korea). We measured the following characters : shell length, shell height, shell depth, length of pallial sinus (PL) and height of pallial sinus (PH) (see Figure 2). Figure 2. Measurement position. Description of Northwestern Pacific species Family Tellinidae de Blainville Subfamily Macominae Olsson Genus Macoma Leach, 1819 Type species.—Macoma tenera Leach, 1819 by monotypy (= Tellina calcarea Gmelin, 1791). Subgenus Rexithaerus Tryon, 1869 Type species.—Tellina secta Conrad, 1837, by subsequent designation of Dall, 1900. Macoma (Rexithaerus) hokkaidoensis Amano and Lutaenko sp. nov. [Japanese name : Yezo-sagigai | Figures 3—1-3, 5-6, 8; 4—6 Macoma sectior Oyama. Evseev, 1981, pl. 8, figs. 10,12. [non Oyama, 1950] Macoma (Rexithaerus) sectior Oyama. Kafanov and Lutaenko, 1996, p. 16-18, figs. 2a, c, 5, 6. [non Oyama, 1950] Type specimens.—JUE no.15652 (Holotype); JUE no. 15653, 15654 (Paratypes). Type locality —Oshamanbe, Hokkaido, Recent. Description.—Shell of medium size (attaining 63.1mm in shell length), rather thick, elongate-ovate, inflated, in- equilateral, inequivalve ; beak situated slightly posteriorly ; orthogyrate or weakly opisthocline ; posterior Commissure line strongly flexed toward right valve; posterior part moderately gaping; periostracum thin, brownish gray in = Figure3. 1-3,5,6,8: Macoma (Rexithaerus) hokkaidoensis Amano and Lutaenko, sp. nov. 1, 5a-b, 6a-b; JUE no. 15652 (Holotype), Oshamanbe (Recent). 2a-b; IGPS no. 13981, Yamada, Chiba Pref., Narita Formation. 3a-b ; ZMFU no. 9324/Bv-220, Gornostay Inlet of Ussuri Bay (Peter the Great Bay; Recent). 8a-b; ZMFU no. 10003/Bv-474, Kievka Bay (60 km east of Nakhodka; Recent). 4, 7: Macoma (Rexithaerus) sectior Oyama. 4; MIMB no. 2404, Kallam Village near Samchok City, South Korea (Recent). natural in size. 7a-b; JUE no. 15660, Hossaku, Chiba Prefecture, Narita Formation. All figures Northwestern Pacific Macoma (Rexithaerus) 97 Kazutaka Amano et al. Table 1. Measurements (in mm) of Macoma (Rexithaerus) hokkaidoensis Amano and Lutaenko, sp. nov. Specimens Length Height PIE PH* Valve JUE no. 15652 (Holotype) 57.4 38.0 24.5 13.0 Right „ 56.6 87.5 26.0 14.8 Left JUE no. 15653 (Paratype) 51.7 34.8 22.9 13.4 Right JUE no. 15654 (Paratype) 61.6 38.6 26.5 15.8 Left JUE no. 15655-1 54.4 36.4 25.1 13.3 Right JUE no. 15655-2 50.7 32.9 23.0 12.1 Right JUE no. 15655-3 49.7 34.1 22.1 12.2 Right JUE no. 15655-4 53.5 35.2 25.1 13.5 Right JUE no. 15655-5 53.5 34.7 22.0 12.8 Right JUE no. 15655-6 59.1 38.9 25.0 14.2 Right JUE no. 15655-8 54.9 36.8 24.5 13.7 Right JUE no. 15655-9 63.1 40.9 29.2 15.5 Right JUE no. 15655-10 61.1 39.7 28.2 14.0 Right JUE no. 15655-11 57.5 | 37.0 25.0 14.1 Right JUE no. 15655-12 51.8 | 35:3 24.4 14.3 Right JUE no. 15655-13 59.9 40.0 27.4 16.4 Right JUE no. 15655-14 53.4 36.2 24.2 13.9 Right JUE no. 15655-15 48.0 32.2 23.0 13.9 Right JUE no. 15655-16 48.0 32.3 2183 12.3 Right JUE no. 15655-17 47.8 | 31.1 21a 11.8 Right JUE no. 15655-18 | 42.9 | 28.5 19.8 ala Right JUE no. 15655-19 | 43.3 26.7 | 19.3 deal Right JUE no. 15655-22 | 57.5 | 38.1 | 25.0 14.0 Left JUE no. 15655-23 | 57.6 | 36.8 [NN 25;7 15.1 Left JUE no. 15655-24 | 56.0 | 36.4 24.7 15.0 Left JUE no. 15655-25 | 53.9 | 34.5 | 25.9 13.9 Left JUE no. 15655-26 | 50.6 33.4 24.2 14.4 Left JUE no. 15655-27 52.6 | 35.1 25.6 15.8 Left JUE no. 15655-28 | 49.4 | 31.9 24.0 13.6 Left JUE no. 15655-29 | 46.2 29.9 22.1 11.1 Left JUE no. 15655-30 49.7 | 32.4 | 23.9 13.0 Left JUE no. 15655-31 47.2 31.6 | 23.2 14.3 Left JUE no. 15655-32 47.4 30.4 24.3 14.2 Left JUE no. 15655-33 46.9 30.2 23.0 | 12.2 Left JUE no. 15655-34 41.7 27.4 | 20.2 11.6 Left JUE no. 15656-1 36.6 24.6 16.1 9.2 Right | 36.7 23.9 18.2 10.1 Left JUE no. 15656-2 56.0 37.2 27.1 14.8 Left ZMFU no. 220 56.1 38.8 | 26.9 | 15.3 Right ZMFU no. 1621 44.1 30.2 | 21.8 12.3 Right ZMFU no. 1553 42.3 29.1 2158 10.3 Right ZMFU no. 23407 60.4 40.0 28.5 16.6 | Left ZMFU no. 474 56.9 39.2 26.2 15.5 | Right „ 56.1 39.1 26.7 | 15.9 Left ZMFU no. 1215 42.1 28.3 20.9 11.5 Left * PL=length of pallial sinus ; PH=height of pallial sinus. See Fig. 2. + Figure4. 1,3,5: Macoma (Rexithaerus) sectior Oyama. 1a-b, 3a-b; JUE no.15657, Zushi, Kanagawa Prefecture (Recent). 5; JUE no. 15661, Kakuma, Ishikawa Prefecture, Omma Formation. 2a-b: Macoma (Rexithaerus) secta (Conrad) ; JUE no. 15662, Monterey Bay, California (Recent). 4: Macoma (Rexithaerus) cf. hokkaidoensis Amano and Lutaenko, sp. nov. ; JUE no. 15659, Kami-tokushibetsu, Hokkaido, Shibiutan Formation. 7-9: Macoma (Rexithaerus) shiratoriensis (Ma- tsubara). 7a-b, 9a-b; IGPS no. 102563 (Paratypes), Shiratori, Iwate Prefecture, Kadonosawa Formation. 8; IGPS no. 102562 (Holotype), Shiratori, lwate Prefecture, Kadonosawa Formation. All figures natural size. Northwestern Pacific Macoma (Rexithaerus) 99 100 Kazutaka Amano et al. 45 oo ———— ———— = ——— — r “ 1 40 7 | —e— M. hokkaidoensis u. = 7 E — #& - M. sectior 4 ue were 35 — M. shiratoriensis “Te Pe Ë FE | 698 = 30 0977 E ak E Ë Le = 25 5 weg D CT 2 20 F a E a —— H=0.64L+0.93 A= 0.977 15 5 a 4 F ye — -H=0.75L -1.70 R= 0.996 10 | —# 5 bs ot ln, tr Sn 4 ı N 10 20 30 40 50 60 70 Length (mm) Figure 5. Relation between shell length and shell height. GREC or x e— M. hokkaidoensis Seo 14 “- - M. sectior x nine à . M. shiratoriensis CA . — 4 . = 12 Pp, E re . IE 10 + a PH=0.66PL-2.12 R= 0.922 8 * PH=0.71PL-1.30 R= 0.984 PL (mm) Figure 6. Relation between length of pallial sinus (PL) and height of pallial sinus (PH) of left valve. color ; nymph short, produced. Right valve moderately inflated; a strong ridge running from beak to posterior corner ; area in front of ridge distinctly concave, especially near ventral margin ; anterodorsal mar- gin broadly arcuate ; posterodorsal margin behind ligament upwardly elevated forming dorsal flange; posterior margin obliquely truncated ; anterior muscle scar elongated oblong and its inner margin undulated ; posterior muscle scar subovate ; pallial sinus deep, low ovate in shape, and slightly concave between highest and deepest end of pallial sinus ; hinge plate rather wide; anterior cardinal tooth thin and smooth ; posterior cardinal tooth large and subdivided by a distinct groove. Left valve less inflated ; a very weak ridge running from beak to posteroventral corner; a shallow groove running along just posterior part of ridge ; anterodorsal margin broad- ly arcuate ; posterodorsal margin behind ligament slightly upwardly elevated forming dorsal flange ; posterior margin obliquely subtruncated ; ventral margin broadly arcuate and excavated just before posteroventral corner ; posteroventral corner bluntly pointed ; anterior muscle scar deeply impress- ed, elongated oblong and its inner margin undulated ; poste- rior muscle scar subcircular ; pallial sinus deep, but low ovate in shape; anterior cardinal tooth elevated and sub- divided by deep groove ; posterior cardinal tooth very thin, inclined posteriorly and smooth. Remarks.—The present species had already been illus- trated as Macoma sectior Oyama from the Primorye region (Holocene and Recent), Russia (Evseev, 1981; Kafanov and Lutaenko, 1996). The previously figured specimens have a transversely elongate shell, obliquely truncated posterodorsal margin, less prominent dorsal flange, and low pallial sinus shape. Based on these characteristics, they are referred to the present new species. Rexithaerus cf. sectior (Oyama) was recorded from the Middle Miocene Shibiutan Formation of northeastern Hok- kaido by Fujimoto et al. (1998). Some specimens at hand (e.g. JUE no. 15659, see Figure 4—4) from this formation have an elongated shell with obliquely truncated posterior margin, a strong posterior ridge and low ovate pallial sinus, which are in common with the new species. However, it is difficult for them to be exactly identified with Macoma (Rexithaerus) hokkaidoensis because the shell material had eroded out. Thus, we compare the specimens from the Shibiutan Forma- tion with the present new species. Comparison.—The living species, Macoma (Rexithaerus) sectior Oyama, 1950, differs from M. (R.) hokkaidoensis by having a less elongated shell (Table1; Figure 5), higher pallial sinus of both right and left valves (Figure 6), vertically truncated posterior margin, no concave area in front of the posterior ridge, a narrower hinge plate and a prominent dorsal flange. It is especially easy to distinguish the left valves of the two species by the shapes of the posterior part and pallial sinus. Macoma (Rexithaerus) shiratoriensis was described from the uppermost lower to lower middle Miocene Kadonosawa Formation in lwate Prefecture by one of the authors (Ma- tsubara, 1994). This species closely resembles the present new one in its low pallial sinus (Figure 6), less prominent flange and obliquely truncated posterior margin. However, the straight line between the deepest and highest points of the pallial sinus, the higher shell and the concave area in front of the posterior ridge distinguish M. (R.) shiratoriensis from the present new species. Macoma (Rexithaerus) indentata Carpenter, 1864, a Recent species of Northwest America, is similar to the present new species in its protruded posterior part and its elongated shell form. However, it is easy to distinguish the two species by comparing the pallial sinus shape. M. (R.) indentata has a much higher pallial sinus than M. (R.) hokkaidoensis. More- over, M. (R.) indentata has a more elongate shell with a distinct depressed area in the posteroventral part of the shell, and a bill-like posterior end. Right valve of M. (R.) indentata has a pronounced flexure of gully-like type on the surface much deeper than in M. (R.) hokkaidoensis. Macoma (Rexithaerus) indentata flagleri Etherington, 1931, described from the lower middle Miocene Astoria Formation of Washington, is an allied subspecies in its shell outline. However, M. (R.) i. flagleri lacks the pointed posteroventral corner. Unfortunately, we could not compare the internal shell characters of this subspecies because no description of the interior of the shell has been published. Measurements (in mm).—See Table 1. Northwestern Pacific Macoma (Rexithaerus) 101 Distribution —Late middle Miocene: Shibiutan Formation of Hokkaido (cf.). Pleistocene: Narita Formation in Chiba Prefecture. Recent: Oshamanbe and Yufutsu in Hokkaido, Aniva Bay in Sakhalin, Kunashiri Is., Peter the Great Bay and Ussuri Bay in Primorye, Russia. Macoma (Rexithaerus) sectior Oyama, 1950 [Japanese name : Sagigai] Figures 3—4, 7; 4—1,3,5 Macoma secta (Conrad). Yokoyama, 1922, p. 143-144, pl. 11, fig. 1; Nomura, 1938, p. 263-264, pl. 36, figs. 5, 6. [non Conrad, 1837 | Macoma (Rexithaerus) sectior Oyama, 1950, p.3; Kira, 1954, p. 160, pl. 60, fig. 26; Yamamoto and Habe, 1959, p. 106, pl. 9, figs.1,2 ; Kaseno and Matsuura, 1965, pl. 17, figs. 10, 11; Habe and Kosuge, 1967, p. 163, pl. 61, fig. 24; Ohara, 1971, pl. Q-10, figs. 5a-b; Habe, 1977, p. 210, pl. 42, figs. 11,12; Matsuura, 1985, pl. 42, fig. 15; Fujii and Shimizu, 1991, pl. 1, fig. 20 ; Fukuda et al., 1992, p. 91, pl. 34, fig. 538 ; Izawa and Matsuoka, 1996, p. 8, pl. 6, fig. 9. Macoma hokiensis Akutsu, 1964, p. 287-288, pl. 60, fig. 8. Rexithaerus sectior Oyama. Chiba-ken Chigaku Kyoiku Ken- kyu-kai, 1968, pl. 12, figs. 10a-b ; Kuroda et al., 1971, p. 697 (in Japanese), p. 458-459 (in English), pl. 100, fig. 5; Oyama, 1973, p. 113, pl. 52, figs. 14a-b ; Ogasawara, 1977, p. 122-123, pl.14, figs.5a-b, 7; Koyama et al. eds., 1981, p.134 ; Ogasawara et al., 1986, pl. 74, figs. 9a-b; Ishii, 1987, p. 14, pl.12, figs. 12a-b ; Baba, 1990, p. 289; Baba, 1992, p. 540, pl. 69, fig. 11; Matsubara, 1994, pl. 2, figs. 6a-b, 7a-b. Macoma sectior Oyama. Okutani and Habe, 1983, p. 139, 215; Nemoto and Akimoto, 1990, p. 42, pl. 11, fig. 7 ; Kondo, 1991, fig. 3-4. Macoma (Rexithaerus) sectior (Oyama). 379, figs. 91-6-1, and 91-6-2. Macoma “hokiensis” Akutsu. Matsubara, 1994, pl. 2, fig. 5. non Macoma sectior Oyama. Evseev, 1981, pl. 8, figs. 10, 12. | =Macoma (Rexithaerus) hokkaidoensis sp. nov. | non Rexithaerus sectior Oyama. Ogasawara, 1981, pl.1, fig. 9. | =Macoma (Macoma) tokyoensis Makiyama, 1927 | non Rexithaerus sectior (Oyama). Ogasawara and Naito, 1983, pl. 7, fig. 3. [?=Macoma (Macoma) tokyoensis Makiyama, 1927 | non Macoma (Rexithaerus) sectior Oyama. Kafanov and Lutaenko, 1996, p. 16-18, figs. 2a, c, 5, 6. |=Macoma (Rexi- thaerus) hokkaidoensis sp. nov. | Kwon et al., 1993, p. Type specimen.—UMUT CM21317 (Lectotype, designated herein). Type locality and Formation.—Otake, Narita City, Chiba Prefecture, Narita Formation, Pleistocene. Original description —“Macoma secta” in North America has a large, very high, rather thick shell, which is similar to Nuttallia in shape. On the other hand, the shell of the present new species [M. (R.) sectior| is normal in shape, low, thin, fragile, and does not attain a large size. Posterior ridge of American species is highly elevated while that of the present new species is rather weak. Inner side of posterior end of ligament becomes strongly thickened in American species, whereas that of the present new species does not. Posterior adductor muscle scar is situated rather near beak, and a contacting point between pallial line and sinus is separated from anterior adductor muscle scar. The type specimen was collected from Sagami Bay (Enoshima).” (trans- lated from the Japanese original description) Remarks.—Although Oyama (1950) designated the type locality of the present species as Enoshima in Kanagawa Prefecture, he neither designated nor illustrated the type specimen. In addition, the depository still remains unknown. However, Oyama (1950) did list Macoma secta of Yo- koyama (1922) as a synonym. Consequently, we designate herein the specimen illustrated as Macoma secta by Yo- koyama (1922) as the lectotype. This specimen is registered in the University Museum of the University of Tokyo as CM21317 (Oyama, 1973). Macoma hokiensis Akutsu, 1964, described from the Kanomatazawa Formation in Tochigi Prefecture, is regarded as synonymous with the present species on the basis of its rather high shell and pallial sinus shape (see pl. 2, fig. 5 of Matsubara, 1994). Macoma secta (Conrad) by Otuka (1940), from the lower middle Miocene Wakkauenbetsu Formation of Hokkaido, was recently considered as synonymous with M. (R.) sectior Oyama by Kafanov and Lutaenko (1996). However, at least the specimen shown in pl. 11, fig.1 of Otuka (1940) is not referable to the subgenus Rexithaerus because of its rounded posterior margin and the absence of a posterior ridge. Macoma izurensis illustrated by Masuda and Takegawa (1965), from the Fukuda Formation in Miyagi Prefecture, much resembles the present species in the pallial sinus shape rather than either M. (R.) hokkaidoensis or M. (R.) shiratoriensis. However, it differs in having a more obliquely truncated posterodorsal margin. Thus, we treat the speci- mens of Masuda and Takegawa (1965) as M. (R.) aff. sectior Oyama, although they were questionably referred to M. (R.) shiratoriensis by Matsubara (1994). Comparison.—The present species closely resembles Macoma (Rexithaerus) secta (Conrad, 1837) (Fig. 4—2) known from the western coast of North America. However, M. (R.) sectior is distinguished from M. (R.) secta by having a smaller, lower, less inflated shell. Distribution —Late middle or early late Miocene: Kanomatazawa Formation in Tochigi Prefecture (Akutsu, 1964). Pliocene: Tatsunokuchi Formation in Miyagi Prefec- ture (Nomura, 1938); Mita Formation in Toyama Prefecture (Matsuura, 1985; Fujii and Shimizu, 1991). Early Pleis- tocene : Omma Formation in Ishikawa Prefecture (Kaseno and Matsuura, 1965; Ogasawara, 1977 ; Matsuura, 1985) ; Haizume Formation in Niigata Prefecture (this study) ; Naka- tsu Group in Kanagawa Prefecture (Baba, 1992). Middle to late Pleistocene : Nagahama Formation in Chiba Prefecture (Baba, 1990); Narita Formation in Chiba Prefecture (Yo- koyama, 1922; Chiba-ken Chigaku Kyoiku Kenkyu-kai, 1968 ; Oyama, 1973; Baba, 1990); Kioroshi Formation (7?) in Chiba Prefecture (Kondo, 1991); Semata Formation in Chiba Prefecture (Ohara, 1968); Uji Shell Bed in Ishikawa Prefec- ture (Matsuura, 1985) ; Anden Formation in Akita Prefecture (Ogasawara et al., 1986). Holocene: Yokohama in Kanagawa Prefecture (Matsushima, 1969); Osaka in Osaka Prefecture 102 Kazutaka Amano et al. (Ishii, 1987); Anan in Tokushima Prefecture (Nakao, 1995). Recent: Honshu, Shikoku, Kyushu and South Korea (Higo and Goto, 1993); ? Formosa (Taiwan) (Kuroda, 1941; Wu, 1980). Macoma (Rexithaerus) shiratoriensis (Matsubara, 1994), combin. nov. [Japanese name : Shiratori-sagigai | Figures 4— 7-9 Macoma cf. tokyoensis Makiyama. Ogasawara, 1973, pl. 13, fig. 4. [non Makiyama, 1927] Macoma aomoriensis Nomura. Ogasawara, 1973, pl.13, fig. 9. [non Nomura, 1935] Macoma izurensis (Yokoyama). Ogasawara et al., 1986, pl. 1, figs. 12,18. [non Yokoyama, 1925] Macoma sp. B. Ogasawara and Morita, 1986, pl. 2, figs. 25, 28. Rexithaerus shiratoriensis Matsubara, 1994, p. 24-27, tab. 1, pl. 1, figs. 1, 2, 3a-c, 4a-c, 5a-b, pl. 2, figs. 1a-c, 2, 3, 4. Type specimen.—IGPS no. 102562 (Holotype), 102563-1 to -10 (Paratypes). Type locality.—A small tributary of the Shiratorigawa River, south of Shiratori, Ninohe City, lwate Prefecture. Remarks.—The present species is characterized by its moderate-sized (maximum length 61.4mm), transversely elongate-ovate shell (height/length 0.71 to 0.79) with a rather weakly developed posterior ridge, less elevated dorsal flange, obliquely subtruncated posterodorsal margin and low pallial sinus. All species questionably listed by Matsubara (1994), Macoma cf. tokyoensis and Macoma aomoriensis of Ogasa- wara (1973), and Macoma izurensis of Ogasawara et al. (1986), from the same locality belonging to the Nishikurosawa Formation in Akita Prefecture, are considered to be synony- mous with the present species. On the other hand, Macoma izurensis of Kamada (1962), from the Honya and Nakayama Formations in Fukushima Prefecture, is not referred to the present species. As a result of the reexamination of the hypotypes, it becomes clear that the flange-like posterodor- sal margin in the figures of Kamada (1962) is not original, but is due to matrix covering shell material. Thus, these speci- mens are referred to Macoma (Macoma) izurensis (Yokoyama, 1925) as Kamada (1962) thought. Macoma sp. B of Ogasawara and Morita (1986) from the middle Miocene Yanagawa Formation in Fukushima Prefec- ture is considered to be M. (R.) shiratoriensis based on its transversely elongate ovate shell with obliquely truncated posterodorsal margin. Comparison.—M. (R.) shiratoriensis closely resembles M. (R.) indentata flagleri Etherington, 1931. However, the former species can be distinguished from the latter subspecies by having a larger shell with less distinct growth lines and less developed posterior ridge. As already mentioned, the inter- nal characteristics of M. (R.) indentata flagleri are unavailable and thus an exact comparison is difficult. The present species is easily distinguished from M. (R.) indentata indentata Carpenter, a Recent northeastern Pacific species, by having a weaker ridge, less protruding posterior margin, less compressed posteroventral margin in front of a ridge, and lower pallial sinus. Distribution.—Latest early Miocene : Kadonosawa Forma- tion in Iwate Prefecture (Matsubara, 1994). Latest early- early middle Miocene Nishikurosawa Formation in Akita Prefecture (Ogasawara, 1973; Ogasawara et al, 1986). Early middle Miocene: Yanagawa Formation in Fukushima Prefecture (Ogasawara and Morita, 1986). Temporal and spatial distributions of Macoma (Rexithaerus) in Northwest Pacific The subgenus Rexithaerus was considered to be one of those elements which originated in northwestern North America in late Oligocene and migrated into the Northwest Pacific by the late early Miocene (Matsubara, 1994). The earliest Rexithaerus species in the Northwest Pacific region; M.(R.) shiratoriensis (Matsubara), occurs from the upper lower to lower middle Miocene in formations in northeastern Honshu (Figure 7). According to the climato-paleogeogra- phic map of Ogasawara (1994), this species lived in the subtropical realm, but could not invade the tropical one. The next fossil occurrence is M. (R.) cf. hokkaidoensis from the upper middle Miocene Shibiutan Formation of Hokkaido, described above. According to Fujimoto et al. (1998), the molluscan assemblage including M. (R.) cf. hokkaidoensis is correlated with the upper sublittoral “Pitar’-Anadara Assem- blage of the Lower Togeshita fauna (Amano, 1983, 1986). This fauna occupied the mild- or cool-temperate realm in the middle Miocene of Hokkaido (Ogasawara et al., 1993; Ogasawara, 1994). On the other hand, the earliest fossil record of Macoma (Rexithaerus) sectior Oyama is known from the Kanomata- 130° 140° late early-early middle Miocene OM. (R.) shiratoriensis OM. (R.) sp. VA late middle-late Miocene 4 AM. (R.) sectior YA OM. (R.) cf. hokkaidoensis / Wi Va S AM. (R.) aff. sectior GL x FA) 7 ce? @M. (R.) sp. ae > =) X se Y 20) 47 Pr 40°. = 4 1 — V4 G | Pliocene-early Pleistocene vM. (R.) sectior middle Pleistocene-Holocene @M. (R.) hokkaidoensis aM. ) sectior 30° Figure 7. Distribution of the fossil Macoma (Rexithaerus). Northwestern Pacific Macoma (Rexithaerus) 103 zawa Formation in Tochigi Prefecture (Akutsu, 1964, as Macoma hokiensis). The age of the horizon bearing this species is somewhere between the N. 14 and N. 16 zones of the late middle to early late Miocene based on the plank- tonic foraminiferal data (Saito, 1963; Otsuki and Kitamura, 1986). According to Ogasawara (1994), the Kanomatazawa Formation was deposited in the warm-temperate realm. Macoma secta (Conrad) was recorded from the lower middle Miocene Ilyinskaya and the upper Miocene Ermanovskaya Formations in Kamchatka by Sinelnikova (1976) and Gladen- kov et al. (1984). However, these are referred to Macoma s.s. because the specimens lack the posterior ridge. Pliocene M. (R.) sectior is recorded in the cool- to mild- temperate realm. This species was described from the Tatsunokuchi Formation in Miyagi Prefecture (Nomura, 1938), whose age is the latest Miocene to early Pliocene (Yanagi- sawa, 1990, 1998). On the other hand, M. (R.) sectior was also illustrated by Fujii and Shimizu (1991) from the Mita Formation in Toyama Prefecture. Early Pleistocene records of M. (R.) sectior Oyama exist from the Omma-Manganji fauna recognized in the Japan Sea borderland in central and northern Japan. The distribu- tion of this species is restricted to the Omma-Manganji (proper) and Kanto-type subprovinces of Ogasawara (1986), both of which correspond to the mild-temperate marine climate (Ogasawara, 1994). Thus, M. (R.) sectior in the early Pleistocene was confined to the mild-temperate water. In the Recent, M. (R.) hokkaidoensis lives in the cool- temperate and subarctic shallow waters in Hokkaido, south Sakhalin, south Kurile Islands and Primorye while M. (R.) sectior Oyama lives in the upper sublittoral (10-30 m in depth) of the mild-temperate to subtropical waters around Honshu, Kyushu, Shikoku, and South Korea (Higo and Goto, 1993). After the subgenus Rexithaerus arrived in the northwestern Pacific, it lived in the subtropical realm during the late early to early middle Miocene, or the so-called “Climatic Optimum” age. By the late middle Miocene, the subgenus had adapt- ed to the temperate zone as climates cooled after the “Climatic Optimum”. From the late middle Miocene to the Plio-Pleistocene, the subgenus Rexithaerus lived in the mild- or cool-temperate realm. In the Holocene, M. (R.) sectior extended its range to subtropical waters. Kuroda (1941) and Wu (1980) only listed M. (R.) sectior from Formosa (Taiwan). If this is true, M. (R.) sectior may live in the tropical water. However, there is no illustration of the Formosa specimen. The muricid gastropod genus Ceratosoma, a member of the westward-spreading group, shows a history of expansion similar to that of Rexithaerus. Both Macoma (Rexithaerus) and Ceratostoma invaded the subtropical waters around Japan by the early middle Miocene and adapted to the cool- to mild-temperate zone by the early Pleistocene. After or during the middle to late Pleistocene, their distribution extended southward to subtropical waters (Amano and Vermeij, 1998). On the other hand, one of the same west- ward-spreading muricids, Nucella, only lives in mild-temper- ate to arctic waters (Higo and Goto, 1993). One plausible reason why Nucella did not invade warmer waters may be related to its original adaptation not to the subtropical water as Macoma (Rexitherus) or Ceratostoma, but to the cool- temperate water around Japan in the early middle Miocene (Amano et al., 1993). Acknowledgments We are greatful to Geerat J. Vermeij (Univ. California, Davis) and Eugene V. Coan (Santa Barbara Mus.) for their critical reading of this manuscript. We thank Alexander I. Kafanov (Marine Biol. Inst.), Svetlana M. Darkina (Zool. Mus. of Far East Univ.), Masanori Shimamoto (Tohoku Univ.), Jun Nemoto (Tohoku Univ.) and Reishi Takashima (Tohoku Univ.) for their help in studying the fossil and Recent specimens. References Akutsu, J., 1964: The geology and paleontology of Shiobara and its vicinity, Tochigi Prefecture. 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(in Russian) Tryon, G.W., 1869: Catalogue of the family Tellinidae. American Journal of Conchology, vol. 4, no. 5, p. 72-126. Wu, W.L., 1980: The list of Taiwan bivalve fauna. Quar- terly Journal of Taiwan Museum, vol. 33, nos. 1/2, p. 55- 208. Yamamoto, G. and Habe, T., 1959: Fauna of shell-bearing mollusks in Mutsu Bay. Lamellibranchia (2). Bulletin of the Marine Biology Station of Asamushi, vol. 9, no. 3, p. 85-122, pls. 6-14. Yanagisawa, Y., 1990: Diatom biostratigraphy of the Neogene Sendai Group, northeast Honshu, Japan. Bulletin of the Geological Survey of Japan, vol. 41, no. 1, p. 1-25, pl.1. (in Japanese with English abstract) Yanagisawa, Y., 1998: Diatom biostratigraphy of the Neogene Tatsunokuchi Formation in the western Kita- kami City, Iwate Prefecture, Japan. Research Report of the Iwate Prefectural Museum, vol.14, p. 29-36. (in Japanese with English abstract) Yokoyama, M., 1922: Fossils from the Upper Musashino of Kazusa and Shimosa. Journal of the College of Sci- ence, Tokyo Imperial University, vol. 44, p.1-200+ viii (indices), pls. 1-17. Yokoyama, M., 1925: Molluscan remains from the upper- most part of the Joban Coal-field. Journal of the College of Science, Tokyo Imperial University, vol. 45, p. 1-34, pls. 1-6. Paleontological Research, vol. 3, no. 2, pp. 106-120, 7 Figs., June 30, 1999 © by the Palaeontological Society of Japan The turrilitid ammonoid Mariella from Hokkaido — Part 1 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXV) TATSURO MATSUMOTO’, AKITOSHI INOMA’ and YOSHITARO KAWASHITA’ ‘c/o Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, 812-8581, Japan *Daida 6-29-19, Setagaya, Tokyo, 155-0033, Japan ®Tomatsu-Chiyoda 2-179, Mikasa, 068-2134, Japan Received October 30, 1998 ; Revised manuscript accepted April 5, 1999 Abstract. Three species of the genus Mariella (Turrilitidae) from the Lower Cenomanian (Cretaceous) of Hokkaido are described. They include the two widespread species, M. (M.) dorsetensis (Spath, 1926) and M.(M.) oehlerti (Pervinquiere, 1910). but distinguished from M. (M.) oehlerti. The third species, M.(M.) pacifica sp. nov., is somewhat similar to it is also compared with some other species. The problem of dimorphism in the turrilitid ammonoids is discussed. Key words : Cenomanian, dimorphism, Hokkaido, Mariella, Turrilitidae Introduction Ammonoids of the family Turrilitidae have been recorded from various regions of the world. They occur in the mid Cretaceous (Albian and Cenomanian) and include a number of widespread species which are useful for biostratigraphic zonation and correlation. Some of them are, however, apparently endemic. Turrilitids would be also useful to investigate some aspects of palaeogeography and palaeoenviroments during mid-Cretaceous times. Aside from several stratigraphic papers in which some turrilitid species are listed or briefly mentioned, very few species have been hitherto described from Japan, although such a magnificent example as Turrilites komotai Yabe, 1904 (p.7, pls.1,2) [now referred to Hypoturrilites| was once reported. In our present knowledge ammonoids of the Turrilitidae occur fairly commonly in the mid-Cretaceous sediments of certain biofacies in Hokkaido. A rare but important occurrence of Mesoturrilites from Hokkaido has been recently reported (Matsumoto and Inoma, 1999). More species of the family are to be described successively. In this paper three species of the genus Mariella are described, of which two are well Known and widespread. The third species is regarded as new and has not been known elsewhere. Incidentally, T.M. had opportunities to examine some specimens at the Natural History Museum, London, and several other overseas institutions. Moreover, W. J. Ken- nedy kindly sent several specimens to Kyushu University as reference material. Geographic and stratigraphic setting The specimens dealt with in this paper were obtained mainly from the Soeushinai area [Shumarinai-Soeushinai area by some authors] of the Teshio Mountains, northwest- ern Hokkaido. The Cretaceous strata are exposed in the Shumarinai Valley, the Sounnai Valley and the smaller rivu- lets, such as the Kyoei-Sakin-zawa and the Sanjussen- zawa, which are all tributaries of the River Uryu, and also in the upper reaches of the River Kotanbetsu. This area was geologically mapped by Hashimoto et al. (1965) and has been recently reinvestigated by Nishida et al. (1992, 1993, 1996, 1997, 1998a, 1998b). The localities where megafossils and microfossils were collected are pinpointed in the papers by Matsumoto and Inoma (1975) and Inoma (1980) and, further- more, in a number of route maps of the stratigraphic papers by Nishida et a/. (1992, 1993, 1996-1998a, b). Moreover, a locality guide is to be given as an Appendix to this paper. As has been clarified by the above authors, a thick series of strata comprehensively called the Middle Yezo Subgroup of late Albian through Turonian age is extensively distributed in this area. The conformably underlying Lower Yezo Subgroup and the transitionally overlying Upper Yezo Sub- group are partly observable in the area. In a revised scheme of Nishida et al. (1996, fig. 10) the Middle Yezo Subgroup in this area is lithostratigraphically subdivided into the Members My1 to My8 in ascending order. The Mem- bers My1 and My2, together with the uppermost portion of the Lower Yezo Subgroup, are Upper Albian, the Member My3 is Lower Cenomanian, and the Members My4 and My5 represent the rest of the Cenomanian. The age correlation is based on the assemblage of ammonoid and inoceramid species and also on that of some microfossils (Nishida et al., Mariella from Hokkaido—Part 1 107 1992, 1993, 1996-1998a, b). As there is a lateral change in the lithofacies and thickness of the members from place to place, boundary planes of the successive members may be somewhat diachronous in some Cases. The turrilitid ammonoids have been obtained from the Members My2, My3 (most commonly) and My5 and also the upper part of the Lower Yezo Subgroup. These members consist primarily of mudstones, which are sometimes sandy or have intercalated sandy layers and laminae. Conventions Repository.—The illustrated and/or measured specimens are registered in the following institutions which are indicated by the abbreviated symbols as follows : GK : Type Room, Department of Earth and Planetary Sciences, Kyushu University, Hakozaki, Fukuoka GS : Geological Collections, Faculty of Culture and Education, Saga University, Saga MCM : Mikasa City Museum, Mikasa, Hokkaido TKD : Institute of Geosciences, Tsukuba University, Tsukuba [reconstitution of the Tokyo Kyoiku Daigaku | : University Museum, University of Tokyo, Hongo, Tokyo Morphological terms.—For the morphological terms to describe the turrilitid ammonoids, we. follow those used by Wright and Kennedy (1996). Setting the apex of the turrical shell at the top, the terms upper and lower or adapical and adoral | —abapical] are defined and the rows of tubercles or ribs on the face of each whorl are described in descending order as the first, the second and so on. The term flank (see Forster, 1975) may be used for the exposed whorl face of Wright and Kennedy (1996). Palaeontological descriptions Order Ammonoidea Zittel, 1884 Suborder Ancyloceratina, Wiedmann, 1966 Family Turrilitidae Gill, 1871 Genus Mariella Nowak, 1916 Type species.—Turrilites bergeri Brongniart, 1822 (p. 395, pl. 7, fig. 3) by original designation (Nowak, 1916, p. 10). Remarks.—Wright and Kennedy (1996, p.330) have given an ample generic diagnosis and discussed problems of nomenclature. The genus includes the two subgenera, Mariella (Mariella) Nowak, 1916 and Mariella (Wintonia) Adkins, 1920, the latter of which is a senior synonym of Mariella (Plesioturrilites) Breistroffer, 1953 (See Wright and Kennedy, 1996, p. 331). An undoubted example of M. (Wintonia) has not been so far found from Japan, whereas there are a number of specimens from Hokkaido which are referable to at least eight species of M. (Mariella). Mariella (Mariella) dorsetensis (Spath, 1926) Figure 1 Turrilites bergeri Brongniart. Sharpe, 1857, p. 65, pl. 26, fig. 11 only. Turrilites dorsetensis Spath, 1926, p. 429. Mariella dorsetensis (Spath). Spath, 1937, p. 513; Marcinowski, 1970, p. 431, pl. 3, fig. 1; Seyed-Emami and Aryai, 1981, p. 26, pl. 6, figs. 5, 6. Paraturrilites lewesiensis (Spath). 436 (pars.), pl. 40, figs. 8, 9 (?). Benavides-Cäceres, 1956, p. Figure1. Mariella (Mariella) dorsetensis (Spath). 3a, b. GS. G180, two lateral views (different sides from 1), x2. 4a-c. GS. G182, two lateral and basal views, x 1.5. 1. GS.180, 1. 2a, b. GK. H8504, two lateral views, x 2. 108 Tatsuro Matsumoto et al. Mariella (Mariella) dorsetensis (Spath). Atabekian, 1985, p. 35, pl. 6, figs. 6, 9; Wright and Kennedy, 1996, p. 344, pl. 100, figs. 5,11, 17, 19, 22, 25; pl. 102, fig. 7 ; text-figs. 136B, E (with full synonymy). Holotype.—BMNH. C3834, figured by Sharpe, 1857, pl. 26, fig. 11 and named as Turrilites dorsetensis Spath, 1926, p. 429 (by monotypy). Material. GS. G180 (Figure 1-1, 3) and GS. G181, both from loc. R905 | = YKC080621b |, Hotei-zawa ; GK. H8504 (Figure 1-2) from loc. R518p5, East Suribachi-zawa; GK. H8505 from loc. R438p, GK.H8506 from loc. R433p, and TKD 30081A,B from loc. 81007, in the upper reaches of the Suribachi-zawa ; TKD 30080A-D from loc. 71204 in the middle course of the River Shumarinai ; GS. G182, (Figure 1- 4), from loc. YKC060824, Sanjussen-zawa. These are all from the Lower Cenomanian Member My3 of the Soeushinai area. Description.—The available specimens are all small and incomplete, as seen in the illustration (Figure 1). In general, the apical angle is acute (20-25° in our estimation). The whorl is rounded in section, showing a moderately or broadly convex outer face ; the whorl junction is well defined and crenulated. The tubercles in four rows are of moderate density and number 20 to 25 per whorl in each row. The tubercles on the outer whorl face are disposed slightly obliquely in three rows at subequal intervals and of nearly equal moderate intensity. The tubercle of the first row is elongated upward to a distinct rib on the upper face of the whorl. In some specimens the fourth tubercle is slightly smaller than the others and close to the third one, although it is beyond the lower whorl seam. On the lower whorl face ribs run from the third row tubercles to the narrow umbilicus by way of the fourth row tubercles, showing a gentle curvature. Septal sutures are partly exposed (GK. H8505). Comparison.—The above-described specimens from Hok- kaido are well comparable with the holotype and other examples of M.(M.) dorsetensis from England (Wright and Kennedy, 1996, pl.100, figs. 5, 11,17,19, 22,25) and also previously illustrated specimens from several regions of the world (See synonymy list). Affinities with other allied species are discussed below, together with some remarks on ques- tionable points. Occurrence.—As for material. This species has been reported from the Lower Cenomanian of southern England, northern France, Poland, Turkmenistan, Iran, Madagascar and Peru (See synonymy list). Discussion.—M. (M.) dorsetensis is similar to and could be interpreted as a descendant from M.(M.) bergeri of the uppermost Albian. The apical angle of the former is smaller than that of the latter. In fact the apical angle of M. (M.) bergeri is recorded as 33-38 by Spath (1937, p. 511) and an example of Pictet and Campiche (1862, pl. 58, fig. 2) reillus- trated by Renz (1968, pl. 18, fig. 4) gives 34°, as compared to the 20-25° of M.(M.) dorsetensis. On the average the tubercles are somewhat more crowded and more distinctly connected by longitudinal ribs in M. (M.) bergeri. The relationship between M. (M.) dorsetensis and M. (M.) lewesiensis (Spath, 1926) is a moot problem, as has been discussed by Kennedy (1971, p. 28) and Klinger and Kennedy (1978, p. 31). The difficulty can be guessed from the con- fused state in the lists of synonymy between authors (even between the same palaeontologist writing on different dates) (see Wright and Kennedy, 1996, p. 339-340 and p. 344). Collignon (1964, pl. 331, fig. 1482) has shown an example of M. (M.) dorsetensis with a rostrate last whorl. This suggests the small size of this species. We notice, however, that an example of the same species illustrated by Atabekian (1985, pl. 6, fig. 6, 6b) is nearly as large as the holotype of M.(M.) lewesiensis (see Sharpe, 1857, pl. 20, fig. 10 or Wright and Kennedy, 1996, p. 101, fig. 3). There is no difference in the estimated apical angle between the two species. There may be differences in the ornament. The relative smooth- ness of the upper face of the whorl was regarded as a criterion by which to distinguish M. (M.) lewesiensis from M. (M.) dorsetensis, but some of the coarse tubercles of the first row in the former show faint elongations on a part of the upper whorl face, depending probably on the mode of light- ing (see Kennedy, 1971, pl. 8, figs. 1,4, 5,8). Wright and Kennedy (1996, p. 340) have recently given their opinion that rounded subequal tubercles in the upper two rows plus feeble spiral (i.e. clavate) elongation of the tubercles in the lower two rows characterize M.(M.) lewesiensis. Indeed, the tubercles on the outer whorl face are coarse and globular in M.(M.) lewesiensis and rather granular but transversely elongated in M. (M.) dorsetensis, although there is no marked difference in the number of tubercles to a whorl. For us it is difficult to understand the significance of the “feeble spiral elongation of the lower tubercles’. The tubercles of the lower two rows are Clavate in the holotype, but the feature is not well shown in the illustration of some other specimens (e.g., Wright and Kennedy, 1996, pl. 100, figs. 23, 27). According to Klinger and Kennedy (1978, p. 31, pl. 7, fig. F), in M. (M. lewesiensis | =M. (M.) dorsetensis in their paper] ribs are absent or only a few traces are discernible on the lower whorl face, although they did not give a photograph of the basal view. On the lower whorl face of the holotype ribs are extended very faintly from the tubercles of the fourth row (T.M.'s observation at the Naturat History Museum, London). This character is also shown on some examples of M.(M.) lewesiensis by Atabekian (1985, p. 37, pl. 7, fig.1,1b; pl. 8, fig. 1, 1a), whereas ribs are distinctly developed on the lower whorl face of M.(M.) dorsetensis from the Kopet Dag (see Atabekian, 1985, p.35, pl.6, fig.6,6b) as well as in our specimens (e.g., Figure 1-4 of this paper). If this difference is confirmed in a sufficient number of specimens, it would become one of the reliable criteria to distinguish the two species. So far, an undoubted example of M. (M.) lewesiensis is not found in the material of the Soeushinai area. The speci- mens which were tentatively identified with M. lewesiensis by A.l. (as written on the labels) are actually M.(M.) oehlerti (Pervinauiere). Mariella from Hokkaido—Part 1 109 Mariella (Mariella) oehlerti (Pervinquiere, 1910) Figures 2-4 Turrilites gresslyi Boule, Lemoine and Thevenin, 1907 (non Pictet and Campiche, 1861), p. 57, pl. 18, fig. 2, 2a. Turrilites oehlerti Pervinquiere, 1910, p. 53, pl. 5, figs. 14-17; Collignon, 1929, p. 65, pl. 6, figs. 16, 17 ; Matsumoto, 1938, p. 23, pl. 2, fig. 7; Collignon, 1964, p.15, pl. 320, figs. 1398, 1399. Mariella (Mariella) oehlerti (Pervinquiere, 1910); Forster, 1975, p. 190, pl. 7, figs. 7, 8; text-fig. 52; Atabekian, 1985, p. 30, pl. 6, figs. 4, 5; Wright and Kennedy, 1996, text-fig. 138 J,O,V. Mariella (Mariella) oehlerti oehlerti (Pervinquiere, 1910). Klinger and Kennedy, 1978, p. 31, pl. 3E; pl. 4E ; pl. 6H-N; pl. 7G; pl. 8G-H; text-figs. 1A, B; 7B, D; 8G. Mariella (Mariella) oehlerti sulcata Klinger and Kennedy, 1978, p. 33, pl. 8, fig. D; text-figs. SE, 8H (? non pl. 3D; text-fig. 3D). Holotype.—The specimen figured by Pervinquiere (1910, pl. 5, fig. 16) from the Cenomanian of Aumale, Algeria (by original designation). Klinger and Kennedy's (1978, p. 31) designa- tion of a lectotype (Pervinquiere, 1910, pl. 5, fig. 15) was misleading, and Atabekian (1985, p. 30) erroneously followed them. Material.—A large number of specimens from the Member My3 of the Soeushinai area are referable to this species. The representative ones among them are as follows: GK. H8500 (Figure 2-1) and GK. H8501 obtained by T.M. at loc. R518p5 and GS. 166 (Figure 2-7) collected by Y.K. at loc. R518p! from the East Suribachi-zawa ; TKD 30086A (Figure 3-2), TDK 30086B (Figure 3-3) and TKD 30086C (Figure 2-6) obtained by A.l. from a nodule at loc. 81001 in the Suribachi- zawa; TKD 30546B (Figure 2-2) and A collected by W. Hashimoto from a nodule at loc. P2 in the River Shumarinai and provided to A.l. for study ; GS. G163 (Figure 2-3) and GS. G164 (Figure 2-4) collected by Y.K. at loc. YKC060824 in the Sanjussen-zawa ; GS. G165 (Figure 2-5) collected by Y.K. at loc. YKC050610 in the Bishamon-zawa ; GS. G167 (Figure 3- 1) collected by Y.K. at loc. YKC591014 and also GS. G168 (Figure 4-1) and GS. G169 (Figure 4-2) collected by Y.K. at loc. YKC020619 in the Kyoei-Sakin-zawa. Description.—Although completely preserved specimens are hard to come by larger examples are approximately estimated at 250mm in total whorl height and 70mm in diameter of the last whorl. Several specimens which pre- serve the rostrum suggest a size dimorphism. The above larger ones, as represented by GS. G168 (Figure 4-1), may represent a macroconch, whereas GS. G167 (Figure 3-1) and TKD 30086A, B (Figure 3-2, 3) may be microconchs, for they are half of the macroconch in size. The rostrate peristome of a larger form, exemplified by GS. G169 (Figure 4-2), is twice as large as that of a smaller form, e.g., TKD 30086C (Figure 2-6). The apical angle is low but seems to be somewhat variable between individuals and probably also with growth. On account of incomplete preservation, the actual angle is hard to measure with precision. It is roughly estimated at 25 (+5) on the average. The whorl is asymmetrically subquadrate to broadly rhom- boidal in section. Its upper flank [i.e. upper part of the exposed whorl face] slopes down, forming an obtusely angular (costal) or a subrounded (intercostal) shoulder at the first row of tubercles ; its middle flank [i.e., main part of the exposed whorl face] is nearly vertical and forms an obtuse shoulder at the second row of tubercles with the narrow, lower flank which inclines steeply inward ; the whorl junction is thus fairly deep and crenulated. The aperture is suboval and provided with a rostrum that extends at first downward and then recurves obliquely upward (See Figures 3-3; 2-6; 4-1, 2). The tubercles are moderate in strength and coarseness ; those of the first row are more prominent than others and extend upward to the ribs on the upper flank. Those of the three rows on the exposed whorl face are nearly equidistant, arranged more or less obliquely and sometimes connected by blunt riblets ; those of the third row may be granular or sometimes rather clavate (i.e. extended spirally); the inter- space between the second and third rows of tubercles is sometimes narrower than that between the first and second rows and, furthermore, it may be grooved to various depths (see Figure 2-5). The tubercles of the fourth row are close to those of the third row in some specimens but they are disposed along the outer margin of the basal part of the whorl. The tubercles of each row in our sample normally number from 20 to 28 to a whorl. TKD 30546B (Figure 2-2) may exemplify an extreme case (30 to a whorl), but it is referred to this species in consideration of other characters. Aside from the bullate extension to the ribs, the tubercles of the upper two rows are conical with a rounded base. In some cases they may preserve a sharply pointed summit, but so far a highly extended spine has not been observed in our material. Near the apertural margin the tubercles are obliquely bullate and extended to gently flexuous narrow ribs. The last rib goes on to form a blunt ridge on the rostrum, whereas the other side of the rostrum is ornamented by very fine and delicate riblets and dots (see Figures 2-6a, b, 4). The septal suture is not well traced in our material, because the internal mould is not well exposed. It was illustrated by Förster (1975, fig. 52) on a young example from Mozambique and partly by Klinger and Kennedy (1978, fig. 1A, B) on middle-aged specimens from South Africa. Comparison and discussion.—As the types originally de- scribed by Pervinquiére (1910) and also the specimens dealt with by subsequent authors up to 1975 are so small it was difficult for us to understand the diagnosis of this species. Based on a great number of specimens from the Lower Cenomanian of South Africa, Klinger and Kennedy (1978) have clarified the diagnosis of this species and also its relations with or distinctions from other species. Wright and Kennedy (1996, text-fig. 138 J,O,V) have finely reillustrated Pervinquiére’s holotype and paratypes. These two works have enlightened us in getting a proper conception of M. (M.) oehlerti. In our material there are specimens which closely conform with the holotype. GK. H8500 (Figure 2-1) is such an exam- ple. They are, however, immature. The full-grown adult shell has a rostrate aperture. The three specimens illus- trated in Figure 3 exemplify the abult shells of moderate size, 110 Tatsuro Matsumoto et al. Figure 2. Mariella (Mariella) oehlerti (Pervinquiere). 1a, b. GK. H8500, two lateral views, 1.2 (The terminal protuberance is not a rostrum but an attached juvenile of Anagaudryceras sp.). 2a-c. TKD 30546B, two lateral and basal views, 1.5. 3. GS.G163, x15. 4. GS.G164, x4/3. 5. GS.G165, 4/3. 6a,b. TKD 30086c, detached rostrum, external and the other sides, «1. 7. GS. G166, a large but incomplete example, 1. Mariella from Hokkaido—Part 1 Figure 3. Mariella (Mariella) oehlerti (Pervinquiére). More or less deformed examples of a smaller form with a rostrate peristome, all «1. 1a-c. GS. G167, three lateral views. 2a,b. TKD 30086A, two lateral views. 3a-c. TKD 300868, three lateral views. 111 112 Tatsuro Matsumoto et al. Figure 4. Mariella (Mariella) oehlerti (Pervinquiére). Examples of a larger form, x0.9. 1a-c. GS. G168, two lateral views (a, b) and aperture (c). 2a, b. GS. G169, two views of a detached rostrum. Mariella from Hokkaido—Part 1 113 although they are considerably affected by secondary defor- mation. Among a number of South African specimens, BMNH C79806 (Klinger and Kennedy, 1978, pl. 6, fig. K) is an illustrated example of the adult stage. It is similar in size to our examples mentioned above, but it preserves only two whorls of the late growth stage. In our material from the Member My3 there are much larger adult specimens which preserve the rostrate oral part. GS. G168 (Figure 4-1) is an example of such a large form. It is nearly twice as large as the specimens mentioned above. GS. G166 (Figure 2-7) is referable to a similarly large form, although its later part is not preserved. GS. G169 (Figure 4- 2) is a detached piece of a rostrate oral part. It is nearly twice as large as TKD30086C (Figure 2-6), which is a detached oral part of a smaller form. The facts described above suggest the existence of a dimorphic pair in this species. To confirm the dimorphism, it is necessary to get further evidence from the materials of other regions. Although “several hundred specimens” of this species from South Africa have been treated by Klinger and Kennedy (1978, p. 32), they did not make mention of the size variation or dimorphism. The specimens figured by them are more or less incomplete, consisting of a few whorls. The largest example among them is BMNH C79860 (op. cit., pl. 8, fig. H). [Note that figure is actually x 5/4, although it was indicated as x1.] It could be comparable with a part of the large specimen (GS. G168, Figure 4-1) from Hokkaido, but it lacks the oral end. On the other hand, a specimen from South Africa (op. cit. pl. 6, fig. K) which possesses an incomplete rostrum is comparable with the smaller form from Hokkaido. Dimorphism in the Turrilitidae has been noted by Wright and Kennedy (1996, p. 349) for Turrilites scheuchzerianus Bosc and certain other species, but Lehmann (1998, p. 37) has given comments and suggested that the observed difference might simply be size variation. There could be, however, size variation in both microconch and macroconch. For a final conclusion one should examine a sufficient number of samples. There is another problem to be discussed. Some speci- mens of M. (M.) oehlerti from the Member My3 of the Soeushinai area show a spiral sulcus between the second and third rows of tubercles. In such cases, the tubercles rest on low ridges and may be obliquely clavate. The groove is thus variable in its degree of distinctness among the specimens and the sulcate specimens often occur together with normal ones. This feature is similar to that already noticed in the material of South Africa. Klinger and Kennedy (1978, p. 33, pl. 3, fig. D; pl. 8, fig. D ; text-figs. 3D, D; 8H) have established a subspecies M. (M.) oehlerti sul- cata. One of us (T.M.) examined some of the specimens labelled as “M. (M.) oehlerti sulcata”, such as BM. C79952 (op. cit., pl. 8, fig. D), C79951, C79950 and C79949. They seem to show a gradual change in morphology from “M. (M.) oehlerti oehlerti” to “M.(M.) oehlerti sulcata.” The holotype of the subspecies M. (M.) oehlerti sulcata Klinger and Kennedy, 1978 is SAS A2908. Although we have yet no opportunity to examine the actual specimen itself, its fine illustration (op. cit., pl. 3, fig. D) gives us a strong impression that it resembles a form of Mesoturrilites aumalensis (Coquand) such as was figured by Pervinquiere (1910, pl. 14, fig. 22) (see Wright and Kennedy, 1996, text-fig. 138 S-T). Furthermore, we see that the specimen in ques- tion (SAS A2908) is similar to, if not identical with, Mariella (Mariella) bicarinata (Kner, 1852) (see Atabekian, 1985, p. 40, pl. 8, figs. 2-9; pl. 9, figs. 1, 2; Wright and Kennedy, 1996, p. 335, pl. 98, figs. 7, 12; pl. 102, fig. 11). We are thus, inclined to consider that it would be better to exclude the holotype of M. (M.) oehlerti sulcata from M. (M.) oehlerti. Incidentally, the above observation may be favourable to the suggestion of Wright and Kennedy (1996, p. 346) to seek the origin of Mesoturrilites in M. (M.) bicarinata. Occurrence.—As for material. In addition, incompletely preserved specimens which can be called M. (M.) cf. oehlerti are found commonly in the Member My3 of the Soeushinai area. At least some of the specimens, including GK. H8500 and H8501, occur in the lower part of the Member My3 together with Graysonites adkinsi Young. Records of this species from other areas in Hokkaido are so far poor, except for a fine specimen MCM A517 collected by Reishi Takashima and Koji Hasegawa from the Oyubari area. This is to be reported in detail on another occasion. Outside of Hokkaido in Japan a few small specimens of this species were described by Matsumoto (1938, p. 23, pl. 2, fig. 7) from the Unit lle of the mid-Cretaceous Goshonoura Group of Kyushu ; Graysonites cf. fountaini Young occurs in the same unit (Matsumoto, 1960, p. 44, pl. 6, fig. 1; pl. 7, figs. 1-4; text-figs. 1-7, with Matsumoto et al., 1960, p. 51). M.(M.) oehlerti has been reported from the Lower Cenomanian of Algeria, Madagascar, Mozambique, South Africa and Turkmenistan (Kopet Dag) (see references in the synonymy list). The record of its occurrence in the Gulf Coast (Texas and Mexico) (Young and Powell, 1978, pl. 8, figs. 4,6) is not clear. As species of Graysonites occur there, undoubted example of M.(M.) oehlerti should be searched for. Mariella (Mariella) pacifica sp. nov. Figure 5 Material. —Holotype is GS. G170 (Figure 5-1) from a nodule contained in the siltsone of the middle part of the Member My3, collected by Y.K. and N. Egashira at loc. R905 of the Hotei-zawa, a branch stream of the River Shumarinai, Soeushinai area (see Figure 7 in the Appendix). In the same nodule as that of the holotype there are ten specimens, of which registered paratypes are GS. G171 (Figure 5-2), GS. G172 (Figure 5-3), GS. G173 (Figure 5-4), GS. G174 (Figure 5-5), GS. G175 (without figure), GS. G176-G177 (Figure 5-6), GS. G178 (Figure 5-7) and GS. G179 (without figure). Unregistered specimens are recorded from R906, at a slightly higher horizon than R905. TKD30558 (Figure 5-8) and TKD30559 (Figure 5-12) from a nodule at loc. P4 and TKD30561A, B (Figure 5-9, 10) from a nodule at loc. P2, all taken by W. Hashimoto and transferred to Al. for study, are probably derived from the Member My3 exposed along the middle course of the River Shumarinai. 114 Tatsuro Matsumoto et al. 1a-c. Holotype, GS. G170, three lateral views, «1.5. Note that the upper whorl of the holotype is encrusted with some other organism. 2. GS. G171, with a rostrate oral part, < 4/3. 3a,b. GS. G172, with a rostrate oral part where a juvenile Anagaudryceras sp. is attached, <1.5. 4a, b. Figure 5. Mariella (Mariella) pacifica sp. nov. GS. G173, lateral and basal views, x2. 5a,b. GS. G174, lateral and basal views, <1.5. 6. GS. G176 and G177 (obliquely embedded), «1.5. 7. GS. G178, deformed larger form with a rostrate oral part, «4/3. 8. TKD 30558, <1.5. 9. TKD 30561A, 1.5. 10. TKD 30561B, 1.5. 11. GK.H8503, x2. 12. TKD 30559, x2. 13. GK. H8502, x2. 14. TKD 30560, x2. TKD 30560 is tentatively called Mariella (Mariella) aff. pacifica. GK. H8502 (Figure 5-13) and GK. H8503 (Figure 5-11) preserved. obtained by T.M. at loc. R518 p5 of the lower part of the Diagnosis.—Small, sinistrally coiled and slenderly shaped Member My3 in the East Suribachi-zawa, are probably M. (Mariella), ornamented densely by numerous, small tuber- referable to this species, although they are incompletely cles and delicate riblets in four rows at unequal intervals, Mariella from Hokkaido—Part 1 115 Table 1. Measurements of Mariella (M.) pacifica. Specimen GS. C170 (holotype) G171 G172 Whorl il 2 SE 4 2 Si 3 + Diameter 15.2 13.0 11122 9.3 13.0 10.8 12.8 Height 9.6 75) 5.7 4.3 7.0 46 6.2 H./D. 63 .58 .51 46 54 43 48 Ribs 32 33 33 31 32 33 32 Height means the distance between the upper and lower seams at the adoral end of the measured whorl. Ribs mean the number of ribs or tubercles per whorl. 1°, 2°,------ indicate the first, second, ------ whorls in ascending order from the bottom. Note that an undeformed whorl is selected for the measurements. with the interspace between the first and second rows at about the mid-flank. Ribs extend upward from the tuber- cles of the first row; often the tubercles of the second and third rows closely but obliquely disposed, forming weak spiral ridges with a narrow groove in between; the extended fine riblets recurved on the basal surface by way of the fourth tubercles. Description.—The shell is small and slender; its apical angle is apparently low (less than 30°); junction of whorls rather shallow ; whorl section suboval to subrhomboidal, with outward sloping and gently convex upper portion of flank, nearly flat or slightly convex main part of flank, and narrow and inward-sloping lower portion. Obtuse shoulders may thus be formed at the upper and lower edges of the main part of flank. Basal surface of the whorl is gently convex, sloping to a narrow umbilicus. Ornament consists of numerous, densely set, fine tuber- cles and extended delicate riblets, numbering about 30 to 40 to a whorl in each row. The tubercles are normally in four rows at unequal intervals; the first row slightly above the mid-flank, the second somewhat below the mid-flank, the third close to the second and the fourth along the lower whorl seam on the outer margin of the basal surface, where riblets are recurved. The tubercles are of unequal intensity between the rows; those of the first row are slightly coarser than others and extend upward to short ribs; those of the second and third rows are finer, somewhat oblique and disposed en echelon; often they appear to form blunt spiral ridges with a sulcus in between. The tubercles of the fourth row are very fine and close to those of the third row; occasionally the fourth-row tubercles are scarcely discern- ible or undeveloped. Near the apertural margin ribs become flexuous and continuous, connecting transversely elongates tubercles (see GS. G171, G172 and G178; Figure 5-2, 3, 7). Regrettably, the recurved part of the rostrum is not preserved. At any rate, the above three specimens represent the adult shell. The holotype (GS. G170) is also nearly adult. The three specimens, GS. G170, G171 and G172 (Figure 5-1—3) are equally small, with total whorl heights about 40mm and diameters of last whorl 15 mm or so. On the other hand GS. G178 (Figure 5-7) is somewhat larger, although it is deformed and lacks earlier whorls. Again dimorphism can be consid- ered, if not definitely concluded. Measurements.—See Table 1. Comparison.—In respect of a small and slender shell with Linear dimensions are in mm. numerous, fine and delicate tubercles and riblets, this species may be closely allied to M. (M.) numida (Pervinquiere) (1910, p. 53, pl. 5, figs. 12, 13), from the Cenomanian of Algeria, but the holotype of that species (refigured by Wright and Kennedy, 1996, text-fig. 138L) is dextral and seems to pos- sess a lower apical angle (about 18) and four rows of tubercles wholly exposed on the outer face of a whorl. For the exact comparison more specimens including an adult example of M. (M.) numida are required. In having numerous tubercles and obliquely extended riblets, M.(M.) pacifica is apparently similar to M.(M.) tor- quatus Wright and Kennedy, 1996 (p. 334, pl. 100, figs. 2, 20, 21), from the Lower Cenomanian of England. In the latter the rows of closely set tubercles form distinct spiral ridges. In the former the tubercles are normally not so much crowded and the ridges are weaker. TKD30560 (Figure 5- 14) from loc. Pi is exceptional in that its tubercles and riblets are so crowded and numerous (about 50 to a whorl) that the rows of tubercles form fairly distinct spiral ridges. There is, however, some extent of variation in the distinct- ness of the ridges in M.(M.) pacifica. For instance, TKD30559 (Figure 5-12) and TKD30558 (Figure 5-8) appear to show intermediate features. There is, thus, a certain extent of variation in the fineness of tubercles and appear- ance of ridges in M. (M.) pacifica and also in M. (M.) torquatus (see the three figures cited above). The undoubted differ- ence between the two species is in the disposition of the rows of tubercles. Namely, in M. (M.) torquatus the first row is higher in the upper part of the whorl face and the second row is at the middle of the whorl, whereas in M. (M.) pacifica the interspace between the first and second rows is at the mid-flank. This is maintained even in TKD30560. There is also a difference in whorl shape between the two species ; rectangular versus suboval in whorl section. In respect of the small and slender shell, M. (M.) pacifica is somewhat similar to M.(M.) camachoensis (Böse) (1923, p. 149, pl. 10, figs. 32-37) (see also Clark, 1965, p. 48, pl. 15, figs. 6, 8; pl. 18, fig. 8), from the Upper Albian (a unit correlatable with the Pawpaw Formation) of Mexico, but the tubercles of M. (M.) pacifica are more numerous and disposed in rows at unequal intervals; those of the first row are coarser and extended upward to ribs. M.(M.) pacifica resembles M.(M.) oehlerti (Pervinquiere) (vide supra) in general appearance and especially in the disposition of the rows of tubercles. The former is char- acterized by its slender shell shape, with a shallower inter- 116 Tatsuro Matsumoto et al. whorl junction, suboval instead of subquadrate to rhom- boideal whorl section and on the average finer, denser and more numerous tubercles and riblets in comparison with the latter. Should the suggested dimorphism be warranted in each of the two species, the size difference at the adult stage would be distinctive. Klinger and Kennedy (1978) found in their South African material of M.(M.) oehlerti large variation in the number of tubercles. The number ranges from 15 to 28 per whorl with an exceptional 30; for the majority the range is from 18 to 24. This is conformable with our material of M. (M.) oehlerti. In the case of M. (M.) pacifica under investigation, the count- ed range is normally from 30 to 40 per whorl. The two species are thus separable on this point, although the range is fairly wide in each of them. However, TKD30560 mentioned above (with 50 tubercles per whorl) is rather extreme and it is better to call it tentatively M.(M.) aff. pacifica. With respect to numerous, densely set tubercles, M. (M.) miliaris (Pictet and Campiche, 1861) (p. 136 ; 1862, pl. 58, fig. 5) (see Renz, 1968, p. 88, pl. 18, fig. 10 for the reillustration of holotype) is somewhat similar to M. (M.) pacifica, but the rows of tubercles are nearly equidistant and the apical angle has been described as larger in that species. It is closely related to M. (M.) bergeri, as Spath (1937, p. 515) has already mentioned. M.(M.) miliaris normally occurs in the Upper Albian but ranges up to the Lower Cenomanian in England (see Wright and Kennedy, 1996, p. 333). Occurrence.—As for material. The type locality is in the middle part of the Member My3. This species occurs so far in the Lower Cenomanian of Hokkaido. Its true veritcal range and geographical distribution should be determined by further investigations. Acknowledgments For the material of this palaeontological study we are indebted to the cooperative field work conducted by W. Hashimoto and also by T.Nishida. We have been much enlightened by the results of previous palaeontological studies, especially those by Clark (1965), Klinger and Ken- nedy (1978), Atabekinan (1985) and Wright and Kennedy (1996), although our views may not be always agreeable with them. Naoko Egashira and Seiichi Toshimitsu helped us in photography and Kazuko Mori assisted us in preparing the manuscript. Appendix Locality guide for selected Cretaceous fossils of the Soeu- shinai area TATSURO MATSUMOTO and TAMIO NISHIDA‘ ‘Faculty of Culture and Education, Saga University, Saga 840-8502, Japan The localities of the Cretaceous fossils in the Soeushinai area and the lists of identified species (mainly Mollusca and Foraminifera) have been indicated in a number of route maps and tables in the papers by Nishida et al. (1992, 1993, 1996, 1997, 1998a, b). These papers are written in Japanese and the maps are too numerous. Hence, two comprehensive maps (Figures6 and 7) are presented here. They are compiled from some of the previous maps with necessary modifications. The specimens of Mariella species with register numbers in the descriptions and a few unregistered ones are indicated in the maps. Moreover, the maps con- tain localities of selected mid-Cretaceous guide species which are particularly important for interregional correlation. The geology is outlined in the maps. A thick broken line is a fault and a dotted line is a boundary of lithostratigraphic units. The Lower Yezo and Middle Yezo Subgroups are abbreviated to Ly and My. Myl, My2, My3 and so on are successive members of My; T is the Tertiary (mainly Miocene); Q is a leucocratic intrusive body. A megafossil locality is indicated by a small solid circle (in situ) or by a cross mark (fallen or transported nodule). Notes are briefly given below in accordance with the investigated routes, of which (1)-(3) are shown in Figure 6 and (4)-(10) in Figure 7. (1) Main course of the River Sounnai (part) (upstream). —R887 (a nodule derived probably from the upper part of Ly): Hysteroceras orbignyi (Spath), Pseudohelicoceras sp. etc. R880 (nodules in mudstone in the upper part of My1): Mortoniceras (Deiradoceras) sp., etc. R34 (mudstone alter- nated with sandstone, lower part of My2): M. (Durnovarites ) cf. subquadratum Spath etc. R803 (laminated mudstone and sandstone, upper part of My2): Mariella bergeri (Bron- gniart), Mortoniceras (M.) cf. minor Spath. R813 (ditto): M. bergeri, Bhimaites kawai Matsumoto and Egashira. The above faunules at four levels are correlated with successive zones of the Upper Albian. (2) East Suribachi-zawa (E in Figure 6).—R525 (laminated mudstone in the upper part of Member My2): Bhimaites cf. kawai and Inoceramus n. sp. (small, nearly equivalve, finely ornamented species, probably identical with the late Albian species from Mont Risou illustrated in Gale et al., 1996, figs. 21f, j; 31g). R520 (nodules derived from the basal part of My3): Mariella aff. bergeri (to be described in Part 2), Graysonites adkinsi Young, Stoliczkaia (Lamnayella) san- ctaecatherinae Wright and Kennedy etc. R518 (nodules from the lower part of My3): Mariella oehlerti, M. dorsetensis, M. cf. pacifica etc. R515 (mudstone in the lower part of My3): Graysonites sp. (3) Suribachi-zawa (S in Figure 6 and branch rivulets) (upstream).—R875 (a nodule derived from My3): Mariella miliaris (Pictet and Campiche) (to be described in Part 2). AI81001 (nodule from My3) and R543 (nodules in mudstone of My3) : M. oehlerti etc. R575 (ditto): M. dorsetensis, M. oe- hlerti, Graysonites cf. adkinsis (nearby derived nodule). Inoceramus aff. reachensis Etheridge. R534 (nodules in laminated sandstone and mudstone of My2): Inoceramus n. sp. (same as sp. at R525), Mortoniceras cf. minor etc. R433 and IA81007 (nodules from My3): M. dorsetensis, Stoliczkaia (Lamnayella) cf. sanctaecatherinae etc. R438 (nodules from My3): M. dorsetensis etc. R471 (mudstone of My3): Inoceramus aff. reachensis. R449 (nodule from My3 ?): M. cf. carrancoi (Böse) (to be described in Part 2). R456 (nod- Mariella from Hokkaido—Part 1 117 dis „433, )07 ART coy ™~s~ [N AI 8100 pet | 875 | BON À = \ = 34 , SOUNNA IR. \My2: \ A Figure 6. Route map of the Suribachi-zawa and part of the Sounnai River, showing localities of Mariella and selected guide species (compiled from Nishida et al., 1996, figs. 3-5 and 8 and also Nishida et al., 1997, figs. 1, 2). See text for the marks and abbreviations. specimens. Some of the numbered localities with prefix Al are referred to TKD Many others are concerned with the main material of this study. They should have the prefix R, which is omitted in this and the other map for brevity. Note that prefix Al is not used in the original label of TKD and in the main text of this paper. ule in sandy siltstone of My3): M. dorsetensis, Stoliczkaia (Lamnayella) cf. amanoi Matsumoto and Inoma. R460 (nod- ule in mudstone of My3): M. oehlerti, Graysonites cf. adkinsi. R407 (nodule from My3): M. cf. pacifica. (4) NW branch rivulet of the Sanjussen-zawa.—Loc. YKC060824 (nodule from My3): M. dorsetensis, M. oehlerti etc. (5) Upper reaches of the Kyoei-Sakin-zawa.—At two localities YKC591014 and YKC020619 Mariella oehlerti was collected in nodules from My3. Not far from these localities Graysonites wooldridgei was obtained in situ at loc. YKCO10618 and in a transported nodule at loc. YKC040808. Somewhat downstream from them at loc. KY768 S. (L.) sanctaecatherinae was obtained from a transported nodule. These localities are all in the area of MyS. Still further downstream at locs. YKC060918 and KY356 G. adkinsi was collected from transported nodules. The two localities suggest a small outcrop of My3 within an otherwise Tertiary area. (6) Eb’su-zawa and Hotei-zawa (EB, HT in Figure 7). —R557 and R560 (laminated mudstone and sandstone) : Inoceramus n.sp. (same as the one from R525). R567 (nodule from My3) : M. cf. oehlerti. R901 (nodule from My3) : Graysonites wooldridgei. R905 (nodule in mudstone of My3): M. pacifica, M. dorsetensis etc. R906 (ditto): M. pacifica, M. gallienii (Boule, Lemoine and Thevenin), S. (Lam- nayella) sanctaecatherinae. (7) Middle course of the R. Shumarinai and a branch rivulet Fukuroku-zawa (FR in Figure 7) (upstream).—R8003 (laminated mudstone and sandstone of My2): Bhimaites kawai, Inoceramus n. sp. (same at R525). AI71204 (nodule from My3): M. dorsetensis. KY350 [=R8054] (nodule in mudstone with sandy laminae of My3): S. (L.) sanctaecather- inae. Al Pi. P2, P4 (nodules from My3): M. aff. pacifica, M. oehlerti, M. pacifica. R926 (large nodule derived from Mys) : M. oehlerti etc. R917 (nodule from My3): M. oehlerti. R919 (nodule in mudstone of My3): M. oehlerti, Ostlingoceras cf. bechii (Sharpe), Inoceramus aff. reachensis etc. R930 (nod- ule from My3): M. oehlerti, I. aff. reachensis. R931 (nodule from My3): M. cf. oehlerti. 118 YKC060718-- Fe Tatsuro Matsumoto et al. 997..\ YKC050610---\ KY350 = (8054) 7380 N My4 à ©7300 \ \ \ YKCO10618.. \ YKCO40808 | "3003 \ \ \ YKC060918 KY356 KY768/ \ YKCS591014* | T Ne ZEEE SANJUSSEN -Z4 y 4 YKC060824 Figure 7. Route map of the area across the middle course of the Shumarinai River, showing localities of Mariella and selected guide species (compiled from Nishida et a/., 1996, fig. 7 ; Nishida et al., 1997, figs. 7,8; Nishida et al., 1998b, figs. 2-4 and 7). See text for the marks and abbreviations. Prefix KY or YKC to a locality number refers to Katsujo Yokoïs or Y.K.'s collections by their independent field work. Other numbers are as for Figure 6. Mariella from Hokkaido—Part 1 119 (8) Middle course of the Nakamata-zawa and its tributary Bishamon-zawa (BS in Figure 7) (upstream).—YKCO50610 (nodule derived from My3) : M. oehlerti. R997 (nodule from My3): S.(L.) sanctaecatherinae. R993 (nodule in mudstone of My3): M. oehlerti, M. pacifica, Graysonites sp., Zelandites cf. inflatus Matsumoto. R994 (nodule in mudstone of My3) : Inoceramus aff. reachensis. (9) Upper-middle course of the R. Shumarinai and a branch rivulet Fuku-no-sawa (FK in Figure 7) (upstream). —R949 (nodule from lower part of My5): Turrilites acutus Passy, Inoceramus pictus minus Matsumoto. R7380 (mud- stone in the middle part of My5): Inoceramus ginterensis Pergament. R7300 (sandy mudstone in the upper part of My5): Wellmanites japonicus Matsumoto, Takahashi and Sanada, Inoceramus cf. pennatulus Pergament etc. (10) Jyurou-zawa (JR in Figure 7) (upstream).—R7313 (nodule from My7): Vascoceras durandi (Thomas and Peron). YKC060718 (nodule from My7): Muramotoceras yezoense Matsumoto, /noceramus kamuy Matsumoto and Asai, Mytiloides subhercynicus (Seitz), etc. R7319 [=YKC010625] (huge nodules in mudstone of My7): Pter- opuzosia kawashitai Matsumoto. Based on the above species My7 is referable to the lower part of the Turonian. No species of the Turrilitidae has been found from My7. Being separated by a fault, mudstones with some beds of sandstone are exposed in the uppermost course of the Jyurou-zawa where ammonoids and inoceramids of the upper to middle Cenomanian have been collected at locs. R7320-7326, while turrilitids have yet to be searched for. We thank A. Inoma, K. Yokoi and Y. Kawashita for their kind information about some localities of their independent collections. References cited Adkins, W.S., 1920 : The Weno and Pawpaw Formations of the Texas Comanchean. University of Texas Bulletin, no. 1856, p. 1-172, pls. 1-11. Atabekian, A.A., 1985: Turrilitids of the late Albian and Cenomanian of the southern part of the USSR. Acad- emy of Sciences of the USSR, Ministry of Geology of the USSR, Transactions, vol.14, p.1-112, pls. 1-34. (in Russian) Benavides-Cäceres, V.E., 1956: Cretaceous System in northern Peru. Bulletin of the American Museum of Natural History, vol. 108, p. 353-494, pls. 31-66. Bose, E., 1923: Algunas faunas Cretacicas de Zacatecas, Durango y Guerrero. Instituto Geolögico de Mexico, Boletin, no. 42, p. 1-219, pls. 1-19. Boule, M., Lemoine, P. and Thévenin, A. 1907: Cé- phalopode cretaces des environs de Diégo-Suarez. Annales de Paléontologie, vol. 2, p. 1-58, pls. 1-8. Breistroffer, M., 1953: L'évolution des Turrilitides albiens et cenomaniens. Comptes Rendus Hebdomadaires des Sciences de l'Académie des Sciences, vol. 237, p. 1349-1351. Brongniart, A., 1822: In, Cuvier, G. and Brongniart, A. Description géologique des environs de Paris, 428 p., 9 pls. Paris. Clark, D. L., 1965 : Heteromorph ammonoids from the Albian and Cenomanian of Texas and adjacent areas. Geo- logical Society of America Memoir, vol. 95, p. 1-99, pls. 1-24. Collignon, M., 1929 : Paléontologie de Madagascar, xv. Les cephalopodes du Cénomanien pyriteux de Diego-Suar- ez. Annales de Paléontologie, vol. 18, p. 1-50, pls. 1-2. Collignon, M., 1964: Atlas des fossiles caracteristiques de Madagascar (Ammonites). Fascicle 11 (Cenomanien). Service Geologique. Tananarive, p.1-152, pls. 318- 375. Förster, R., 1975: Die geologische Entwicklung von Süd- Mozambique seit der Unterkreide und die Ammoniten- Fauna von Unterkreide und Cenoman. Geologisches Jahrbuch, Reihe B, vol. 12, p. 1-324, pls. 1-17. Gale, A.S., Kennedy, W.J., Burnett, J. A. Caron, M. and Kidd, B. E., 1996: The late Albian to Early Cenomanian succession at Mont Risou near Rosans (Hautes-Alpes, SE France); an integrated study (ammonites, inocer- amids, planktonic formainifera, nannofossils, oxygen and carbon isotopes). Cretaceous Research, vol. 17, p. 515-606. Hashimoto, W., Nagao, S. and Kanno, S., 1965 : Soeushinai. Explanatory Text of the Geological Map of Japan, scale 1: 50,000, p. 1-92, quadrangle map. Geological Survey of Hokkaido. 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J., 1996: The Ammonoidea of the Lower Chalk, part5. Monograph of the Palaeontographical Society, London, p. 320-403, pls. 95-124. (Publication no. 601, part of vol. 50 for 1996) Yabe, H., 1904: Cretaceous Cephalopoda from the Hok- kaido, part 2. Journal of the College of Science, Impe- rial University of Tokyo, vol. 20, p. 1-45, pls. 1-6. Young, K. and Powell, J. D., 1978: Late Albian —Turonian correlation in Texas and Mexico. Annales du Museum d'Histoire Naturelle, Nice, vol. 4 (for 1976), xxv, p. 1-36, pls. 1-9. Paleontological Research, vol. 3, no. 2, pp. 121-136, 8 Figs., June 30, 1999 © by the Palaeontological Society of Japan A new crayfish Family (Decapoda: Astacida) from the Upper Jurassic of China, with a reinterpretation of other Chinese crayfish taxa ROD S. TAYLOR', FREDERICK R. SCHRAM' and SHEN YAN- BIN? ‘Institute for Systematics and Population Biology, University of Amsterdam, P.O. Box 94766, 1090 GT Amsterdam, The Netherlands “Nanjing Institute of Geology and Palaeontology, Academia Sinica 39 East Beijing Road, Nanjing 210008, The People’s Republic of China Received 14 October 1998 ; Revised manuscript accepted 15 April 1999 Abstract. The highly sporadic fossil record of freshwater crayfish is improved by the discovery of several new specimens from the Upper Jurassic Jehol Group of Liaoning Province, north-east China. As a result of work on this material, the Family Cricoidoscelosidae is erected to accommodate specimens possessing highly atypical features among the Infraorder Astacidea belonging to the new genus and species Cricoidoscelosus aethus. Furthermore, Astacus spinirostrius Imaizumi (1938) is synonymized with A. lincenti van Straelen (1928b) and is moved from the Family Astacidae to the family Cambaridae and to the new genus Palaeocambarus. Thus, a solution is suggested to the problematic biogeographic issue of the presence of the genus Astacus in a region presently occupied only by cambarid crayfish, a generic assignment that was made tentatively in the first place. In addition, new questions now arise with respect to the origins and early development of crayfish in the Asiatic region and perhaps even globally. Key words: Astacida, China, crayfish, palaeobiogeography Introduction Members of the decapod Infraorder Astacidea, commonly referred to in English by the vernacular term ‘crayfish’, are also known by many other common names worldwide : crawfish, paper-shell crabs, ecrevisse, yabbies, mud-bugs, flusskrebs, rak, ditch bugs and koonac are just some of these names. With over 500 species currently known, which occur indigenously in tremendous numbers on all continents with the exception of Africa, this is perhaps not surprising (Adegboye, 1981; Hobbs, 1988 ; Pitre, 1993). The evolutionary history of the Superfamily Astacoidea is currently the subject of some debate. The more traditional perspective, as suggested originally by Ortmann (1902, 1905), is that the crayfish as we know them today originated in a benthic marine environment similar to that occupied by the marine lobsters. From this ancestral stock emerged three major lines: the extinct Erymidae ; the relatively conserva- tive Nephropidae (ancestors of the modern true lobsters) ; and tne highly varied and widely dispersed Astacoidea and Parastacoidea, the ‘true crayfishes’, which then moved into the freshwaters of Laurasia and Gondwana as the result of two separate invasions. A more recent perspective, however, is that of Scholtz (1995) and Scholtz and Richter (1995), in which the freshwater crayfishes are more closely related to the Thalassinida and Meiura (Brachyura and Anomala) than to the Homarida (forming a monophyletic group they refer to as the Fracto- sternalia). They suggested that the worldwide distribution of freshwater crayfish is the result of a single invasion into freshwater during the Triassic onto the ‘supercontinent’ Pangaea, which then diversified into the groups Para- stacoidea (in Gondwana) and Astacoidea (in Laurasia) with the Late Mesozoic break-up of Pangaea. Despite their relatively long geologic history, the fossil record for the crayfish is not very well understood. Many of the recent references to fossil crayfish originate from the research group of Rodney Feldmann, including the descrip- tion of new taxa and/or redescription of previously described taxa (Feldmann, 1994 ; Feldmann et al., 1981) as well as such oddities as evidence of crayfish predation (Feldmann and May, 1991). Other sources of information on the palaeontological record for the Astacida include Rathbun (1926), van Straelen (1928a), Albrecht (1982, 1983) and Cope (1871). Much work has been done with respect to the global distribution patterns of the living Astacidea (e.g., Hobbs, 1988 ; Huxley, 1884; Ortmann, 1902), stemming largely from their wide use as an aquaculture crop; however, relatively 122 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin little has been done with respect to a comprehensive analy- sis of the fossil members of this group beyond strict taxon- omy. Among the more intriguing of fossil astacidans has been material from the Late Mesozoic of China. We will here build on the original works of van Straelen (1928b) and Imaizumi (1938) and their respective description of two species of fossil freshwater crayfish, Astacus licenti and A. spinirostrius, from the Upper Jurassic (Jehol Group) of Liao- ning Province, north-east China. This reassessment is prompted by the discovery of several new, well-preserved specimens from the region. Collection localities New material described in this paper was obtained from outcrops in Dawangzhangzi and Daxinfazi villages, Ling-yuan County, Liaoning Province, probably belonging to the Yixian Formation of the Upper Jurassic Jehol Group (Figure 1). While the general collection regions are known, their actual locations are vague because local farmers, who sell the specimens they collect to visiting academics, refuse to 1 119°1S°E vt ® Daxinfanzi Xiaochengzi ff \ 4 N Linyuan À An E eZ, Ershilipu == 4 A \ Er at Songzhangzi WARE Y 4 nt Dawengzhangzi Wangjiazi an 10 / / Wafandian e L ie reveal their exact locations (one of which has actually been buried by the Chinese government to avoid poaching !). Enough is known of the geology of the region, however, to allow determination of the formations from which they have been collected. Systematic Paleontology Order Decapoda Infraorder Astacida Superfamily Astacoidea Family Cambaridae Subfamily Cambarinae Genus Palaeocambarus gen. nov. Type species.—Astacus licenti van Straelen, 1928b Diagnosis.—Entire dorsal surface of cuticle covered with fine granulations. Rostrum with basal lateral spines. Elon- gate, bladelike scaphocerite. Chela of first pereiopod long and narrow with extensive pitting and spination. No hooks visible on ischia. Pleura large and rounded on abdominal segments 2-5, 2nd pleuron being largest. Pleopods elon- I BR 5 10 km — | —| T Figure 1. SF Locality map showing fossil crayfish collection localities near Daxinfanzi and Dawengzhangzi (stars). A new crayfish family (Decapoda: Astacida) 12 gate and blade-like, with no specialization on first. Telson subrectangular with pair of large lateral spines and rounded distal margin. Etymology.—The name of the genus is formed from ‘palaeo’, meaning ‘ancient’, in combination with ‘Cambarus’, reflecting the new placement of its sole retained species in the Family Cambaridae. Palaeocambarus licenti (van Straelen), 1928b Figures 2, 4-6 Astacus licenti Van Straelen, 1928b, p. 133-135, figs. 1,2; Ima- izumi, 1938, p. 176, pl. 23, figs. 1, 2, 4, 5, 6,11; Hamada and ltoigawa, 1983, p. 74, PI. 3, fig. 6; Hobbs, 1988, p. 73. Astacus spinirostrius Imaizumi, 1938, p. 176-177, pl. 23, figs. 9, 10, 12, 13, pl. 22, fig. 1; Hobbs, 1988, p. 73. Diagnosis.—As for genus. Emendation to Description.—Rostrum elongate and tri- angular with smooth margins. Approximately twice as long as wide at base (largest observed being 15 mm long and 7 mm wide at base). Length roughly one-third that of ce- phalothorax. A pair of anteriorly directed spines near base of rostrum that extend to approximately one-third rostrum’s length (NIGP 126338). One specimen (NIGP 126342) shows two rows of small tubercles on ventral surface of rostrum. A single specimen (NIGP 126338) possesses small mid-dorsal spine at base of rostrum (Figures 4b, 4c). Carapace developed, covers thorax completely. It extends partially over first pleomere mid-dorsally and com- pletely so laterally due to slight postero-lateral enlargement (Figures 5a, 6a); simply decorated, possessing only a sinusoidal cervical groove (concave medially, curved convex- ly mid-laterally, concave again at lateral carapace margin) as well as a pair of short branchiocardic grooves that extend posteriorly from medial cervical groove (NIGP 126353, 126338 : Figure 4c). A single specimen (NIGP 126338) pos- sesses a pair of well-developed gastric spines (Figure 4c). A slight ridge along lateral and posterior edges, but not evident along anterior margin. Optic notch well developed ; adjacent anterolateral margin gently rounded (Figure 6a). Entire carapace surface with granulated texture, several small spines/protrusions situated near cervical groove and around anterolateral region of carapace (NIGP 126338, 126353). Antennules biflagellate, with medial flagellum larger than lateral flagellum. Peduncle not fully preserved on any specimens, although several specimens possess some peduncular segments. NIGP 126338 shows distal segment only, which is subrectangular in shape, slightly longer than wide, has rounded edges and is very small (less than 1 cm’). NIGP 126346 with two distalmost segments, in shape with rounded edges and similar size dimensions. Middle seg- ment noticeably more square than distalmost segment but equal in size. Distalmost segment similar in shape to others mentioned but with slight anterior projection on outer margin, possibly remains of small spine. Second segment approxi- mately twice as wide as distal segment, suggesting it may be portion of basal segment, which is typically considerably Ww Figure 2. A reconstruction of Palaeocambarus licenti in dorsal view. Scale bar equals 1 cm. larger than the other two antennular peduncle segments in recent crayfish. Antennular flagellae exceed 10cm in length (Figures 4b, c, 5a, 6a). Antennae each possess a single flagellum that is consid- erably longer than those of antennules (NIGP 126339 possess- es a flagellum ~60mm long, almost equal to total body length). Distal segments of peduncle relatively clear, but proximal peduncle arrangement difficult to interpret due to their frequently being overlapped by other structures such as antennal scales or rostrum. Distalmost segment rectangular in shape with concave proximal margin, long axis along length of antennae, and shows dimensions of approximately 3mm width by 4mm length. Adjacent segment similar in 124 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin Figure 3. A reconstruction of Cricoidoscelosus aethus in lateral view. Scale bar equals 1 cm. shape and size but lacks curved proximal edge. Middle segment rectangular in shape and similar in length to two distalmost segments, approximately 2/3 as wide as long; attached laterally to basis, which is short (approximately 2 mm) and wide (4mm) and possesses an arcuate proximal margin. Coxa rectangular in shape with slightly convexly curved posterior margin, slightly less wide than basis and possesses medial anterior projection, which ‘fills’ the poste- rior groove in basis (NIGP 126338 ; Figures 4c, 6a). Well-developed, blade-shaped scaphocerites extend from lateral half of each antennal basis. They reach maximum length of 15 mm, are setose along lateral margins (only setal bases, not setae themselves, preserved). One specimen (NIGP 126343) possesses small, medially directed process at anterior end of scaphocerite (Figures 4a, 4c, 5a, 6a). Eyes located near base of scaphocerites, always some- what deformed but were probably round or slightly ovoid and approximately 2mm wide. They were probably closely associated with body, with short eyestalks of 1-2 mm, are always found superimposed over rostrum and/or antennal peduncle (i.e., NIGP 126342). Prominent epistome, close to 10 mm in width, visible on ventrally preserved specimens suggesting it was heavily sclerotized in life (as seen with recent crayfish). It possess- es an arched v-like shape and is directed anteriorly. Medial process present near the anterior end, with two small longitu- dinally arranged pits. Anteriormost end possesses forward- directed process, approximately one-quarter width of labrum and_ trapezoidal in shape, wider edge anteriormost (NIGP 126342 : Figure 6c). Some dorsoventrally oriented specimens show details of well-developed gastric mill, triangular in shape, directed posteriorly and found immediately behind labrum (NIGP 126342); made up of two sets of very small, serially arranged peg-like teeth in slightly inwardly curved rows, approximately 16 teeth per element. No median tooth present. Moulds of paired circular gastroliths, up to 7 mm in width, prominent in several specimens: in NIGP 126338 and 126353, one has rounded convex surface while other possesses an outer depressed ridge with raised circular region (Figures 4c, 5a, 6c). Elements of first and second maxillipedes preserved on some specimens ; however, they are impossible to interpret with any certainty due to being damaged and/or obscured by anterior structures such as carapace, 3rd maxillipede and ist thoracomere. Third maxillipede possesses large is- chium, up to 10 mm in length and 3 mm in width. Extensive crista dentata found along ischial inner margin. Merus is small, approximately 2 mm long and 4 mm wide and ovoid in shape. Carpus slightly less in width than merus and is rectangular in shape. Propodus rectangular in shape and approximately 2mm by 4mm. Dactyl slightly smaller than preceding segments, approximately 1.5 mm by 3mm, and elongate with pointed distal end (NIGP 126338 ; Figures 4b, 6a). Pereiopods 1 to 5 large and well developed. Pereiopod 1 considerably larger than others, propodus and dactylus modified to form large claw (heavily decorated with spines and pits, especially medially), may exceed 40 mm in total length. Carpus reaches maximum length of approximately 10 mm, is rectangular (almost square in some specimens) in shape and usually narrows slightly at proximal end. Merus A new crayfish family (Decapoda: Astacida) Nee aE ER? 2 ne PE à TERN 2 Figure 4. A. Lateral view of incomplete specimen (NIGP 126339) of Palaeocambarus licenti (with Lycopteran fish) (An=antenna, P=pereiopods, R=rostrum). Scale bar—2 cm. B. Close-up of rostrum, distal end of 3rd maxillipede and antennules of specimen of P. licenti (NIGP 126338) (A — antennule, M=third maxillipede, R=rostrum, Rs=rostral spine) «5.4. C. Anterior end of incomplete specimen of P. licenti (NIGP 126338) (AnP=antennal peduncle, C=cervical groove, G=gastrolith, R=rostrum, S=scaphocerite). Scale bar=2 cm. 126 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin Bia ae é A à L ; Figure 5. A. dorsal view of complete specimen (NIGP 126353) of Palaeocambarus licenti (with incomplete chelipede from another specimen) (A1=first abdominal segment, A6=sixth abdominal segment, G=gastrolith). Scale bar=2cm. B. close-up of tailfan of the same specimen (A6=sixth abdominal segment, E=uropodal endopod, Ex=uropodal exopod, T=telson, Ts=telson spines). Scale bar=2 cm. A new crayfish family (Decapoda: Astacida) Figure 6. A. Specimen of P. licenti from Imaizumi’s material (=“Astacus spinirostrius” : IGP 57272) (Al=first abdominal segment, A6=sixth abdominal segment, P=pereiopods, R=rostrum, S=scaphocerite). Scale bar=2 cm. B. Close-up of pleopods of IGP 57272, anterior to bottom (A2=second abdominal segment, PL1=first pleopod). «5.0. C. Ventral view of anterior end of specimen of P. licenti (NIGP 126342) (e=epistome, GT = gastric teeth). «6.4. 128 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin is elongate and approximately one-half the length of propodus (up to 7-8 mm); is rectangular in lateral view but triangular in dorsal view, by far the most common style of preservation seen in this material. Dactylus, propodus, carpus and merus decorated with large spine-like process- es, most commonly so on dactyl and propodus. Those on carpus and merus largest, reaching almost 1mm in width at base (NIGP 126338). Ischium is small and roughly square in shape, showing no sign of hooks. Basis triangular in shape, with rounded proximal margin where it comes into contact with rectangular coxa (NIGP 126339 ; Figures 4a, 5a, 6a). Pereiopods 2 to 5 considerably smaller than pereiopod 1, developed as walking legs (as opposed to the chela of pereiopod 1). Coxa possesses lateral distal groove to accommodate basis, is slightly longer than basis (NIGP 126339, 126346). Basis concave distally, forming a groove where it contacts ischium, but is rounded proximally and slightly wider at its distal than proximal end. Ischium short (approximately 0.4 cm) and tapered slightly where it connects with basis. Merus elongate (approx. 1.5-2.0 cm) while car- pus considerably shorter (approx. 0.5 cm) and acts as ‘knee joint’ (NIGP 126339, 126354). In pereiopods 2 and 3, elon- gate (approx. 1.5 cm) propodus acts with dactylus to form small chelipede at distal end of pereiopod, much smaller than those of 1st pereiopods (NIGP 126339) (Figures 4a, 6a). Abdomen elongate and rectangular in dorsal view, narrow- ing slightly distally. Segment length consistent over first 4 segments with largest specimen seen (NIGP 126353) showing lengths of 0.6mm. Fifth and sixth segments somewhat shorter with lengths of 0.5 and 0.45 mm, respectively (Figure 5a). Pleura rounded and well-developed on tergites 2-5, 2nd expanded slightly posteriorly and thus larger than others. No pleurae seen on tergite 1, pleurae on tergite 6 greatly reduced to accommodate uropods. Sternites reduced in width distally, but sternite/tergite size ratio (sternites being approximately 70 percent as wide as tergites) remains fairly consistent along abdomen. Sternal bars 'bar-belled’ in shape, narrow medially but several times wider distally ; this results in ovoid gaps, pointed laterally, where arthrodial membranes would have been located in life (NIGP 126353, 126346 ; Figure 5a). Circular/ovoid scars evident near antero-lateral regions of sternites. Pleopods elongate, blade-like in shape. There is no evidence of styliform first pleopod in material collected for this study (but see Discussion). Tailfan very well developed (Figure 5b). Telson large and subrectangular with slightly convex anterior margin. Tapers distally, possesses straight lateral margins, with well-rounded setose distal margin, which is delineated by complete trans- verse suture. A pair of posteriorly directed spines located just posterior to transverse suture. Uropods are also large, with exopod slightly longer than endopod. Exopod possess- es diaresis, is setose along its rounded distal end and along posteriormost portion of lateral margin. Endopod also setose along distal margin (NIGP 126346, 126353). Etymology.—Van Straelen’s specific epithet /icenti is retained. Measurements.—Measurements (in mm) are given in Table 1. Types.—Van Straelen (1928b) indicated his ‘nearly com- plete’ specimen in PI. 1, Figure 1 as the type specimen for A. licenti. His material was housed at Hoang Ho Pai Ho Museum, Tientsin, China. Imaizumi’s (1938) material (Reg. Nos. 57254, 57267, 57271, 57272 and 57274) is stored in the Institute of Geology and Palaeontology (abbreviated here as IGP), Tohoku University, Sendai, Japan. Material examined.—New material used in this study includes NIGP (Nanjing Institute of Geology and Palaeontology) 126338-126339, 126341-4 and 126346- 126354. Several other uncatalogued specimens are cur- rently in the NIGP collections, some of which were photo- graphed for use in this study (owing to the difficulty in transporting the large slabs upon which these specimens are found or the inferior quality of preservation of several of these specimens). Specimens 57254,57267 and 57272 from the Institute of Geology and Palaeontology, Tohoku University, Sendai, Japan were also used in this study. Occurrences.—The material used in the original descrip- tion of Astacus licenti was collected from an unspecified locality, representing Upper Jurassic Lycoptera/Ephemerop- sis shales, south-west of Shenyang City, Liaoning Province, China. Astacus spinirostrius was described from material collected from equivalent Lycoptera beds in Lingyuan County, Liaoning. The newest material was collected from beds believed to be of equivalent age in Daxinfanzi and Dawangzhangzi villages, Lingyuan County. This locality cannot be described with any greater detail, as these (as well as other) specimens were bought by the Nanjing Institute of Geology and Palaeontology from local farmers, who refused to divulge the exact locations. Remarks.—The gastric teeth found in this taxon are atypical when compared to those of other crayfish and other decapods in general. Icely and Nott (1992) and Felgenhauer and Abele (1989) have described in considerable detail the foregut morphology as found in various decapod taxa. The physical make-up of the decapod foregut and the gastric mill in particular are particularly complex systems, made up of up to 60 ossicles of varying size and shape. While we are unable to determine the nature of these ossicles in our fossils, we are able to see evidence of the gastric mill elements. It would probably be best described as ‘relatively primitive’, based on the classification scheme provided by Felgenhauer and Abele (1989). In their 3-tiered system, the most primitive ‘type |’ foregut possesses heavily sclerotized lateral teeth that work in association with the median tooth to filter and/or masticate food. In their ‘type Il’ foregut, the gastric mill is “completely absent” : the median tooth is never present, while the lateral teeth may be replaced by setose lateral ridges. The gastric mill found in P. /icenti appears to be an intermediate between these two forms: it possesses no medial tooth, but the paired lateral teeth are present and well developed. However, the system suggested by Felgenhauer and Abele (1989) is derived from studies of the ‘lower Decapoda’ (includ- ing the suborders Dendrobranchiata and Pleocyemata). Recent crayfish are known to possess both a single medial and paired lateral gastric teeth (e.g., Holdich and Reeve, 1988). 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AUS] ‘d =: m =} moh m m + + 7: =i = = Pr =F ah =. m m ja} ie} A Sy o ; 4 oO En el ee a ae Q > o fe) =] 5 3 3 @ © 5 5 ® @ x x 3 3 S = D =D = Sr D D = = 3 a a x x 5 5 a a 3 3 © 3 D = om ® = = = ® a a © © © Q ke] ke} 5 5 s — = 8 Be an ee wur ® [om ® ® à a =} + 3 3 a 2 St = = a) a ia Q = ® a a ® ® = st 2 = = < = = o 2 a =’ 5 & Ba men ee RAT Se ee ae GS 5 genen ae a eee See = en de 3 Q © = a >; + =F ct =F zs = 3 fe = Er =) ‘SF (= oO on © © =} =| a ses ‘snyjae ‘D pue 1Uad!/ ‘4 10} (WU Ul) SjuaWAINSeaWW ;eoIBojOYdIoy| ‘L aIqeL 130 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin possibly reflecting an intermediate state between the three- toothed array seen in recent crayfish and the reduced system seen in many of the ‘lower’ Decapoda. Family Cricoidoscelosidae fam. nov. Type Genus.—Cricoidoscelosus gen. nov. Diagnosis.—Rostrum with rounded base and lateral spines. Bladelike scaphocerite. Well-developed first chelae. No ischial hooks on pereiopods. Rounded pleurae. First pleopod styliform in males, remainder annulate. Large tel- son with large lateral spines. Etymology.—The name of this family is derived from the Greek words ‘cricoides’ (meaning ‘annular’) and ‘scelos’ (meaning ‘leg’. Cricoidoscelosus gen. nov. Type species.—Cricoidoscelosus aethus sp. nov. Diagnosis.—Rostrum with rounded base and curved lateral spines. Scaphocerite long, bladelike. Chela of first pe- reiopod well developed, highly nodose. No ischial hooks evident. Rounded pleura on abdominal segments 2-5, the 2nd being the largest. Pleopods annulate, with the first specialized as styliform copulatory appendages in males. Female with paired circular ‘pores’ on 3rd abdominal sternite. Telson with large lateral spines and rounded distal margin. Etymology.—Same as for the family. Cricoidoscelosus aethus sp. nov. Figures 3, 7-8 Diagnosis.—Same as for genus. Description.—Rostrum elongate, approximately 9mm in length, narrow and triangular along its anterior two-thirds ; posterior third roughly circular in shape. Pair of short, Curved spines projects anterolaterally from anterior end of basal portion of rostrum (NIGP 126337 : Figure 7a, b). Carapace heavily sclerotized, covers thorax completely and partially covers first abdominal segment dorsally, almost completely covers first abdominal segment ventrolaterally due to enlargement (NIGP 126340). Sinusoidal cervical groove present, no other carapace grooves visible. Slight ridge visible along carapace dorsal and lateral margin. Optic notch well developed. Surface of carapace granulate with small spines near anteriormost end of carapace. Antennules are biflagellate, medial flagellum slightly longer than outer flagellum. Peduncles not completely preserved on any specimens: two distalmost peduncular segments rectangular, approximately 1.5 mm by 1.5 mm. Other pedun- cular segments are unclear (NIGP 126337, 126340). Antennae each with single elongate flagellum, longest seen 5.1cm in length (NIGP 126337). No specimens with complete antennal peduncules, but some segments are preserved. Distalmost segment rectangular in shape, approximately 4 mm°, with proximal margin concave. Adja- cent segment similar in shape and size but with lateral side extended to approximately 5mm long. Proximalmost seg- ment rectangular and elongate, approximately 4mm wide and 2mm long. Coxa and basis unclear. Antennal gland present. Scaphocerites elongate, up to 10mm in length: outer margin straight, inner margin slightly curved. Setal bases present along outer margin (NIGP 126337). Eyes present but not preserved intact: remains found lateral to base of scaphocerites. No peduncle preserved (NIGP 126337). Epistome v-shaped and directed anteriorly, with anterior process as described for P. licenti. However, medial proc- ess possesses no pits and is anteriorly directed (NIGP 126337). Gastric structures not evident. 3rd maxillipede well developed, reaching anteriorly to antennal peduncles. Ischium large, 8mm in length and 3 mm in width, with cristata dentata along inner margin. Merus ovoid, 2mm wide and 4mm long. Remaining ele- ments unclear (NIGP 126337). Pereiopod 1 with propodus and dactylus modified to form large claw (up to 25 mm long), decorated with spines and pits distally and medially. Carpus rectangular in shape, up to 7 mm wide and 5mm long. Merus large and elongate, exceeding 10 mm. Ischium square, lacking hooks. Basis triangular, gently rounded at contact with rectangular coxa (NIGP 126337, 126355). Pereiopods 2 to 5reduced, developed as walking legs with small distal chelae on 2-3 formed from dactyl and propodus. Coxa slightly longer than basis, 2-3mm in length. Basis with concave interface with ischium, which is approximately 5mm long and slightly broader distally. Merus rectangular, may exceed 10mm in length; carpus also elongate and rectangular, up to 10 mm in length (NIGP 126337, 126355). Abdomen elongate and rectangular, slightly wider at its anterior. Segment length regular for first 4 segments, with last two slightly shorter in length. Abdominal pleura well developed, posterolaterally oriented. Pleurae absent on tergite 1, reduced on tergite 6 to accommodate uropods. Sternites developed across tergite ventral surface, pointed laterally (NIGP 126337, 126345, 126355). Pleopod 1 visible in one laterally oriented specimen (NIGP 126355), developed as elongate, styliform appendage, prob- ably utilized as a copulatory structure (as in Astacidae and Cambaridae). Distalmost portion only preserved: approxi- mately 10 mm in length and 3 mm wide at base, tapering to slightly less than 2mm wide distally. It is simple and undecorated (Figures 8a-b). Telson large and subrectangular with convex anterior margin; tapers distally, has rounded setose distal margin with complete transverse suture. Pair of posteriorly directed spines adjacent to transverse suture, one on either side of telson. Uropods large, exopod slightly longer than endopod. Exopod and endopod with setose distal margins; exopod also with setose posterolateral margin and diaresis (NIGP 126337, 126345). Etymology.—The species name is derived from the Greek word ‘aethus’ (meaning ‘unusual’. Type.—Holotype NIGP 126337, paratype NIGP 126355 ; housed at the Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing, the People’s A new crayfish family (Decapoda: Astacida) 131 Figure 7. A. Ventral view of Cricoidoscelosus aethus holotype (NIGP 126337) (A=antennules, An=antenna, P=pereiopods, S=scaphocerite). Scale bar=2cm. B. Close-up of ventral view of C. aethus (NIGP 126337) (AnP=antennal peduncle, R=rostrum, Rs=rostral spines, S=scaphocerite). «4.9. C. Close-up of ventral view of abdomen with pleopods of specimen of C. aethus (NIGP 126345) (AS2= abdominal sternite 2, AS5 — abdominal sternite 5, PL = pleopods). x 5.4. 132 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin À a Yin ® Figure 8. A. Lateral view of Cricoidoscelosus aethus paratype (NIGP 126355) (A1=first abdominal segment, A6=sixth abdominal segment, An=antenna, P=pereiopods, Tn=tailfan. 0.64. B. Close-up of pleopods of the same specimen (PL=pleopods, PL1=first pleopod, Ex=uropodal exopod). x 4.1. A new crayfish family (Decapoda: Astacida) 133 Republic of China. Material examined.—NIGP 126337, 126340, 126345, 126355. Remarks.—Few specimens exist that can definitively be placed in this taxon from the several specimens in our collections. There is no doubt as to its distinct nature, however, due to its highly characteristic and unique pleopods that are fortunately preserved in several orienta- tions. Discussion.—A reconstruction of P. licenti is provided in Figure 2 while C. aethus is shown reconstructed in Figure 3. Astacus licenti was first described by van Straelen (1928b), based on 3 specimens collected from an unspecified “point south-west of Moukden, in Eastern Mongolia” (actually in north-east Liaoning Province, People’s Republic of China). In this description, his assignment of this new species to the genus Astacus was “provisional... in the most extensive sense of the genus” (he felt, however, that it belonged “undoubtedly to the family of the Astacidae”) (van Straelen, 1928b). Imaizumi (1938) described a second species, Astacus spinirostrius, based on two new specimens collected from equivalent Lycoptera davidii beds from Niehhutzekow, near Lingyuan, China (three specimens of A. licenti were also collected at the same time from the region). In his paper, he discussed how both A. licenti and A. spinirostrius are in fact more similar (“particularly in the long slender chelipede and the rounded-off pleural plate”) to the fossil form Pseudoas- tacus than to the recent Cambaroides [then Astacus (Cam- baroides)| species in Asia (Imaizumi, 1938). Apparently there was, in the minds of both van Straelen and Imaizumi, considerable question as to the definitive generic assign- ments of these new fossil taxa. Hobbs (1988) discussed how the chelipedes of A. licenti are in fact more similar to the eastern American cambarid genus Procambarus than to either Astacus or Cambaroides ; he also suggested that the chelae and the abdominal pleurae of A. licenti more closely resemble those of the primitive cambarine genus Procambarus than either of the Eurasian genera. These issues, coupled with the discrep- ancies between the early descriptions and the nature of the fossils examined for this study, were keys that forced us to rethink the taxonomic affinities of this species. Unfortunately, the key characters used to separate the Astacidae from the Cambaridae (Hobbs, 1974,1989) are impossible to observe from our material. For example, cyclic dimorphism (present in the Cambaridae, absent in the Astacidae) is impossible to identify in these fossils ; and the detailed nature of the 1st pleopod (subtubular distally and lacking ornamentation in the Astacidae, with shallow groove or deep sperm groove and with terminal ornamentation in the Cambaridae) is also not evident in the specimens described nere. Our decision to move this taxon from the Family Astacidae to the Family Cambaridae is, then, based on less specific features, such as the absence of astacid crayfish from (and presence of cambarid genera in) the Asian region. The shape of the chelae is another feature mentioned by previous authors (Imaizumi, 1938 ; Faxon, 1885) as suggest- ing alternative relationships for P.licenti: it has been compared to the chelae of the extinct Pseudastacus and to the recent genus Procambarus, presumed to be the most ‘primitive’ of the cambarid genera (Hobbs, 1988). While we can give no definitive answer to the question of what P. licenti may be most closely related to, we feel that these points warrant the movement of this species from the Family Astacidae to the Family Cambaridae. After examining the original plates of van Straelen (1928b) and Imaizumi (1938) and some of Imaizumi’s original material (IGP specimens 57272, 57254 and 57267, Tohoku University, Japan), we determined that several of the features proposed by Imaizumi as distinguishing characters between A. licenti and A. spinirostrius are in fact artifacts of preservation. For example, his ‘spines on the mid-dorsal line’ of the rostrum appear to be the pair of lateral spines found near the base of the rostrum but viewed from a slightly skewed angle, giving them the appearance of projecting from the middle of the rostrum. These spines are clearly located on the pos- terolateral region of the rostrum when dorsally preserved specimens are examined, something Imaizumi lacked. The same is true for such features as the shape of the pleural plates and the relative lengths of the exo- and endopods of the uropods : these features appear to lose their usefulness in defining separate taxa when several specimens preserved in multiple orientations are examined. Imaizumi (1938) also suggested the presence of gastric spines as being a characteristic of A. licenti not shared with A. spinirostrius. This question of the presence/absence of a pair of gastric spines is one that must be addressed here, for several reasons. First, no gastric spines were noted with re-examination of the material described by Imaizumi, removing this character as a potential feature in distinguish- ing between the previously established taxa from this region. Secondly, a single specimen of the new material examined does possess a set of well-developed, anteriorly directed gastric spines (closely associated with several smaller spines and processes). This specimen is, however, far from com- plete with only the ‘head’, anteriormost carapace and first pereiopods preserved ; thus, it is impossible to Compare it with the other specimens with respect to either abdominal or appendage characters. Gastric spines aside, this specimen is largely identical to the other specimens of P. licenti examined, suggesting that these gastric spines may not be a species-specific character. They may instead represent a sex-specific character, but this cannot. be determined with- out a better understanding of other sex-specific differences within this species. Another possibility is that they may simply reflect a character that shows flexibility in expression and/or preservation and may vary from individual to individ- ual within a species, as seen in the Palaeozoic pygoce- phalomorphs (Schram, 1979). Such features would seem to provide no taxonomic information for this material. The question of sexual dimorphism is further complicated by the narrow range of morphological characters that exhibit a truly dimorphic state in the crayfish. Some dimorphic characters, such as the generally wider abdomen seen in females, are too general to be of any use in a study utilizing fossil specimens. Sexual dimorphism in the Cambaridae, for example, is characterized by several features : males exhibit 134 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin cyclic dimorphism with the presence of a sperm groove (and sometimes ornaments such as spines) on the distal portion of the first pleopod, while females possess a seminal recepta- cle between the 4th and 5th pereiopods. In addition, males possess hooks on at least one set of ischia. Sexual dimor- phism in the Astacidae is characterized by a lack of cyclic dimorphism and an unornamented subtubular first pleopod in the males, while the females lack a seminal receptacle (Hobbs, 1988). Such features are difficult if not impossible to determine with fossil material. Such dimorphic features, in general, present a problem with respect to our material. None of our specimens of P. licenti possesses a styliform first pleopod : whether this is due to its complete absence in this species, to our having no males in our material, or to this feature simply not being preserved is impossible to evaluate. None of our specimens appears to possess hooks on the ischia ; this may be due to our relative lack of males, as suggested earlier, or to the fact that few of our specimens possess well-preserved pe- reiopods. It is possible that perhaps those that we possess are female and thus would have not possessed these ischial hooks. However, two (IGP 57272,57254) of the specimens presented by Imaizumi (1938) do possess a pair of styliform first pleopods, whose distalmost segments are unfortunately the only parts preserved. Those of IGP 57272 are preserved laterally and are elongate, slightly curved anteriorly and tapered distally, being 5 mm in length and 1 mm wide at their widest point (Figures 6a, b). IGP Specimen 57254 shows only one of the pair of first pleopods, preserved in ventral view. It is 7 mm long and 1 mm wide, and is slightly laterally directed proximally. No other pleopods are visible on this specimen. These styliform pleopods suggest that this species belongs to either the Cambaridae or the Astacidae (both characterized by the presence of a styliform first pleopod in the males ; it is absent in the Parastacidae). We consider these specimens to be males of the species P. licenti, Supporting again a cambarid/astacid taxonomic position for this genus. Pleopods 2-6 of IGP 57272 are more ‘typical’ crayfish pleopods, being elongate and blade like, than the annulate pleopods possessed by C. aethus. The distinct annulate pleopods (2-6) of C. aethus are, we feel, sufficiently different from those seen in any other crayfish to warrant placing them in their own family. The presence of styliform first pleopods, however, is an indication that this taxon is related in some degree to at least one (if not both) of the northern hemisphere astacoidean families, Astacidae and Cambaridae. One phenomenon that is shared by specimens of both C. aethus (NIGP 126340) and P. licenti (NIGP 126338, 126346, 126353, 126354) is the presence of gastroliths. Those in P. licenti are preserved here as moulds of their actual state in recent animals (e.g., Lowrey, 1988), in which the ridged face is the attachment surface to the wall of the cardiac region of the foregut. This is presumed to be the natural state in our animals as well. These gastroliths are present in freshly molted animals and act as calcium storage packages to be reused in the recalcification of the exoskeleton after ecdysis. It is evident that our sample possesses both recently molted and fully calcified animals. This also is reflected in the general preservation of these animals, as most of the speci- mens with gastroliths appear to have been less heavily sclerotized than those without gastroliths. Ortmann [1902 ; 1905 (summarized in Hobbs, 1988)] made the first attempt to interpret the history of origin, diversification and dispersal for the crayfish, in a synthesis that has remained largely unchallenged until just recently. He suggested that the ancestors of the Potamobiidae (=Astacoidea) and Parastacidae lived in Sino-Australia (and possibly Antarctica) in the Lower Cretaceous, with Astacoides reaching Madagascar during the Middle Cretaceous via a Lemurian land-bridge. The Upper Cretaceous saw the splitting of eastern Asia and Australia, resulting in the differentiation of the Potamobiidae in eastern Asia (and then into western North America and Mexico) and the Parastacidae in Australia and Antarctica. In the Lower Tertiary, the genus Cambarus arose from Potamobius in Mexico, which then spread through eastern North America ; while the Parastacidae extended its range through much of South America and Australia, splitting into several genera in the process. During and since the Upper Tertiary, the Potamobiidae moved into western Asia and Europe, with the Parastacidae remaining in South America, Australia and New Zealand. Following Ortmann’s reasoning, the ancestor to the crayfish that we recognize today is believed to have originated in a benthic environment similar to that occupied by the modern marine lobsters. From this ancestral stock, three major lines emerged : the extinct Erymidae ; the rela- tively conservative Nephropidae (ancestors of the modern true lobsters); and the highly varied and widely dispersed Astacoidea and Parastacoidea, the true crayfishes. More recently, however, Scholtz (1995) and Scholtz and Richter (1995) have proposed a closer relationship between the Astacida and the Thalassinida and Meiura than between the Astacida and Homarida. This suggestion is based on phylogenetic systematic studies and a far better understand- ing of the fossil record for this group. Their research suggests that many of the morphological similarities once cited as uniting the Astacida and the Homarida are in fact plesiomorphic characters, with no true synapomorphies join- ing these two taxa. Instead, their phylogenetic analysis revealed two characters that support their taxon Fractoster- nalia (including the Astacida, Thalassinida, Anomala and Brachyura) : a movable last thoracic sternite and a pattern of calcified pleural parts connecting thorax and pleon. Scholtz (1995) further goes on to suggest that the invasion into freshwater by the astacoidean ancestor occurred during the Triassic on the “supercontinent” Pangaea. This ancestor then developed into the Parastacidae in the Southern Hemisphere and the Astacidae and Cambaridae in the Northern Hemisphere with the break-up of the Pangaea landmass into Amero-Eurasia and Gondwana. Our fossil material, dating back to the Jurassic, confirms that crayfish did indeed move into freshwater considerably earlier than the time suggested by Ortmann. However, the features suggested by Scholtz and Richter (1995) as allying the Astacida with the Thalassinida instead of the Homarida are impossible to distinguish with the fossil material at hand. A new crayfish family (Decapoda: Astacida) 135 lt may perhaps be interesting to briefly comment on the rationales behind these two suggested evolutionary histories for the ‘crayfish’. Ortmann’s (1902, 1905) scheme was very much a product of his time, when distributions were believed by many [e.g., Darwin (1859, Chs. 12 and 13) and Wallace (1876 ; in Hallam, 1994)] to be strictly dispersalist in nature. By his reckoning, crayfish distributions enlarged slowly with the movement of these animals from one point to another and their subsequent establishment in these new territories. He explained problematic distributions, such as the appear- ance of crayfish on Madagascar, by the presumed presence of land bridges (in this case, a Lemurian land bridge). Scholtz’s considerations, on the other hand, are a product of our modern understanding of how plate tectonics or conti- nental drift (Wegener, 1924 ; in Hallam, 1994) and its associa- tion with vicariance biogeography (Croizat et al., 1974) allow for the presence of closely related organisms in isolated localities via the movement of land masses towards and away from each other with time (Hallam, 1994). Acknowledgments This research has been made possible by a grant (no. 750. 195.17) from ‘de Stichting Geologisch, Oceanografisch en Atmosferisch Onderzoek’, Nederlandse Organisatie voor Wetenschappelijk Onderzoek (the Foundation for Geological, Oceanographic and Atmospheric Research, the Dutch Orga- nization for Scientific Research). Thanks for support also go out to the Chinese Academy of Sciences (grant no. KZ951-B1-410-2). Special thanks also go out to Mark Joseph Grygier and Kei Mori for their asistance in obtaining material on loan from the Institute of Geology and Palaeontology, Tohoku University, Sendai, Japan, as well as to Dave O'Neill for his valuable assistance. References Adegboye, D., 1981: On the non-existence of an indigenous species of crayfish on the continent of Africa. In Goodman, C.R. ed., Freshwater Crayfish, Papers from the Fifth International Symposium on Freshwater Cray- fish. Davis, California, USA, p. 564-569. AVI Publish- ing Company, Inc., Westport, Connecticut, USA. Albrecht, H., 1982: On the origin of the Mediterranean crayfishes. Quaderni de/ Laboratorio di Tecnologia della Pesca, vol. 3, p. 355-362. Albrecht, H., 1983: Die Protastacidae n. fam., fossile Vorfah- ren der Flusskrebse ? Neues Jahrbuch für Geologie und Palaontologie, Monatshefte, vol. 1983, p. 5-15. Cope, E.D., 1871: On three extinct Astaci from the fresh- water territory of Idaho. 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Jr., 1988: Crayfish distribution, adaptive radia- tion and evolution. In, Holdich, D. M. and Lowery, R. S. eds., Freshwater Crayfish: Biology, Management and Exploitation. p. 52-82. Croom Helm, London. Hobbs, H. H. Jr., 1989: An illustrated checklist of the Amer- ican Crayfishes (Decapoda: Astacidae, Cambaridae, and Parastacidae). Smithsonian Contributions to Zool- ogy, no. 480, 236 pp. Holdich, D. M. and Reeve, |. D., 1988: Functional morphol- ogy and anatomy. In, Holdich, D. M. and Lowery, R. S., eds., Freshwater Crayfish: Biology, Management and Exploitation. p. 11-51. Croom Helm, London. Huxley, T.H., 1884: The Crayfish (an introduction to the study of zoology), 371pp. C.Kegan Paul and Co., London. Icely, J. D. and Nott, J. A., 1992: Digestion and absorption : digestive system and associated organs. In, Harrison, F. W. and Humes, A. G., eds, Harrison, F. W., series ed. Decapod Crustacea. Microscopic Anatomy of Inverte- brates vol.10. Wiley-Liss, Inc., New York. Imaizumi, R., 1938: Fossil crayfishes from Jehol. Science Reports of the Tohoku Imperial University, |ser. 2 Geology |, vol. 19, p. 173-178. Lowrey, R.S., 1988: Growth, moulting and reproduction. In, Holdich, D. M. and Lowery, R.S., eds. Freshwater Crayfish : Biology, Management and Exploitation. p. 83- 113. Croom Helm, London. Ortmann, A.E., 1902: The Geographical Distribution of Fresh Water Decapods and Its Bearing upon Ancient Geography. Proceedings of the American Philosophi- cal Society, vol. 41, p. 267-400. Ortmann, A. E., 1905: The Mutual Affinities of the Species of the Genus Cambarus, and Their Dispersal over the United States. Proceedings of the American Philo- 136 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin sophical Society, vol. 44, p. 91-136. Pitre, G., 1993: The Crayfish Book (the story of man and mudbugs starting in 25,000 B.C. and ending with the batch just put on to boil), 211p. University Press of Mississippi, Jackson. Rathbun, M.J., 1926: The fossil stalk-eyed Crustacea of the Pacific slope of North America. United States National Museum Bulletin, no. 138, 155 p. Scholtz, G., 1995: Ursprung und Evolution der Flußkrebse (Crustacea, Astacida). Sitzungsberichte der Gesell- schaft Naturforschender Freunde zu Berlin, vol. 34, p. 93-115. Scholtz, G. and Richter, S., 1995 : Phylogenetic systematics of the reptantian Decapoda (Crustacea, Malacostraca). Zoological Journal of the Linnean Society, vol. 113, p. 289-328. Schram, F.R., 1979: British Carboniferous Malacostraca. Fieldiana Geology, vol. 40, p. 1-129. Van Straelen, V., 1928a: Astacus edwardsi Munier-Chal- mas Ms., Astacidae du Paleocene de Sézanne (Cham- pagne). Bull. Soc. Géol. France, vol. 28, p. 3-6. Van Straelen, V., 1928b: On a fossil freshwater Crayfish from eastern Mongolia. Bulletin of the Geological Society of China, vol. 7, p. 133-138. 137 The Palaeontological Society of Japan has revitalized its journal. 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[Pele mA eet ns me ii Ps UT yo. sine #4 oo te inane ten) 4 ne ‘ort Auen I ER we RENTNER on Riso os ye er Hu SE “i DMP Alvar Riess Me oe a eel yey pant OES "2 Aue | fa OT 4—= oo SE I nt RE RER Op IE | er er rer er rer er ee nn en ‘ { J OS 2HAAÉEÆMÉESENT 2 D a 07, ERR HMWO BERS) 27 -vE 4 1999 F 9A 23 H-26 HISIIRF ZRH EL TITRES (EN: IRRE ER SRA: MoBDEE.: RRASRARABWEE SUG (Bad : 0888-56-0422 ; ey 03- 3815-7053 ; e-mail: kanazawa @ um.u-tokyo.ac.jp) ©2000 FES HEIL, 2000 4F 1A 28 H (&)} 1 À 80 À (A) ic) PRR AS) CHS NET. — HSE O À LA Zfié 0] D 1X 1999 Æ 12 H 3 A TS. OF 149RPFIS FHÉTERHH : 2000 F0 6 ARE) Uk, FÉRIÉS ETÉMRE] 2 à BER LAB ED EL, O1999 FRAC, 2001 FDS DES + KS CHSOPMÉRMOZENNRE SE LE, FR cf SILO A FH 7 RONDE GHEOPIZO RAE), Az A FHS 2AOM Ota Ei FEO TES RZOREHFH) PESTLE DS. 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TYFATTAMRASÉ MAIRTÆGOE + HEM KENNT MAAR oe BHARRMBRASH F9 1 + 2 7 t+ n b+ À El HR À S # KERVALHBRDOBEME 21-072 7RHRERÈMÉE (7472716) ONHBEHFHRERNE (WIRRANGER) CE 2, i oe, MAN AMEN EL Yu EE 1999 £6 A 2748 EN inl] 7113-8622 HAR AB IC HK AN BAIA 5-16-9 1999 Æ 6 A 3048 FE {J BOARS Se ey — A ean N E # 03—-5814—58 01 fi À A MA — KR - MEERE Paleontological Research & HEHE à MK — ft + EHER B34, #25 - N ET M <4 984-0011 Anke T Do Eh 8-45 2,500 F FERAL SH MER Se Att 022-288-5555 HR aR 03-3455-4415 Paleontological Research VolFSxNor2 June 30, 1999 CONTENTS Cheol-Soo Yun: Three Ordovician nautiloids from Jigunsan Formation of Korea .................. 65 Masamichi Takahashi, Peter R. Crane and Hisao Ando: Esgueiria futabensis sp. nov.; a new an- giosperm flower from the Upper Cretaceous (lower Coniacian) of northeastern Honshu, Japan 81 Jun-ichi Tazawa: Boreal-type brachiopod Yakovlevia from the Middle Permian of Japan .......... 88 Kazutaka Amano, Konstantin A. Lutaenko and Takashi Matsubara: Taxonomy and distribution of Macoma (Rexithaerus) (Bivalvia: Tellinidae) in the northwestern Pacific .. ...................... 95 Tatsuro Matsumoto, Akitoshi Inoma and Yoshitaro Kawashita : The turrilitid ammonoid Mariella from Hokkaido—Part1 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXV) . 106 Rod S. Taylor, Frederick R. Schram and Shen Yan-Bin: A new crayfish family (Decapoda: Astacida) from the Upper Jurassic of China, with a reinterpretation of other Chinese crayfish taxa ........ 121 Paleontological Research Formerly Transactions and Proceedings of the chee Palaeontological Society of Japan 4 N ISSN 1342-8144 Vol. 3 No.3 September 1999 The Palaeontological Society of Japan | Co-Editors Kazushige Tanabe and Tomoki Kase Language Editor Martin Janal (New York, USA) Associate Editors Jan Bergström (Swedish Museum of Natural History, Stockholm, Sweden), Alan G. Beu (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Satoru Chiba (Tohoku University, Sendai, Japan), Yoichi Ezaki (Osaka City University, Osaka, Japan), James C. Ingle, Jr. (Stanford University, Stanford, USA), Kunio Kaiho (Tohoku University, Sendai, Japan), Susan M. Kidwell (University of Chicago, Chicago, USA), Hiroshi Kitazato (Shizuoka University, Shizuoka, Japan), Naoki Kohno (National Science Museum, Tokyo, Japan), Neil H. Landman (Amemican Museum of Natural History, New York, USA), Haruyoshi Maeda (Kyoto University, Kyoto, Japan), Atsushi Matsuoka (Niigata University, Niigata, Japan), Rihito Morita (Natural History Museum and Institute, Chiba, Japan), Harufumi Nishida (Chuo University, Tokyo, Japan), Kenshiro Ogasawara (University of Tsukuba, Tsukuba, Japan), Tatsuo Oji (University of Tokyo, Tokyo, Japan), Andrew B. Smith (Natural History Museum, London, Great Britain), Roger D.K. Thomas (Franklin and Marshall College, Lancaster, USA), Katsumi Ueno (Fukuoka University, Fukuoka, Japan), Wang Hongzhen (China University of Geosciences, Beijing, China), Yang Seong Young (Kyungpook National University, Taegu, Korea) Officers for 1999-2000 President : Kei Mori Councillors : Kiyotaka Chinzei, Takashi Hamada, Yoshikazu Hasegawa, ltaru Hayami, Hiromichi Hirano, Noriyuki Ikeya, Junji Itoigawa, Tomoki Kase, Hiroshi Kitazato, Itaru Koizumi, Haruyoshi Maeda, Ryuichi Majima, Makoto Manabe, Hiroshi Noda, Ikuo Obata, Kenshiro Ogasawara, Terufumi Ohno, Tatsuo Oji, Tomowo Ozawa, Yukimitsu Tomida, Tsunemasa Saito, Takeshi Setoguchi, Kazushige Tanabe, Akira Yao Members of Standing Committee : Hiroshi Kitazato (General Affairs), Tatsuo Oji (Laison Officer), Makoto Manabe (Finance), Kazushige Tanabe (Editor in Chief, PR), Tomoki Kase (Co-Editor, PR), Ryuichi Majima (Planning), Hiromichi Hirano (Membership), Kenshiro Ogasawara (Foreign Affairs), Haruyoshi Maeda (Publicity Officer), Noriyuki Ikeya (Editor, “Fossils”), Yukimitsu Tomida (Editor in Chief, Special Papers), Tamiko Ohana (Representative, Union of Natural History Societies). 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Phone : (978)750-8400, Fax : (978)750-4744, www.copyright.com Cover: Idealized sketch of Nipponites mirabilis Yabe, a Late Cretaceous (Turonian) nostoceratid ammonite. Various reconstructions of the mode of life of this species have been proposed, because of its curiously meandering shell form (after T. Okamoto, 1988). All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN c/o Business Center for Academic Societies, Honkomagome 5-16-9, Bunkyo-ku, Tokyo 113-8622, Japan Paleontological Research, vol. 3, no. 3, pp. 141-150, 5 Figs., September 30, 1999 © by the Palaeontological Society of Japan Papyridea harrimani Dall, 1904 (Bivalvia, Cardiidae) ~ as a marker for upper Eocene and lower Oligocene strata of the North Pacific ALEXANDER I. KAFANOV', KONSTANTIN B. BARINOV’ and LOUIE MARINCOVICH, JR: ‘Institute of Marine Biology, Far East Branch, Russian Academy of Sciences, Vladivostok 690041, Russia Geological Institute of the Russian Academy of Sciences, Moscow 109017, Russia “Department of Invertebrate Zoology & Geology, California Academy of Sciences, San Francisco, California 94118, U.S.A. Received 27 November 1998 ; Revised manuscript accepted 19 April 1999 Abstract. Statistical analysis indicates that Papyridea (Fulvia) nipponica Yokoyama, 1924, Papyridea matschigarica Khomenko, 1938, and Papyridea matschigarica uspenica Barinov in Gladenkov et al., 1987, are synonyms of Papyridea harrimani Dall, 1904, which was originally described from the lower Oligocene Stepovak Formation in Popof Island, Shumagin Islands, southwestern Alaska. Papyridea harrimani occurs only in late Eocene and early Oligocene faunas and is useful for correlating strata from northern Honshu to Alaska: Stepovak Formation, southwestern Alaska; Mallenskaya and lonayskaya Suites, Koryak Upland ; Aluginskaya Suite and lower part of the Pakhachinskaya Suite, eastern Kamchatka ; Amanin- skaya, Utkholokskaya and Viventekskaya Suites of western Kamchatka ; Machigarskaya, Arakayskaya, Gastellovskaya and Akhsnayskaya Suites, Sakhalin ; Nuibetsu, Charo and lower Sankebetsu Formations, Hokkaido ; Asagai Formation, Honshu. In views of the stratigraphic ranges of Papyridea harrimani and other molluscs, strata 3 and 4 of the Pakhachinskaya Suite in eastern Kamchatka may be assgined an age of early Oligocene. Key words: biostratigraphy, Bivalvia, Cardiidae, Cenozoic, North Pacific, Paleogene, Papyridea Introduction Marine bivalve molluscs occupy a central position in the Cenozoic stratigraphic framework of the tectonically active North Pacific region from northern Japan to Alaska. Prog- ress in refining this framework has sometimes been inhibited by differing species concepts among Russian, American and Japanese paleontologists. One of the most widespread and biostratigraphically useful bivalve families in this extensive region is the Cardiidae. Kafanov (1997) emphasized the widespread occurrence of a high-latitude North Pacific group of relatively large cardiid species centered around Papyridea harrimani Dall, 1904 and P. matschigarica Kho- menko, 1938. The genus Profulvia established by Kafanov (1976) for North Pacific Papyridea is considered to be a subgenus of the latter (Kafanov, 1997). Here we analyze the taxonomic relations between these species and with Papyridea (Fulvia) nipponica Yokoyama, 1924, and emphasize the usefulness of this group for broad- scale age control and regional correlations. Materials and methods Some of the specimens of P. matschigarica examined in this study were collected from the Machigar section in the Schmidt Peninsula, northern Sakhalin, by Y.B. Gladenkov in 1969 and 1979, and by K.B. Barinov in 1996 (Figure 1). The description of the Machigar section we use here is based on a stratigraphic study of the lower part of the Machigarskaya Suite by Y.B.Gladenkov (Barinov and Gladenkov, 1998). We also examined specimens of Papyridea in collections of the Central Scientific-Research Geological-Exploration Museum (CNIGRM), St. Petersburg, the All-Russia (formerly All-Union) Petroleum Scientific-Research Geological-Explo- ration Institute (VNIGRI), St. Petersburg, the Geological (GIN) and Paleontological (PIN) Institutes, Russian Academy of Sciences, Moscow, the University of California Museum of Paleontology, Berkeley, and the California Academy of Sciences, San Francisco, U.S.A. We have quantitatively defined the main shell characters of P. matschigarica by studying numerous topotype speci- mens, and used statistical analysis to determine the mor- phological relationships among P. matschigarica, P. mats- 142 Alexander |. Kafanov et al. un < wa Macoma- MIOCENE | = Lower 170 Nuculana Delectopec- ten TUMSKAYA 320-340 Periploma OLIGOCENE 175 Conchocele Column Ta embase Dominant species m m Macoma simizuensis Lucinoma | Lucinoma acutilineata Nuculana tumiensis* Delect. watanabei* Periploma besshoensis Conchocele smekhovi Papyridea | Papyridea harrimani* | Nemocardium iwakien- Associated species Chlamys donmilleri* Chl. wajampolkensis* Mytilus ochotensis* Nucula tumiensis* Portlandella nitida Macoma simizuensis Cardiomya maja- natschensis* Acila oyamadensis* Glycymeris nakosoensis Ciliatocar- dium ATCHIGARSKAYA 220 O|2 ==) Ciliatocardium matchgarense x Bee: se*, Trachycardium kin- simarae*, Mya grewin- eki* Ess [2]? Figure 1. Machigar stratigraphic section on the Schmidt Peninsula, northern Sakhalin (type locality of P. matschigarica). Legend: * carbonate concretions. chigarica uspenica, P. harrimani and P. nipponica. The sta- tistical null hypothesis was reduced to probability analysis of belonging of type-specimens of the above four species to a sampling composed by topotypes of P. matschigarica. For that purpose we used the procedure of multidimensional analysis of ejections by sample Mahalanobis distance D? (Afifi et al. 1971). The procedure is as follows. Let x, ... x, equal a random sampling with distribution N( 4, 2 ), and x equal a certain vector of observations with the same distribu- tion. Then D’=(x— X) S (x—X) in which X and S are the sampling mean and covariance matrix, respectively. The value of F=|(k—p)k/(k?—1)| - D* has an F-distribution with p and k—p degrees of freedom. The checking procedure for the availability of ejections among the observation data utilizes F-statistics in which X and S are calculated from a subset of vectors of the same sample, which has already been checked for ejections. Each of the four variables was preliminarily tested for Gaussian distribution based on x? and Kolmogorov-Smirnov index species, 1-volcanic rocks, 2-coal, 3-conglomerate, 4-sandstone, 5-siltstone, 6-tuffaceous siltstone, 7- criteria. All the variables proved to be normally (Gaussian) distributed and required no transformation of the initial data. The shell characters referred to herein are: L=shell length, H= shell height, B=convexity of one valve (all dimen- sions in mm), R=number of radial ribs. The dimensions of the holotypes given here differ somewhat from those in the original descriptions, owing to differences in shell orientation during measurement (see Kafanov et al., 1997 ; Kafanov, 1998). Results The nominal species to be described below form a morphologically coherent group consisting of P. harrimani, P. nipponica, P. matschigarica and P. matschigarica uspenica. Each is discussed separately. Papyridea harrimani from North Pacific 143 Papyridea (Profulvia) harrimani Dall, 1904 Figures 2-1, 4—6; 3-1—5 Papyridea harrimani Dall, 1904, p. 114, pl. 10, fig. 5. Type locality.—Coastal bluffs on the north shore of Popof Island, Shumagin Islands, southwestern Alaska. Stepovak Formation, lower Oligocene. Depository of the type material —Holotype, U.S. Natl. Mus. no. 164867. Comments.—This was originally described as a Miocene species by Dall (1904 ; see also Schuchert et al., 1905), who thought that the type-locality of P. harrimani in Popof Island was correlative with beds in adjacent Unga Island (Figure 4), to which he erroneously assigned a Miocene age. These Unga Island strata were later determined to be largely nonmarine and to contain no molluscs (Marincovich and Wiggins, 1991). Dall’s (1904) mollusc collections that are purportedly from these Unga Island strata contain an artifi- cially mixed fauna of Miocene and Oligocene species (Mac- Neil et al., 1961). Assignment of a Miocene, or possible Miocene age to the Unga Island strata (Dall, 1896, 1904) was repeated by later workers (Schuchert et al., 1905; Burk, 1965 ; Detterman et al., 1996). The exclusive presence of Oligocene molluscs with P. harrimani in the strata of Popof and Unga Islands assigned to the Stepovak Formation has been verified by one of us (Marincovich, 1988, 1989, 1990 ; Marincovich and McCoy, 1984) during field studies. The early Oligocene age of the Unga Island beds with P. harrimani was established by Marincovich and Wiggins (1991) on the basis of dinoflagellates and a potassium-argon age of 31.3+ 0.3 Ma from biotite in a tuff bed. In the nearby Popof Island, the type-locality of P. harrimani, the Stepovak Formation contains the same molluscan fauna as in the Stepovak strata on Unga Island and is undoubtedly of early Oligocene age. Distribution.—Lower Oligocene, Stepovak Formation at East Head stratigraphic section, Popof Island (type-locality), and West Head stratigraphic section, Unga Island, Shumagin Islands, southwestern Alaska (Dall, 1904 ; MacNeil in Burk, 1965 ; Marincovich, 1989). Oligocene Asagai Formation of Honshu. In Japan P. harrimani is reported also from the upper Eocene Sakasagawa (= lower Sankebetsu) Formation of the Haboro coal-field, Hokkaido (Noda, 1992a) and from the Paleogene Charo Formation of the Kushiro coal-field, Hokkaido (Honda, 1989). The ages of the Sakasagawa and Charo Formations are controversial. Prof. K. Ogasawara (pers. comm. to A. Kafanov, June 12, 1997) informs us that the Sakasagawa Formation is a tentative name for strata which were previously included in the Sankebetsu Formation. Noda (1992a) reported P. harrimani from the Sankebetsu Formation (then of presumed Miocene age), and he divided the Sankebetsu Formation of previous workers into the Sakasagawa Formation and the Sankebetsu Formation. Based on planktonic foraminifers and calcareous nannofos- sils, the Sakasagawa Formation is now assigned an Eocene age, even though presumed Miocene molluscs (Anadara and Dosinia) are reported in the upper part of the Sankebetsu Formation (Noda, 1992b). Honda (1989) reported an Oligocene age for molluscs of the Charo Formation, although planktonic foraminifers (Kaiho, 1984) and calcareous nan- nofossils (Saito et al., 1984) suggest an Eocene age. “Papyridea harrimani” cited from the middle Miocene Ainonai Formation in Hokkaido (Uozumi et al., 1966, p. 177, pl. 15, figs. 1, 7) cannot be reliably assigned to this species, and more closely resembles Papyridea (Profulvia) kurodai Sawada, 1962. Papyridea (Profulvia) nipponica Yokoyama, 1924 Papyridea (Fulvia) nipponica Yokoyama, 1924, p. 17, pl. 3, figs. 3, 4. Type locality.—Tatsuta coal-field, Futaba District, Fuku- shima Prefecture, Honshu. Asagai Formation, Oligocene. Depository of the type material.—Lectotype (designated as holotype by Hatai and Nisiyama, 1952, p. 105), CM 22090- University Museum, University of Tokyo, missing. It was refigured by Makiyama (1957, pl.13, figs. 4, 4a) and by Kafanov (1997, pl. 1, fig. 7). Distribution.—Known only from Asagai Formation of Fuku- shima Prefecture, Honshu (Kamada, 1962). Comments.—This species has been synonymized with P. harrimani Dall, 1904 by most Japanese paleontologists (e.g. Oyama et al., 1960), with the exception of Kamada (1962) and Masuda and Noda (1976). Papyridea (Profulvia) matschigarica Khomenko, 1938 Figures 2-2,3 Papyridea matschigarica Khomenko, 1938, p. 47, pl. 7, figs. 5-7 ; pl. 8, fig. 6; pl. 9, fig. 7. Type locality—Between Cape Marii and Monchigar Bay, Schmidt Peninsula, Okha Province, Sakhalin. Lower part of Machigarskaya Suite, upper? Eocene-lower Oligocene. Depository of the type material.—Lectotype (designated by Slodkewitsch, 1938, p. 407), CNIGRM no. 81/5044. Distribution.—Upper Eocene and lower Oligocene of Far- eastern Russia. Upper Eocene Takaradayskaya Suite and lower part of Machigarskaya Suite of Sakhalin. Lower Oligocene Machigarskaya, Arakayskaya, Akhsnayskaya and Gastellovskaya Suites of Sakhalin; Mallenskaya and lonayskaya Suites of the Koryak Upland; Amaninskaya Suite of western Kamchatka. Comments.—According to Slodkewitsch (1938, p. 408), Khomenko (1938, p. 48) noted the wide morphologic variabil- ity of this species, along with the similarity of some young individuals to P. nipponica and P. harrimani, and inferred that “... under the name of P. nipponica and P. harrimani only young specimens of P. matschigarica were described”. This inference has yet to be substantiated, although the close relationship between these species is quite evident. P. harrimani Dall and P. nipponica Yokoyama are easily distin- guishable from P. matschigarica by their much smaller size, more equilateral contour and smaller number of ribs. Fol- lowing Slodkewitsch (1938), nearly all Russian authors have considered P. matschigarica to be a separate species, even though its shell shape (Figure 5) is similar to that of large P. 144 Alexander |. Kafanov et al. Papyridea harrimani from North Pacific 145 harrimani. In fact, Makiyama (1934) described Machigarian specimens under the name P. harrimani. Papyridea (Profulvia) matschigarica uspenica Barinov in Gladenkov et al., 1987 Figures 3-6—8 Papyridea matschigarica uspenica Barinov in Gladenkov et al. 1987, p. 39, pl. 13, figs. 9, a, b, 22. Type locality—Ugol’naya River, coast of the Gulf of Korf, eastern Kamchatka. Aluginskaya Suite, bed 1, Oligocene. Depository of the type material—Holotype, PIN no. 1/1-1. Distribution.—Oligocene to lower(?) Miocene of Kamchat- ka. Aluginskaya and Pakhachinskaya Suites of eastern Kamchatka. Facies-related variability of Papyridea matschigarica Table 1 and Figure5 both support Khomenko's (1938) conclusion concerning the wide variability of P. matschigarica and very close morphological relationships among all consid- ered Papyridea species. The distribution of P. matschigarica in the Machigar section of the Schmidt Peninsula, northern Sakhalin (Figure 1) is as follows. P. matschigarica first appears virtually at the base of the Machigarskaya Suite in fine grey pebble conglomerates (up to 2 m in diameter) directly overlying a sand- and coal- bearing member (30-32 m thick) that contains remnants of Mytilus littoralis Slodkewitsch, Corbicula sitakaraensis Suzuki and Cerithidea quadrimonilicosta Khomenko. At a horizon 45-50m above the base of the section, P. matschigarica occurs in flat-lying strata (up to 85m thick) of alternating conglomerate (0.5-1 m in diameter), sandstone and claystone (3-5 m thick), and in a superjacent strata (up to 80 m thick) of alternating sandstone (1.5-2 m thick) and claystone (3-14 m thick). In the part of the Machigar stratigraphic section described above, P. matschigarica occurs only in beds of fine pebbly conglomerate and conglomeratic sandstone associated with the following molluscs: Nemocardium iwakiense (Maki- yama), Mya cf. grewingki Makiyama, Thracia schmidti Krish- tofovich, Pododesmus schmidti Krishtofovich, Trachycardium kinsimarae (Makiyama), Chlamys matchgarense Makiyama, Modiolus matchgarensis (Makiyama), ? Megacardita mats- chigarica (Khomenko), Yoldia matschigarica Krishtofovich, Y. caudata Khomenko, Ciliatocardium asagaiense (Makiyama), Laevicardium taracaicum (Yokoyama), Liocyma furtiva (Yo- koyama), Arca sakamizuensis Hatai and Nisiyama, Neptunea ezoana Takeda, and Turritella importuna Yokoyama. In situ specimens of P. matschigarica are mostly molds of single valves, with some molds of paired valves, and their chaotic orientation indicates post-mortem transport. Specimens in the lowest 75 m of the Machigar section are almost identical in size and shape with the holotype of P. harrimani (Figure 5). Higher in the section the same Papyridea is abundant in fine pebbly conglomerate and conglomeratic sandstone. How- ever, these specimens are larger in size and more distinctly convex, and they most closely resemble the holotype of P. matschigarica. An increase in their average shell size toward the top of the Machigar sequence seems to correlate with a gradual reduction in the proportion of coarse clastics. The type locality of P. matschigarica evidently lies in the upper part of the lower member of the Machigarskaya Suite (see Khomenko, 1938). In our opinion, the size and shape differences seen in Papyridea (Profulvia) from the upper and lower parts of the Machigar section are related to differences in ecological conditions such as substrate and depth. Conglomerates with a shallow-water molluscan fauna con- tains “P. harrimani,” whereas sandstones with deeper-water molluscs contain “P. matschigarica” (Figure 5). The number of ribs varies widely and is highly dependent on shell preser- vation. Most specimens are molds that do not allow for accurate rib counts, because they often lack ribs on their anteriormost and/or posteriormost portions. It should also be noted that in many present-day Cardiidae (subfamily Clinocardiinae), a difference in the number of ribs to the extent of 10-12 is considered to be in the realm of intraspecific variation, including ontogenetic variation (e.g., Kafanov, 1981, 1998). A statistical analysis of basic shell dimensions for the type specimens of P. matschigarica, P. matschigarica uspenica, P. nipponica and P. harrimani, and in topotypes of P. matschigarica (Figure 5), clearly shows that they all belong to one general group (Table 2). These data suggest that P. matschigarica, P. matschigarica uspenica and P. nipponica are junior synonyms of P. harrimani. It is espe- cially notable that the holotype of P. harrimani is more closely related in form to topotypes of P. matschigarica than the lectotype of P. matschigarica (Table 2). Discussion P. harrimani s.\. occurs in upper Eocene to lower Oligocene strata over a wide area of the high-latitude North Pacific, from southwestern Alaska to Hokkaido and northern Honshu. Based on these occurrences, correlations may be made between the following strata: Stepovak Formation, south- western Alaska; Mallenskaya and lonayskaya Suites, Kor- yak Upland ; Aluginskaya Suite and lower part of the Pakha- chinskaya Suite, eastern Kamchatka; Amaninskaya, Utk- holokskaya and Viventekskaya Suites of western Kamchat- ka; Machigarskaya, Arakayskaya, Gastellovskaya and Akh- Figure 2. 1a, b. Holotype of Papyridea harrimani Dall, 1904. Formation. North shore of Popof Island, southwestern Alaska ; Stepovak U.S. Natl. Mus. no. 164867. 2. Lectotype of Papyridea matschigarica Khomenko, 1938. Between Marii Cape and Monchigar Bay, Schmidt Peninsula, Okha District, northern Sakhalin; lower part of Machigarskaya Suite. CNIGRM no. 81/ 5040. 3. Paralectotype of Papyridea matschigarica Khomenko, 1938. The same locality as on Fig. 2-2. CNIGRM no. 85 5044. 4. P. harrimani. Machigarskaya Suite. Nairo River, eastern Sakhalin, analog of Machigarskaya Suite. rimani. The same locality as on Fig.2-4. CNIGRM no. 104/6818. 6. P. harrimani. PIN no. 90/3962. All figures shown natural size. CNIGRM no. 1038/6818. 5. P. har- Schmidt Peninsula, northern Sakhalin, 146 Alexander |. Kafanov et al. Papyridea harrimani from North Pacific 147 Type section, Unga lomerate „Member of pe Ormation UNGA ISLAND KILOMETERS PACIFIC OCEAN Figure 4. Index map showing the type section of Unga Conglomerate and the type locality (East Head) of Papyridea harrimani. snayskaya Suites, Sakhalin; Nuibetsu, Charo and lower Sankebetsu Formations, Hokkaido ; Asagai Formation, Hon- shu. These many occurrences of P. harrimani and allow us to judge it as a significant marker for upper Eocene to lower Oligocene strata of the North Pacific. This conclusion may at first seem to contradict the pres- ence of P. matschigarica uspenica in beds 3 and 4 of the Pakhachinskaya Suite of the main Gulf of Korf section (Ugol'naya River), and in beds5 and 6 of an additional section (Bol’shaya Medvezhka River), both of which were assigned to the early and middle Miocene by Gladenkov et al. (1987). However, we suggest that the stratigraphic distri- bution of many common bivalve species in Japan and Sakhalin argues for assigning the middle part of the Pakha- chinskaya Suite in eastern Kamchatka (beds 3 and 4 along the Ugol’naya River) to the lower Oligocene. The molluscan fauna of the Pakhachinskaya Suite in this part of the Gulf of Korf section is comparable to the faunas of the Asagai Formation in the Joban coal-field, Honshu, the Utkholokian and Viventekian horizons of western Kamchatka (see also Gladenkov, 1992), and the Machigarian and Kholmskian horizons of South Sakhalin (See Kafanov and Savizky, 1995). Thus, beds3 and 4 of the Pakhachinskaya Suite of eastern Kamchatka characteristically contain Ciliatocardium asagaiense (Makiyama) and Thracia kidoensis Kamada, which Japanese workers (Mizuno, 1964 ; Honda, 1986) have described as representatives of the Asagai-Poronai fauna (Otuka, 1939). The Asagai-Poronai fauna contains plank- tonic foraminifers as old as Eocene (Ibaraki, 1986). The consideration of a precise Paleogene age for beds 3 and 4 of the Pakhachinskaya Suite also involves “Cardium esutor- uensis” mentioned by Gladenkov et al. (1987) for bed 4 of the Pakhachinskaya Suite; this species should rather be re- ferred to as Laevicardium tristiculum (Yokoyama) (Kafanov and Amano, 1996). The Laevicardium tristiculum (= Cardium esutoruensis) bearing horizon was established in Sakhalin as a marker of the Arakayskaya Suite and its correlatives by Krishtofovich (1954, 1964) and by Margulis and Savizky (1969). The Asagai Formation in the Joban coal-field of central Honshu contains Laevicardium tristiculum. According to Yanagisawa et al. (1989), the age of the Shiramizu Group, which includes the Asagai Formation, is early Oligocene according to its diatom flora, molluscs and mammals. In the Uglegorsk Province of southwestern Sakhalin, L. tristiculum Table 1. Measurements (in mm) of type specimens of Papyridea (Profulvia) harrimani, P. (P.) nipponica, P. (P.) matschigarica and P. (P.) matschigatica uspenica. : 4 ; Convexity of Number of Species (subspecies) Shell length Shell height ale dielribs P. harriman 48.0 40.0 9.5 42 P. nipponica 69.7 51.3 13.0 52 P. matschigarica 95.0 76.4 20.3 55 P. matschigarica uspenica 70.0 59.0 18.0 47 Figure 3. 1. Papyridea harrimani Dall, 1904. Schmidt Peninsula, northern Sakhalin, Machigarskaya Suite. PIN no. 90/ 3962. 2. P. harrimani. Machigar section of the Schmidt Peninsula, site 4/7, GIN no. 3618/1. 3. P. harrimani. Machigar section of the Schmidt Peninsula, site 5/29, GIN no. 3618/2. 4. P. harrimani. 5/24, GIN no. 3618/3. 5. P. harrimani. Machigar section of the Schmidt Peninsula, site Machigar section of the Schmidt Peninsula, site 2/15, GIN no. 3618/4. 6. Paratype of Papyridea matschigarica uspenica Barinov in Gladenkov et al., 1987. Ugol'naya River, Gulf of Korf section, eastern Kamchatka, site 10/2-3. Pachachinskaya Suite. GIN no. 3669/3. 7. Paratype of Papyridea matschigarica uspenica Barinov in Gladenkov et al., 1987. Ugol’naya River, Gulf of Korf section, eastern Kamchatka, site 10/2-5. Pachachinskaya Suite. GIN no. 3669/4. 8. Paratype of Papyridea matschigarica uspenica Barinov in Gladenkov et al., 1987. Bol’shaya Medvezhka River, Gulf of Korf section, eastern Kamchatka, site 18/7. Pakhachinskaya Suite. GIN no. 3669/7. All figure shown natural size. 148 Alexander |. Kafanov et al. OO Figure 5. Location of type specimens of Papyridea har- rimani (A), P. nipponica (B), P. matschigarica uspenica (C) and P. matschigarica (D) in space of characters of P. matschigarica topotypes from lower (dotted circles) and upper (white circles) parts of the Machigar section in northern Sakhalin. Abbrevia- tions : L=shell length (in mm); H=shell heigh (in mm); B= convexity of one valve (in mm); R=number of radial ribs. Table 2. Probability of assignment of type specimens of Papyridea matschigarica, P. matschigarica uspenica, P. nipponica and P. harrimani to sampling of topotypes of P. matschigarica. Probabilities P (D?) of assignment to sam- pling of each topotype account for the range between 0.998 and 0.131; P (F) between 0.997 and 0.066. Type specimens P (D?) P (A P. harrimani 0.780 0.816 P. matschigarica uspenica 0.749 0.790 P. matschigarica 0.696 0.745 P. nipponica 0.653 0.707 has been found in the upper member of the Arakayskaya Suite. Okamura (1994) assigned a K-Ar age of 38.6 Ma and 30.6 Ma to the lower and middle parts of the Arakayskaya Suite respectively. Thus, in terms of molluscs, strata 3 and 4 of the Pakhachinskaya Suite in eastern Kamchatka may be assgined in age to early Oligocene. Acknowledgements We render our sincere gratitude to Yuri B. Gladenkov and Valentina N. Sinelnikova (Geological Institute, Moscow) for providing specimens of Machigarian Papyridea matschigarica, to Igor V. Volvenko (Institute of Marine Biology, Vladivostok) for assistance in statistical analysis, to Kazutaka Amano (Department of Geoscience, Joetsu University of Education), to Yoshikazu Noda (Fukui Museum) for assistance accessing the Japanese literature, and also to Kenshiro Ogasawara (Institute of Geoscience, the University of Tsukuba) for discussions about the conclusions. This research was partly supported by the Russian Foundation for Basic Research (grants no. 95-04-11134, no. 95-05-14997, and no. 98-04-49168). 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Yanagisawa, Y., Nakamura, K., Suzuki, Y., Sawamura, K., Yoshida, F., Tanaka, Y., Honda, Y. and Tanahashi, M., 1989: Tertiary biostratigraphy and subsurface geology of the Futaba district, Joban coal field, northeast Japan. Bulletin of the Geological Survey of Japan, vol. 40, no. 8, p. 405-467. (in Japanese) Yokoyama, M., 1924: Molluscan remains from the lowest part of the Jo-Ban coal-field. Journal of the College of Science, Imperial University of Tokyo, vol. 45, no. 3, p. 1-22, pls. 1-5. Paleontological Research, vol. 3, no. 3., pp. 151-161, 8 Figs., September 30, 1999 © by the Palaeontological Society of Japan Upper Paleozoic biostromes in island-arc carbonates of the eastern Klamath terrane, California RODNEY WATKINS Geology Department, Milwaukee Public Museum, 800 West Wells Street, Milwaukee, Wisconsin 53233, USA Received 8 January 1999 ; Revised manuscript accepted 26 April 1999 Abstract. The eastern Klamath terrane (eKt) of California, a geographically isolated, island-arc area, was invaded by biostromal communities during three intervals of carbonate deposition in the Carboniferous and Permian. Visean/Serpukhovian biostromes were formed on short-lived carbonate banks by the Tethyan brachiopod Striatifera and phylloid algae. Bashkirian biostromes on similar banks were formed by the cosmopolitan microproblematica Tubiphytes and Donezella. \Wolfcampian biostromes occur in a thick carbonate platform and slope section and were formed by Tubiphytes, the phylloid alga Eugonophyllum, and Palaeoaplysina, an enigmatic taxon known mainly from Laurentia. Species diversity of biostrome dwellers increased from the Early Carboniferous to Early Permian, when it reached the level of high- diversity shelf-mud communities. Biostromes in the eKt record the global recovery of Carboniferous- Permian reef biotas during temporal intervals of quiescent volcanism that permitted carbonate deposition. Key words: biostromes, California, Carboniferous, island-arcs, Permian Introduction The Late Paleozoic, noted for its paucity of frame-building metazoans, was an interval of ecologic recovery of reef communities following their collapse in the Late Devonian extinctions (Sheehan, 1985 ; Copper, 1988). Island-arc car- bonates of the eastern Klamath terrane, California (Figure 1), offer a picture of this recovery in a setting of geographic isolation, limited availabily of favorable environments, and recurring biogeographic invasions from outside areas. Although no Late Paleozoic reefs or mound-like structures are known from the terrane, several reef-forming taxa are locally abundant in tabular limestone beds that represent biostromes. Biostrome formation was dominated by bind- ing, baffling, and production of skeletal grains, and bio- stromal taxa included a mixture of algae, problematica and brachiopods (Figure 2). Geologic setting Devonian through Early Jurassic rocks of the eastern Klamath terrane (eKt) formed in a succession of island-arcs and arc-related basins (Albers and Bain, 1985; Renne and Scott, 1988; Miller, 1989). Renne and Scott (1988) summa- rized paleomagnetic data for the eKt, which indicate paleolatitudes equivalent to cratonic North America since at least Permian times. Paleozoic longitudinal position of the eKt with respect to North America has been a matter of debate. Miller (1987), Rubin et al. (1990), Miller and Saleeby (1991), Miller et al. (1992), and Darby et al. (1997) placed the eKt near the western margin of cratonic North America, based on provenance of detrital zircons and stratigraphic ties with adjacent terranes. In contrast, Stevens et al. (1990) and Belasky and Runnegar (1994) concluded that the eKt formed in an oceanic setting thousands of km west of North America, based on Permian faunal composition and biogeo- graphic models. In either scenario, the eKt represents an isolated area of shallow marine environments in the Pale- ozoic. Like a number of Cordilleran terranes (Soja, 1996), it contains a mixture of cosmopolitan, endemic, Tethyan and North American taxa (Watkins and Wilson, 1989 ; Watkins et al., 1989; Potter et al., 1990: Stevens et al., 1990; Noble and Renne, 1990). Upper Paleozoic stratigraphy and carbonates Early to Middle Devonian arc construction in the eKt was followed by extension and development of a large, arc- related basin in which submarine fan sequences of the Upper Devonian to Lower Carboniferous Bragdon Formation were deposited (Watkins, 1986, 1990 ; Miller and Cui, 1987 ; Miller and Saleeby, 1991). Volcaniclastic deltaic sediments with shallow marine limestone lenses appear locally at the top of the Bragdon and in the lower part of the overlying Baird Formation. The brachiopods Striatifera and Titanaria indicate a Visean or Serpukhovian (Late Mississippian) age for these limestones (Watkins, 1973; Gordon and Dutro, 1993). The lenses reach 17 m thick and 1.2 km in length, and consist of bank and slope facies that were deposited over delta lobes (Watkins, 1993a). Deposition of the lime- 152 Rodney Watkins 122° iS 2 = En Q = S Ss à ST & x EN = SQ, 2 5 Sos) SIR fo carbonate < Ss = a 8 § 3 ES = © S S cr} banks & platforms ira = 2 S 3S zZ i ee ie 5 fF] volcaniclastic = az poy ana i ra J sediments =[McCLOUD = Cores) = m Sz 41° FR tubiditefilof |4l DD < —— 2 ‘= extensional basins | © 08 « ESS = FT u felsic volcanics |2 | INVASION TEVENTS 2) er © |o| BRAGDON W 1 - Visean/Serpukhovian z ‘ . 26 fees 2 - Bashkirian 2 = mafic volcanics O} == 3 - Wolfcampian 5 — - 2 1000 4 ET = BIOSTROMES: ® Tubiphytes pac 5 2 RAA } ® Palaeoaplysina ® Donezella F = 0 m COPLEY ® Phylloid © Striatifera 3 = c =F Yn Figure 1. taxa indicates their relative importance in biostrome formation. in Watkins (1973, 1993a, 1993b). A, B.C, D Striatifera biostromes Donezella biostromes Carboniferous Tubiphytes biostromes Occurrence of Upper Paleozoic biostromes in the eastern Klamath terrane, California ; width of bars for the five Detailed geologic maps of areas with biostromes are contained CREME = DE Permian ee Palaeoaplysina biost. phylloid biostromes Tubiphytes ™ 7 7 Donezella 94% Palaeoaplysina É phylloid algae Epimastopora | foraminifers u echinoderms brachiopods Te) 9 1% ms 502 "other groups Jj Zo) A ONCE = ge. VL is 40 40 0 40 (6) PERESZENT OF TOTAL SKELETAL. MATERIAL Figure 2. Environmental occurrence, life habit reconstructions, and skeletal composition of biostromes (*other groups include corals, bryozoans, annelids, molluscs, and ostracods). stone lenses was related either to sea-level rise that cut off volcaniclastic sediment supply, or to switching of active delta lobes. Carbonate deposition on deltas was short-lived and terminated by progradation of volcaniclastic sediments. Bashkirian (Early Pennsylvanian) limestone lenses in the Baird Formation are dated by the fusulinid Pseudostaffella (Skinner and Wilde, 1965). The fusulinid-bearing limestones occur at Kabyai Creek (Watkins, 1973, fig.4) and Hirz Mountain | the Hirz Mountain Limestone Member of Watkins (1973, fig. 3), who erroneously dated it as “Late Pennsylvanian or Early Permian”|. The lenses include bank and slope apron facies (Figure 3), and they reach 20 m in thickness and 2km in breadth. In both areas, the limestone lenses are overlain by a thick section of volcaniclastic sediments that probably ranges from Bashkirian to latest Carboniferous age. The Baird is overlain by the Lower Permian McCloud Limestone, which contains basal Wolfcampian to early Leonardian fusulinids (Skinner and Wilde, 1965). The McCloud was deposited during an interval of volcanic quies- cence as several carbonate platforms that reached tens of km in breadth (Miller, 1989; Watkins, 1990). Platforms developed over volcanic highs and grew by progradation of slope deposits and aggradation of platform-top deposits, resulting in carbonate sections over 800 m thick (Watkins, 1993b). McCloud deposition was terminated by platform subsidence and drowning in the Leonardian, and volcanism Upper Paleozoic biostromes in California 153 3 echinoderms 2 foraminifers 3 gtz/lithic sand 3 bryozoans 3 brachiopods 3 ostracods BANK | spar/microspar | Tubiphytes = = Ÿ N Ÿ = a een 2 Komia vun u uw O 100 PERCENT OF TOTAL SEDIMENT VOLUME 1 scale for thin sections 3 3 DETTE! | Tubiphytes | GRAINSTONE BOUNDSTONE SLOPE APRON Hil Tubiphytes Donezella GRAINSTONE Donezella BOUNDSTONE Limestone [ M MUDSTONE Es | W WACKESTONE [=] RIPPLE LAMINATION qj Calcareous | P PACKSTONE 4 CROSS STRATIFICATION shale | G GRAINSTONE 3 PARALLEL LAMINATION [ f FINE DJ EROSIONAL BASE Fl Voleaniclastic | — abundant Tubiphytes Te ci 2 LJ sandstone | m MEDIUM LL) in gravity-displaced sediment | ¢ COARSE Figure 3. Occurrence of Donezella and Tubiphytes in bank and slope apron facies of Bashkirian limestone, Baird Formation, Kabyai Creek (NE1/4 NE1/4 sec. 36, T36N R4W). Sketches of thin sections, traced from photos, show typical fabrics and textures. resumed in the eKt during early Guadelupian time (Renne and Scott, 1988). Small carbonate bank deposits of Guadelupian age occur in the volcanic and volcaniclastic Bollibokka Group, but no biostromes have been reported (Stevens et al., 1987 ; Miller, 1989). Methods Data on biostromes were collected as part of a sedimentologic study of Upper Paleozoic carbonates in the eKt (Watkins, 1993a, 1993b). This study involved outcrop mapping and bed-by-bed logging of five depositional lenses of Visean/Serpukhovian limestones (80 m of total section), three depositional lenses of Bashkirian limestones (142 m of total section), and one Wolfcampian slope and platform complex (901 m of total section). In the course of this work, 81 samples were made from 60 biostromes, and 39 samples were made from beds of gravity- displaced biostromal sediment. All samples were prepared as thin sections. Compositional data were obtained as counts of 100 to 200 points per thin section, and data were pooled for samples from the same biostrome type to yield the histograms in Figure 2. Samples with larger biostrome for- mers were also studied as polished slabs. Twelve samples were etched in HCl to obtain silicified fossils used for measurement of species diversity. Comparative paleoecology of biostrome and shelf-mud faunas, discussed later, uses the guild concept. Reef and biostrome guilds recognized by Fagerstrom (1987) include constructors, bafflers, binders, destroyers, and dwellers. This report follows Watkins (1993c) in subdividing the dweller guild on the basis of class-level taxonomy and functional morphology. Biostromal deposits Biostromes formed by Striatifera, phylloid algae and Palaeoaplysina are readily apparent in the field, but their lateral extent is difficult to determine because of brush cover. Striatifera biostromes have been traced for lateral distances of 45m, and Palaeoaplysina and phylloid biostromes have been traced for distances of 130 m. Biostromal beds dominated by Donezella and Tubiphytes, which appear as medium-grained, relatively featureless limestone in the field, were identified by thin sections. These beds have been traced only across small roadcuts and ledges. Striatifera biostromes Striatifera is a linoproductid brachiopod that attached to conspecific shells with its spines, forming biostromes similar to modern mussel beds (Muir-Wood and Cooper, 1960). An undescribed species of Striatifera, similar to S. striata Fischer de Waldheim, occurs as a biostrome former in Visean Serpukhovian limestones of the Bragdon and Baird forma- tions. The biostromal beds range from 40 to 110 cm thick and contain a loose framework of in-place Striatifera. Articulat- ed individuals rest upon one another in a convex-downward 154 Rodney Watkins orientation (Figure 4A) and are attached by cementing spines. Growth asymmetry caused by crowding is common, and shells range from juveniles a few mm in size to adults 18 cm in length. These beds contain 28 to 58% Striatifera and 33 to 59% micrite and microspar matrix. Small encrusta- tions of Tubiphytes are present on Striatifera (Figure 5A) and form <1 to 14% of sediment volume. Other skeletal taxa are mainly matrix-supported and scattered between the large productoids ; they form <1 to 10% of sediment volume and 100 DEBCENT NE TATA) CKEIETAI MATERIA © PERCENT O 0 AL OKELEIAL MAIERIA | = PARALLEL LAMINATION CROSS STRATIFICATION STRIATIFERA IN GROWTH POSITION (SEE A ABOVE) IFERA FRAGMENTS SEE B ABOVE Figure 4. A. Striatifera in growth position. B. Rede- posited Striatifera valves and fragments. C. Occurrence of Striatifera biostromes in limestone of the Baird Formation at Tom Dow Creek ; see Watkins (1993a) for photos and location of this section. include crinozoans, foraminifers, small brachiopods, gas- tropods, corals, echinoids, and bivalves (Watkins, 1973). Beds with in-place productoids are interbedded with erosively based packstones that contain sorted, horizontally stratified Striatifera valves and fragments (Figure 4B). These two lithologies, which form horizons up to 3m thick (Figure 4C), were deposited in a moderate to high energy, bank- edge setting (Watkins, 1993a). Donezella biostromes Boundstone, packstone, and grainstone beds with abun- dant Donezella lutugini Maslov occur in Bashkirian lime- stones of the Baird Formation (Figure 3). Mamet (1991) placed Donezella and similar genera in the algal group Palaeosiphonocladales, but they have also been interpreted as sponges (Termier et al., 1977) and possible foraminifers (Riding, 1977). Mamet et al. (1987) interpreted the tubules of Donezella as branching thalli that stood upright above the bottom and functioned as sediment baffles. However, a sediment-binding habit for donezellids is also possible (Davies and Nassichuck, 1988). Massive beds from 35 to 120 cm thick contain 25 to 30% Donezella as an open-branching network of septate tubules 0.08 to 0.27 mm in diameter. The tubule network is partly contained in micrite (18-55% of sediment volume) and partly encloses spaces to 3.5 mm in size that consist of sparite (6 to 30%) and pelloidal grainstone (14-25%). Fragments of echinoderms, bryozoans, foraminifers, and monaxial spicules occur in the micrite matrix, and areas of Tubiphytes up to 1.3 mm in size encrust Donezella tubules. These beds are interpreted as boundstone. Their texture and fabric are very similar to beresellid-donezellid boundstone in Bashkirian to early Moscovian reefs in the Canadian Arctic (Davies and Nassichuk, 1988). Massive to cross-stratified beds of grainstone and pack- stone are 30 to 105 cm thick and contain 60 to 70% broken Donezella tubules (Figure 5C), 18 to 34% sparite or micrite matrix, and 1 to 8% other bioclasts, including Komia, Tubi- phytes, echinoderms, foraminifers, bryozoans, brachiopods, and ostracods. Tubule fragments are 8mm or less in length, and in some beds they show a parallel alignment of long axes. Other bioclasts, which reach 10 mm in size, are dispersed and often abraded. These beds represent sedi- ment derived from Donezella boundstone, and they formed in moderate to high energy, bank and bank-edge settings. Tubiphytes biostromes Tubiphytes is an encrustor that has been interpreted as a cyanobacterium, alga, foraminifer, sponge, or metazoan of uncertain affinity (Riding and Guo, 1992). It consists of an outer envelope of dark, fine-grained calcite and internal tubules. Senowbari-Daryan and Flügel (1993) recognized only the envelope as Tubiphytes and considered the internal tubules as separate, overgrown organisms. Grainstones dominated by Tubiphytes obscurus Maslov occur in Bashkir- ian limestones of the Baird Formation and Wolfcampian zones A, B and G of the McCloud Limestone (Figures 3, 6). Upper Paleozoic biostromes in California 155 In the bank facies of Bashkirian limestones, Tubiphytes grainstone forms massive to cross-stratified beds 30 to 140 cm thick. In the slope facies of these limestones, Tubi- phytes grainstone and packstone form 10-to-30-cm-thick beds that include normal grading and small-scale cross- lamination (Figure 3). Wolfcampian Tubiphytes grainstone forms isolated, massive beds 0.4 to 5 m thick within platform successions of thick-bedded crinoid packstone, fusulinid packstone, and skeletal packstone (Figure 6). In Wolf- campian slope deposits at McCloud Bridge (fusulind zone A of Skinner and Wilde, 1965), Tubiphytes grainstone is inter- bedded with limestone conglomerate and forms 10-to-60- cm-thick beds that include small-scale cross-lamination, horizontal lamination, and normal grading. At Tombstone Mountain, pebbles to small boulders of Tubiphytes grain- stone are abundant in limestone conglomerates of fusulinid zone G. The grainstones contain 43 to 80% Tubiphytes (Figure 5E) and 11 to 38% sparite to microspar matrix. Tubiphytes grains range from 0.3 to 1.5 mm, with a maximum size of 5 mm. Abrasion and rounding are common, particularly among smaller Tubiphytes grains that contain no other bioclasts. Larger Tubiphytes grains contain nuclei of small skeletal fragments or envelop and bind together several bioclasts. Other bioclasts, which include echinoderms, fo- raminifers, corals, bryozoans, brachiopods, and ostracods, reach 10 mm in size and form 1 to 19% of sediment volume. Permian beds also include the dasycladacean Epimastopora and indeterminate phylloid algae. The grainstone beds indicate abundant Tubiphytes growth in shallow, high-energy settings where the volume of binders exceeded that of encrusted skeletal grains. Although small areas of Tubiphytes boundstone occur within skeletal pack- stone, no Tubiphytes bed with a complete boundstone fabric has been observed. This may indicate that Tubiphytes crusts were more or less continuously reworked as they formed. Kershaw (1994), in a classification of biostrome types, noted that not all biostromes consist of in situ skele- tons. In Kershaw’s classification, the Tubiphytes grainstone beds can be considered as “parabiostromes,” which consist largely of reworked biostrome-formers, with 20% or less in situ material. Much of this sediment was also redeposited on slope aprons bordering bank and platform margins. Phylloid biostromes Phylloid algae are a morphological group of leaf-like genera that may include both red and green algae (Riding and Guo, 1991). In Late Paleozoic reefs and biostromes, their functional role included sediment baffling and volumi- nous production of skeletal particles (Toomey and Babcock, 1983). Phylloid packstone occurs as two 20-cm-thick beds in a single Visean/Serpukhovian limestone lens in the Baird Formation (Watkins, 1993a). Baird phylloids (Figure 5B) are recrystallized and generically indeterminate. In the Wolf- campian McCloud Limestone, phylloid packstone forms massive beds 0.3 to 4.5m thick in platform successions (Figure 6). In McCloud slope deposits, gravity-displaced phylloid packstone occurs as clasts in limestone conglomer- ate and thin beds with erosional bases and normal grading. Slope deposits also include less common, massive beds to 80 cm thick that represent in-place biostromes. McCloud phylloids include Eugonophylium sp., but specimens in most samples are too recrystallized for identification. Packstones in the McCloud Limestone include 24 to 43% phylloids (Figure 5D) and 42 to 66% micrite and microspar matrix. Phylloid plates are 2 to 18mm long, variably ori- ented, and closely to loosely packed. Edges of plates often appear broken but are unabraded. Tubiphytes forms <1 to 9% of sediment volume and occurs as loose grains and encrustations up to 4mm long on phylloid plates. Spiror- bids, fenestellid holdfasts, other bryozoans, and tetrataxiid foraminifers also encrust phylloids. Other bioclasts form 6 to 14% of sediment volume and are scattered, mostly matrix- supported, and mainly less than 5 mm in size. They include Palaeoaplysina, Epimastopora, bryozoans, foraminifers, echinoderms, gastropods, brachiopods, ostracods, and corals. Palaeoaplysina biostromes The enigmatic genus Palaeoaplysina, which consists of thin calcareous plates with an internal canal system and cellular structure, has features in common with hydrozoans, sponges, and algae (Davies and Nassichuk, 1973). Palaeo- aplysina is an important reef and biostrome former, but its mode of life is uncertain (Beauchamp et al., 1988). Breunin- ger (1976) inferred a binding habit for the plates, but Davies and Nassichuk (1973) and Watkins and Wilson (1989) presented evidence for an erect, frond-like growth habit. Palaeoaplysina laminaeformis Krotov is locally common in the Wolfcampian McCloud Limestone (Figure 6). In the platform facies of the McCloud, massive beds of Palaeo- aplysina wackestone to packstone are 0.7 to 2.2m thick. These beds occur both as isolated units within successions of skeletal wackestones, packstones, and grainstones, and they are also interbedded with phylloid packstones as composite biostromal horizons over 4 m thick (Watkins and Wilson, 1989). McCloud slope deposits with limestone conglomerates also include common Palaeoaplysina beds (Watkins, 1993b). Massive Palaeoaplysina wackestone to packstone beds from 0.5 to 3m thick are identical to those in the platform facies, and they are interpreted as in place biostromes of slope aprons. Less common, redeposited beds of Palaeoaplysina packstone are 10 to 30 cm thick and have loaded bases and ripple-laminated tops. Beds of intergrading wackestone to packstone consist of 23 to 49% Palaeoaplysina (Figure 5F) and 38 to 69% micrite and microspar matrix. Plates of Palaeoaplysina reach 20 cm long, are mainly oriented parallel to bedding, and range from loosely to closely packed. Encrustors on Palaeoaplysina include Tubiphytes, which forms <1 to 4% of sediment volume, as well as spirorbids and bryozoans. Other bio- clasts, which form 3 to 11% of sediment volume, include phylloid algae, Epimastopora, echinoderms, foraminifers, corals, bryozoans, brachiopods, gastropods, bivalves, and ostracods. Rodney Watkins Upper Paleozoic biostromes in California 157 Palaeoaplysina Phylloids a | ea DH 1-4: PERCENT OF TOTAL SEDIMENT VOLUME BIOSTROMAL DEPOSITS: — in-place biostrome -- reworked biostromal sediment = Qravity-displaced biostromal sediment PLATFORM PLATFORM MARGIN * ZONE [ | M&W - Mudstone & Wackestone P -Packstone; G - Grainstone; CGL -Limestone conglomerate | = Limestone Figure 6. Biostrome occurrence in the Lower Permian McCloud Limestone at McCloud Bridge ; see Watkins (1993b) for location, details of nonbiostromal lithologies, and bed-by bed logs of parts of the section. + Wolfcampian fusulinid zones of Skinner & Wilde (1965) Argillaceous limestone Volcaniclastic sediments Biogeographic and sedimentary relations of biostrome formers Three intervals of Late Paleozoic carbonate deposition in the eastern Klamath terrane were accompanied by bio- strome formation. Biostromal taxa appear at or near the base of each carbonate horizon and range throughout their entire thicknesses ; they have not been recorded through intervening clastic deposits. This suggests three separate invasions of the terrane by biostromal communities. Biostromes were poorly developed during the Visean/ Serpukhovian interval of carbonate deposition. The bra- chiopod Striatifera formed beds with a loose framework structure in several limestone lenses. However, Striatifera beds are not present in all lenses of this age (Watkins, 1993a), and their level of binding and sediment production was much less than those of other biostromes. Striatifera probably arrived in the eKt from the east, as it is a Tethyan genus that occurs in North Africa, Western Europe, Russia, Kazakhstan, China, and Japan (Muir-Wood and Cooper, 1960; Gordon and Dutro, 1993). Phylloid algae, which dominate two beds in one limestone lens, had only a limited role in sediment production, and their occurrence in the Baird Formation predates their Late Carboniferous rise as important producers of carbonate sediment (Chuvashov and Riding, 1984). The binder Tubiphytes is a minor constituent of the Visean/Serpukhovian biostromes, where its occur- rence also predates its attainment of global abundance. Bashkirian limestones of the eKt record the return of Tubiphytes and the appearance of Donezella as important biostrome formers. Tubiphytes grainstone forms up to 50% of the thickness of bank sections, and redeposited beds of Tubiphytes form up to 40% of sections deposited as slope aprons. The Bashkirian occurrence of Tubiphytes grain- stones in the eKt corresponds to its rise in abundance during the Late Carboniferous, when it attained a cosmopolitan distribution as both a major and accessory reef and bio- strome former (Chuvashov and Riding, 1984 ; Mamet, 1991 ; Senowbari-Daryan and Flugel, 1993). Donezella beds also form up to 50% of Bashkirian bank sections in the eKt. The Bashkirian/Moscovian was the temporal acme of Donezella as a sediment producer, and it forms reefs and biostromes of this age in North Africa, Eurasia, and North America (Mamet, 1991). Although phylloid algae were important and widely distributed reef and biostrome formers during the Late Carboniferous (Chuvashov and Riding, 1984 ; Mamet, 1991), they have not been observed in Bashkirian limestones of the Baird Formation. Biostromes played a minor role in the constuction of Wolfcampian carbonate platforms in the eKt. Beds dominated by Tubiphytes, phylloid algae and Palaeoaplysina form less than 10% of the thickness of platform sections. Lack of importance of biostromes and absence of reefs on McCloud platforms may be due to very high rates of subsi- dence and absence of well-defined platform margins (Wat- kins, 1993b). Tubiphytes and phylloids had a cosmopolitan distribution as important reef and biostrome formers in the Early Permian (Chuvashov and Riding, 1984; Riding and Guo, 1991; Senowbari-Daryan and Flugel, 1993). Palaeo- Figure5. A. Detail of Striatifera bed showing small encrustations of Tubiphytes (t) on Striatifera valves (s), Baird Formation, Tom Dow Creek. B. Phylloid packstone, Baird Formation, North Fork. C. Donezella grainstone, Baird Formation, Kabyai Creek. D. Phylloid packstone, McCloud Limestone, McCloud Bridge. Tombstone Mountain. F. Palaeoaplysina packstone, McCloud Limestone, McCloud Bridge. E. Tubiphytes grainstone, McCloud Limestone, All scale bars are 2 mm. aplysina first appears in the Middle Pennsylvanian of Utah, and by the Wolfcampian it is present as a major reef and biostrome former in a belt around the northern margin of Laurentia, including occurrences in Idaho, British Columbia, the Canadian Arctic, Svalbard, and the Urals (Ritter and Morris, 1997). Palaeoaplysina is also known from the Akiyo- shi terrane of Japan (Machiyama, 1991). Early Permian Palaeoaplysina buildups appear to have had a relatively wide environmental range, occurring in the Canadian Arctic from inner shelf to upper slope settings (Beauchamp et al. 1988). This relation is also evident in the McCloud Limestone, where Palaeoaplysina biostromes are present in both platform and slope deposits. McCloud slope deposits consist of alternations of thin-bedded argillaceous limestones and horizons with limestone conglomerates (Fig- ure 6). Palaeoaplysina biostromes form 15 to 45% of the thickness of conglomeratic horizons. Occurrence of Palaeoaplysina biostromes on tops of conglomerates, as well as on volcaniclastic breccia at the very base of the McCloud Limestone (Watkins, 1993b, fig. 4), suggest a role as a pioneer community among carbonate sediment producers. Comparison of biostromes and shelf-mud biofacies Paleoecological aspects of the biostromes can be best understood by comparison with contemporaneous shelf-mud biofacies of the eKt (Figure 7). The shelf biofacies occur in bioturbated, clastic and carbonate muds of Visean/Serpuk- hovian to early Guadelupian age (Coogan, 1960 ; Watkins, 1973; Yancey and Hanger, 1985). Echinoderms (mainly crinoids) form 50-70% of skeletal material in these biofacies, followed by brachiopods (4-36%), bryozoans (3-13%), for- aminifers (1-11%), and molluscs, corals, and minor groups Rodney Watkins brachiopod guilds, and a gastropod “superguild” include most of their macrofaunal species. Species data for echinoderms, which occur as disarticulated ossicles, are not available. In contrast, all five types of biostromes are dominated by a single binding, baffling, or framebuilding species that forms over 70% of skeletal material (Figure 2). Although several such species may cooccur within a biostrome, only one predominates. For example, Tubiphytes, phylloids, and Palaeoaplysina commonly occur together in Lower Permian beds, but in each case one of these taxa is clearly dominant (Figure 6). Dweller guilds generally form 20% or less of skeletal material in beds, and their composition is similar in all five types of biostromes. Crinozoans and foraminifers are the most common dweller taxa (Figure 2), and small amounts of skeletal material (usually 2% or less each, except for Striatifera biostromes) are represented by brachiopods, bryozoans, molluscs, corals, annelids, and ostracods. Bulk collections of silicified specimens from Striatifera and phylloid biostromes permit a more detailed consideration of dweller taxa (foraminifers, ostracods, and echinoderms have not been studied and are not included in this discussion or in plots of species diversity in Figures 7 and 8). The most diverse groups among dweller taxa are brachiopods and gastropods, followed in decreasing order by bryozoans, bivalves, corals, rostroconchs, and annelids. The composi- tion and species diversity of dweller taxa in the biostromes is nearly identical to that in carbonate shelf-mud biofacies of Bashkirian and Wolfcampian age (Figure 7). In the Wolf- campian, the same species occur in shelf-mud biofacies, phylloid biostromes, and Palaeoaplysina biostromes (Watkins and Wilson, 1989). These relations suggest that most dweller taxa in the biostromes were not specialized for these (<1-10%). Four bivalve guilds, three bryozoan guilds, two habitats, but were immigrants from level-bottom, carbonate wm A NA we iP [7 1 2 5255 en SSL TP |MACROFAUNAL TEE aeoure era ot SQ 5 025 Z| 2 2.8 8818| M Mealesig|Al0| GUILDS 4 corals, bryozoans, (>) = > Sea pd EHEN 12] 2 1„>lz>lö2lögl | E CLASTIC brachiopods, molluscs, = Q2 = 23 EN „NIENIZO | 9 15218215555 2 annelids & trilobites Sao 5020120125 ARE ENT ee] |9 SHELF MUD SAMPLE * , = FE se Fi SE oe 2 222 gelte ig BIOFACIES BIOSTROME SAMPLE # H 5 (arse tener tion lips Beedle Lou luulo O jou Lalo] + TE T Ro AA f 0 3 & ar | l | 1[X| 1] 1] 116 1[4|2 | XV | X | Shelf Mud Biofacies 5 Guadelupian week K t EE En 111151313118 2215 112 4X]/2] Shelf Mud Biofacies 4 : * 4 1112111316 171212] 2X 1 X| [PHYLLOID BIOSTROME! Wolfcampian ett | = 1) 1} 3) 3) 2/14} [28/2 | Lele X | 2|1 Shelf Mud Biofacies 3 Bashkirian * * < 11213] ı 117110. 15 18177413 SL) Shelf Mud Biofacies 2 3 ek 19 11713] 1] 2] 1] 1x] 1] | Shelf Mud Biofacies 1 Serpukhovian/ * x l 1131116 FIIXPIBEN 1 FHYLLOD BIOSTROME HT Visean Kr x ee Of total skeletal 1 11x] 1 312 6 < X 1 EDTTX | Srriarifera BIOSTROMEHT] tok Wr mud biofacies raw number of species Figure 7. Faunal comparison of Upper Paleozoic biostromes and shelf-mud biofacies of the eastern Klamath terrane. Biofacies are arranged vertically by four intervals of time, but this plot is not a stratigraphic section. For the Serpukhovian/ Visean, relative stratigraphic position of phylloid and Striatifera biostromes is not known, and both overlap in stratigraphic range with shelf-mud biofacies. For the Wolfcampian, plotting of the phylloid biostrome below the shelf-mud biofacies is arbitrary, as these biotas are interbedded. Shelf-mud biofacies and number of specimens in samples (n) are as follows : 1-Dorsoscy- phus association, Bragdon Formation, n —442 ; 2-Rugosochonetes association, Baird Formation, n=1203 ; 3-Lissomarginifera association, Hirz Mountain Limestone Member of Baird Formation, n=1734 ; 4-“Crurithyris” (= 1663 ; 5-Anidanthus-Spiriferella faunule, n=435. Sample sizes for biostromes are as follows : Wolfcampian Limestone, n= Cruricella) association, McCloud phylloid, n=472 ; Serpukhovian/Visean phylloid, n=2496 ; Striatifera, n=1261. Upper Paleozoic biostromes in California 159 Al T Ar = T en ar ae Silurian reefs | Il o! es Permian shelf mud biofacies 4 | 40 F LAS ee PRE ee | er Bern. RER | = | Sia Permian phylloid biostrome | [ 30 F x ————~ Carboniferous shelf mud biofacies 2 SS 4 a ee a et nn "TL Carboniferous phylloid biostromes 7 | LE BER er | ER i N Il 20 — Permian phylloid BIO SLOT oe At Se ER A 7 L 10 R EEE Neri ai Se ice toe eg Striatifera biostrome 4 (\ - Se = Sriatifera biostrome | ea Er ñ L L 1 1 L 1 O 100 200 300 400 500 600 700 800 900 IN Doin’ FD URLS NN Lo COLON Es Figure 8. Rarefaction curves for Upper Paleozoic biostromes and shelf-mud biofacies of the eastern Klamath terrane. Also shown for comparison are two samples from Silurian reefs (Watkins, 1996). Data are for corals, bryozoans, brachiopods, molluscs, annelids and trilobites. mud environments. Trends in species diversity Following the Late Devonian extinctions, the global num- ber of marine families increased rapidly, reaching a stable level near the end of the Early Carboniferous that was maintained for the rest of the Paleozoic (Sepkoski, 1992). This pattern of Late Paleozoic stasis is also shown by species diversity of Visean/Serpukhovian to early Guadelupian shelf-mud biofacies of the eKt, as measured by Hand rarefaction (Figures 7,8). Reef biotas were much slower to recover from the Late Devonian extinctions, and complex reef communities were not reestablished until the Middle Permian (Sheehan, 1985 ; Copper, 1988). This slow recovery is also suggested by species diversity data from Upper Paleozoic biostromes in the eKt. Average species- diversity in eKt Carboniferous biostromes is less than that of shelf-mud biofacies. Species diversity in phylloid bio- stromes increased by the Early Permian, when they attained a diversity equivalent to that of carbonate shelf-mud biofacies (Figures 7,8). Even so, diversity of the Early Permian biostromes did not reach the levels of reefs that existed before the Late Devonian extinctions, as shown by rarefaction curves for Silurian reefs (Figure 8). Conclusions Three intervals of Late Paleozoic volcanic quiescense and carbonate deposition in the eastern Klamath terrane were accompanied by development of biostromal communities. Except for loosely cemented productoid brachiopods, framebuilders are absent, and bafflers and binders of algal or problematic affinity are the dominant biostrome formers. Stratigraphic ranges and peaks in abundance of eKt bios- tromal taxa are like their occurrences elsewhere. Biostrome formers include a mixture of cosmopolitan, Tethyan and Laurentian affinities. An increase in species diversity from Early Carboniferous to Early Permian biostromes in the eKt probably reflects global recovery of reef biotas following the Late Devonian extinctions. Acknowledgments Fieldwork was supported by the Petroleum Research Fund of the American Chemical Society (Grant 19845-B2) and assisted by K.J. Bergk. P.S. Mayer provided instruction in computer drafting, and J. Petrella assisted with photomicro- graphy and work on phylloid biostrome samples. Oliver Weidlich very helpfully reviewed the manuscript, and photos were printed by J. Peterson. References cited Albers, J.P. and Bain, J.H.C., 1985: Regional setting and new information on some critical geological features of the West Shasta district, California. Economic Geol- ogy, vol. 80, p. 2072-2091. Beauchamp, B., Davies, GR. and Nassichuk, W.W., 1988 : Upper Carboniferous to Lower Permian Palaeoaplysina- phylloid algal buildups, Canadian Arctic Archipelago. In, Geldsetzer, H.H.J., James, N.P. and Tebbutt, G.E. eds., Reefs, Canada and Adjacent Areas. Canadian Society of Petroleum Geologists Memoir 13, p. 590-599. Belasky, P. and Runnegar, B., 1994: Permian longitudes of Wrangellia, Stikinia, and eastern Klamath terranes based on coral biogeography. Geology, vol. 22, p. 1095-1098. Breuninger, R.H., 1976: Palaeoaplysina (hydrozoan ?) car- bonate buildups from Upper Paleozoic of Idaho. 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Sheehan, P.M., 1985: Reefs are not so different-they follow the evolutionary pattern of level-bottom communities. Geology, vol. 13, p. 46-49. Skinner, J.W. and Wilde, G.W., 1965: Permian biostratigra- phy and fusulinid faunas of the Shasta Lake area, northern California. University of Kansas Paleontological Contributions, Protozoa, article 6, 98 p. Soja, C.M., 1996: Island-arc carbonates : Characterization and recognition in the ancient geologic record. Earth- Science Reviews, vol. 41, p. 31-65. Stevens, C.H., Miller, M.M. and Nestell, M., 1987: A new Permian waagenophyllid coral from the Klamath Moun- tains, California. Journal of Paleontology, vol. 61, p. 690-699. Stevens, C.H., Yancey, T.E. and Hanger, R.A., 1990 : Signifi- Upper Paleozoic biostromes in California 161 cance of the provincial signature of Early Permian faunas of the eastern Klamath terrane. Geological Society of America Special Paper 255, p. 201-218. 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Watkins, R., 1993a : Carbonate sedimentation in a volcani- clastic arc setting : Lower Carboniferous limestones of the eastern Klamath terrane, California. Journal of Sedimentary Petrolology, vol. 63, p. 966-973. Watkins, R., 1993b : Permian carbonate platform develop- ment in an island-arc setting, eastern Klamath terrane, California. Journal of Geology, vol. 101, p. 659-666. Watkins, R., 1993c : The Silurian (Wenlockian) reef fauna of southeastern Wisconsin. Palaios, vol. 8, p. 325-338. Watkins, R., 1996: Skeletal composition of Silurian benthic marine faunas. Palaios, vol. 11, p. 550-558. Watkins, R. and Wilson, E.C., 1989: Paleoecologic and biogeographic significance of the biostromal organism Palaeoaplysina in the Lower Permian McCloud Lime- stone, eastern Klamath Mountains, California. Palaios, vol. 4, p. 181-192. Watkins, R., Wilson, E.C. and Hanger, R.A., 1989 : Carbonif- erous and Permian biogeography of the eastern Klamath terrane, California. Geological Society of America Abstracts with Programs, vol. 21, p. 156. Yancey, T.E. and Hanger, R.A., 1985: Biotic replacement along a ramp gradient on a Permian island arc, McCloud Fm., California. Geological Society of America Abstracts with Programs, vol.17, p. 756. Paleontological Research, vol. 3, no. 3, pp. 162-172, 5 Figs., September 30, 1999 © by the Palaeontological Society of Japan The turrilitid ammonoid Mariella from Hokkaido — Part 2 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin —— LXXXVI) TATSURO MATSUMOTO! and YOSHITARO KAWASHITA’ ‘c/o Kyushu University 33, Fukuoka 812-8581, Japan °2-179, Tomatsu Chiyoda, Mikasa 068-2134, Japan Received 23 February 1999; Revised manuscript accepted 26 April 1999 Abstract. The following five taxa of the genus Mariella of the Turrilitidae from the Upper Albian and Lower Cenomanian of Hokkaido are described: (1) M. (Mariella) bergeri (Brongniart, 1822), (2) M.(M.) aff. bergeri (Brongniart), (3) M.(M.) miliaris (Pictet and Campiche, 1861), (4) M.(M.) cf. carrancoi (Böse, 1923) and (5) M.(M.) gallienii (Boule, Lemoine and Thévenin, 1907). The present study gives new or revised information as to the taxonomy and stratigraphic occurrences of these species. Key words: Late Albian-early Cenomanian, Mariella (Mariella) bergeri, M.(M.) carrancoi, M. (M.) gallienii, M.(M.) miliaris Introduction In Part1 Matsumoto et al. (1999) described three well defined species of Mariella from the Lower Cenomanian of the Soeushinai area (northwestern Hokkaido). In Part 2 we continue to describe some more species (five taxa) from the Upper Albian and Lower Cenomanian of Hokkaido. The material is mostly from the Soeushinai area, except for a supplementary specimen from the Shuparo | =Shuyubari | area of the Yubari Mountains (central Hokkaido). With respect to the location and stratigraphic assignment of the material from the Soeushinai area, readers may refer to the route maps in the two papers by Nishida et al. (1996, figs. 3-5 ; 1997, fig. 11) and for more information to the locality guide and maps given by Matsumoto and Nishida (1999, figs. 6, 7) as an Appendix to Part1. The locality in the Shuparo area will be identified more specifically in the description of the species concerned. The following symbols are used for the repositories of the specimens described in this paper. GK: Type room, Department of Earth and Planetary Sciences, Kyushu University, Fukuoka GS : Geological Collections, Faculty of Culture and Edu- cation, Saga University, Saga Palaeontological descriptions (Continued from Part 1) Mariella (Mariella) bergeri (Brongniart, 1822) Figure 1 Turrilites bergeri Brongniart, 1822, p. 395, pl. 7, fig. 3. Mariella bergeri (Brongniart). Spath, 1937, p. 510, pl. 57, fig. 28; text-fig. 178; Drushchits, 1960, p.266, pl.12, figs. 2,3; Seyed-Emami, 1982, p. 419, pl. 7, figs. 11, 12. Mariella (Mariella) bergeri (Brongniart). Chiriac, 1960, p. 6, pl. 1, figs. 10, 11; Klinger and Kennedy, 1978, p.28, text-fig. 6E (only); Atabekian, 1985, p. 27, pl. 2, figs. 4,5; pl. 3, figs. 1- 11; pl. 4, figs. 1-7 ; Kennedy, 1996, in Gale et al., p. 583, figs. 160, 28a, b, i, j, |, 0, p ; 29h, i, m. Paraturrilites (Bergericeras) bergeri (Brongniart). Wiedmann and Dieni, 1968, p. 80, pl. 7, fig. 5; pl. 9, figs. 2, 5. Turrilites (Bergericeras) bergeri bergeri (Brongniart). 1979, p. 40, pl. 8, figs. 12, 14, 15, 17. Scholz, Holotype.—The original of Turrilites bergeri Brongniart, 1822, pl. 7, fig. 3 (by monotypy). Material.—GS. G183 (Figure 1-1, 2) collected by Y.K. on 25 September 1995 at loc. R803 and GS. G184 (Figure 1-3) collected by Y.K. and others on 15 August 1996 at loc. R813, both in situ from the upper part of the Member My2, (mud- stone with frequently intercalated laminae and beds of sandstone), well exposed on the floor of the Sounnai River (for its location see fig.6 in Part1); GK. H8512, a small specimen collected by Jun Aizawa and T.M. on 14 August 1998 at loc. R8005 (close to R803) from a lenticular layer of sandstone in the Member My2. Description.—Each of the three specimens is a fragmen- tary whorl of half ammonoid preservation. They can be regarded as representing whorls of roughly successive growth stages. The small, unillustrated GK. H8512 pre- serves shelly matter, showing small tubercles in four rows at Mariella from Hokkaido—Part 2 163 Figure 1. Mariella (Mariella) bergeri (Brongniart). 1. GS. G183, slightly oblique, lateral view showing the sedimentary structure of the host rock in the left part, x1. 2. GS. G183, upside-down lateral view, showing the whole part of the preserved flank, 1.2. 3. GS.G184, upside-down lateral view, <1. (Photos by N. Egashira without whitening.) subequal intervals. The tubercles are connected by weak ribs. GS. G183, about 22 mm in height, is somewhat deformed. It shows three rows of transversely elongated tubercles at equal intervals on the flank. The tubercles are aligned obliquely on weak ribs. Eleven tubercles are counted on the exposed part of the flank, showing ornamentation of moderate density. There is an extra tubercle in the upper row, but it is finer and its upwardly extended rib is faint (see the upper left part of Figure 1-1 or the lower right part of Figure 1-2). As the specimen is an abraded internal mould, the tubercles are not pointed. The tubercles of the fourth row are not exposed on the flank. GS. G184 is comparatively large, 32mm in whorl height and 65mm in diameter. It is in a nodule and slightly deformed. Shell material is preserved for the most part. The exposed whorl face is subrounded, with a broadly convex main flank and a well rounded upper shoulder. The tubercles are in four rows. They are uniformly spinose and conical at their base. The three rows on the main flank are equidistant ; the fourth row is closer to the third at the base. The heads of the spines are, however, nearly equidistant, since the first spine extends obliquely upward, the second laterally, the third slightly downward and the fourth vertically downward (see Figure 1-3, in which the whorl is set upside down). The tubercles are connected transversely by low ribs in sowewhat oblique orientation and those of the first row extend upward to the ribs. Some of the ribs appear to be doubled between the tubercles of adjacent rows. Comparison.—The small specimen (GK. H8512) is compa- rable with a young specimen illustrated by Atabekian (1985, pl. 3, fig. 1). The second specimen (GS. G183) is comparable with a middle-aged whorl of a figured example (e.g., Atabe- kian, 1985, pl. 4, fig. 6). The third specimen (GS. G184) is roughly as large as the preserved last whorl of such exam- ples as figured by Scholz (1979, pl. 8, figs. 12, 14, 15), but the uniform spinosity of its ornamentation seems to be peculiar. It should be noted, however, that on a portion of this speci- men where the shell layer is stripped off, there are no spines and the tubercles are expressed as transversely elongated elavations like those of GS. G183. Judging from the above observations, the described speci- mens can be identified with M. (M.) bergeri, although they are incomplete. Occurrence.—As for material. The upper part of the Member My2 is regarded as the uppermost Albian (Nishida et al., 1996, p. 93; Matsumoto and Nishida, 1999, p. 116). Discussion.—Klinger and Kennedy (1978, p. 28, pl. 7, figs. C,D; text-fig. 7A) have recorded M. (M.) cf. bergeri from the “Lower Cenomanian |” of Zululand (South Africa). It shows a lower apical angle and its lower three rows of tubercles are according to those authors equidistant. It is possibly an example of M.(M.) dorsetensis (Spath) from South Africa, whereas “M. (M.) dorsetensis” of Klinger and Kennedy (1978, p.31, pl.7, fig. F; text-figs. 3A, 8A) is certainly M.(M.) lewesiensis (Spath). Mariella (Mariella) acanthotuberculata Klinger and Kennedy (1978, p. 30, pl. 7, figs. C, D; text-fig. 7A), from the “Lower Cenomanian Il” of Zululand, has spinose tubercles in four rows on every whorl, but its ribs and tubercles are relatively coarser and less numerous than those of our specimen (GS. G184). Moreover, it shows a higher apical angle (50°-60') and it is different in whorl shape from any example of M. (M.) bergeri, for its whorls show a quadrate section and a much lower ratio of height to diameter. Incidentally, the described specimens of M. (M.) acanthotuberculata are tiny but beauti- fully preserved. Here again the spinosity is finely shown when the shell is well preserved. 164 Tatsuro Matsumoto and Yoshitaro Kawashita Mariella (Mariella) aff. bergeri (Brongniart, 1822) Figures 2; 3-1 Material. A single specimen, GS. G185 (Figure 2), col- lected by Y.K. on 29 June 1992 from one of the boulders (p4) at loc. R520 of the East Suribachi-zawa (for the location see Matsumoto and Nishida, 1999, fig. 6). It was probably de- rived from the basal part of the Member My3. Graysonites adkinsi Young was obtained from another boulder at R520. Description.—Shell is of moderate size, about 140 mm in tower height (total whorl height, including the inferred missing portion) and 55 mm in diameter of the last septate whorl. The rate of size increase between successive whorls is moderate, maintaining a value of 1.37. The apical angle is estimated at 42. The ratio between whorl height and diameter in the septate stage is constant at 0.43 (See Table 1). The exposed part of the whorl face is rounded in gross view. In more detail, a nearly flat but narrow space is recognized in the uppermost part of the whorl face. This slopes down gradually to the convex main flank, which then Figure 2. Mariella (Mariella) aff. bergeri (Brongniart). (Photos by N. Egashira without whitening.) slopes down inward toward the lower whorl seam. The whorl junction is thus deep and well marked. The siphuncle runs along the midline of the uppermost flat belt. Despite the regular shell shape in the septate stage, the last part (/.e., the body chamber) of this specimen is much distorted and curved upward. This aberrant shape is similar to that in certain species of Eubostrychoceras Matsumoto, 1967. However, whether it is an original character or a product of secondary deformation cannot be decided from this single specimen. There are three rows of tubercles on the exposed whorl face. The first row is somewhat above the middle of the flank, the second row is well below the midline and closer to the third row, which in turn runs slightly above or nearly along the lower whorl seam. These three rows tend to shift downward with growth. The tubercles of the fourth row are not observable from the outside. They probably lie on the unexposed lower whorl face. The tubercles increase in number with growth, from 24 in the preserved young whorl to 34 in the last septate whorl. Those of the two rows on the main flank are moderately coarse and strengthen with growth. The tubercles in the first row extend upward to B GS. G185, two lateral views, in which A is turned 180° to B, x1. Mariella from Hokkaido—Part 2 165 Figure 3. 1. Mariella (Mariella) aff. bergeri (Brongniart). and Campiche). GS. G186, lateral view, «11. (Photos by N. Egashira with whitening.) form distinct ribs which fade away onto the uppermost flat belt. The tubercles of the second row are conical and become slightly larger than those of the first row with growth. On the body chamber the tubercles of these two rows strengthen and become spinose. The spines of the tuber- cles in the second row are much elongated and sharply pointed terminally. The suture is observable here and there, although it is not traced completely. Measurements.—See Table 1. Comparison.—In gross view the septate part of this speci- men is similar to some specimens of Mariella (Mariella) bergeri (see list of synonymy in the preceding species). The apical GS. G185, lateral view, 14. 2. Mariella (Mariella) miliaris (Pictet Table 1. Measurements of Mariella (Mariella) aff. bergeri (Brongniart). Measured specimen: GS. G185 (Figure 2). Whorl (Order)* ist 2nd 3rd 4th 5th Diameter (in mm) 165 255 350 480 65.0 Height (in mm) (OL MOM ANSON 20:0. 28:0 Height/Diameter 45 43 43 42 43 Tubercles per whorl 24 26 28 30 33 * The 1st, 2nd, 3rd etc, on the line “Whorl” indicate the descending order of the whorl (=in an adapertural direction) within the preserved part of the specimen. 166 Tatsuro Matsumoto and Yoshitaro Kawashita angle of the former is certainly larger than the average of the latter, but it can be placed at the extreme end of the wide range of variation in the latter. The existence of a flat belt in the uppermost part of the exposed whorl face seems to be particular to this specimen, although the belt is narrow. The increase in the number of tubercles or ribs per whorl with growth from 24 in youth to 34 in the last septate stage may be characteristic of this taxon. This rib density is between that of M.(M.) bergeri and of M.(M.) miliaris (vide infra), but the ribs and tubercles are not so fine as those of M.(M.) miliaris, becoming rather coarser with growth. The strong tubercles on the flank in the adult whorl have promi- nent spines. This is another diagnostic feature of this specimen. If the ascending feature of the last part of the body chamber were an original character, it could be regard- ed as another diagnostic feature, but this should be con- firmed by additional material. To sum up, this specimen probably represents an early Cenomanian new species which was derived from typical M. (M.) bergeri of late Albian age. As only a single specimen from a boulder nodule is available, it would be better to call it provisionally Mariella (M.) aff. bergeri (Brongniart). Occurrence.—As for material. Discussion.— Turrilites spinosus Kossmat (1895, p. 142, pl. 20, fig. 3) | = Turrilites brazoensis of Stoliczka, 1866, p. 189, pl. 88, fig. 3, (non Roemer, 1852)|, from the lower Utatur Group of South India, has four rows of spinose tubercles. The original specimen is a large fragmentary whorl (probably body chamber) on which ribs are often bifurcated at the tubercle and some riblets are irregularly added. Certainly it has no affinity with the present taxon. It might be a Pseud- helicoceras, as Breistroffer (1947, p. 44) suggested. Mariella (Mariella) miliaris (Pictet and Campiche, 1861) Figures 3-2; 4-1,2 Turrilites bergeri Brongniart var. miliaris Pictet and Campiche, 1861, p. 136 ; 1862, pl. 58, fig. 5. Mariella miliaris (Pictet and Campiche). 57, figs. 25, 26, text-fig. 179. Mariella (Mariella) miliaris (Pictet and Campiche). Chiriac, 1960, p. 456, pl. 1, figs. 14-16 ; pl. 2, figs. 17-20; Renz, 1968, p. 88, pl. 18, fig. 10 ; text-figs. 31m, 32h ; Förster, 1975, p. 189, pl. 7, figs. 6; Klinger and Kennedy, 1978, p. 29, pl. 8, fig. J, text fig. SE ; Atabekian, 1985, p. 29, pl. 5, figs. 5-12, pl. 6, figs. 1 3; Wright and Kennedy, 1996, p. 333, pl. 100, fig. 28. Turrilites (Bergericeras) bergeri bergeri Brongniart. Scholz, 1979, p. 40 (pars), pl. 9, fig. 1 only. Spath, 1937, p. 514, pl. Holotype.—The original of Pictet and Campiche, 1861, p. 136 ; 1862, pl. 58, fig. 5 (reillustrated by Renz, 1968, pl. 18, fig. 10) (by monotypy). Material.—GS. G186 (Figures 3-2 and 4-1), obtained by Y.K. on 16 August 1982 from a transported nodule at loc. R575 of the Suribachi-zawa, probably derived from the Member Mys. GS. G187 (half ammonoid preservation) found by Y.K. on 31 July 1997 in a transported nodule at loc. R967 (for the location see Nishida et al., 1997, fig. 11) on the upper course of the River Kotanbetsu within the outcropping area of the Member My5. GS.G188 (Figure 4-2) (half ammonoid preser- vation) obtained by Y.K. on 18 October 1993 from a nodule in the second northern branch rivulet of the Kita-no-sawa, a tributary of the River Shuparo in the Yubari Mountains. It is inferred to have been derived from one of the Members Mc to Me of Kawabe et al. (1996, p.449, fig.4-3). These members correspond to units Ilc and Ild of Matsumoto (1942) and are referred to the lower part of the Cenomanian. Description —The three specimens are moderately large. They preserve several whorls. GS. G186 consists of four slightly distorted whorls with a low ratio of increase in diameter. Hence, the apical angle appears to be acute, although whorls of earlier growth stages are not preserved. In the two other specimens of middle to late growth stages, the ratio of increase in diameter is slightly larger than the above and the estimated apical angle would be about 25’, provided that their original total whorl height (=tower height) was about 200 mm. The exposed whorl face is semielliptical, although the main part of the flank is less convex in GS. G186 in compari- son with the two others. The contact between whorls is moderate, showing an impressed junction. Tubercles in four rows are moderately crowded and numerous, 36 per whorl in GS. G186 and 17 or 18 to half a whorl in GS. G188. They are disposed regularly ; those of the first row are placed some way above midflank and extend upward to the ribs which reach the upper whorl seam with decreasing intensity. The conical tubercles of the second row lie below midflank. The tubercles of the third row are somewhat smaller than the above and appear to be granular. The tubercles of the fourth row lie in the inter- whorl junction. They may be somewhat clavate. The tubercles of the three rows on the flank are disposed on an adaperturally displaced line, i.e., an approximate extension of the upper rib. The interval of the three rows on the flank slightly decreases downward. The fourth tubercle lies close to the third and the rib is bent at the lower whorl seam, running on the lower whorl surface with a gentle curvature toward the umbilicus. The suture is only partly exposed and hardly traced wholly. Measurements.—See Table 2. Comparison.—The holotype of this species is a piece of a whorl as shown by a photographic illustration of Renz (1968, pl. 18, fig. 10). It was distinguished as a variety from typical “Turrilites bergeri” by finer and denser ornament. Although M. miliaris was raised to the status of an independent species by Spath (1937, p. 514), the available material was not ample. More material was added by subsequent authors, especially by Chiriac (1960) from Eastern Europe and by Atabekian (1985) from Western Asia. Thus, it has become clear with time that this species shows a considerable extent of variation in morphological characters. The number of tubercles (or ribs) in each row is around 36 in our specimens. This is within the range of variation from 33 to 40 in the material of Atabekian (1985, p. 29). The apical angle is recorded as 42° in a British specimen (Wright and Kennedy, 1996, p. 333), whereas it is 35°, 30° and even 25 in some specimens from Western Asia (Atabekian, 1985, p.29). In this respect the described specimens from Hok- kaido can be regarded as examples with a comparatively Mariella from Hokkaido—Part 2 167 Figure 4. 1,2. Mariella (Mariella) miliaris (Pictet and Campiche). 1. GS. G186, lateral view (90° anticlockwise turned from the view of Figure 3-2), «1. view, “1.5. (Photos by N. Egashira without whitening.) smaller apical angle within the range of this species. Hitherto described specimens of this species from various regions of the world are rather small. Most of them are not adult. In fact, the two specimens figured by Atabekian (1985, pl. 5, fig. 5 ; pl. 6, fig. 1) appear to exemplify whorls of younger stages which can be succeeded developmentally by specimens such as ours which are of middle to late growth stages. The largest of the whorls measured by Atabekian (1985, p. 29) is 50 mm in diameter, but in GS. G188 (Figure 4-2) from Hokkaido the diameter of the whorl preceding the last is 62 mm. The last whorl (i.e., body chamber) of this shell is deformed, but it has an eroded remnant of the rostrum and, thus, represents an adult shell. 2. GS. G188, lateral view, «1. 3. Mariella (Mariella) cf. carrancoi (Böse). GK. H8507, lateral Occurrence.—As for material. Discussion.—The relationship between M. (M.) bergeri and M.(M.) miliaris has been discussed by previous authors. Morphologically and also stratigraphically they are intimate. They cannot be distinguished by the difference in apical angle, since the extent of variation in the angle is great in both species. The proportion of the height (H) to diameter (D) of a whorl is fairly constant in our specimens, 0.46 to 0.48 (See Table 2). This is the same as that of the holotype, in which D=37.5, H=18.0, H/D=0.48 on the basis of Renz’ (1968, pl. 18, fig. 10) illustration. A similar value can be estimated for the whorls of many, if not all, of the illustrations of less deformed specimens of M. (M.) bergeri (e.g., Renz, 1968, pl. 18, figs. 3, 4 ; 168 Tatsuro Matsumoto and Yoshitaro Kawashita Table 2. Measurements of Mariella (Mariella) miliaris (Pictet and Campiche). Whorl (Order)* ist 2nd Srd 4th Measured specimen: GS. G186 (Figure 4-1) Diameter (in mm) 31.0 35.2 39.2 44.0 Height (in mm) 14.2 16.8 18.7 = Height/Diameter 46 .48 48 = Tubercles per whorl 36 36 36 35 Measured specimen: GS. G188 (Figure 4-2) Diameter (in mm) 42.0 52.6 ~60.0 — Height (in mm) 19.5 25.2 28.0 31.5 Height/Diameter 46 .48 AT = Tubercles/half whorl 17 18 ~17 - *: as for Table1. —: apporoximate Atabekian, 1985, pl. 2, figs. 4, 5; pl. 3, fig. 9). This is another feature that shows the resemblance between the two species. A sole distinction between the two species is in the ornamentation, namely finer, denser and more numerous ribs and tubercles in M.(M.) miliaris in comparison with M. (M.) bergeri. In both species, however, there is a considerable variation even in this. The number of tubercles to a whorl is recorded to extend from 33 to 54 in M. (M.) miliaris against 25 to 30 in M. (M.) bergeri. Thus, the extent of variation in the number of tubercles appears to be continuous between the two taxa. A Statistical examination would give a clear solution of the problem. Stratigraphically M.(M.) miliaris has been recorded from the Upper Albian dispar Zone in many cases, but in England it is reported also from the Lower Cenomanian (Wright and Kennedy, 1996, p. 333). Our present material suggests, if not clearly indicates, the occurrence in the lower part of the Cenomanian in Hokkaido. Mariella (Mariella) cf. carrancoi (Böse, 1923) Figure 4-3 Compared. Turrilites carrancoi Böse. 1923, p. 147, pl. 10, figs. 25-31. Turrilites multipunctatus Böse, 1923, p. 154, pl. 10, figs. 48-58. Mariella (Mariella) carrancoi (Bose). Clark, 1965, p. 44, pl. 13, figs. 1-4, 7, 10. Lectotype.—IGM. 1076-C, figured by Clark, 1965, pl. 13, fig. 3 (designated by Clark, 1965, p. 44). Material.—GK. H8507 (Figure 3-3) and GK. H8508-H8511 from a transported nodule collected by Nishida and others on 20 August 1988 at loc. R449 of the upper reaches of the Suribachi-zawa (for the location see Matsumoto and Nishida, 1999, fig. 6). The nodule is inferred to have been derived from the Member My3 from its location and lithology, although the sandstones and mudstones in thin-bedded alternation like those of the Member My2 crop out narrowly between R456 and R460. Description.—The specimens are more or less incomplete ; six whorls are preserved in GK.H8507, three in H8508, two in H8509, slightly over one in H8510 and only one in H8511. They are small; the largest one, H8507, is about 30 mm in tower height and 17 mm in diameter of the last whorl. The apical angle is 43° in H8507 and H8508 but maybe some- what more acute in H8509. The whorl is subquadrate in section with a trapezoidal flank. The ratio of height to diameter in each whorl is very low, about 0.33 to 0.35 in H8507 and H8508, but it varies to some extent with growth and also between individuals (e.g., 0.42 in H8509). Whorls are tightly coiled and their junction is deep. The main part of the flank is ornamented by two rows of relatively coarse tubercles, with an apparent spiral groove between them. This feature is more pronounced on young whorls where these tubercles show nodular protuberances and are apparently crowded. The tubercles of the third row are disposed along the lower whorl seam. Those of the fourth row are on the lower whorl face and concealed by the succeeding whorl, unless the basal surface is exposed. The number of tubercles per whorl is 24 to 27. Ribs are scarcely discernible on the younger whorls, but on later whorls the tubercles of the first row extend shortly upward in riblike fashion, the tubercles of the second row are some- what transversely elongated as if connected with the tuber- cles of the third row, which in turn give rise to radial ribs on the lower face. The tubercles of the fourth row are tiny and each rests on arib. This feature is observable partly in GK. H8508 and impressed on the upper surface of GK. H8509. Suture (E/L saddle and L) is partly discernible on the flank of the middle-aged whorl in GK. H8507. Comparison.—The above-described specimens are rather peculiar to Japan, but they are well comparable with M. (M.) carrancoi (Bose), from the “Vraconian” of Zacatecas, Mexico, redefined by Clark (1965, p.44, pl.13, figs. 1-4, 7, 10). Although the absence of ribs is taken as a character of this species by Clark and also by Klinger and Kennedy (1978, p. 31), this is applied to the flank ornament of rather earlier growth stages. At least the riblike extension is observable even in the illustration of the lectotype (Clark, 1965, pl. 13, fig. 3) and more elongated ribs are discernible on the whorl of later growth stages in other specimens (e.g., Clark, 1965, pl. 13, figs.1,7 and 10). Even in our specimens the mode of lighting, especially its orientation, gives dissimilar appear- ances to this character. Some of the figures by Böse (1923, pl.10, figs. 25-31, 48-58) show variation in the ornament between individuals and also with growth. The low ratio between whorl height and diameter is another diagnostic character of this species. The lectotype, measured on the illustration (Clark, 1965, pl. 13, fig. 3), gives 0.31, 0.32, 0.40 and 0.42 in accordance with growth. Our specimens fall in the same ratio range. To sum up, a set of specimens from loc. R449 can be almost certainly identified with Mariella (Mariella) carrancoi (Bose, 1923). However, the five specimens have some deficiencies in preservation. It would be better to call them tentatively M. (M.) cf. carrancoi, until material of better preser- vation is obtained from rocks of a definite stratigraphic level. Occurrence.—As for material. It should be noted that the present material is inferred to have been derived from the Member My3 of early Cenomanian age, whereas M. (M.) carrancoi has been reported to occur in the upper part of the Mariella from Hokkaido—Part 2 169 Albian of Zacatecas, Mexico. The species may range across the Albian-Cenomanian boundary. This should be examined in future. Mariella (Mariella) gallienii (Boule, Lemoine and Thevenin, 1907) Figure 5 Turrilites puzosianus d'Orbigny var. gallienii Boule, Lemoine and Thevenin, 1907, p. 40, pl. 7, figs. 4, 4a, 4b, 5, 5a. Turrilites gallienii Boule, Lemoine and Thevenin. Collignon, 1931, p. 89, pl. 9, figs. 15, 16. Paraturrilites gallienii (Boule, Lemoine and Thevenin). Collignon, 1964, p. 12, pl. 320, figs. 1379, 1380. Mariella (Mariella) gallienii (Boule, Lemoine and Thevenin) evoluta Klinger and Kennedy, 1978, p. 29, pl. 8, figs.C,H,1; pl. 6, figs. B, D, O; pl. 7, figs. A,B; text-figs. 1E; 4E-G. Mariella (Mariella) gallienii gallienii (Boule, Lemoine and Thevenin). Wright and Kennedy, 1996, p. 333, pl. 98, figs. 2, 3, 25, 27 ; text-fig. 134, D. E, L. Lectotype.—The original of Boule, Lemoine and Thevenin, 1907, pl. 7, figs.4,4a,4b, from the Cenomanian of Diego Suarez, northeastern Madagascar (designated by Wright and Kennedy, 1996, p. 333). Material —GS. G189 (Figure 5-1), GS. G190 (Figure 5-2, 3), GS. G191 (Figure 5-4), GS. G192 (half ammonoid preservation) and GS. G193 (fragmentary), collected by Y.K. and N. Ega- shira on 21 June 1996 from a nodule contained in the mudstone of the Member My3 at loc. R906 of the Hotei- zawa, Soeushinai area (for the location see fig. 7 in Part 1). Description.—GS. G189 consists of two tightly coiled whorls, although the earliest part is unpreserved. Its whorl is subrounded in cross section, with a broadly convex main part of the flank which passes across the abruptly rounded shoulder to the narrow upper face and likewise downward to the gently convex lower surface. The estimated apical angle is high (60°). The ornament of this specimen consists of numerous, densely disposed, weakly oblique ribs on which small tubercles are set in four rows at subequal intervals. The ribs start at the upper whorl seam and run across the upper shoulder to the main part of the flank and further across the lower shoulder to the basal surface. The ribs are thus continuous, but they slightly weaken at the interspaces of the three tubercles, resulting in two shallow spiral depres- sions on the flank (Figure 5-1a, b). The tiny fourth tubercles are discernible on the basal surface where ribs run to the umbilical margin with a gentle curvature (Figure 5-1c). The three specimens, GS. G190-G192, show a tall turreted shape, consisting of several (4 to 6) whorls. They seem to show an apparently low apical angle, but the actual apex is not known, because several whorls of the youngest stage are not well shown. The whorls are rather loosely coiled in the main to later growth stages and the last one (body chamber) is detached in GS. G191 (Figure 5-4), although this feature might be secondary. It should be noted that the whorls in earlier stages seem to be fairly tightly coiled (Figure 5-2, 3, 4). In the young stage of these specimens the whorl shape is fairly similar to that of the above small specimens Figure 5. Mariella (Mariella) gallienii (Boule, Lemoin and Thevenin). 1. GS. G189, two lateral (a, b) and basal (c) views, x 4/3. 2. GS. G190, lateral view, «1. lateral view, X 4/3. 3. GS. G190, lateral view before it is detached from the host rock, x1.4. 4. GS. G191, (Photos by N. Egashira without whitening.) 170 Tatsuro Matsumoto and Yoshitaro Kawashita (GS. G189), but in later stages the whorl becomes increasing- ly higher, with a weakly convex to nearly flat main flank and a rather oblong section. The ornamentation of these speci- mens is fundamentally similar to that of the first specimen (GS. G189), but the rib density (or the number of ribs per whorl) varies with growth and between individuals. The variation in the rib density and also in shell shape may be expressed by the columns Ribs and H/D in Table 3. Thus, the ribbing becomes less dense with growth. In GS. G190 the ornament is especially coarse on the loosely coiled last whorl (Figure 5-3): Septal sutures are observable where the shell layer is taken away, as on the third whorl from the bottom in GS. G190. Measurements.—See Table 3. Comparison.—GS. G189 (Figure 5-1) is fairly similar to the lectotype (see above) of this species. Although the ribs are denser in the latter, the difference is by no means great (see Table 3). Our specimen is morphologically intermediate between the lectotype and paralectotype (Boule et al., 1907, pl. 7, figs. 4 and 5) from Madagascar. The two whorls of the middle growth stage in GS. G190 and GS. G191 resemble those of MNHP R1073 from Madagascar described by Collignon (1931, pl. 9, fig. 16) and reillustrated by Wright and Kennedy (1996, text-fig. 134 L). Another specimen from the lectotype locality in Madagascar, illustrated by Collignon (1964, pl. 320, fig. 1379) and reillustrat- ed by Wright and Kennedy (1996, text-fig, 134E) exemplifies a distinct change of relative whorl diameter at a certain young stage. This may support the presumed shape of the missing or poorly preserved young part of the three speci- mens (GS. G190-192) mentioned above. Occurrence.—As for material. Outside Hokkaido, this species has been recorded in the Lower Cenomanian of Madagascar, South Africa and England (see references in the synonymy). Discussion.—This species was entablished as a variety of Table 3. Measurements of Mariella (Mariella) gallienii (Boule, Lemoine and Thevenin). Specimen Whorl* Diameter Height H./D. Ribs GS. G189 (1st) 10.2 3.4 539 GS. G189 (2nd) 14.5 6.5 45 46 GS. G190 (2nd) 13.5 6.8 50 ~36 GS. G190 (4th) 20.4 13:83 65 42 GS. G191 (1st) 17.0 6.4 .38 32 GS. G191 (2nd) 21.0 10.0 48 34 GS. G191 (3rd) 23.0 13.5 59 37 Lectotype 16.0 765) AT 50 GK specimen 19.0 10.5 55 34 * The order in the column “Whorl” as for Table1. Ribs: number of ribs per whorl ; ~approximate number of ribs estimated from the measurable number in case of half whorl preservation. Lectotype is measured on the illus- tration in Boule et al., 1907, pl. 7, fig. 4a, b. GK specimen means an example from the Lower Cenomanian | at Skoenberg, Zululand, South Africa, kindly donated by W. J. Kennedy. Ostlingoceras puzosianus. This assignement has been revised by subsequent authors, as indicated in the synonymy list. Klinger and Kennedy (1978, p. 29, pl. 3, figs. C,H, 1; pl. 6, figs. B, D, O; pl. 7, figs. A,B; text-figs. IE, 4E-G) established a subspecies M. (M.) gallienii evoluta, “which is characterized by loose coiling in which successive whorls are only slightly impressed.” Although we have not looked at the actual specimen, the holotype of subspecies evoluta (op. cit., pl. 6, fig. C) does not seem to be so loosely coiled as the middle- to-late-stage of GS. G190 and G191. In our material the mode of coiling (loose or tight coiling) varies with growth and also between individuals. Moreover, the tightly coiled small specimen and larger ones with loosely coiled later whorls are contained in the same nodule. The Hokkaido material shows good conformity with that from Madagascar, which lay close to Zululand in mid-Cretaceous time. Some of the specimens from England (e.g., Wright and Kennedy, 1996, pl. 98, fig. 25) seems to show a rather loose coiling. A speci- men from Zululand, donated to GK by Kennedy, is intermedi- ate in the mode of coiling and rib density. For these rea- sons we are inclined to regard the subspecific separation as unnecessary and unnatural. Concluding remarks The genus Mariella of the Turrilitidae ranges from the Upper Albian to the Lower Cenomanian and includes a fair number of species. In these two successive papers alto- gether eight species of the subgenus Mariella (Mariella) from Hokkaido (northern Japan) have been described. In Part 1 M. (M.) dorsetensis (Spath), M. (M.) oehlerti (Pervin- quiere) and M. (M.) pacifica Matsumoto, Inoma and Kawashita have been recorded to occur fairly commonly or very abun- dantly (the second species) in the Lower Cenomanian of the Soeushinai area (northwestern Hokkaido). M.(M.) dorseten- sis and M. (M.) oehlerti are distributed worldwide in the Lower Cenomanian. They can be regarded as cosmopolitan ele- ments of the fauna and are useful for interregional correla- tion. M.(M.) pacifica, which was established in Part 1, is so far endemic, but its wider distribution would be expected in view of its similarity to M. (M.) torquatus Wright and Kennedy and M. (M.) numida (Pervinquiere) and its having some affinity with late Albian M. (M.) camachoensis (Böse). The five species described in Part 2 are based on a rather small number of specimens, but they are interesting in creating some problems either in taxonomy or in stratigraphic occurrence. M.(M.) bergeri was obtained from the upper part of the Member My2 in the Soeushinai area, that is a correlative of the uppermost Albian. One of the specimens shows finely preserved spines. The second species tenta- tively called M.(M.) aff. bergeri is probably new for its particular characters. It came from the lower part of the Member My8, ie. the basal Cenomanian. The third is identified with M. (M.) miliaris redefined by Atabekian (1985). It is based on three specimens which are inferred to have been derived from the Lower Cenomanian. The fourth is referred to M.(M.) cf. carrancoi (Bose). M.(M.) carrancoi is originally from the Upper Albian of Mexico, but our material Mariella from Hokkaido—Part 2 171 probably came from the Lower Cenomanian. The fifth is M. (M.) gallienii from the Lower Cenomanian. The subspecific separation of M.(M.) gallienii gallienii and M.(M.) gallienii evoluta may be unnecessary, for the reasons stated. Acknowledgments We are indebted to C.W. Wright and W.J. Kennedy for their kind help to this study. We appreciate the appropriate cooperations by Tamio Nishida, Katsujo Yokoi, Jun Aizawa and Naoko Egashira in the field and laboratory works. Kazuko Mori assisted us in preparing the manuscript. References cited Atabekian, A.A., 1985: Turrilitids of the late Albian and Cenomanian of the southern part of the USSR. Acad- emy of Sciences of the USSR, Ministry of Geology of the USSR, Transactions, vol.14, p.1-112, pls. 1-34. (in Russian) Bose, E., 1923: Algunas faunas Cretacicas de Zacatecas, Durango y Guerrero. Instituto Geolögico de Mexico, Boletin, no. 42, p. 1-219, pls. 1-19. Boule, M., Lemoine, P. and Thevenin, A., 1907: Cé- phalopode cretaces des environs de Diego-Suarez. Annales de Paléontologie, vol. 2, p. 1-58, pls. 1-8. Breistroffer, M., 1947: Sur les zones d’ammonites dans l'Albien de France et d'Angleterre. Travaux du Labor- atoire de Geologie de la Faculté des Sciences de l'Université de Grenoble, vol. 26, p. 1-88. Brongniart, A., 1822: In, Cuvier, G. and Brongiart, A. Description geologique des environs de Paris, 428 p., 9 pls. Paris. Chiriac, M., 1960 : Reprezentanti ai Turrilitidae Meek, 1876 in Cretacicul Dobrogei de Sud. Studii si Cercetari de Geologie, vol. 3, p. 449-474. Clark, D.L., 1965 : Heteromorph ammonoids from the Albian and Cenomanian of Texas and adjacent areas. Geo- logical Society of America Memoir, vol. 95, p. 1-99, pls. 1-24. Collignon, M. 1931: Paléontologie de Madagascar, XVI. La faune du Cenomanien a fossiles pyriteux du nord de Madagascar. Annales de Paléontologie, vol. 20, p. 43- 104, pls. 5-9. Collignon, M., 1964: Atlas des fossiles caractéristiques de Madagascar (Ammonites). Fascicle 11 (Cenomanien). Service Géologique. Tananarive, p.1-152, pls. 318- 375. Drushchits, V.V., 1960: Ammonites. /n, Drushchits, V.V. and Kudriavtseva, M.P. eds., Atlas of the Lower Cretaceous fauna of the northern Caucasus and the Crimea, p. 249-355, pls. 1-22. (in Russian) Förster, R., 1975: Die geologische Entwicklung von Süd Mozambique seit der Unterkreide und die Ammoniten- Fauna von Unterkreide und Cenoman. Geologisches Jahrbuch, Reihe B, vol.12, p. 1-324, pls. 1-17. Kawabe, F., Hirano, H. and Takagi, K., 1996: Biostratigraphy of the Cretaceous System in the northern Oyubari area, Hokkaido. Journal of the Geological Society of Japan, vol. 102, p. 440-459, pls. 1-3. (in Japanese with English abstract) Kennedy, W.J., 1996: Systematic palaeontology. In, Gale, A.S., Kennedy, W.J., Burnett, J.A., Caron, M. and Kidd, B.E.: The late Albian to early Cenomanian succession at Mont Rison near Rosans (Drome, SE France): an integrated study (ammonites, inoceramids, planktonic foraminifera, nannofossils, oxygen and carbon isotopes). Cretaceous Research, vol. 17, p. 543-590. Klinger, H.C. and Kennedy, W.J., 1978: Turrilitidae (Cretaceous Ammonoidea) from South Africa, with a discussion of the evolution and limits of the family. Journal of Molluscan Studies, vol. 44, p. 1-48, pls. 1-9. Kossmat, F., 1895: Untersuchungen uber die Südindische Kreideformation. Beiträge zur Paläontologie und Geologie Österreich-Ungarns und des Orients, vol. 9, p. 97-203, pls. 15-25. Matsumoto [Matumoto], T., 1942: Fundamentals in the Cretaceous stratigraphy of Japan. Part1. Memoirs of the Faculty of Science, Kyushu University, Series D, Geology, vol. 1, no. 3, p. 129-280, pls. 5-20. Matsumoto, T., 1967: Evolution of the Nostoceratidae (Cretaceous heteromorph ammonites). Memoirs of the Faculty of Science, Kyushu University, Series D, Geol- ogy, vol. 18, no. 2, p. 331-347, pls. 18-19. Matsumoto, T., Inoma, A. and Kawashita, Y., 1999: The turrilitid ammonoid Mariella from Hokkaido — Part 1, with an Appendix by Matsumoto, T. and Nishida, T. Paleontological Research, vol. 3, no. 2, p. 106-120. Matsumoto, T. and Nishida, T., 1999. Appendix. Locality guide for selected Cretaceous fossils of the Soeushinai area. Paleontological Research, vol. 3, no. 2, p. 116-119. Nishida, T., Matsumoto, T., Kawashita, Y., Egashira, N., Aizawa, J. and Ikuji, Y., 1997: Biostratigraphy of the middle part of the Cretaceous Yezo Group in the Shumarinai area of Hokkaido — with special reference to the transitional part from Lower to Upper Cretaceous : supplement —. Journal of the Faculty of Culture and Education, Saga University, vol. 1, no. 1, p. 237-279. (in Japanese with English abstract) Nishida, T., Matsumoto, T., Yokoi, K., Kawashita, Y., Kyuma, Y., Egashira, N., Aizawa, J., Maiya, S., Ikuji, Y. and Yao, A., 1996 : Biostratigaphy of the Cretaceous Middle Yezo Group in the Soeushinai area of Hokkaido — with spe- cial reference to the transitional part from Lower to Upper Cretaceous —. Journal of the Faculty of Educa- tion, Saga University, vol. 44, p.65-149. (in Japanese with English abstract) Pictet, F.J. and Campiche, G., 1861; 1862: Description des fossiles du terrain Cretace de environs de Sainte Croix, part 2. Matériaux pour la Paléontologie Suisse, Series 3, 1861, p. 1-144, pls. 44-57 ; 1862, p. 145-348, pls. 58- 76. Renz, O., 1968: Die Ammonoidea im Stratotyp des Vraconien bei Sainte Croix (Kanton Waadt). Schwe- izerische Paläontologische Abhandlungen, vol. 87, p. 1- 97, pls. 1-18. Roemer, F.A., 1852: Die Kreidebildungen von Texas und ihre organischen Einschlüsse. Adolf Marcus, Bonn. vi+100 p., 11 pls. Scholz, G., 1979: Die Ammoniten des Vracon (Oberalb, dispar-Zone) des Bakony-Gebirge (Westungarns) und eine Revision der wichtigsten Vracon-Arten der West- Mediterranen Faunenprovinz. Palaeontographica, Abt. A, vol. 165, p. 1-136, pls. 1-30. Seyed-Emami, K., 1982: Turrilitidae (Ammonoidea) aus den Glaukonitkalk bei Esfahan (Zentraliran). Neues Jahr- buch für Geologie und Paläontologie, Abhandlungen, vol. 163, p. 417-434. Spath, L.F., 1937 : A monograph of the Ammonoidea of the Gault, part12. Palaeontographical Society, London, for 1936, p. 497-540, pls. 37-58. Stoliczka, F., 1866: Ammonitidae, with revision of the Nautilidae. In, Blanford, H.F. and Stoliczka, F. eds., The fossil Cephalopoda of the Cretaceous rocks of southern India. Memoirs of the Geological Survey of Tatsuro Matsumoto and Yoshitaro Kawashita India, Palaeontologia Indica, series 3, vol.1, p. 155-216, pls. 76-94. Wiedmann, J. and Dieni, |., 1968: Die Kreide Sardiniens und ihre Cephalopoden. Palaeontographia Italica, vol. 64, p. 1-171, pls. 1-18. Wright, C.W. and Kennedy, W.J., 1996 : The Ammonoidea of the Lower Chalk, part 5. Monograph of the Palaeonto- graphical Society, London, p. 320-403, pls. 95-124. (Publication no. 601, part of vol. 50 for 1996). Paleontological Research, vol. 3, no. 3, pp. 173-192, 9 Figs., September 30, 1999 © by the Palaeontological Society of Japan Planktonic foraminifera and biochronology of the Cenomanian- Turonian (Cretaceous) sequence in the Oyubari area, Hokkaido, Japan TAKASHI HASEGAWA Division of Global Environmental Sciences and Engineering, Graduate School of Natural Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan/Department of Earth Sciences, Faculty of Science, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan Received 3 March 1999; Revised manusript accepted 5 May 1999 Abstract. A Cenomanian and Turonian (Late Cretaceous) sequence along the Shirakin River, Oyubari area, central Hokkaido, Japan contains seven datum planes of planktonic foraminifera that can be used to establish international correlations. These datum planes are marked by the first appearance of Praeglobotruncana gibba, Rotalipora greenhornensis, Rotalipora deeckei, Marginotruncana schneegansi and Marginotruncana pseudolinneiana, and the last appearance of Rotalipora deeckei and Rotalipora cushmani. These datum planes can be correlated with international Cretaceous planktonic foraminiferal zones in the interval KS17-KS22. Seventeen planktonic foraminiferal species are described including five new species: Hedbergella kyphoma, Praeglobotruncana compressa, Praeglobotruncana inermis, Praeg- lobotruncana shirakinensis, and Dicarinella takayanagii. Key words: biostratigraphy, Cenomanian, Cretaceous, datum plane, planktonic foraminifera, Turonian, Yezo Group Introduction The Cretaceous Yezo Group in Hokkaido, Japan yields abundant ammonites and inoceramids that have been used to create a number of regional biostratigraphic zones. However, most of these molluscan fossils cannot be used for high resolution biochronology and international correlation (e. g. Matsumoto, 1942, 1943 ; Hirano et al., 1977, 1981; Hirano, 1982). On the other hand, there have been few biostrati- graphic studies of calcareous microfossils in the Yezo Group. A planktonic foraminiferal biostratigraphy of the Yezo Group was first established by Takayanagi in 1960. Subsequently, Takayanagi and Iwamoto (1962) and Takayanagi and Okamura (1977) have reported planktonic foraminiferal occurrences from the group. Maiya and Takayanagi (1977) and Maiya (1985) summarized a Japanese planktonic for- aminiferal zonation. However, these zonations have not been adequate for detailed interregional correlation of local Japanese Cretaceous sequences. In this decade, Motoyama et al. (1991), Hasegawa and Saito (1993), Hase- gawa (1997) and Takashima et al. (1997) reported Cretaceous planktonic foraminiferal biostratigraphy from the Oyubari area of central Hokkaido and their reported taxa suggest that age-diagnostic species are available for international corre- lation. Nishida et al. (1993) presented additional data on the biostratigraphic correlation of the Oyubari sequence based on micro- and megafossils. Hasegawa (1995) further clar- ified the precise stratigraphic position of the last appear- ances of Rotalipora greenhornensis and Rotalipora cushmani and of the first appearance of Marginotruncana schneegansi near the Cenomanian/Turonian (C/T) boundary. Recently, Hasegawa (1997) used a comprehensive biostratigraphy of planktonic foraminifera to demonstrate interregional synchroneity of carbon isotopic events during Cenomanian Turonian age. However, with the exception of Kaiho’s (1992) work on Campanian species, no descriptive work on planktonic foraminiferal species of the Yezo Group has been presented in recent years. This study describes seven planktonic foraminiferal datum planes recognized in the Cenomanian-Turonian sequence exposed along the Shirakin River in the Oyubari area and attempts biostratigraphic correlation with the international zonation established by Sliter (1989). Planktonic foraminifer- al species, including twelve age-indicative species and five new species, are described. Materials and methods Samples used in this study were collected from the Yezo Group mainly along the Shirakin (=Hakkinzawa) River, 174 Takashi Hasegawa Oyubari area, central Hokkaido, Japan (Figures 1,2). The Yezo Group is interpreted as a forearc basin facies (Okada, 1979, 1983). In the Oyubari area, the Cenomanian- Turonian sequence of the group is represented by the Hikagenosawa and Takinosawa Formations as defined by Motoyama et al. (1991). Approximately 300 samples were collected and processed. Near the C/T boundary, sampling was at approximately 2.5 m intervals. Faunal analyses are based on 49 planktonic foraminifera-bearing samples consisting largely of siltstone in the Cenomanian-Turonian section. Samples weighing approximately 240 g were disaggregated using sodium sulfate, naphtha solution (Maiya and Inoue, 1973), and sodium tetraphenylborate plus sodium chloride (Hanken, 1979), washed through a 63 um screen and dried. All specimens larger than 180 um were identified. Addition- ally, larger samples (500-800 g) were analyzed in the bound- ary sequence from 7m below to 40m above the C/T boundary. All specimens described herein are deposited in the Department of Geoenvironmental Science, Faculty of Science, Tohoku University. Biostratigraphy The planktonic foraminiferal assemblages are listed in Table 1. A detailed biostratigraphy near the C/T boundary has been established along the Shirakin River, based on continuous occurrences of planktonic foraminifera (Hase- gawa, 1995; Hasegawa, 1997). Common occurrence of internationally recognized species, especially those within the genera Rotalipora and Marginotruncana allow correlation with datum planes as summarized by Caron (1985) and Sliter (1989). e Sapporo The stratigraphic distribution of planktonic foraminifers in the Oyubari section is shown in Figures 3 and 4. In addition, two late Cenomanian samples collected from the Kashima- migimata River (Figure 2) are included in the data presented in Figure 3. Although the Hikagenosawa Formation (Figure 8) includes a low-diversity assemblage, several species have biostratigraphic utility, including Rotalipora gandolfii (Luterba- cher and Premoli-Silva) from the lower to middle, and Praeglobotruncana gibba Klaus, Rotalipora greenhornensis (Morrow) and Rotalipora deeckei (Franke) from the uppermost part of the formation. On the other hand, the lower part of the Takinosawa Formation is characterized by highly diver- sified assemblages including such international zonal species as Rotalipora cushmani (Morrow) and Helvetog- lobotruncana helvetica (Bolli) as well as the age-indicative species R. greenhornensis, R. deeckei and Marginotruncana schneegansi (Sigal). In the middle to upper part of the Takinosawa Formation and in the overlying Shirogane For- mation, the planktonic foraminiferal diversity declines again, with only two biochronologically important species, Mar- ginotruncana pseudolinneiana Pessagno and Marginotrun- cana coronata (Bolli), having correlational significance. Datum planes Based on the stratigraphic distribution of the species that belong to the genera Rotalipora and Marginotruncana and other important age-diagnostic species (e.g., Helveto- globotruncana helvetica and Praeglobotruncana spp.), seven bioevent horizons (i.e., FAD, first appearance datum ; LAD, last appearance datum) were recognized in the Shirakin River section as reliable datum planes. These are discus- HOKKAIDO - Ÿ 12 Oyubari area (Fig. 2) ya 42N Figure 1. Index map showing the locality of the Oyubari area. Planktonic foraminifera from Hokkaido 175 ( Kashima-migimata River SRN-062 SRN-058 SRN-054 N + ea) 22 FL ae, GEILE nn KMZ-002 KMZ-003 SRN-029 SRN-026 SRN-021 SRN-017 SRN-013 SRN-011 SRN-521 Figure 2. Map showing sampling localities in the Oyubari area. sed separately below. A: FAD of Praeglobotruncana gibba This datum is early Cenomanian. FAD of P. gibba in the middle part of the Hikagenosawa Formation is observed about 180 m below the FAD of R. greenhornensis. Accord- ing to Caron (1985), the FAD of P. gibba is located just below the FAD of R. greenhornensis, which is consistent with its first occurrence in the Oyubari section. Rotalipora brotzeni first occurred above this datum, but its occurrence is too rare to establish a reliable datum level. The planktonic for- aminiferal assemblage below this datum is mainly composed 176 Table 1. Takashi Hasegawa Stratigraphic occurrences of planktonic foraminifera in the Oyubari area. Symbols denote the number 2” or “1/4” written under the total number mean that 1/2 or 1/4 fraction of residues of 240 g rock samples were rences shown with parentheses indicate the inclusion of specimens of which specific name can only be given with Species sample No. SRN SRN SRN SRN SRN SRN KMZ SRN SSS SSS KMZ SSS SSS SSS SSS SSS SSS SSS SRN SRN SRN SRN On 013 O17 021 022 025 003 026 001 003 002 005 006 007 020 010 ON O12 029 201 205 206 Globigerinelloides ultramicra R F R G. cf. bentonensis G. cf. eaglefordensis R G. spp. Hedbergella delrioensis Cc R F R A VA F C VA R R R F (A H. planispira IF R R F VA R R Cc H. kyphoma sp. nov. FE H. SPP. R Rotalipora cf. appenninica R R gandolfii R R R R. brotzeni R R R R greenhornensis F R C R FE F R R deeckei R E R cushmani F R R spp. R R Praeglobotruncana delrioensis R A VA R A R A C Cc F C A Cc R R P stephani C VA R R A VA C FV Are F R A VA C A R A F P. gibba F A A MAN iC A F F FF R A C F R A C P. anumalensis R VA VA R VA VA VA A E ARC P. shirakinensis sp. nov. A G Cc P. inermis sp. nov. R A C E F R C R A P. compressa Sp. nov. R iP F R RC P. spp. A C C R A [> R A Whiteinella cf. archaeocretacea A R F R R R W. aprica R R in) W. baltica A Ir A C W. brittonensis E A R (R W. inornata W. spp. C LF R C A Cc Dicarinella imbricata R E R R F D. canaliculata A D. takayanagii sp. nov. A (R) D. hagni (R) D. roddai D japonica D. spp R R Helvetoglobotruncana helvetica Marginotruncana marginata M. schneegansi M. pseudolinneiana M cf. coronata Indeterminable specimens 1 4 1 1 0 0 9 4 1 1 30 24 10 1 3 237511 2 0 17 ie) Total number 2 14 28 35 7 2 20 56 132 103 22 164 154 25 9 29 100 109 15 CON, TE) (1/2) (1/2) (1/2) of long-ranging species such as Hedbergella delrioensis (Carsey), Hedbergella planispira (Tappan), Globigerinelloides ultramicra (Subbotina), Praeglobotruncana delrioensis (Plum- mer) and Praeglobotruncana stephani (Gandolfi). B: FAD of Rotalipora greenhornensis This datum is early-middle Cenomanian. The FAD of Rotalipora greenhornensis occurs in the upper part of the Hikagenosawa Formation. According to Caron (1985) and Sliter (1989), R. greenhornensis and R. cushmani have the same FAD. However, Rotalipora cushmani first occurs above the FAD of R. greenhornensis in the Oyubari section. The first occurrence of R. cushmani in the Oyubari section is observed above the LAD of Rotalipora deeckei and even above the first-occurrence horizon of the genus Dicarinella. This delayed first occurrence of R. cushmani is interpreted as a migration event of this species in this area. The strati- graphic relationship of the FAD of R. greenhornensis with other bioevents is concordant with that shown by Caron (1985) and Sliter (1989). The planktonic foraminiferal assem- blage between the FAD of P. gibba and the FAD of R. greenhornensis is similar to that occurring below the FAD of P. gibba. C: FAD of Rotalipora deeckei This datum is late Cenomanian. Rotalipora deeckei is a short-ranging age-diagnostic species of late Cenomanian age. According to Sliter (1989) and Robaszynski and Caron (1979), the total range of R. deeckei characterizes the upper part of the Rotalipora cushmani Zone (the range of Rotalipora deeckei is not shown in the range distribution chart of Caron, 1985). Stratigraphically, the FAD of R. deeckei lies near the top of the Hikagenosawa Formation. The occurrences of Whiteinella spp. and Dicarinella spp. within the total range of Planktonic foraminifera from Hokkaido 177 of specimens included in each 240 g rock sample. VA: >21 specimens, A: 10~20,C: 6~9,F: 3~5,R: 10r2. “1/ examined. The abundance of those samples are indicated by converted number into 240 g equivalent. The occur- “cf”. The specimens of which species name bear “aff.” are indicated by italic. SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN SRN 207 208 209 210 21 212 216 218 220 223 224 228 229 230 233 521 236 525 033 132 526 101 034 037 054 058 062 R VA EF R R R R R R GC.) ar R R R VA A C A A A VA A R C A R R VAR F BER VA. VAS TE VA A F R F R F R R F R R F VA Cc A A R G R FE VA A VA E R R R R R Bar F VA VA A F RR F R A F Cc VA F VA VA VA R R A F F er, Ani Vz Aten (R) R ER RF A Ra wR crak VAC AY Dre WA RE F R VA R A R = Of Feros (Ry aR MVA EVA LR) EVA R c RR F VA F R R R R F C R A) (VA) A ) (R) R (F) R R R (VA) (A) (A) (R) R R F C R A (VA) © (R) (©) R (R) R R R R VA C R F R E R R R F R Riese FOR FOR R F IF R C R R (R) R F FOF R R (VA) (A) (R) (R) (R) VA Es air R FOF VA R C VA F F F FOF R (F) (R) Cc R (R) FA F R (Aue OA OT TONI O EE NE On Szenen 5 UT MENTON EMTEC TOUT 80 3 24 30 62 24 5 5721208126 1627 4 15) 5 3 84 81 62 214 74 64 105 42 24 1 3 (1/4) R. deeckei indicate that both the FAD and LAD of R. deeckei Formation. A drastic faunal turnover was observed within are reliable datum planes in the Oyubari section. Between FADs of À. greenhornensis and À deeckei, the species Praeglobotruncana anumalensis (Sigal) and Praeglobotrun- cana shirakinensis n. sp. appear. However, the constituent species of the assemblage are similar to those occurring below the FAD of R. greenhornensis. The last occurrence of Rotalipora gandolfii Luterbacher and Premoli-Silva is observed at the same level as the FAD of R. deeckei, which shows considerable inconsistency with their stratigraphic relationship as summarized by Sliter (1989) and Caron (1985). Apparently À gandolfii survived later in the northwestern Pacific. D: LAD of Rotalipora deeckei This datum is late Cenomanian. The LAD of Rotalipora deeckei is recognized near the bottom of the Takinosawa the total range of R. deeckei. This faunal modification is characterized by the entry of Dicarinella spp., Whiteinella spp. and Praeglobotruncana inermis n. sp. E: LAD of Rotalipora cushmani This datum is latest Cenomanian. The last occurrence of Rotalipora cushmani is observed at the same horizon as that of Rotalipora greenhornensis. Caron (1985) and Sliter (1989) reported the LAD of R. greenhornensis just below the LAD of R. cushmani. However, recent precise biostratigraphical studies of planktonic foraminifera indicate that these LADs are almost synchronous. Leckie (1985) described a Cenomanian/Turonian planktonic foraminiferal biostratigra- phy in Pueblo, Colorado, for one of the best studied Cenomanian/Turonian boundary sections, in which R. greenhornensis and R. cushmani show synchronous last Takashi Hasegawa 178 eu0z “WEIO} IIUOJYUEI JEUOIEUIAIU! 2A12181109 auejd une euerauuopnasd eueounjoulbleyy 0 _ van BJBUOIOD 9 eueounjoulbieyy Z Da eat = 1 ane ney BUBIUNNOIOIBOJSNJOH isuebaauyos Bueounnoudlew ejeulbsew eueounyoulbleny eouodel ejjsunesig sısusuoJusg ‘jo saplojjauuabiqo/ dds sapliojjauuabigol5 EJEUJOUI EJJ8UISJIYM leppol ejjeuuieaig ıubey ejjauneoig sisuapsojajbea ‘jo saplojjauuabiqo/y ‘où ‘ds essaidwoo euuReoUNOqo/baeld et al. (1991) /UBUIYSNd Blodıle]oy Bone B//AUIa}IYM eaoejslooseyaie ‘J9 ejfaulisltyMm °— = — ‘dds eyaulayiym sısuauoyug B/JBUIANYM dds eyabiaqpay dds ejjaunesig nou ‘ds 1BeueAeye] ejjsuneaig ejejnoıjeues ejjsuneaig dds euesunsyogojdaelg egjuiuuadde ‘jo eiodyjejoy ejesugwi ejjauneoig ‘nou ‘ds siuuaul eueaunnogojdaeig nou ‘ds ewoydhy ejjebiaqpay Rare (1-2 specimens) Few (3-5) D Common (6-9) , Specimens with "aff." Abundant (10-20) _) Very abundant (>21) € Specimens with "cf." x Data from Motoyama Legend ) intercarations Slump structure (weak lamination) Blackish gray siltstone Sandy siltstone Tuff layer (>80cm) (frequent tuff Stratification Sandy siltstone with alternation units of sandstone and siltstone Radiolarian sandstone ] Alternation of -sandstone and siltstone 194999p eIodijejoy Dark gray siltstone Par eoude eyjaulayiyy sısusjewnue eueounnogojdaelg Aou ‘ds sısuaumyeuys eueounnogojdaelg IN sısuaWoyugaaıb Blodıle]oy dds esodyejoy (uazjolq e10d/jeJ0H + eqqib eue9unnogoJbaeld RD A lueydajs eueounsogojbaelg € CO À > SISU80118p eueounoqo/faei4 — CD SiSuaol118p ejabiaqpay = ae > —* 5 x eidsiuejd eyablaqpay BOIWeYN saplojauabiqo/5 ıopueb e1odijejoy | Planktonic foraminiferal species ABojoyy 3 een Bia YVMVSONADVHI uonewios | ANVOOHIHS | | VMYSONDIVL Mo ee ‘SO o6e]S UEIEILOI ueluoIn | UEIUEWOUSN Seven Symbols denote the number of Figure 3. Stratigraphic distribution of planktonic foraminiferal species along the Shirakin River and the tributary of Penkemoyuparo River in the Oyubari area (reproduced from Hasegawa, 1997, with permission from Elsevier Science). reliable datum planes are recognized in the section (see text for notation of datum planes). specimens included in each 240 g rock sample. 179 Planktonic foraminifera from Hokkaido Z 410 | pue Ajewoue 9,,9 anılsod yo syeed um} JO SUOZLOH :OleH 'S-E : M84 ‘6-9 : UOWWOD ‘OZ~O} : JUepunqy 'suswioads |Z< :}uepunge MSA yore ul papnjoul suswıoads jo Jaquinu ay} s}oUEP sjoquAS “payedipu! OSIE ase S9OUSUNDDO [BJSJIUILUBIOJ oluoyqued evel Jo eHues Sıydesßirens ‘ajdues 490! 6 Org ulMeulus ey) Buoje Aepunoq ueluoin | /uelUeWOUSI eu} SS0198 Jsn! saloeds jeJeylUIWeJO} DIUOPyUeI|G JO UOINqUISIP olydeisirejs “py auNBIy QUOZ |CJOJIUILUCIOY DIUO}YURIA BANL|910D (LZSM) QUOZ EINaNJaU ‘AJOH (0ZSM) 9U07 P992)8/908PU91E ‘M (6LS») QUOZ IUPWUYSNI ‘EH (ueder jo A81008 jed!Hojoay ou} Aq payiwued uoNonpoJdsy : G66L ‘emebeseH) 18AIH ısueßaauyss EUBOUNHOUIBIEN —. eyeulbsew eueounjoulbieyy + EJEUJOUI B//AUIA}IYUM, eoıuodel eyjauesiq (S66L 'emeßaseH) Alewoue adojosı uoqgie9 aAHISOd Jo syeed UML u leppod ejjsuneoig . ıubey ejlsunesig — ao = = 13 a > fe Oo o € os DIS = ae = oO ei Sandy sillstone with some units of alternating beds of sandstone and dark gray siltstone (darker part) Chondrites-like trace fossils ~ > Bentonite bed (Aff, (darker part) lee Marker sandstone bed beds of sandstone and siltstone Radiolarian silty fine sandstone Unit of alternatin: eonjeg ejjauajıym | + 2992J81908P49/E ‘Jo EJJ8UISJIYM + + | 4 dds eyaulayiyj, -—* sisuauoyug ejjaulallyM =—* dds eyabsaqpay -—* dds eyauuecig = nou ds Ibeurfeye) ejljauneaig = EJEINOIEUEO ejjsunesig -—* BJBOLIQUI ellsuneaig *— nou ‘ds seul PUPIUNOGoO/BaelYy BIDIWENIN Saplojjauuabiqo/yH ~—* eoude BIBUIAIY + sısusjewnue Buesunyogolbaselg +—e eagıb eueounjogo|baes, lueydajs eueounyoqgojbaely -— sisuaoujap elleblegpaH -—@ euidsiuejd eyjabiaqpay -—@ sisuauojuaq ‘jo saplojjauiabiqoj5 . sisuapsoja/bea ‘jo saployjauebiqo/y . dds eueounyoqo|beei4 Aou ds Bwoydiy eyjabieqpey . Aou ‘ds sisuaulyesys eUeoun10qo|beri4 Ri dds sapjojjauabiqo/5 Aou ‘ds essasdiuoo euuesunyogolbaeld sIisusonjap eUbounoqo/beri4 Planktonic foraminiferal species ABoloyy uozuoy ajdwes abeis ® = . 1 U a Zone of rare occurrence + /JUBWYSNd elodıleloH SISUBLUOYUEAIB BJOAI/EJOY ueluonn] UEIUEWOUSN | ) Specimens with "cf." A Specimens with "aff." ° Common @ Abundant @ Very abundant © 180 Takashi Hasegawa occurrences. Jarvis et al. (1988) and Hart and Leary (1989) also noted nearly synchronous last occurrences of these two species in Southeast England. Therefore, the LAD of R. cushmani observed in Hokkaido is regarded as a reliable datum plane for interregional correlation. The planktonic foraminiferal assemblage between the LAD of R. deeckei and LAD of R.cushmani shows the highest diversity in the Oyubari area. The most abundant species of the assem- blage are Praeglobotruncana spp. with common Whiteinella spp. and less Rotalipora spp. and Dicarinella spp. In the northern Oyubari area, Takashima et al. (1997) attempted to recognize KS zones (Sliter, 1989). Rare occur- rences of Rotalipora species did not allow them to correlate their upper Cenomanian sequences to KS zones directly with zone-indicative species. Such rare occurrences of Rotalipora may partly depend on the marine paleoenviron- ment of the northern Oyubari area being a shallower one than in the southern area, where the samples of this study were collected. F: FAD of Marginotruncana schneegansi This datum is early Turonian. The FAD of Marginotrun- cana schneegansi occurs just above the “Radiolarian sand- stone” (Hasegawa and Saito, 1993 ; Hasegawa, 1995) devel- oped in the lower-middle part of the Takinosawa Formation. Helvetoglobotruncana helvetica, which is a commonly used datum species for the recognition of early Turonian age occurred above the FAD of M. schneegansi. According to Caron (1985) and Sliter (1989), the concurrent range of these two species is quite restricted. Therefore, the FAD of M. schneegansi is interpreted to be a reliable datum plane in Hokkaido. The planktonic foraminiferal assemblage between the LAD of R.cushmani and the FAD of M. schneegansi is also a high-diversity assemblage except in the middle part of the interval (Figure 4). Between SRN-224 and SRN-236, planktonic foraminifers are rare and the diversity is low despite a high density of large samples (500- 800 g). This low-diversity event has also been recognized in other areas of the world (e.g. Hart and Leary, 1989). An oceanic event termed “Oceanic Anoxic Event (OAE)” (Schlanger and Jenkyns, 1970) or “Cenomanian Turonian Boundary Event (CTBE)” (Thurow and Kuhnt, 1986) may be responsible for this worldwide synchronous phenomenon. G: FAD of Marginotruncana pseudolinneiana This datum is middle Turonian. The FAD of Marginotrun- cana pseudolinneiana is located in the middle of the Takino- sawa Formation and this species is a common one in the middle Turonian and Coniacian interval. The stratigraphic distributions of other international species across this datum in the Oyubari section are consistent with occurrences known from other parts of the world (e.g. Robaszynski and Caron, 1979 ; Caron, 1985 ; Sliter, 1989). Therefore, the FAD of M. pseudolinneiana is considered to be a reliable datum plane. The stratigraphic interval between the FAD of M. schneegansi and the FAD of M. pseudolinneiana yields a moderately diversified assemblage. However, the upper part of this interval and sequence above the FAD of M. pseudolinneiana yield less abundant and lowly diverse assemblages. Recognition of zonal boundary Stratigraphic units equivalent to the international plank- tonic foraminiferal zones are recognized in the Oyubari section (Figures 3 and 4) by correlating these datum planes with those shown by Sliter (1989) and Caron (1985). The upper limit of each zone is drawn as follows : KS18: at the FAD of R. greenhornensis ; KS19a : estimated to lie just below the FAD of R. deeckei and above the FAD of R. greenhornensis ; KS19b : at the LAD of R. cushmani ; KS20: estimated to lie just below the FAD of Pseudaspidoceras flexuosum (an ammonoid) below the FAD of M. schneegansi (see Hasegawa, 1995 for further discus- sion). At the north of the studied area, Takashima et al. (1997) recognized the zonal marker species, Helveto- globotruncana helvetica ; KS21: estimated to occur near the FAD of M. pseudolin- neiana. Systematic paleontology Superfamily Rotaliporacea Sigal, 1958 Family Hedbergellidae Loeblich and Tappan, 1961 Subfamily Hedbergellinae Loeblich and Tappan, 1961 Genus Hedbergella Bronnimann and Brown, 1958 Hedbergella kyphoma sp. nov. Figures 5-1—4 Diagnosis.—A low trochospiral species of Hedbergella with last four chambers umbilically shifted, compressed, and spirally elongate. Umbilicus narrow, sutures of last four chambers slightly curved. Description.—Test of medium size, initially very low tro- Figure 5. 1—4. Hedbergella kyphoma sp. nov. 1. Holotype, IGPS No. 102504, sample loc. no. SRN-525A, lower part of the Takinosawa Formation, lower Turonian. Takinosawa Formation, lower Turonian. awa Formation, lower Turonian. Formation, lower Turonian. 207, lower part of the Takinosawa Formation, upper Cenomanian. 7. Intermediate form between Praeg/obotruncana inermis sp. nov. lower part of the Takinosawa Formation, upper Cenomanian. 5, 6. Praeglobotruncana compressa Sp. nov. 2. Paratype, IGPS No. 102505, sample loc. no. SRN-525A, lower part of the 3. Paratype, IGPS No. 102506, sample loc. no. SRN-525A, lower part of the Takinos- 4. Paratype, IGPS No. 102507, sample loc. no. SRN-525A, lower part of the Takinosawa 5. Holotype, IGPS No. 102707, sample loc. no. SRN- 6. Paratype, IGPS No. 102708, sample loc. no. SRN-207, and Praeglobotruncana shirakinensis sp. nov., IGPS No. 102508, sample loc. no. SRN-210, lower part of the Takinosawa Formation, upper Cenomanian. 210, lower part of the Takinosawa Formation, upper Cenomanian. 8. Praeglobotruncana shirakinensis sp. nov., holotype, IGPS No. 102523, sample loc. no. SRN- Scale bar=100 vum Planktonic foraminifera from Hokkaido 181 182 Takashi Hasegawa chospiral, later becoming medium trochospiral, equatorial periphery lobulate ; chambers initially globular, later slightly compressed and spirally elongated, 11 to 14 in all arranged into 2.5 to 3 whorls, enlarging gradually in size as added except for last 3 or 4 which enlarge irregularly, 6 or 7 in last whorl, last 3 or 4 characteristically elongated, compressed and shifted toward umbilicus, last chamber variable in size and shape; sutures initially radial and depressed on dorsal side except for last 3 or 4 chambers in which they are curved, slightly curved and depressed on ventral side; coiling axis initially stable, later rapidly tilted for last 3 or 4 chambers, as a result, initial umbilicus occasionally being covered by last 3 or 4 chambers; umbilicus shallow, very narrow, less than 1/5 of maximum diameter of test ; primary aperture bordered by a narrow lip, interiomarginal, umbilical- extraumbilical, extending to periphery; wall calcareous, surface poorly ornamented. Remarks.—This species resembles Hedbergella planispira (Tappan) in its initially very low trochospiral shape and the number of chambers in the last whorl, but differs from the latter species in having a narrower umbilicus and umbilically shifted and compressed last 3 or 4 chambers. Etymology.—From kyphoma, a Greek noun referring to the humpbacked nature of the pattern of chamber growth in this species. Material —Holotype IGPS No. 102504, paratypes IGPS No. 102505-102507. Dimensions. — Maximum diameter of holotype 0.36 mm, maximum thickness 0.20 mm. Type locality and horizon.—The holotype and paratypes are all from sample SRN-525A (43°2.50'N, 142°9.72’E), lower part of the Takinosawa Formation, lower Turonian. Subfamily Rotundininae Bellier and Salaj, 1977 Genus Praeglobotruncana Bermudez, 1952 Praeglobotruncana compressa sp. nov. Figures 5-5, 6 Diagnosis.—A low trochospral species of Praeglobotrun- cana with compressed and wedge-shaped chambers in last whorl. Description.—Test of medium to small size, very low tro- chospiral, equatorial periphery slightly lobulate ; chambers wedge-shaped on dorsal side, triangular and slightly inflated on ventral side, about 10 chambers in all, enlarging rapidly in size as added, about 4.5 chambers in last whorl, with a peripheral band formed of aligned pustules ; final chamber occasionally obliquely shifted toward umbilical direction ; chambers in last whorl diagnostically elongated toward spiral direction ; sutures on dorsal side gently curved, depressed, ventrally radial or slightly curved and depressed ; umbilicus shallow, medium in size, about 1/3-1/4 of maximum diameter of test, umbilical flaps extending into an umbilicus from each chamber ; primary aperture bordered by a narrow lip, inter- iomarginal, umbilical-extraumbilical ; wall calcareous, earlier chambers pustulated. Remarks.—This species is distinguished from Praeg- lobotruncana compressiformis (originally described as Praeg- lobotruncana hessi compressiformis by Pessagno, 1962) and other species of Praeglobotruncana in possessing wedge- shaped chambers having depressed sutures in the last whorl on the dorsal side, spirally elongated chambers in the last whorl, and in its generally compressed shape. Etymology.—From Latin, compressa referring to the com- pressed feature of chambers compared with other species of Praeglobotruncana. Material.—Holotype IGPS No. 102707, paratype IGPS No. 102708. Dimensions.—Maximum diameter of holotype 0.30 mm, maximum thickness 0.10 mm. Type locality and horizon.—The holotype and paratype specimens are both from sample SRN-207 (43°2.60’N, 142° 9.78'E), lower part of the Takinosawa Formation, upper Cenomanian. Praeglobotruncana gibba Klaus, 1960 Figure 6-5 Praeglobotruncana stephani (Gandolfi) var. gibba Klaus, 1960, p. 304-305, holotype designated in Reichel, 1950, pl. 16, fig. 6, pl. 17, fig. 6. Praeglobotruncana stephani (Gandolfi). Loeblich and Tappan, 1961, p. 280-284, pl. 6, figs. 4a, b, 5a-c, 6, 7a-c. Praeglobotruncana gibba Klaus. Robaszynski and Caron, 1979, p. 33-38, pl. 44, figs.1a-c, 2a-c, pl. 45, figs. 1a-c, 2a-c; Caron, 1985, p. 65, pl. 30-5a-c, 6a-c. Remarks.—This species is easily distinguished from Praeg- lobotruncana stephani by its high trochospire and from Praeglobotruncana inermis n. sp. by its distinct raised suture with a beaded keel on the dorsal side. This species is abundant in the upper part of the R. cushmani Zone. Material.—Hypotype IGPS No. 102508. Locality and horizon.—The figured specimen is from sam- ple SSS-020, lowermost part of the Takinosawa Formation, upper Cenomanian. Praeglobotruncana inermis sp. nov. Figures 6-1—4 Diagnosis.—A high trochospiral species of Praeglobotrun- cana with slight peripheral pustule lines, distinct lip near umbilicus and 4 smooth-walled chambers in last whorl. Description.— Test of medium to large size, medium to high trochospiral, equatorial periphery lobulate ; chambers petaloidal in shape on dorsal side, trapezoidal to subglobular, inflated on dorsal side, about 12 in all arranged into 2 to 2.5 whorls, enlarging gradually in size as added, characteristi- cally 4 chambers in final whorl, with a weak peripheral band formed of an aligned concentration of pustules which tends to be shifted toward spiral side; final chamber shifted toward umbilical direction ; sutures on dorsal side radial and depressed except for that of first chamber in last whorl which occasionally is raised, ventrally radial and depressed ; um- bilicus shallow, medium to narrow in size, less than 1/4 of maximum diameter of test; primary aperture bordered by a Planktonic foraminifera from Hokkaido Figure 6. 1—4. Praeglobotruncana inermis sp. nov. of the Takinosawa Formation, uppermost Cenomanian. of the Takinosawa Formation, uppermost Cenomanian. of the Takinosawa Formation, uppermost Cenomanian. of the Takinosawa Formation, uppermost Cenomanian. SSS-020, lower part of the Takinosawa Formation, upper Cenomanian. 1. Paratype, IGPS No. 102703, sample loc. no. SRN-220, lower part 2. Holotype, IGPS No. 102704, sample loc. no. SRN-220, lower part 3. Paratype, IGPS No. 102705, sample loc. no. SRN-220, lower part 4. Paratype, IGPS No. 102706, sample loc. no. SRN-220, lower part 5. Praeglobotruncana gibba Klaus, IGPS No. 102503, sample loc. no. Scale bars=100 um. 184 Takashi Hasegawa distinct lip that expands markedly near umbilicus, interiomar- ginal, umbilical-extraumbilical ; wall calcareous, surface smooth, earlier chambers weakly pustulated. Remarks.—This species closely resembles Praeglobotrun- cana anumalensis (Sigal), but differs in lacking the conspicu- ous pustules on earlier chambers, in having diagnostically 4 chambers in the last whorl, more lobulated periphery and more inflated chambers. Etymology.—From Latin, inermis referring to the smooth- walled chambers of this species compared with other species of Praeglobotruncana. Material.—Holotype IGPS No. 102704 ; paratypes IGPS No. 102708, 102705, 102706. Dimensions.—Maximum diameter of holotype 0.34 mm, maximum thickness 0.21 mm. Type locality and horizon.—The holotype and paratypes are all from sample SRN-220 (43°2.60'N, 142°9.72’E), lower part of the Takinosawa Formation, uppermost Cenomanian. Praeglobotruncana shirakinensis sp. nov. Figure 5-8 Praeglobotruncana sp. Leckie, 1985, p. 139-149, pl. 3, figs 9-15. Diagnosis.—A medium trochospiral species of Praeg- lobotruncana with about 5 moderately compressed and slightly lobulated chambers of last whorl. Description.—Test of medium size, medium trochospiral, equatorial periphery slightly lobulate ; chambers initially in- flated and globigerine-like, later ones becoming petaloidal on dorsal side, trapezoidal in shape on ventral side, about 10 to 12 chambers in all arranged into about 2.5 whorls, enlarg- ing gradually in size as added, about 5 slightly compressed chambers in final whorl, with a peripheral band formed of an aligned concentration of pustules paralleling periphery ; sutures on dorsal side curved, raised and beaded, ventrally radial or slightly curved, depressed ; umbilicus shallow and narrow, its width about 1/4 of maximum diameter of test; primary aperture bordered by a wide distinct lip, interiomar- ginal, umbilical-extraumbilical, extending nearly halfway to periphery ; wall calcareous, with marked accumulation of pustules on early chambers. Remarks.—This species resembles Praeglobotruncana ste- phani, but differs in the following characters: spirally slightly elongated and ventrally more inflated chambers of the last whorl; fewer chambers (normally4 to 5) having almost similar size in the last whorl; less lobulated periphery ; and thinner spiral sutures. An intermediate form between P. iner- mis and P. shirakinensis is also figured (Figure 5.7). Etymology.—With reference to the type locality (the Shira- kin River) where the holotype specimen occurred. Material.—Holotype IGPS No. 102523. Dimensions.—Maximum diameter of holotype 0.38 mm, maximum thickness 0.20 mm. Type locality and horizon.—The holotype specimen is from sample SRN-210 (43°2.60'N, 142°9.77’E), lower part of the Takinosawa Formation, upper Cenomanian. Subfamily Helvetoglobotruncaninae Lamolda, 1976 Genus Helvetoglobotruncana Reiss, 1957 Helvetoglobotruncana helvetica (Bolli, 1945) Figure 9-1 Globotruncana helvetica Bolli, 1945, p. 226, pl. 9, fig. 6. Praeglobotruncana helvetica (Bolli). Robaszynski and Caron, 1979, p. 39-42, pl. 46, figs. 1a-c, 2a-c. Helvetoglobotruncana helvetica (Bolli). Wonders, 1980, p. 117, pl. 3, fig. 2a-c ; Caron, 1985, p. 60, figs. 30-7, 8a-c ; Loeblich and Tappan, 1988, p. 463-464, pl. 498, figs. 4-7. Remarks.—Poorly preserved specimens of this species were obtained from only one horizon. Nevertheless, the figured specimen is identified as H. helvetica on the basis of its asymmetrical planoconvex lateral view, thick single keel that is shifted toward the spiral side, and staircase-like imbricate structures on the spiral side. This species is very rare in the area of study; however, it is quite important for interregional correlation. Materail.—Hypotype IGPS No. 102517. Locality and horizon.—The figured specimen is from sam- ple SRN-101, middle part of the Takinosawa Formation, middle Turonian. Subfamily incertae sedis Genus Dicarinella Porthault, 1970 Dicarinella hagni (Scheibnerova, 1962) Figure 7-5 Praeglobotruncana hagni Scheibnerova, 1962, p. 219, figs. 6a-c. Praeglobotruncana sp. cf. P. hagni Scheibnerova. Butt, 1966, p. 174, figs. 2a-c (not 1a-c, 3a-4c). Globotruncana kupperi Thalmann. Marianos and Zingula, 1966, p. 340-341, pl. 39, figs. 6a-c. Dicarinella hagni (Scheibnerova). Robaszynski and Caron, 1979, p. 79-86, pl. 56, figs.1a-c, 2a-c, pl.57, figs.1a-c, 2a-d; Caron, 1985, p. 45, figs. 18-2a-c, 3a-c. Remarks.—This species differs from Dicarinella roddai in having chambers which increase their size more gradually and in having a greater number of chambers in the last whorl. Material.—Hypotype IGPS No. 102509. Locality and horizon.—The figured specimen is from sam- ple SRN-034, middle part of the Takinosawa Formation, Figure 7. 1—3. Dicarinella roddai (Marianos and Zingula). 1. IGPS No. 102520, sample loc. no. SRN-220, lower part of the Takinosawa Formation, uppermost Cenomanian. 2. IGPS No. 102511, sample loc. no. SRN-132, lower-middle part of the Takinosawa Formation, lower Turonian. 3. IGPS No. 102512, sample loc. no. SRN-034, middle part of the Takinosawa Formation, middle Turonian. 4. Dicarinella imbricata (Mornod), IGPS No. 102510, sample loc. no. SRN-034, middle part of the Takinosawa Formation, middle Turonian. 5. Dicarinella hagni (Scheibnerova), IGPS No. 102509, sample loc. no. SRN-034, middle part of the Takinosawa Formation, middle Turonian. Scale bars=100 um. Planktonic foraminifera from Hokkaido 186 Takashi Hasegawa middle Turonian. Dicarinella imbricata (Mornod, 1950) Figure 7-4 Globotruncana (Globotruncana) imbricata Mornod, 1950, p. 589- 590, figs. 5 (Ill a-d). Dicarinella imbricata (Mornod). Robaszynski and Caron, 1979, p. 87-92, pl. 58, figs. 1a-c, 2a-d, pl. 59, figs. 1a-c, 2a-c ; Caron, 1985, p. 45, figs. 18-4a-c, 5a-c. Remarks.—This species is easily distinguished from other species by its diagnostic stair-like imbrication of chambers on the dorsal side. Material—Hypotype IGPS No. 102510. Locality and horizon.—The figured specimen is from sam- ple SRN-034, middle part of the Takinosawa Formation, middle Turonian. Dicarinella roddai (Marianos and Zingula, 1966) Figures 7-1—3 Globotruncana roddai Marianos and Zingula, 1966, p. 340, pl. 39, 5a-c. non Praeglobotruncana roddai (Marianos and Zingula). 1969, p. 171-172, pl. 2, 2a-c. Douglas, Description.—Test medium to large in size, initially a low to medium-height trochospire, equatorial periphery slightly lobulate ; chambers dorsally semicircular, ventrally trap- ezoidal in shape, somewhat inflated on ventral side, about 9 to 11 chambers in all arranged into 2 to 2.5 whorls, enlarging gradually in size as added, last 4 chambers almost similar in size, 5 slightly imbricated chambers in final whorl, with distinct double peripheral keels; sutures on dorsal side curved, raised with a keel which continues to one of double peripheral keels, ventrally radial, depressed, occasionally slightly raised; umbilicus shallow, its width about 1/4 of maximum diameter of test; primary aperture bordered by distinct, narrow- to medium-width lip, interiomarginal, umbili- cal-extraumbilical extending nearly to periphery ; wall cal- careous, weakly pustulated on earlier chambers. Discussion.— This species resembles Dicarinella hagni but is distinguished by having less inflated chambers on ventral side, fewer and slightly imbricated chambers. Although Takayanagi (1965) described this species as Globotruncana marginata, Jirova's neotype figures of G. marginata, (Jirova, 1956, p. 253, figs. 1a-c) and one of the figured specimens of Reuss's syntypes which was later selected as the lectotype by Bolli et al. (1957) (Jirova’s neotype has priority) are appar- ently different from Takayanagis (1965, figs.3a-c, 4a-c) figures in having more chambers in the last whorl which are more globular and inflated, more gradually increasing in size as added, equatorial periphery more lobulate, narrower spaced keels, and a wider umbilicus. Marianos and Zingula (1966) stated that D.roddai (originally described as Globotruncana roddai) was a good marker for the lower Turonian in the type locality of this species, however, the stratigraphic distribution of this species in the area of study is restricted to the uppermost Cenomanian to lower part of the middle Turonian (Figure 3). In this stratigraphic range, this species occurs commonly. Therefore, it may be a useful supplemental species to locate the interval of the Cenomanian/Turonian boundary in Japan. Material.—Hypotype IGPS No. 102520, 102511, 102512. Locality and horizon.—The specimen IGPS No. 102520 is from SRN-220, lower part of the Takinosawa Formation, upper Cenomanian. IGPS No. 102511 is from sample SRN- 132, lower-middle part of the Takinosawa Formation, middle Turonian. IGPS No. 102512 is from sample SRN-034, middle part of the Takinosawa Formation, middle Turonian. Dicarinella takayanagii sp. nov. Figures 8-1—4 Diagnosis.—A low trochospiral species of Dicarinella with wedge-shaped chambers in last whorl and small umbilicus. Description.—Test of medium to large size, low trochospir- al, equatorial periphery lobulate ; chambers initially globiger- ine-like, later ones becoming wedge-shaped and flat on dorsal side, triangular and inflated in shape on ventral side, about 10 chambers in all, enlarging rapidly in size as added, about 4.5 chambers in last whorl, with widely separated weak double peripheral keels, one of which is shifted toward spiral side ; final chamber obliquely shifted toward umbilical direction, as a result, keels being discontinuous to final chamber ; final chamber diagnostically elongated in spiral direction, occasionally lacking peripheral keels ; sutures on dorsal side gently Curved, raised with keels that are continu- ous to one of peripheral keels, sutures on ventral side radial and depressed; umbilicus shallow and narrow, its width about 1/4 of maximum diameter of test; primary aperture bordered by a distinct lip, interiomarginal, umbilical-extraum- bilical ; wall calcareous, earlier chambers weakly pustulated. Remarks.—This species is distinguished from other species of Dicarinella in possessing wedge-shaped cham- bers in the last whorl on the dorsal side, spirally elongated final chamber and a narrower umbilicus. Etymology.—In honor of Prof. Emeritus Y. Takayanagi in recognition of his contribution to the study of Cretaceous Figure 8. 1—4. Dicarinella takayanagii sp. nov. 1. Paratype, IGPS No. 102513, sample loc. no. SRN-223, lower part of the Takinosawa Formation, uppermost Cenomanian. Takinosawa Formation, uppermost Cenomanian. Takinosawa Formation, uppermost Cenomanian. Takinosawa Formation, uppermost Cenomanian. 2. Paratype, IGPS No. 102514, sample loc. no. SRN-223, lower part of the 3. Holotype, IGPS No. 102515, sample loc. no. SRN-223, lower part of the 4. Paratype, IGPS No. 102516, sample loc. no. SRN-223, lower part of the 5. Rotalipora deeckei (Franke), IGPS No. 102519, sample loc. no. KMZ-002, the uppermost part of the Hikagenosawa Formation, upper Cenomanian. 6. Rotalipora cushmani (Morrow), IGPS No. 102472, sample loc. no. SRN-220 (last occurrence horizon of R. cushmani), lower part or the Takinosawa Formation, uppermost Cenomanian. Same specimen as that shown in Hasegawa and Saito (1993). Scale bars=100 um. Planktonic foraminifera from Hokkaido 188 Takashi Hasegawa foraminifera in Japan. Material.—Holotype IGPS No. 102515 ; paratypes IGPS No. 102513, 102514, 102516. Dimensions.—Maximum diameter of holotype 0.29 mm, maximum thickness 0.17 mm. Type locality and horizon.—The holotype and all paratypes are from sample SRN-223 (43°2.60'N, 142°9.73’E), lower part of the Takinosawa Formation, uppermost Cenomanian. Family Rotaliporidae Sigal, 1958 Subfamily Rotaliporinae Sigal, 1958 Genus Rotalipora Brotzen, 1942 Rotalipora cushmani (Morrow, 1934) Figures 8-6; 9-4 Globorotalia cushmani Morrow, 1934, p. 199, pl. 31, fig. 4a-b. Rotalipora cushmani (Morrow). Loeblich and Tappan, 1961, p. 297-298, pl. 8, figs. 1-8, 10 (not fig. 9); Pessagno, 1967, p. 292-293, pl. 51, figs. 6-9; Robaszynski and Caron, 1979, p. 69-74, pl.7, figs.1a-c, pl.8, figs.1a-c, 2a-c; Wonders, 1980, p. 125-126, pl. 3, fig. 3a-c ; Caron, p. 69, figs. 31-8-11. Remarks.—This species is distinguished from other species of Rotalipora by having a lobulated periphery, semi- circular chambers ornamented by pustules in the last whorl, pronounced supplementary apertures with developed lips. The last occurrence of this species corresponds to that of the genus Rotalipora in this study. This species is a very important index in Japan for interregional correlation. Material.—Hypotypes IGPS No. 102471, 102472. Locality and horizon.—Two figured specimens are from SRN-220 (last occurrence horizon of À. cushmani), lower part of the Takinosawa Formation, uppermost Cenomanian. Rotalipora deeckei (Franke, 1925) Figure 8-5 Rotalia deeckei Franke, 1925, p. 88,90, pl. 8, figs. 7a-c (This inaccessible literature is indirectly accessible from “Ellis and Messina, 1940 et seq., Catalogue of Foraminifera’). Rotalipora deeckei (Franke). Robaszynski and Caron, 1979, p. 75-80, pl. 9, figs. 1a-2c, pl. 10, 1a-2c. Remarks.—This species is very similar to Rotalipora rei- cheli, but differs in having periumbilical ridges extended from raised sutures on the ventral side and narrower umbilicus. Material—Hypotype IGPS No. 102519. Locality and horizon.—The figured specimen is from KMZ- 002, uppermost part of the Hikagenosawa Formation, upper Cenomanian. Rotalipora sp. aff. R. gandolfii Luterbacher and Premoli-Silva, 1962 Figure 9-3 Remarks.—This species resembles Rotalipora gandolfii, but differs in having the hemispherical last two chambers. This morphological feature is rather reminiscent of Rotalipora cushmani. Material.—Hypotype IGPS No. 102524. Locality and horizon.—The specimen IGPS No. 102524 is from SSS-020, lowermost part of the Takinosawa Formation, upper Cenomanian. Rotalipora greenhornensis (Morrow, 1934) Figure 9-5 Globorotalia greenhornensis Morrow, 1934, p. 199, pl. 31, figs. 1a- €: Rotalipora greenhornensis (Morrow). Loeblich and Tappan, 1961, p. 299-301, pl. 7, figs. 5-10 ; Pessagno, 1967, p. 295-297, pl. 50, fig. 3, pl. 51, figs. 15-17, 19-21 (not figs. 13, 14, 18); Pes- sagno, 1967, p. 289-292, pl. 50, figs. 4-6 ; Robaszynski and Caron, 1979, p. 85-90, pl. 12, figs. 1a-c, 2a-c, pl. 18, figs. 1a- c, 2a-c; Caron, 1985, p. 69, text-figs. 32-1, 2. Remarks.—This species is easily distinguished from other species of Rotalipora by having greater number of chambers in the last whorl and crescent-shaped chambers which are often concave on the dorsal side. The last occurrence of this species is at the same stratigraphic horizon as that of Rotalipora cushmani in the area of study. Material.—Hypotype IGPS No. 102473. Locality and horizon.— The figured specimen is from SRN- 220, lower part of the Takinosawa Formation, uppermost Cenomanian. Subfamily Globotruncaninae Brotzen, 1942 Genus Marginotruncana Hofker, 1956 Marginotruncana pseudolinneiana Pessagno, 1967 Figure 9-6 Marginotruncana pseudolinneiana Pessagno, 1967, p. 310, pl. 65, figs. 24-27 ; Robaszynski and Caron, 1979, p. 123-128, pl. 67, 1a-2d, pl. 68, 1a-2c ; Caron, 1985, p. 61, text-figs. 26-7, 8. Remarks.—This species is easily distinguished from other Figure 9. 1. Helvetoglobotruncana helvetica (Bolli), IGPS No. 102517, sample loc. no. SRN-101, middle part of the Takino- sawa Formation, middle Turonian. middle part of the Takinosawa Formation, lower Turonian. 2. Marginotruncana schneegansi (Sigal), IGPS No. 102521, sample loc. no. SRN-132, lower- 3. Rotalipora sp. aff. R. gandolfii Luterbacher and Premoli-Silva, IGPS No. 102524, sample loc. no. SSS-020, lowermost part of the Takinosawa Formation, upper Cenomanian. 4. Rotalipora cushmani (Morrow), IGPS No. 102471, sample loc. no. SRN-220 (last occurrence horizon of R. cushmani), lower part or the Takinosawa Formation, uppermost Cenomanian. Same specimen as that shown in Hasegawa and Saito (1993). 5. Rotalipora greenhornensis (Morrow), IGPS No. 102473, sample loc. no. SRN-220, lower part of the Takinosawa Formation, uppermost Cenomanian. Same specimen as that shown in Hasegawa and Saito (1993). IGPS No. 102522, sample loc. no. SRN-062, lower part of the Shirogane Formation, upper Turonian. 6. Marginotruncana pseudolinneiana Pessagno, Scale bar=100 um. 189 Planktonic foraminifera from Hokkaido 190 Takashi Hasegawa species by its diagnostically rectangular shape in lateral view. This species characterizes the middle Turonian to Coniacian interval in Japan. Material—Hypotype IGPS. No. 102522. Locality and horizon.—The figured specimen is from SRN- 062, lower part of the Shirogane Formation, upper Turonian. Marginotruncana schneegansi (Sigal, 1952) Figure 9-2 Globotruncana schneegansi Sigal, 1952, p. 33, text-fig. 34. Marginotruncana schneegansi (Sigal). Robaszynski and Caron, 1979, p. 135-140, pl. 70, fig. 1a-2e, PI. 71, 1a-2d ; Caron, 1985, p. 61, text-figs. 27, 3-6. Remarks.—The first occurrence of this species character- izes the lower Turonian in Japan. Material.—Hypotype IGPS No. 102521. Locality and horizon.—The figured specimen is from SRN- 132, lower-middle part of the Takinosawa Formation, lower Turonian. Acknowledgments The author expresses his deep appreciation to T. Saito (retired from Tohoku Univ.) and A.S. Horowitz (Indiana Univ.) for their critical readings of the manuscript and helpful discussions. The author wishes to extend his appreciation to K. Ishizaki (retired from Tohoku Univ.) and H. Nishi (Kyusyu Univ.) for providing helpful advice about the manuscript. Acknowledgments are also due to J. Nemoto (Tohoku Univ.) for his assistance in photographic work, S. 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Thurow, J. and Kuhnt, W., 1986: Mid-Cretaceous of the Gibraltar arch area. In, Summerhayes, C.P. and Shack- leton, N.J. eds., North Atlantic Paleoceanography, Geo- logical Society Special Publication, vol. 22, p. 423-445. Blackwell Scientific Publications, Oxford. Wonders, A.A.H., 1980: Middle and Late Cretaceous plan- ktonic foraminifera of the western Mediterranean area. Utrecht Micropaleontological Bulletins, vol. 24, p. 7-157, pls. 1-10. Paleontological Research, vol. 3, no. 3, pp. 193-201, 5 Figs., September 30, 1999 © by the Palaeontological Society of Japan Tidal growth patterns and growth curves of the Miocene potamidid gastropod Vicarya yokoyamai BUNJI TOJO and FUJIO MASUDA Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan Received 10 August 1998 ; Revised manuscript accepted 24 May 1999 Abstract. Continuous growth sequences are recorded in vertical (= median longitudinal) sections of the columella of the fossil potamidid gastropod Vicarya yokoyamai Takeyama, from subtropical Miocene faunas of Japan. Shells from the Mizunami, Uchiura, Bihoku, and Masuda groups show semidiurnal tidal growth patterns. This suggests that V. yokoyamai lived in the intertidal zone. Growth curves were reconstructed on the basis of numbers of tidal growth lines. These growth curves were found to be very similar with one another, and indicated that shell-height increased from 1.5 cm to 8 cm in two years. Key words: columella, growth rate, intertidal, micro-growth increment, micro-growth line, tide Introduction Invertebrate hard parts such as molluscan shells and coral skeletons grow incrementally, forming alternating sequences of micro-growth lines and micro-growth increments that constitute their micro-growth patterns. Micro-growth pat- terns reflect physiological and environmental changes that occurred during their formation. Reconstruction of these changes from micro-growth patterns observed in the hard parts of a variety of organisms has been attempted in many studies (e.g. Wells, 1963; Berry and Barker, 1968 ; House and Farrow, 1968; Pannella and MacClintock, 1968 ; Pan- nella et al., 1968 ; Dolman, 1975; Scrutton, 1978; Lutz and Rhoads, 1980 among others). Intertidal organisms such as bivalves, gastropods, and barnacles record the effects of changing tides, as exposure and immersion are commonly reflected in their micro-growth patterns (Evans, 1972; Bourget and Crisp, 1975; Crisp and Richardson, 1975; Richardson et al., 1979, 1980a, 1980b, 1981; Richardson et al., 1980c ; Ekarante and Crisp, 1982 ; Ohno and Takenouchi, 1984; Ohno, 1984, 1985, 1989; Ri- chardson, 1987, 1988a, 1988b ; Tojo and Ohno, 1999). Using these records, ancient tidal periods and tidal patterns have been reconstructed from fossil bivalves (Ohno, 1984, 1989 ; Tojo et al., 1999). Tidal growth patterns are also a suitable index for the time scale of growth, so they can be used to reconstruct the growth rates of hard parts (Richardson, 1987 ; Tojo and Ohno, 1999). Previous studies of growth rates are based in many cases on annual rings that were recognized by comparative analysis of growth lines and oxygen isotopes of the shells (Jones et al., 1978; Jones, 1980 ; Thompson et al., 1980 ; Jones, 1981), but many gastropods have no obvious yearly rings. Thus we attempt the reconstruction of growth curves from tidal growth patterns. Few studies of micro-growth patterns in gastropod shells have been undertaken, because coiling of the gastropod shell obstructs the collection of continuous growth sequences spanning the whorls. However, Tojo and Ohno (1999) have proposed an easy method to obtain a continuous micro-growth pattern from one whorl to the next in the Recent potamidid gastropod Terebralia palustris (Linnaeus), using sections of the columella. This method made it easy to access records of gastropod growth. Tojo and Ohno (1999) observed tidal growth patterns in shells of T. palustris. They inferred that one micro-growth line corresponds to a 12.4 hour interval of low tides and reconstructed the growth curve of an individual T. palustris shell. This growth curve was consistent with one that had been reconstructed from a population analysis. Analysis of micro-growth patterns by this method permits the reconstruction of changing growth rates even from a single fossil specimen or species known only from small populations. The fossil potamidid gastropod Vicarya has been regarded as a Characteristic element of warm-water faunas from Eocene to Miocene in age. Tojo and Sakakura (1998) reported tidal growth patterns in shells of Vicarya yokoyamai from the Mizunami Group. However, little is Known of the growth of Vicarya because it is an extinct genus. The method of Tojo and Ohno (1999) can be applied to shells of V. yokoyamai. We observed tidal growth patterns in shells of V. yokoyamai from four localities (Figure 1) and reconstructed their growth curves. Material In this study, we used fragments of V. yokoyamai from 194 Bunji Tojo and Fujio Masuda 134° E 132° E Figure 1. Locality map for Vicarya yokoyamai specimens utilized in this study. subtropical tidal or shallow marine facies of Miocene age in Japan. To reconstruct the growth curve of V. yokoyamai (Figure 2A), we used a total of six specimens, three from the Mizunami Group in Gifu Prefecture, and one each from the Uchiura Group in Kyoto Prefecture, the Bihoku Group in Okayama Prefecture, and the Masuda Group in Shimane Prefecture (Figure 1). In the following discussion, specimens are referred to by the group name, and the three specimens from the Mizunami Group are called Mizunami A, B and C. Two species names that had been established, V. yokoyamai and Vicarya japonica, were synonymized by Kanno (1986). Preparation for columella method In order to prepare vertical (=median longitudinal) and horizontal (— cross) sections of the gastropod shell, samples were cut and ground with a graded series of carborundum and polished with diamond paste. A binocular microscope and a scanning electron microscope (SEM) were used for observation of shell micro-growth patterns (Figure 2B). For observation with the SEM, polished samples were etched with 0.5 mol/l HCl and then coated with gold. Results Micro-growth pattern Micro-growth pattern consists of two components of growth layers, micro-growth lines and micro-growth incre- ments. Micro-growth lines are the layers which are rela- tively resistant to etching. Thus, they are observed as liner- ridges under SEM. Micro-growth increments are the layers between micro-growth lines. Micro-growth lines show various thicknesses, but are generally thinner than micro growth increments. Micro-growth lines of V. yokoyamai appear as relatively light layers under the binocular microscope (Figures 2B, D). Formation of columella Before observing the columella sections, we examined the outer shape of the columella to understand its formation (Figure 2C). The basal part of the columella has a trough- like structure along its coiling axis. One flank of the trough continues to the outer lip ; the other covers the bottom of the preexisting whorl (Figure 2C). During growth of the shell, the trough extends downwards (abapically) in the direction of coiling, the apical end being filled with new shell material. The formation of new growth layers over this surface results in the formation of the columella. Growth layers at the bottom of the trough contribute to growth of the central part of the columella, and those on the preexisting outer surface of the neck contribute to growth of the columella rim and a part of awhorl. This layer becomes part of the “ceiling” of the new shell whorl. The new shell is laid down directly upon that formed in the previous whorl. This surface of contact appears as a line in shell sections that is referred to as the “borderline” (Figures 2B, D; Tojo and Ohno, 1999). Appearance of the growth layers in sections In vertical (=median longitudinal) section, each whorl shows a pair of more or less hyperbolic patterns, alternately on the right and left sides of the coiling axis (Figures 2B, 3). One is the trace of the trough facing the observer, and the other is that of the trough opposing the observer. The center of this hyperbolic pattern is called the “junction” (Figure 2B; Tojo and Ohno, 1999). The shell of the columella between successive junctions on the same side of the coiling axis corresponds to the growth record of one shell whorl. Borderlines are also observed in vertical sections (Figure 2B). Continuous growth sequence on the vertical shell section Correlation of the growth layers was accomplished by tracing them on vertical (= median longitudinal) and horizon- tal (— cross) sections. First a vertical section was made and the growth layers on it were documented (Figure 2B). Then the two halves of the shell were glued together with adhe- sive. The “repaired shell” was then cut horizontally. The cut surface was polished and its growth layers were documented (Figure 2D). Then the surface was ground away until shell corresponding to 90° of coiling had been removed. Polishing and documentation of horizontal sec- tions at 90° intervals was repeated for more than one full whorl of the shell (Figure 3). The columella occupies the center of the cross section, Figure 2. A. A shell of Vicarya yokoyamai Takeyama, Middle Miocene, Mizunami Group, Gifu Pref. The scale bar is Icm long. B. A vertical section of Vicarya yokoyamai, Middle Miocene, Mizunami Group, Gifu Pref. Along the coiling axis, micro- growth lines and intervening micro-growth increments are observed. The scale bar is 1mm long. C. The basal part of columella of Vicarya yokoyamai, Middle Miocene, Mizunami Group, Gifu Pref. The trough running along the columella and the new shell layer covering the previous whorl surface can be seen. The scale bar is 1cm long. D. A horizontal section of Vicarya yokoyamai with the columella at the center, Middle Miocene, Mizunami Group, Gifu Pref. The scale bar is 1mm long. (Photomicrographs of sections taken with binocular microscope.) 195 Growth patterns of Vicarya yokoyamai ine a = ® Lo) 2] fe) m 196 Bunji Tojo and Fujio Masuda Vertical 1 adapical © i) abapical Figure 3. Correlation of growth layers on vertical ( Horıtzon gen median longitudinal) sections and horizontal (=cross) sections. Growth layers are numbered in temporal order from 1 to 9. Lines A to E show the correspondence of vertical and horizontal sections. On vertical section dots show junctions. with a portion of the whorl extending away from it as if it were a vortex (Figure 2D). One side of the link between the columella and the vortex forms a concave surface and the other side is convex. The concave surface is underlain by an accumulation of numerous U-shaped layers. In succes- sive horizontal sections, viewed abapically, the vortex rotates clockwise. New growth layers are added to the surface of the concave side, move to the convex side abapically, and Growth patterns of Vicarya yokoyamai 197 .\ TeToTT | 353 ai re F Y ® Y e Y ® | ® | © Y © 1 © | T N ES \ :23; 4 Be Fr : D. ® E : ee] £ © \ ES x ; ; 3 BEN RE; Bl TER : î : 7. a Figure 4. Tidal growth patterns recorded in the columella sections of Vicarya yokoyamai. A. Mizunami A specimen. B. Mizunami B specimen. C. Mizunami C specimen. D. Uchiura specimen. E. Bihoku specimen. F. Masuda specimen. Continuous semidiurnal tidal growth patterns are indicated by the alternation of thicker (arrowhead) and thinner (dot) micro- growth lines. The order of micro-growth line thickness changes. All scale bars represent 100 um. (Photomicrographs taken with SEM.) 198 Bunji Tojo and Fujio Masuda finally vanish. Through observation of successive horizontal sections at 90° intervals the growth layers could be examined and numbered. In Figure 3 (right) the stack of numerous U- shaped growth layers is shown diagrammatically. Only lines with characteristic features, which could easily be correlated in vertical and horizontal sections, were numbered; the oldest conspicuous growth layer was numbered 1 and the newest numbered 9. All the corresponding growth layers could be seen on the vertical section for this growth interval, corresponding to more than one shell whorl (Figure 3 left). Since the mode of growth of the V. yokoyamai shell does not change during its ontogeny, all visible growth layers can be recognized and counted on the median longitudinal section of the shell. Tidal growth patterns Vicarya yokoyamai shells from the four localities show two sorts of accretionary patterns of micro-growth lines on the columella (Figure 4). One is the alternation of thicker (in- dicated by arrowheads in Figure 4) and thinner (dots in Figure 4) micro-growth lines. The other is an inversion of the arrangement of thicker and thinner micro-growth lines at approximately every 28.5 growth lines. The same micro growth patterns of V. yokoyama/ were reported in specimens from the Mizunami Group by Tojo and Sakakura (1998). These are characteristic features of tidal growth patterns (Dolman, 1975; Richardson et al. 1979, 1980a, 1981 ; Richardson, 1988b ; Ohno, 1989). Identical alternations and inversions are reported from intertidal bivalves (Richardson et al., 1979, 1981 ; Ohno, 1984, 1989 ; Richardson, 1988b) and gastropods (Ohno and Ta- kenouchi, 1984; Tojo and Ohno, 1999). In bivalve shells from semidiurnal, mesotidal regimes, the alternation of thick- er and thinner micro-growth lines is caused by differences in temperature between daytime and nighttime exposures to the air (Richardson et al., 1980a ; Richardson 1988b ; Ohno, 1989). Inversions in the order of thicker and thinner micro- growth lines result from the different periodicities of approxi- mately semidiurnal tides and of the 24 hour cycle of day and night. The zone where the inversion occurs is called the “switch zone” (Ohno, 1989). This mechanism may be responsible for the alternations and inversions observed in the succession of micro-growth lines of V. yokoyamai (Figure 4) from the Middle Miocene. This result is compatible with the tidal growth patterns of fossil bivalves from the Mizunami Group recognized by Ohno (1989). The preservation of this micro-growth pattern in all specimens suggests that V. yokoyamai lived in the intertidal zone. The relationship between the number of tidal emersions and micro-growth lines in intertidal bivalves and gastropods has been confirmed by several experiments (Richardson et al., 1979, 1980a, 1980b ; Richardson et al., 1980c ; Ekarante and Crisp, 1982 ; Ohno, 1983, 1985, 1989 ; Richardson, 1987, 1988a, 1988b). Hence, it is reasonable to infer that one micro-growth line in the shell of V. yokoyamai is formed in each tidal cycle. Reconstruction of growth curves A continuous growth record can be obtained from the vertical section of a columella (Figures 2, 3). If shell growth was semidiurnal in V. yokoyamai, it should be possible to reconstruct growth curves using these observations. Height of shell To reconstruct the growth curve of V. yokoyamai, we had to estimate the original height of the shell. However, all specimens had lost some part of the apical portion of the shell. We extrapolated to determine the original height from the angle defined by the whorls of the surviving shell (Figure 5). Growth curves of Mizunami specimens We counted the number of micro-growth lines and mea- sured the shell height at which each junction between whorls of the Mizunami specimens was formed (hereafter called junction height: Figure 5). The shell between suc- cessive junctions on the same side of the coiling axis corresponds to the growth record of one shell whorl. Therefore, the number of micro-growth lines between suc- cessive junctions, multiplied by 12.4 hours, represents the Apex V _ == = = = - -0--- = Junction Figure 5. Shell height is the vertical distance between the tip of the columella and the reconstructed position of the apex, extrapolated from the outer surface of surviving shell whorls. Junction height is the shell height at which each junction was formed. Growth patterns of Vicarya yokoyamai 199 time required for growth of the shell whorl. Given the unclear micro-growth lines. Error bars represent the ac- junction heights, we were able to reconstruct the growth cumulated number of unclear micro-growth lines. This curve. graph shows that the growth curves of Mizunami specimens First, the data for Mizunami C were plotted on a graph are similar. The growth rate gradually decreased with (Figure 6A). Then, data for Mizunami A and B were plotted growth. as if their first junction heights lined up with that of Mizunami C (Figure 6A). The points plotted are based on the total Growth curves of other specimens number of clear micro-growth lines plus half the number of We counted the numbers of micro-growth lines and Te eye] 01 A 9 8 = + —6— = 7 © 6 —q— ~~ ah 5 on "© F- ay = F @ Mizunami A 2 a M Mizunami B Va A Mizunami C 0 > Dé RN 0 500 1000 1500 Number of growth lines Estimated time (year) 1 2 10} B 9 8 = Gs A U TZ 6 +— a5 ‘© 4 ay 3 © Uchiura 2 © Bihoku 1 A Masuda 0 2 0 500 1000 1500 Number of growth lines Estimated time (year) 1 2 Figure 6. A. Reconstructed growth curves of Vicarya yokoyamai from the Mizunami specimens. B. Reconstructed growth curves of Vicarya yokoyamai from various areas. The solid line is the approximate growth curve of the Mizunami specimens. 200 Bunji Tojo and Fujio Masuda measured the junction heights of other specimens, plotting similar growth curves (Figure 6B). In the figure, the solid line is the curve of best fit to the Mizunami specimen data. Data from other specimens were plotted so that their first junction heights lie on the Mizunami curve (Figure 6B). This graph shows that the growth curves of the Uchiura, Bihoku, and Masuda specimens are similar to those of shells from Mizunami. Discussion Previous studies have suggested that Vicarya lived in the intertidal zone of a subtropical mangrove swamp (Oyama, 1950 ; Chinzei, 1978; ltoigawa and Tsuda, 1986). This inference is corroborated by the pattern of tidal growth documented here. The alternation of thicker and thinner micro-growth lines is reported only from intertidal organisms. The observation of such alternations in all specimens sug- gests that V. yokoyamai lived in an intertidal zone where it was emersed twice a day. Distinct major growth breaks, such as winter or spawning breaks, were not observed in this study. This is consistent with the subtropical habitat of V. yokoyamai, which lived during the warm Neogene climatic optimum (Chinzei, 1978 ; Chinzei, 1986 ; Ozawa et al., 1995). Hence, there was no necessity for a winter break in growth. We reconstructed the growth curves of six specimens from continuous growth records and the assumption that one micro-growth line formed in a tidal interval. Reconstructed growth curves approximate a logistic form. The logistic pattern of declining growth rate is typical of most inverte- brates, indeed of most animals. This suggests the recon- struction is correct. The shells grew from 1.5 cm to 8 cm in height over two years. The adult shell of Vicarya has a prominent, thick outer lip. The growth curves suggest that these animals reached maturity and formed the prominent outer lip at the age of two years. Jones (1981) showed that the standardized growth rate of Spisula solidissima changes drastically in conjunction with monthly average mean sea surface temperatures. The change of growth rate is largely explained by the presence of the winter break. In contrast to this cool-water species, the reconstructed growth curves of the Vicarya specimens show no or weak seasonal fluctuations. This suggests that V. yokoyamai grew in a stable subtropical environment without any climatic deterioration. This inference should be tested by studies of the growth of cooccurring fossils. The number of specimens studied here is small, due to weathering and recrystallization of most specimens. How- ever, the good agreement of the growth curves in shells from different formations and localities suggests that the columel- la-method and tidal growth analysis can be used to infer high-resolution population dynamics of fossil gastropod assemblages of various ages. Conclusion The columella method yields evidence of continuous growth sequences in shells of the fossil potamidid gastropod V. yokoyamai. The tidal growth patterns of V. yokoyamai shells suggest that this gastropod lived in the intertidal zone, under the influence of semidiurnal tides. The reconstructed growth curves of specimens from the Mizunami, Uchiura, Bihoku, and Masuda groups show that their shells grew at similar rates, from 1.5 cm to 8 cm in height in two years. Acknowledgments T. Ohno (Kyoto University Museum), provided valuable discussion and suggestions. S.M. Kidwell (University of Chicago) and H. Maeda (Kyoto University) read the manu- script and provided valuable comments and suggestions. K. Chinzei, (Osaka Gakuin University), S. Kanno (Joetsu Univer- sity of Education) and N. Sakakura (Kyoto University) also provided valuable discussions, as did Y.Okumura and H. Karasawa (Mizunami Fossil Museum), who provided samples for this study. S. 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Paleontological Research, vol. 3, no. 3, pp. 202-221, 10 Figs., September 30, 1999 © by the Palaeontological Society of Japan Ordovician cephalopods from the Maggol Formation of Korea CHEOL-SOO YUN Department of Earth Science, Teachers College, Kyungpook National University, Taegu 702-701, Korea Received 7 January 1999 ; Revised manuscript accepted 6 July 1999 Abstract. A cephalopod fauna consisting of 11 species belonging to 7 genera is described from the Lower Ordovician Maggol Formation near Taebaeg City in South Korea. The fauna includes two new species, Ormoceras weoni and Michelinoceras cancellatum, and Wutinoceras, a primitive genus of the family Actinoceratidae first reported from South Korea. Ormoceras cricki from the Middle Ordovician Duwibong Formation occurs in the uppermost horizon of the Maggol Formation, and thus may be regarded as a forerunner of the ormocerids in Korea. The Maggolian cephalopod fauna comprising Wutinoceras robustum, Kogenoceras nanpiaoense, and Manchuroceras spp. shows closest affinities with those from the Setul Limestone of the Langkawi Islands, Malaysia and from the Beianzhuang Formation of Hwangho Basin, North China. This fauna is, therefore, assigned in age to the late Ibexian to early Whiterockian in the American Early Ordovician scale. Key words: cephalopod fauna, lower Whiterockian, Maggol Formation, Ormoceratidae, upper Ibexian, Korea Introduction Kobayashi (1927) first described seven cephalopod species from the Ordovician of South Korea, including Kotoceras grabaui from the Middle Ordovician Maggol For- mation. In a subsequent monograph (Kobayashi, 1934), the stratigraphic occurrences of these species were reassigned to the overlying Middle Ordovician Jigunsan Formation. Cephalopod fossils seldom occur in the Maggol Formation. They are commonly found as partial phragmocones whose internal structures are difficult to recognize because of recrystallization. Despite such generally unfavorable fossil preservation, more than fifty well preserved cephalopod specimens have been recently collected from the Maggol Formation of Sanaegol, Taebaeg City, Kangweondo, Korea (Figure 1). This paper describes the cephalopod fauna of the forma- tion based mainly on newly collected material in addition to Kobayashi's (1927) type and figured specimens. Compari- son with contemporary faunas from other regions is also given in this paper, with discussion of the biostratigraphic and paleobiogeographic implications of the Maggol fauna. All specimens described herein are housed in the Depart- ment of Earth Science, Teachers College, Kyungpook National University (prefix KPE), Taegu, Korea. Geological setting The Maggol Formation was originally named by Kobayashi (1927) for a limestone formation “the Great Limestone Group” exposed near the village “Maggol”, at the Sangdong Scheelite Mine, Sangdong, Yeongweol. The formation extends from east to west in the southern limb region of the Baegunsan Syncline where the Duwibong type Joseon Supergroup is widely distributed. The formation ranges from 250 m to 400 m in thickness. The Maggol Formation conformably overlies the Dumugol Formation and is overlain by the Jigunsan Formation. Almost complete sequence of the formation is exposed along the Sanaegol Section, 7 km southwest of Hwangjidong in Taebaeg City (Figure 1). In this section, the lower part of the formation is barren of macrofossils. Cephalopod fossils were found in two stratigraphic units, the middle-upper and uppermost parts of the formation (Figure 2). Lithologic components of the formation consist of biotur- bated limestone, well bedded limestone and bioclastic lime- stone with frequent intercalations of dolomite and dolomitic limestone. Flat pebble conglomerates are included in the lower part of the formation, but they were not observed in the section examined. The boundary between the underlying Maggol and overlying Jigunsan Formations was observed at a small waterfall, about 1.5 km upstream along the valley from Sanaegol village. The lithic facies at this place shows an abrupt change from bioclastic grainstone consisting mostly of Oolitic particles to calcareous black shale. Based on the general compostion and sedimentary structures such as desiccation cracks, ripple marks, bird’s-eye structures, and bioturbation, Paik (1985, 1987, 1988) suggested tidal flats as the depositional environments of the Maggol Formation. Cephalopod fossils were collected mainly from the bioclastic Ordovician cephalopods from Korea 203 Kohan *. Hambaegsan (1573 m) x Cephalopod Yeongweol Figure 1. and bioturbated limestones in the two stratigraphic levels mentioned above, being especially abundant in the upper- most horizon of this formation. Faunal characteristics and correlation Based on a relatively limited number of cephalopod speci- mens, Kobayashi (1966) designated three fossil horizons in the middle and upper parts of the Maggol Formation; Manchuroceras, Polydesmia, and Sigmorthoceras horizons in ascending order (Table 1), and correlated them with upper Canadian, and lower and middle Chazyan (Whiterockian in the present usage) in North America, respectively. Kobaya- shi (1977) studied Takuhito Shiraki’s collection and described four endoceroid species belonging to Manchuroceras from the Maggol Formation, without documentation of their exact localities and stratigraphic positions. Since siphuncular remains of Manchuroceras were not found in the overlying Jigunsan and Duwibong Formations, Kobayashi (1966) as- signed the horizon of the Manchuroceras fauna to the middle part of the Maggol Formation. Hwangjidong TAEBAEG CITY Jangseong LEGEND —--— Provincial boundary Stream Narrow path GED National road 14141 Provincial road Index map of fossil locality on the western area of Taebaeg City, Kangweondo. Table1. Lithostratigraphic and biostratigraphic divi- sion of Ordovician Duwibong type sequence of Joseon Supergroup in Korea (Complied from Kobayashi, 1966 ; Kim et al., 1991). Formation Macrofossil zone Duwibong Actinoceroids Jigunsan Orthoceroids Sigmorthoceras Maggol Polydesmia Manchuroceras Clarkella Kayseraspis Dumugol Protopliomerops Asaphellus Dongjeom Pseudokainella In this study, 53 cephalopod specimens from seven hori- zons in the Maggol Formation were collected and analyzed (Figure 2). The following 11 species belonging to 7 genera 204 Cheol-Soo Yun SANAEGOL SECTION Jigunsan Fm. — SN741 Ormoceras weoni sp. nov. Ormoceras cricki Michelinoceras cancellatum sp. nov. PSS ST Vaginoceras sp. CRE HU Ut Be re its rf rt it rl -20 MIDDLE ORDOVICIAN -30 -40 -50 -60 -70 c © = oO = i © LL © D [°2] oO = o <= — L © a t oa Qa bu © 2 Q 3 : i D vo = -80 90 Kogenoceras nanpiaoense LEGEND LOWER ORDOVICIAN -100 Jiqunsan Formation Well beded limestone -110 Bioclastic limestone Polydesmia sp Bioturbated limestone Dolomitic limestone Wutinoceras sp Wutinoceras robustum Dolomite Manchuroceras cf. wolungense Manchuroceras sp. A, B No exposure -140 m Figure 2. Geologic column of the middle to upper parts of the Maggol Formation at Sanaegol section, showing the cephalopod-bearing horizons. SN stands for the locality name, “Sanaegol”. Ordovician cephalopods from Korea were recognized: Ormoceras weoni sp. nov., Ormoceras cricki Kobayashi, 1934, Michelinoceras cancellatum sp. nov., Vaginoceras sp., Kogenoceras nanpiaoense (Kobayashi and Matsumoto, 1942), Polydesmia sp. cf. P. canaliculata Lorenz, 1906, Wutinoceras robustum (Kobayashi and Matsumoto, 1942), Wutinoceras sp., Manchuroceras sp. cf. M. wolungense (Kobayashi, 1931), Manchuroceras sp. A, and Manchuroceras sp. B. Of these species, the two Wutinoceras species are the first report of the genus in Korea. Wutinoceras is widespread in the lower-middle Whiterockian strata of North America (Flower, 1957, 1968, 1976), Australia (Teichert and Glenister, 1953 ; Flower, 1968 ; Stait, 1984; Stait and Burrett, 1984), North China (Endo, 1930 ; Kobayashi and Matsumoto, 1942 ; Chang, 1965; Zhu and Li, 1996) and Malaysia (Stait and Burrett, 1982). Teichert (1935) and Flower (1968) regarded Polydesmia as the oldest and most primitive of the actinocer- oids, relying on their thick connecting ring and dendritic 205 radial canal system. In the Ordovician of China, however, Polydesmia does not occur prior to Wutinoceras (Chen, 1976 ; Chen et al. 1980). Therefore, Wutinoceras may be the ancestor of the Actinoceratidae, as suggested by Flower (1976). The three species of Manchuroceras from the Maggol Formation listed above are always represented by partial siphuncles and were found in the middle part of the Maggol Formation (Figure 2). The two horizons (SN710 and 712 in Figure 2) yielding these fossils may be equivalent to the Manchuroceras horizon of Kobayashi (1966). The genus name Manchuroceras was first proposed by Ozaki (1927) without describing its type species, and was subsequently emended and redescribed in detail by Kobayashi (1935). This genus characterizes the Wolungian stage in North China. A total of 28 species assigned to Manchuroceras are described from the Ordovician of various regions (Table 2), among which 20 species are known from China, 4 species Table 2. List of Manchuroceras species hitherto described. Species Occurrence Reference Manchuroceras nom. nud. Ozaki Manchuroceras wolungense (Kobayashi) M. endoi Kobayashi SSSS5S585858585 £ S SSS SSISSSSS SESE SS | ozakii Obata . compressa (Kobayashi) platyventrum (Grabau) ishidai Obata yenchouchengense Obata kobayashii Obata katsunumai Obata steanei Teichert excavatum Teichert . asiasticum Balashov sp. gingshuiheense Chen tochuanshanense Chang lemonei Hook & Flower cf. platyventrum (Grabau) tenuise Kobayashi hanense Kobayashi ? Sp. limatum Xu. densum Xu pachymuratum Xu yangteense Xu yazipingense Zou minitum Zou | pianguanense Zou platyventrum (Grabau) . nakamense Stait & Burrett | Wolungian (Lower Ordovician) limestone of Manchoukou, Manchuria Wolungian (L. Ordovician) limestone of Manchoukou, Manchuria | Lower Ordovician Santao Formation, Liaotoug, Manchuria | Daling limestone, Manchuria; Liangjiashan Formation of Hupeh, China | Wolung limestone of Wolung, Manchuria; Liangjiashan Formation of Hupeh, China Daling limeston, Manchuria; Liangjiashan Formation of Hupeh, China | Liangjiashan Formation of Hupeh, China Daling limeston, Manchuria | Liangjiashan Formation of Hupeh; Maggol Formation of Yongyeon-chon, Taebaeg, S. Korea Liangjiashan Formation of Hupeh, China L. Ordovician, Adamsfield, Tasmania L. Ordovician, Adamsfield, Tasmania Early Middle Ordovician Krivolutsky Formation, Siberia Platform L. Ordovician Lower Jiacun Group of Nyalam, Xiuang, China L. Ordovician Liangchiashan Fm., Qingshuihe, Inner Mongolia Lower Ordovician, upper part of Tochuanshan limestone, Chinghai, N.W. | China Florida Mountains Formation, El Paso, Texas Maggol Formation of Gaesan-chon, Taebaeg City, Kangweondo, S. Korea Maggol Formation of Guemdae-chon, Sangjangmyeon, Samcheok-gun, Kangweondo, Korea Maggol Formation of Godoo-am, Guraeri, Samgdong, Yeongweol, Kan- gweondo, S. Koera Maggol Formation of Godoo-am, Guraeri, Samgdong, Yeongweol, Kan- gweondo, S. Koera L. Ordovician Honghuayuan Formation of Yichang, Hupeh, Central China L. Ordovician Honghuayuan Formation of Yichang, Hupeh, Central China L. Ordovician Honghuayuan Formation of Yichang, Hupeh, Central China L. Ordovician Honghuayuan Formation of Yichang, Hupeh, Central China L. Ordovician Liagchishan Formation of Shanxi, North China [5 [E L | U . Ordovician Liagchishan Formation of Shanxi, North China . Ordovician Liagchishan Formation of Shanxi, North China . Ordovician Liagchishan Formation of Hebei, North China pper lbexian Thungsong Formation of Ron Phibum, Southern Thailand Ozaki (1927) Kobayashi (1935), Obata (1939) Kobayashi (1935) cf. Endo (1932) Obata (1939) Obata (1939) Obata (1939) Obata (1939) Obata (1939) Obata (1939), Kobayashi (1977) Obata (1939) Teichert (1947) Teichert (1947) Balashov (1962) Chen (1975) Chen (1976) Chang (1965) Hook & Flower (1977) Kobayashi (1977) Kobayashi (1977) Kobayashi (1977) Kobayashi (1977) Xu (1981) Xu (1981) Xu (1981) Xu (1981) Zou (1981) Zou (1981) Zou (1981) Lai et al. (1982) Stait & Burrett (1984) 206 Cheol-Soo Yun from South Korea, 2 species from Tasmania, 1 species from the Siberian Platform, and 1species from Texas, U.S.A. Most of them, excluding the Russian one, are known to occur in the Lower Ordovician (upper Ibexian). The Man- churoceras horizon of the Maggol Formation in Korea is correlated with the Liangchiashan Formation, Hwangho Region and with the Hunghuayuan Formation, Yangtze Region (Chen et al., 1980). The cephalopod fauna including Manchuroceras nakamense from the Lower Setul Limestone of Malaysia shows some affinities with that from the Maggol Formation. The OT8 zone of the Karmberg Limestone, Tasmania, proposed by Banks and Burrett (1980) may also be correlated with the Maggol Formation. The specialized actinoceroid Polydesmia, which is char- acterized by a vertically lamellate structure of the siphun- cular filling and high obliquity of the radial canal, is only known from East Asia, including North Korea, Inner Mon- golia, South Manchuria and Shandong in China. Kobayashi (1966) designated the Po/ydesmia horizon in the upper part of the Maggol Formation, based on a single specimen of this genus. Unfortunately, he did not illustrate this specimen and it is probably lost. Furthermore, all of the type speci- mens of the four Polydesmia species described by Kobayashi (1940) from China and North Korea are lost. According to Chen et al. (1980), Polydesmia is typically found in the Lower Ordovician Beianzhuang Formation of Hubei and Shandong in North China, which is conformably underlain by the Manchuroceras-bearing Liangchiashan Formation. The occurrence of Polydesmia cf. canaliculata in the upper part of the Maggol Formation supports the validity of the Polydesmia horizon established by Kobayashi (1966). This genus cooc- curs with two other genera, Wutinoceras and Manchuroceras in Korea and China. Since the upper part of the Korean Maggol Formation yields Polydesmia, its age is assigned to the early Whiterockian in the North American scale. Wutinoceras robustum (Kobayashi and Matsumoto, 1942) occurs in the middle part of the Maggol Formation, together with some Manchuroceras specimens (Figure 2). The higher horizons (locs. SN730 and 731 in Figure 2) yield the annulated orthoconic cephalopod Kogenoceras nanpiaoense (Kobaya- shi and Matsumoto, 1942). These two species have previ- ously been recorded from strata of uncertain age within the Ordovician in Nanpiao Coalmine, Nanpiao County, Liaoning Province, and were assigned to the Toufangian in South Manchuria by Kobayashi and Matsumoto (1942). Stait and Burrett (1982) described W. robustum from the Lower Setul Limestone of Whiterockian age in the Langkawi Islands, Malaysia. Subsequently, Stait et al. (1987) described Kogenoceras nanpiaoense from a slightly higher horizon than the W. robustum-bearing strata in the same area and as- signed it a Whiterockian age. These lines of evidence suggest that the cephalopod fauna of the Maggol Formation has strong affinities to the Southeast Asian and North Chinese faunas of equivalent age. Four species belonging to 3 genera were identified among many small-sized cephalopod specimens recovered from the horizon just below the boundary of the Maggol and Jigunsan Formations (loc. SN741 in Figure1). Of these species, Ormoceras weoni sp. nov and O. cricki occur most abundant- ly, making up more than 90 per cent of the cephalopod assemblage. The latter species is common in the Duwibong Formation, the uppermost Ordovician formation in Korea (Kobayashi, 1934), indicating that this species has a long range from the Maggol Formation to the Duwibong Formation. This species possibly represents the oldest type of the ormocerids in the upper Jigunsan and Duwibong Formations. Systematic paleontology The terminology and measurements of various shell morphological characters used in this paper are shown in Figure 3. Subclass Endoceratoidea Teichert, 1933 Order Endocerida Teichert, 1933 Family Manchuroceratidae Kobayashi, 1935 Genus Manchuroceras Ozaki, 1927 emend. Kobayashi, 1935 Type species : Piloceras wolungense Kobayashi, 1931 Manchuroceras sp. cf. M. wolungense (Kobayashi, 1931) Figures 4-1a, b; 7-5a, b Material.—Isolated partial siphuncle, KPE20073 from loc. SN712. Description.—Partial siphuncle with apical end, 71.2 mm in length; its dorsal side somewhat weathered and apical portion distorted by local joint and calcite vein ; apex bluntly pointed ; dorsoventral and lateral diameters nearly equal at a distance of 49.7 mm from apex, i.e., Circular in cross section, 30.5mm in diameter; inner side of siphuncle lined with crystalline calcite, recrystallized endosiphosheaths, this lining thinnest on dorsal side, becoming thicker laterally, ventral side of siphuncle strengthened by additional deposits, form- ing endosiphowedge, 12.4 mm thick at a distance of 49.7 mm from apex; endosiphocone rapidly expanding, its apical angle approximately 45 degrees, its apex continuing into endosiphotube, in which endosiphuncular segments are detected. Remarks.—This species appears to be closely allied to Manchuroceras wolungense (Kobayashi) from the Wolung Limestone of South Manchuria (Kobayashi, 1931 p. 170, pl. 17, figs. 2, 3a, b, 6; pl. 18, figs. 2a, b; pl. 19, fig. 1) in having a circular cross section of the siphuncle and well developed endosiphowedge. Specific identification requires additional better preserved specimens. Occurrence.—Known from the middle part of the Maggol Formation of Sanaegol, Taebaeg City, Kangweondo, South Korea. Manchuroceras sp. A Figures 4-2a, b; 7-1a—c Material.—Isolated partial siphuncle, KPE20256 from loc. SN710. Description.—Internal mould of siphuncle, 77.7 mm long; straight, with its diameter expanding twice as rapidly laterally Ordovician cephalopods from Korea 207 Apical angle Endosiphocone (es) Endocone (ec) Endosiphotube (et) Diaphragm (dp) Septal depth (sd) Septum (s) Camera (c) Cameral height (ch) Hyposeptal deposits (hd) Mural deposits (md) Episeptal deposits (ed) Siphonal deposits (sd) 4 Adoral direction Camera (c) Cameral height (ch) Dorsal (d) Septum (s) Connecting ring (cr) Septal neck (sn) fsa direction Septal foramen (sf) Annulus (an) Septal neck (sn) Septal brim (sb) Area of adnation (aa) Connecting ring (cr) Width of siphuncular segment (ws) Length of siphuncular segment (Is) Figure 3. Terminology and measurements of internal shell structures of idealized endoceroid (1) and actinoceroid (2) cephalopods used in this paper. as dorsoventrally ; its cross section circular in juvenile stage, but becomes elliptically depressed with growth, ratio of dorsoventral to lateral diameters of siphuncle at adoral end being 3:4; endosiphuncular deposits nearly uniform in thickness, not forming endosiphowedge, endocones recrys- tallized; endosiphocone slender, deep, rapidly expanding with apical angle of 25 degrees, its apex acutely pointed and situated at endosiphuncular center, continuing into endosi- photube which pierces apex; outside of siphuncle appears to be smooth. Remarks.—This species is allied to Manchuroceras tenuise Kobayashi from Guemdae-chon, Taebaeg City, Kangweon- do (Kobayashi, 1977) in the small apical angle of the endosi- Abbreviations of various shell characters are written in parentheses. from Teichert et al. (1964), Aronoff (1979), and Zhu and Li (1996). Compiled and modified phocone and ovate cross section, but is distinguished by evenly thickened endosiphuncular linings. Manchuroceras yenchouchengense Obata from the Daling Limestone of Liaoning, South Manchuria (Obata, 1939, p. 108, pl. 7, figs. 4, 6; pl. 8, fig. 2; pl. 10, fig. 6) may be related to this species in the elliptical cross section, but its blunt endosiphocone and greater dorsoventral diameter serve to distinguish this species from M. yenchouchengense. This comparison indi- cates that the present species belongs to Manchuroceras, but well preserved additional specimens are needed for species-level assignment. Occurrence.—Known only from the middle part of the Maggol Formation in Sanaegol. 208 Cheol-Soo Yun Figure 4. Diagrammatic drawings of endoceroid cephalopods described herein. gense (KPE20073), (KPE20256), “1, 2a: cross section at the adoral end, 2b: longitudinal section, 3a, b. Manchuroceras sp. B (KPE20065), 0.9, 3a: longitudinal section, 3b: cross section at the adapical end, 4. Vaginoceras sp. (KPE20230), «1.4. The arrow indicates the adoral direction for 1b, 2b, 3a, and 4. For abbreviations see Figure 3, except for ew: endosiphowedge. Manchuroceras sp. B Figures 4-3a, b; 7-4a, b Manchuroceras sp. indet. Kobayashi, 1977, p. 24, pl. 3, figs. 3a, b. Material.—Partial siphuncle, KPE20065 from loc. SN710. Description.—Imperfect siphuncle ; slowly expanding, with apical angle 13 degrees; adapical end circular in cross section but endosiphocone triangular, its tip Somewhat rounded, more flattened ventrally than dorsally, its basal length and height 5mm and 2.5mm, respectively ; apical angle of endosiphocone about 65 degrees, but abruptly decreasing toward adapical end at broadly curving point of endosipholining, attaining 15 degrees; endocone asym- metrical, rapidly extending anteriorly and more thickened on ventral side than on dorsal side, numerous lamelliform en- docones well developed ; no cameral portion detected. Remarks.—This species is allied to Manchuroceras tenuise Kobayashi from Guemdae-chon, Sangjangmyeon, Sam- cheok, Kangweondo, Korea (Kobayashi, 1977, p. 23, pl. 4, figs. 2a, b) in its triangular endosiphocone in cross section, but differs by its centrally located and more slowly expanding endosiphocone. This species is distinguished from Man- churoceras sp. A described above, in the much more rapidly expanding endosiphocone. Meanwhile, the apical angle of the endosiphocone and <0.9, ja: cross section at the adoral end, 1b: longitudinal section. 1a, b. Manchuroceras sp. cf. M. wolun- 2a, b. Manchuroceras sp. A thickness of endocone in this species are similar to those in the specimen of Manchuroceras ? sp. indet. described by Kobayashi (1977) from Godoo-am, Guraeri, Sangdong, Yeon- gweol. However, incomplete preservation of the present specimen precludes exact specific assignment. Occurrence.—Known only from the middle part of the Maggol Formation in Sanaegol. Family Endoceratidae Hyatt, 1883 Genus Vaginoceras Hyatt, 1883 Type species : Endoceras multitubulatum Hall, 1847 Vaginoceras sp. Figures 4-4; 7-2a, b Material.—Partial SN741. Description.—Partial phragmocone, 36mm in length, medium-sized orthocone containing endosiphocone ; conch wall 0.6 mm thick on ventral side ; slowly expanding ; some- what laterally compressed, ratio of dorsoventral to lateral diameter about 1.4:1; siphuncle submarginal in position, 1.5 mm distant from ventral margin, nearly circular in cross section, broad, its diameter a little less than one-third of dorsoventral conch diameter ; septa on dorsal portion mostly obliterated during fossilization, but two preserved septa at phragmocone, KPE20230 from loc. Ordovician cephalopods from Korea 209 basal part having septal depth one and a half times the cameral height, while septa on ventral side are comparatively well preserved, attached to ventral wall at an angle of 45 degrees ; septal necks holochoanitic, extending just to preceding ones ; connecting rings about three times thicker than septal neck, embracing inside of septal necks ; camer- al height 2.5 mm, six camerae distributed in a length corre- sponding to dorsoventral conch diameter at adoral end; no cameral deposits observed; siphonal deposits well devel- oped, dorsally more extended in longitudinal section, long and slender endosiphocone bounded by last endocone having wedge-shaped section and its apical angle about 15 degrees ; shell surface smooth. Remarks.—The presence of a thick connecting ring and acute endosiphocone indicates that this species belongs to Vaginoceras. Unfortunately, incomplete preservation of the specimen examined precludes species-level assignment. In the long endosiphocone and ectosiphuncular morphol- ogy, this species can be allied to Vaginoceras endocylin- dricum Yu from the beds just below the red limestone near Tawushu, north of the western end of Peiyangshan, Chun- gyanghsien (Yu, 1930, p. 33, pl. 2, figs. 5a-c ; pl. 3, figs. 2a-d, 3a, b), but the former is distinguished from the latter by more closely spaced septa and more compressed conch. Occurrence.—Known only from the uppermost part of the Maggol Formation in Sanaegol. Order Orthoceratida Kuhn, 1940 Superfamily Orthocerataceae M'Coy, 1844 Family Orthoceratidae M'Coy, 1844 Subfamily Michelinoceratinae Flower, 1945 Genus Michelinoceras Foerste, 1932 Type species : Orthoceras michelini Barrande, 1866 Michelinoceras cancellatum sp. nov. Figures 5-1; 7-7, 8a—c Type material.—Holotype, KPE20254 and _ paratype, KPE20255 both from loc. SN741. Diagnosis.—Longiconic orthocone with circular cross sec- tion; siphuncle central; septal spacing wide; camerae with well developed mural-episeptal deposits ; surface or- namented with transverse lines and very fine longitudinal lirae, forming cancellate markings. Description.—Holotype, KPE20254 (Figures5-1and 7- 8a—c) represented by a partial phragmocone of juvenile conch; very slender, longiconic orthocone, 21.4mm in length, consisting of 8 camerae ; circular in cross section ; very slowly expanding at a rate of 1 mm in 15 mm; siphuncle central in position, tubular, parallel to shell wall, narrow, about 1mm in diameter, corresponding to one-sixth of conch diameter ; septa gently concave adorally; its depth one- third of cameral height, septal necks short, orthochoanitic ; connecting rings thin; septa broadly spaced, averaging 2 mm distant between them, 2.5 camerae occurring in a length equal to conch diameter of 6.1 mm; camerae with L-shaped mural-episeptal deposits, remaining space filled with öoid particles and inorganic matrix; siphuncle filled with some Figure 5. Diagrammatic drawings of median dorsoventral section of orthocerid (1-2) and actinocerid (3-4) cephalopods described herein. 1. Michelinoceras cancellatum sp. nov. (holotype ; KPE20254), x2, 3. Ormoceras weoni sp. nov. (holotype ; KPE20260), “2, 4. Ormoceras cricki (KPE20232), 2.5. For (KPE20208), abbreviations see Figure 3. «1.5, 2. Kogenoceras nanpiaoense 210 Cheol-Soo Yun doids and matrix; surface ornamented with transverse growth lines and longitudinal lirae, forming cancellate net- work, spaces between growth lines and between lirae 0.16 mm and 0.07 mm respectively Paratype, KPE20255 (Figure 7-7), a partial phragmocone consisting of 9 camerae, 33.2 mm long ; probably belongs to adolescent stage in view of higher camera and broader conch than those of holotype ; siphuncle central, cylindrical, narrow ; septal distance increasing from 3 mm to 3.5mm during the stage observed; camera with mural-episeptal deposits. Remarks.—In the surface ornament pattern, this species resembles Michelinoceras reticulatum (Kobayashi) from the Jigunsan Formation of Homyeong (Kobayashi, 1934, p. 406, pl. 16, figs. 3-5). In the former species, however, are weaker and thinner longitudinal lirae than transverse growth lines, whereas in the latter species transverse lines are more crowded than longitudinal ones. In addition, the siphuncle in the present species is central in position, not submarginal as in M. reticulatum. This species is similar to Michelinoceras shangliense Qi from the Middle Ordovician Datianba Formation of Anhui, China (Qi, 1980, p. 251, pl. 4, fig. 1) in the expansion rate of conch and septal spacing, but the former is distinguished from the latter by its peculiar latticed ornamentation and central siphuncle. This species is also allied to Mi- chelinoceras paraelongatum Chang from the Middle Or- UUUU Vi fo / % \ N Figure 6. Diagrammatic drawings of actinoceroid cephalopods described herein. For abbreviations see Figure 3, except for ic : interseptal cavity, (KPE20323), <1. 2. Wutinoceras robustum (KPE20206), X1. cc: central canal, rc: ardial canal. dovician of Gansu, North China (Chang, 1962, p. 517, pl. 1, figs. 5a-c) in its small-sized conch with circular cross sec- tion, but the former has more narrowly spaced septa and broader siphuncle than the latter. In its surface markings, Michelinoceras guichiense Ying from the Middle Ordovican Datianba Formation of Guichi, Anhui, China (Ying, 1989, p. 630, pl. 3, figs. 5, 6) exhibits an affinity to the present species, but longitudinal lirae occurring in the present species are absent in M. guichiense. Occurrence.—Known only from the uppermost part of the Maggol Formation in Sanaegol. Superfamily Pseudorthocerataceae Flower and Caster, 1935 Family Stereoplasmoceratidae Kobayashi, 1934 Genus Kogenoceras Shimizu and Obata, 1936 Type species: Tofangoceras huroniforme Kobayashi, 1927 Kogenoceras nanpiaoense (Kobayashi and Matsumoto, 1942) Figures 5-2; 7-3, 6, 9a, b Tofangocerina nanpiaoensis Kobayashi and Matsumoto, 1942, p. 313, pl. 31, figs. 10-12 ; Chao et al., 1965, p. 96, pl. 22, fig. 11. Kogenoceras nanpiaoense (Kobayashi and Matsumoto). Chen et al., 1980, p. 177, pl. 3, fig. 18; Text-fig. 10 ; Lai et a/., 1982, pl. 6, figs. 12,13; Stait, Wyatt and Burrett, 1987, p. 385, figs. 6- 2—4. 1. Polydesmia sp. cf. P. canaliculata Ordovician cephalopods from Korea 2 Material.—Six partial phragmocones from the upper part of the Maggol Formation at localities, SN720 (KPE20282, 20283 and 20327), SN730 (KPE20209), and SN731 (KPE20208 and 20210). Diagnosis.—Annulated cyrtochoanitic orthocone ; camer- ae with episeptal and hyposeptal deposits ; siphuncle with dorsally intermittent and ventrally connected parietal deposits. Description.—Medium-sized annulated longiconic ortho- cone with eccentric siphuncle. KPE20208 (Figures 5-2, 7-9a, b), a fragmentary phrag- mocone with 6 siphuncular segments, 21mm long, very slowly enlarging, circular in cross section ; siphuncle eccen- tric, midway between center and venter, narrow, occupying a little more than one-sixth of dorsoventral conch diameter ; siphuncular segments Huronia-like in shape, greatly expand- ing in upper third, 2.8 mm in length and 2.3 mm in maximum diameter, contracting to 1.2 mm at septal foramen; septa gently concave adorally, partly crushed on dorsal side, septal depth equal to half or more of the cameral height; septal neck cyrtochoanitic, short, 0.3 mm in length ; cameral height low, about 2.8mm at upper part, 5camerae in a length corresponding to the dorsoventral conch diameter on the crest of annuli; Connecting rings thin, not adnate to the septa; camera filled with both episeptal and hyposeptal deposits ; siphuncle deposits with parietal deposits consist- ing of longitudinal thin lamellae, dorsally occurring succes- sively whereas ventrally intermittent; surface ornamented with strong annulations at intervals of 7.3 mm wide, corre- sponding to 2.5 camerae, its height from the base of the interspace about 0.8 mm. KPE20209 (Figure 7-3), 49mm in length, its adapical portion not preserved ; conch nearly circular in cross sec- tion ; siphuncle close to venter, narrow, its width one-eighth of dorsoventral conch diameter; siphuncular segments somewhat expanded between septal foramina at a point about one fourth from its anterior end, ratio of width to length 0.8; septa crowded, septal depth attaining one and a half times cameral height ; camerae with both epi- and hyposep- tal deposits, but siphuncular deposits not distinctly detected ; surface ornamented with broadly rounded annulations at intervals of 6 mm. Remarks.—Kobayashi and Matsumoto (1942) proposed Tofangocerina nanpiaoensis from the Tofangian, Nanpiao Coalmine, based on the type specimen, UMUT PM1903 which are characterized by well-developed endosiphuncular deposits and submarginal siphuncle with the Huronia-like siphuncular segments. However, Chen et al. (1980) and Stait et al. (1987) attributed the generic position of this species to Kogenoceras of Shimizu and Obata (1936) because of the Characteristic features of Kogenoceras such as cyrto- choanitic annulated orthoceracone, circular cross section, and narrow eccentric siphuncle, with Huronia-like segments. The enlarged photo of the siphuncle of K. nanpiaoense from the Lower Ordovician Lower Setul Limestone of the Langk- awi Islands, Malaysia (Stait et a/., 1987, p. 386, fig. 6-4) shows cyrtochoanitic septal necks, though these authors mistaken- ly described the septal neck type as orthochoanitic. This species is similar to Kogenoceras huroniforme (Kobayashi) from the Duwibong Formation of Hwarari, Kang- weondo, Korea (Kobayashi, 1934, p. 435, pl. 27, figs. 9-11, 14) in the Huronia-like siphuncular segments and eccentric siphuncle, but is easily distinguished by the presence of the parietal deposits along the siphuncular wall. Occurrence.—In addition to the present material, speci- mens assigned to this species are known from the Lower Ordovician of Nanpiao Coalmine, Nanpiao County, Liaoning Province, South Manchuria (Kobayashi and Matsumoto, 1942 ; Lai et al., 1982), Beianzhuang Formation of Shandong, North China (Chen et al., 1980) and the Lower Setul Lime- stone on the east coast of Pulau Langgun, Langkawi Islands, Malaysia (Stait et al., 1987). Order Actinocerida Teichert, 1933 Family Ormoceratidae Saemann, 1853 Genus Ormoceras Stokes, 1840 Type species : Ormoceras bayfieldi Stokes, 1840 Ormoceras cricki Kobayashi, 1934 Figures 5-4; 8-1—8 Ormoceras cricki Kobayashi, 1934, p. 444, pl. 23, fig. 7 ; pl. 25, fig. Ths Ormoceras sp. B., Chang, 1959, p. 266, pl. 5, fig. 5. Material.—15 specimens, KPE20231-20245 from loc. SN741, among which 14 are partial phragmocones and one (KPE20231) is a well-preserved, almost complete adult conch. Diagnosis.—Conch cross section elliptical in juvenile stage, but becomes subcircular in adult stage ; eccentric siphuncle with globular segments; camera with episeptal deposits forming a pointed ridge just in front of connecting ring ; hyposeptal deposits absent ; siphuncle filled with pari- etal deposits along the inside of connecting ring. Description.—Small to medium-sized cyrtochoanitic lon- giconic orthoceracone ; smooth shell, no sculpture discern- ible ; conch cross section strongly depressed, elliptical in juvenile stage, but becoming subcircular with growth, adult body chamber nearly circular in cross section ; its diameter moderately expanding at a rate of 1mm per 8 mm in lateral and dorsoventral lengths; siphuncle eccentric, close to venter, located at about 2/3 of conch diameter from dorsal margin, narrow, its diameter a third of dorsoventral conch diameter in juvenile stage, but becoming smaller, being one- fifth of the corresponding diameter in the adolescent shell because of nearly uniform expansion rate of siphuncle ; siphuncular segments globular, as long as broad; septa gently concave adorally, septal depth as wide as a half of cameral height ; septal necks cyrtochoanitic, abruptly recur- ved, adnate for a short distance to adapical part of connect- ing ring, but just meeting the adoral end of connecting ring ; septal brim very short; suture directly transverse, but slightly sloping from dorsal to ventral side ; camerae low, increasing from 1.1 mm to 1.5 mm during ontogeny, four camerae occur- ring in a length equal to dorsoventral conch diameter of 6.5 mm in KPE20232 (Figures 5-4 and 8-2b) ; camera with well developed mural-episeptal deposits, in which mural deposits 212. Cheol-Soo Yun vestigial dorsally but more concentrated ventrally. The degree of development of cameral deposits changes during ontogeny (see Figure 5-4); In juvenile stage, dorsal episeptal deposits becoming thicker toward nummuli, form- ing a pointed ridge just in front of connecting ring and abruptly thinning out to a saucer-like shape, the apex of pointed ridge rather acute and gradually shifting to the shell wall adorally whereas it is difficult to recognize on the ventral side due to secondary recrystallization. In adolescent stage, episeptal deposits shortened dorsally, not swollen and mural-episeptal deposits still thicker ventrally. In adult stage cameral deposits seldom present. Siphuncle filled with biogenic deposits in both juvenile and adolescent stages. The deposits more heavily developed ventrally than dorsally in adult stage, subsequently appearing to be annulosiphonate deposits ventrally. Remarks.—This species resembles Ormoceras woodwardsi Kobayashi from the Jigunsan Formation of Homyeong, Jeongseon (Kobayashi, 1934, p.445, pl. 31, fig.5) in the globular siphuncular segments and submarginal siphuncle, but is distinguished by the absence of episeptal deposits. It is similar to Ormoceras harioi (Kobayashi) from the Tofango Limestone of Tofango, South Manchuria (Kobayashi, 1927, p. 196, pl. 22, fig. 12; pl. 21, fig. 9) in having episeptal deposits, but differs from the latter in the broader siphuncle in propor- tion to conch diameter and the more rapidly expanding conch. In the saucer-like shape of episeptal deposits, Paror- moceras nanum (Grabau) from the Toufango Limestone of South Manchuria (Kobayashi, 1927, p.195, pl. 20. fig. 11; pl. 21, fig. 8; pl. 22, fig. 5) is closely related to this species, but the former is distinguished from this latter by the presence of such characters as Huronia-like siphuncular segments, more rapidly expanding conch and more closely spaced septa. Occurrence.—In addition to the uppermost horizon of the Maggol Formation of Sanaegol described herein, this taxon is known from the Duwibong Formation of Hwajeolchi, Jung- dong-myeon, Yeongweol area, and of Homyeong, Dong- myeon, Jeongseon area and Gaesandong, Taebaeg City, Kangweondo (Kobayashi, 1934). Ormoceras weoni sp. nov. Figures 5-3; 8-912; 9-1—3 Types.—Holotype, KPE20260, an incomplete phrag- mocone with an adjacent part of body chamber; 7 para- types, KPE20261-20267, all from loc. SN741. Material.—In addition to the above type specimens, seven specimens (KPE20268-20274) belong to this species. Of these, six (KPE20268-20273) were collected from the type locality, while one (KPE20330) came from the equivalent horizon of the Maggol Formation at Sesong. Etymology.—The specific name is dedicated to Dal-Gi Weon, who collected many Paleozoic fossils from Kan- gweondo region and kindly provided some specimens to the author. Diagnosis.—Longiconic or slightly curved orthocone; conch subcircular, ovately elliptical in cross section; body chamber long; siphuncle submarginal; siphuncular seg- ments somewhat expanded ; no cameral deposits detected. Description.—Medium-sized longiconic or slightly curved orthocone ; conch diameter moderately expanding at a rate of 1mm per 6.5 mm in conch height of the holotype (Figures 8-9a—d); body chamber long; ovately elliptical in cross section, ratio between dorsoventral and lateral diameters at the apical end 4:5 in one of the paratypes (KPE20262 ; Figure 9-1b); siphuncle submarginal, narrow, occupying about one-eighth of dorsoventral conch diameter ; siphun- cular segments nummuloidal, more or less expanded, 1.5 mm long and 1.4 mm in maximum diameter in the upper third of the height within camerae, contracting to 0.6mm at the septal foramen in the holotype; septa gently concave ad- orally, septal depth ranging from one to one and a half of cameral height, septal necks cyrtochoanitic, very short, just meeting the adoral end of connecting ring ; septal spacing narrow, 7 to 8camerae within the corresponding length of dorsoventral conch diameter; suture directly transverse in two steinkern specimens, KPE20264 (Figure 8-12) and KPE20265 (Figure 8-11); no cameral deposits detected ; siphuncle filled with inorganic matrix, but in the holotype and one of the paratypes (KPE20262 ; Figure 5-1d), endosiphun- cular deposits line siphonal surface of venter; surface smooth. Figure 7. 1a-c. Manchuroceras sp. A. partial siphuncle, KPE20256 from SN710, <1, 1a: ventral view, 1b: cross section at the adoral potion, venter down, 1c: longitudinal section, venter on left, showing endocones and endosiphocone. 2a, b. Vaginoceras sp. partial phragmocone, KPE20230 from SN741, 2a: detail of siphuncle and ventral camerae, showing very slender endosiphocone, 5, 2b: longitudinal section, venter on right, x 1.5. 3,6, 9a, b. Kogenoceras nanpiaoense (Kobaya- shi and Matsumoto, 1942). 3. Partial phragmocone, KPE20209 from SN730, longitudinal section, venter on right, «1.5, 6: Partial phragmocone, KPE20282 from SN720, longitudinal section in lateral direction, KPE20208 from SN731, 9a: longitudinal section, venter on left, <1, 9a, b: Partial phragmocone, <2, 9b: enlarged view of siphuncular structure, showing parietal deposits and moderately expanded siphuncular segments, 7. 4a, b. Manchuroceras sp. B. partial siphuncle, KPE20065 from SN710, 1, 4a: longitudinal section, venter on left, showing more prolonged ventral endocone adorally, 4b: cross section at the adapical end, venter down, showing triangular endosiphocone with flattened ventral side. 5a, b. Manchuroceras sp. cf. M. wolungense (Kobayashi, 1931), partial siphuncle, KPE20073 from SN712, 1, 5a: cross section at the adoral end, venter down, showing circular outline and endosiphowedge, 5b: longitudinal section, venter on left, showing the blunt apical end and endosiphotube. 7, 8a-c. Michelinoceras cancellatum sp. nov. 7. Partial phragmocone, paratype, KPE20255 from SN741, longitudinal section, acetate peel, «1.5, 8a-c. Partial phragmocone, holotype, KPE20254 from SN741, 8a: side view, x2.5, 8b: details of surface ornamentation, showing cancellate ornaments, 12, 8c: longitudinal section, acetate peel, showing well developed mural-episeptal deposits, < 3.5. Ordovician cephalopods from Korea to LL) 214 Cheol-Soo Yun Remarks.—This present species closely resembles Or- moceras yokoyamai (Kobayashi) from the Jigunsan Formation of Maggol and Homyeong (Kobayashi, 1934, p. 439, pl. 27, figs. 1-6 ; pl. 28, fig. 2) in the narrow, submarginal siphuncle with somewhat expanded segments, but differs from the latter by the presence of endosiphunuclar linings and the lack of ventral flattening in cross section. Ormoceras cricki Kobayashi from the Duwibong Formation of Homyeong and Gaesanchon (Kobayashi, 1934, p. 444, pl. 23, fig. 7; pl. 25, fig. 7) and from the uppermost bed of the Maggol Formation at Sanaegol (see Figures 8-1—8 in this paper) is allied to this present species in having closely spaced septa and ectosiphuncular morphology. The for- mer, however, can be distinguished from the latter by the presence of episeptal deposits, more depressed conch, and much smaller siphuncular diameter in relation to conch diameter. Occurrence.—Known only from the uppermost part of the Maggol Formation in Sanaegol. Family Polydesmiidae Kobayashi, 1940 Genus Polydesmia Lorenz, 1906 Type species : Polydesmia canaliculata Lorenz, 1906 Polydesmia sp. cf. P. canaliculata Lorenz, 1906 Figures 6-1; 9-4a, b Material.—Fragmentary phragmocone, KPE20323 from loc. SN720. Description.—Longiconic orthocone, 97 mm long, naturally weathered to the level of siphuncle ; outline of cross section unknown ; siphuncle large, slightly eccentric, conch diame- ter slowly expanding at a rate of 1mm per 8mm in conch height at the adapical portion; siphuncular segments very wide and comparatively low; septal necks cyrtochoanitic, evenly curved and long, equalling about one-third of cameral height, represented by a septal loop which corresponds to two-thirds of a circle ; septal brims broad, moderately sepa- rated from septum ; connecting rings thick, expanded largely into camerae, its posterior part forming a triangular elevation toward adoral side (ic in Figure 6-1), which was called “inter- septal cavity’ by Kobayashi (1940, p. 36); posterior area of adnation very broad; septa moderately concave adorally, septal depth equivalent to one and a half times or less of cameral height; camerae low, 3.2mm high; endosiphun- cular canal system of dendritic type, central canal narrow, off-center, radial canal steeply oblique, extending adapically through about 2 siphuncular segments before entering per- ispatium, its terminating point located at the tip of septal brim; annuli projected toward antero-inner side, horn- shaped in longitudinal section, internal lamellate structure obscure owing to recrystallization ; camerae with mural- episeptal deposits. Remarks.—This species is most closely allied to Polydes- mia canaliculata Lorenz from south of Chiang-chiawan, Liaoyang-hsien, Manchoukuo, North China (Kobayashi, 1940, p. 34, pl.3, figs.1-3 and pl. 4, figs. 17-19) in having the strongly oblique radial canal and triangular interseptal cavity, but incomplete preservation of the present specimen without conch outline and siphuncular position precludes exact species-level assignment. Occurrence.—Known only from the upper part of the Maggol Formation of Sanaegol. Family Wutinoceratidae Shimizu and Obata, 1936 emend. Flower, 1968 Genus Wutinoceras Shimizu and Obata, 1936 emend. Flower, 1957 Type species : Nybyoceras foerstei Endo, 1930 Wutinoceras robustum (Kobayashi and Matsumoto, 1942) Figures 6-2; 10-1, 2 Jeholoceras robustum Kobayashi and Matsumoto, 1942, p. 315, pl. 30, figs. 1-5; pl. 31, fig. 6. Armenoceras robustum (Kobayashi and Matsumoto). al., 1965, p. 70, pl. 17, figs. 7-9. Chao et Armenoceras cf. robustum (Kobayashi and Matsumoto). Chen, 1983, p. 122, pl. 2, figs. 5, 6. Wutinoceras robustum (Kobayashi and Matsumoto). Stait and Burrett, 1982, p. 194, figs. 2A-L Material. Two phragmocones, KPE20206, 20207 from the middle part of the Maggol Formation of Sanaegol at loc. SN712. Diagnosis.—Siphuncle eccentric, close to venter, broad ; siphuncular segments nummuloidal, highly expanded ; thick- ened connecting ring; septal brims longer than necks, varying from recumbent to slightly hooked, nearly touching the septa only at their tip; reticulate canal system ; episep- tal and hyposeptal deposits present. Figure 8. 1-8. Ormoceras cricki Kobayashi, 1934. All collected from SN741. 1a-c. Nearly complete conch without apical portion, KPE20231, x 1.5, 1a: ventral view, 1b: lateral view, venter on right, 1c : septal view at position indicated by arrow given in 1a. 2a-c. Partial phragmocone, KPE20232, 1.5, 2a: ventral view, 2b: longitudinal section, venter on left, showing well developed episeptal deposits, 2c: septal view at position indicated by arrow given in 2a. 3. Partial phragmocone, KPE20237, ventral view, phragmocone, KPE20233, ventral view, <2. 4. Partial phragmocone, KPE20235, longitudinal section, venter on left, 1.5. 5. Partial <1.5. 6. Partial phragmocone, KPE20245, dorsal view, 1.5. 7. Partial phrag- mocone, KPE20234, longitudinal section in slightly askew dorsoventral direction, 1.5. 8. Partial phragmocone, KPE20244, dorsoventral section, venter on right, <1.5. 9-12. Ormoceras weoni sp. nov. All collected from SN741. 9a-d. Adoral phragmocone and contiguous partial body chamber, holotype, KPE20260, 9a: dorsal view, <1, 9b: longitudinal section, venter on right, acetate peel, «1.5, 9c: enlarged view of apical portion, x3, 9d: details of siphuncle and septa, «12. 10. Partial phragmocone, paratype, KPE20261, longitudinal section, venter on left, acetate peel, X1.5. 11. Partial phragmocone, paratype, KPE20265, showing transverse septal sutures, 1.5. 12. Partial phragmocone and contiguous body chamber, paratype, KPE20264, shell exfoliated, showing transverse septal sutures, 1.5. ra) a Ordovician cephalopods from Korea Cheol-Soo Yun Figure 9. 1-3. Ormoceras weoni sp. nov. All collected from SN741. 1a-d. Adoral phragmocone and contiguous body chamber, paratype, KPE20262, 1a: ventral view, body chamber somewhat distorted , x1, 1b: septal view of apical end, showing position of the siphuncle, 1, 1c: dorsoventral section, venter on right, 2, 1d: details of siphuncular structure, showing endosiphuncular linings on ventral side, 7. 2. Partial phragmocone, paratype, KPE20267, dorsoventral section, venter on left, X2.2. 3a-c. Partial phragmocone, paratype, KPE20263, 3a: dorsoventral section, venter on right, <2, 3b: detail of siphuncle, x7, 3c: enlarged view of cyrtochoanitic septal neck, «30. 4a, b. Polydesmia sp. cf. P. canaliculata Lorenz, 1906. partial phragmocone, KPE20321, loc. SN720, 4a: longitudinal section, <1, 4b: enlarged view of siphuncular structure, showing triangular interseptal cavities on the adoral side of septa and steeply inclined radial canals, x5. Ordovician cephalopods from Korea Dig Description.—Large-sized longiconic orthocones with well defined reticulate canal system. KPE20206 (Figures 6-2 and 10-1a, b), a partial phrag- mocone with apical end, 115 mm long consisting of 10 si- phuncular segments including initial chamber ; presumably subcircular in cross section ; cameral portion of apical part mostly lost during taphonomic process ; siphuncle eccentric, its width broad, occupying nearly a half of conch diameter ; siphuncular segments nummuloidal, highly expanded, having a length of 11.2 mm and a width of 27.5 mm at the point of maximum expansion, constricted to 13.7 mm at septal for- amen ; septa moderately curved, septal depth corresponding to a little less than one and a half times cameral height ; septal necks cyrtochoanitic, recurved but free ; septal brims longer than necks, varying from recumbent to slightly hooked, nearly touching the septa only at their tip; cameral height rather high, averaging 10.2 mm; connecting ring rela- tively thick, apically adnate for a long distance, 3.8mm to adoral surface of septum, just meeting the septal brims adorally ; siphuncular deposits of annulosiphonate type, canal system forming reticulate structure, narrow radial canals branched off from irregularly arranged central canal entering to the midpoint of perispatium; episeptal and hyposeptal deposits well developed ; shell surface unknown. KPE20207 (Figures 10-2a, b), represented by a partial phragmocone with one side crushed ; a gastropod belonging to Pagodispira (?) detected in a camera in cross section (indicated by arrow, see Figure 10-2b); conch somewhat flattened and siphuncle slightly elliptical in cross section ; siphuncle eccentric, close to venter ; siphuncular segments uniform in dimension, 8.5 mm long and 23.3 mm in maximum diameter within camerae, pinched to 13.1mm at the septal necks ; posterior area of adnation moderately broad, 3.2 mm; central canal sigmoidally curved in longitudinal direc- tion, its width ranging from 1.6 mm to 3.5mm while radial canal is narrow, 0.4 mm or less, radially distributed bunches of annulosiphonate deposits in cross section of adoral end. Remarks.—The present species is similar to Wutinoceras foerstei (Endo) from the Lower Ordovician Wuting Formation of South Manchuria (Endo, 1930, p. 208, pl. 60, figs. 1A-C) in ectosiphuncular structure and reticulate canal system, but the latter differs from the former in having a more ventrally positioned siphuncle and less cameral deposits. This species may be allied to Wutinoceras logani Flower from the Table Head Formation of Newfoundland (Flower, 1968, p. 8, pl. 10, figs. 1-3; pl. 11, figs. 1-7) in the large-sized conch and strongly flattened siphuncular segments, but the former is distinguished from the latter in having more thickened cameral deposits and less recumbent septal brims. This species is also similar to Wutinoceras remotum Chen from the Lower Ordovician, lower part of Jiacun Group of Nielamu County, China (Chen, 1975, p. 274, pl. 1, figs. 7, 8) in the mode of endosiphuncular and cameral deposits, but the latter differs from the former in the longer septal necks and much narrower siphuncular segments. Occurrence.—In addition to the present materials, this species is known from the Toufangian strata in the vicinity of Nanpiano Coalmine, Nanpiano County, Liaoning Province, South Manchuria (Kobayashi and Matsumoto, 1942) and the Lower Ordovician Lower Setul Limestone on Pulau Langgun of the Langkawi Islands, Malaysia (Stait and Burrett, 1982). Wutinoceras sp. Figures 10-3a—d ? Wutinoceras sp. Zhu and Li, 1996, pl. 1, fig. 11. Material.—Partial SN713. Description.—Medium-sized orthocone, preserved phrag- mocone 60 mm long, its expansion rate not measured owing to secondary deformation, conch subcircular in cross sec- tion ; siphuncle central, large, 11.5 mm in maximum diameter, occupying about one-third of conch diameter ; siphuncular segments strongly nummuloidal, 4.2 mm in length and 11.5 mm in maximum diameter at mid-portion within camerae, contracting to 6.6 mm at septal foramen; septa moderately concave adorally, septal depth one and a half times cameral height, septal necks cyrtochoanitic, strongly recurved, septal brims far longer than necks, its end adnate to the adapical surface of septum, especially in juvenile stage, but not adnate in later stage ; connecting ring adnate for a relatively long distance to adoral surface of septum dorsally, but free ventrally, just meeting the tip of septal brim; suture slightly sloping from venter to dorsum, but transverse when viewed from dorsal side; camera about 4.3mm high, 8 camerae preserved in a partial conch 37 mm in length; annulosi- phonate deposits well developed (Figures 10-3c, d), annuli embracing the inner margin of septa at septal necks, gradu- ally decreasing adorally in bulk, its shape asymmetrical in longitudinal section, more concentrated to the adoral side, adjacent annuli in contact with each other, remaining spaces forming radial canal, which branches off from much broader central canal, in some cases, radial canal divided into two branches and entering in perispatium ; camerae filled with episeptal and hyposeptal deposits only on ventral side, also deposits in ventral camera forming pseudoseptum at mid- portion of camera joining to radial canal. phragmocone, KPE20202 from loc. Figure 10. 1,2. Wutinoceras robustum (Kobayashi and Matsumoto, 1942). 1a, b. Partial phragmocone, KPE20206 from SN712, 1a: longitudinal polished section of an originally weathered specimen, 1, 1b: details of septal necks and reticular canal system, acetate peel, “2.4. 2a, b. Partial phragmocone, KPE20207 from SN712, 1, 2a: longitudinal section, venter on left, 2b: cross section at the adapical end, venter down. Arrow indicates a gastropod, Pagodispia (?) sp. 3a-d. Wutinoceras sp. partial phragmocone, KPE20202 from SN713, 3a: lateral view, venter on right, <1, 3b: septal view of the apical end, venter down, showing position of the siphuncle, «1, 3c: longitudinal section, venter on left, showing the annulosiphonate deposits, «1, 3d: details of siphuncular structure, acetate peel, showing free septal necks, but tip of septal brims adnate to the adapical surface of the septum, and well-developed annulosiphonate deposits, x5. Abbreviations in Figure 3d: an; annulus, cc; central canal, rc; radial canal. Cheol-Soo Yun Ordovician cephalopods from Korea 219 Remarks.—This species resembles Wutinoceras giganteum Flower from the early Middle Ordovician Table Head Limestone of Newfoundland (Flower, 1976, pl. 2, fig. 4 ; pl. 3, fig. 12; pl. 4, figs. 1,2; pl. 5, fig. 6) in the nearly central position of the siphuncle, but is distinguished by its more crowded camera, obliquely inclined septal suture and the presence of the well-developed canal system. In the flattened siphuncular segments and recumbent septal necks, this present species is somewhat similar to Wutinoceras logani Flower from the Table Head Limestone, Newfoundland (Flower, 1968, p. 8, pl. 10, figs. 1-3; pl. 11, figs. 1-7), but differs by its more undulating central endosiphuncle and thicker mural-episeptal deposits. Wutinoceras lui Chang from the Inner Mongolia (Chang, 1959, pl. 2, fig. 3; pl. 3, fig. 5) is also allied to this species, but the former differs from the latter in its eccentric siphuncle and less flattened siphuncular segments. Furthermore, the present species is allied to Wutinoceras shihuigouense Chang from the upper part of the Lower Ordovician To- chuanshan Limestone, Shihuigou, Chinghai (Chang, 1965, p. 352, pl. 1, fig. 4) in the subcentral position of the siphuncle and the constant relation of the septa and segments, but in W. shihuigouense, the septa are more steeply inclined and the connecting ring is rather uneven. Wutinoceras sp. from the Lower Ordovician Xiamajiagou Formation of Southern Jilin, China (Zhu and Li, 1996, pl. 1, fig. 11) may be compared to the present species in its free septal necks and somewhat broader area of adnation. Occurrence.—Known only from the middle part of the Maggol Formation of Sanaegol. Acknowledgments | am deeply grateful to Kazushige Tanabe of the Geologi- cal Institute of Tokyo for his critical reviews of the manu- script and valuable suggestions and for help in collecting some of the specimens utilized. | am indebted to Seong- Young Yang of Department of Earth Sciences, Teachers College, Kyungpook National University in Korea for his kind advice and encouragement. Thanks are also extended to Yasunari Shigeta of National Science Museum for his techni- cal assistance in photographing the fossils. Special thanks are due to Royal H.Mapes of Department of Geological Sciences, Ohio University for going over the language of the present paper. Reference cited Aronoff, S.M., 1979: Orthoconic nautiloid morphology and the case of Treptoceras vs. Orthonybyoceras. Neues Jahrbuch für Geologie und Paläontologie Abhandlun- gen, vol. 158, p. 100-122. Balashov, Z.G., 1962: Ordovician nautiloids of the Siberia Platform, 131p, 52pls. Leningrad University Press, Leningrad. 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Bulle- tins of American Paleontology, vol. 34, no. 144, p. 187- 236, pls. 1-6. Teichert, C., Kummel, B., Sweet, W., Stenzel, H.B., Furnish, W.M., Glenister, B.F., Moore, R.C., and Zeller, D.E.N., 1964: Mollusca3. /n, Moore, R.C. ed., Treatise on invertebrate paleontology. Part K., p.1-519, 361 figs. Geological Society of America and University of Kansas Press, Lawrence. Xu, G.H., 1981: The Lower Ordovician cephalopods of Yichang, Hubei. Bulletin of the Yichang Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, Paleontology 1, p. 60-70, pls. 1-2. (In Chinese with English abstract) Ying, Z.E., 1989: Late Early and Middle Ordovician ce- phalopods from Guichi, Anhui. Acta Palaeontologica Sinica, vol. 28, no. 5, p. 617-633, pls. 1-5. (In Chinese with English abstract) Yu, C.C., 1930: The Ordovician Cephalopoda of Central China. Palaeontologia Sinica, series B, vol. 1, fascicle 1, p. 1-71, pls. 1-9. Zhu, M.Y., and Li, X.S., 1996: Early Ordovician actinocer- oids from Southern Jilin. Acta Palaeontologica Sinica, vol. 35, no. 3, p. 349-365, pls.1-3. (In Chinese with English abstract) Zou, X.P., 1981: Early Ordovician nautiloids from Qingshui- he, Nei Omnggol (Inner Mongolia) and Pianguan, Shanxi Province. Acta Palaeontologica Sinica, vol. 20, no. 4, p. 353-362, pls. 1-2. (In Chinese with English abstract) 999 The Palaeontological Society of Japan has revitalized its journal. Now entitled Paleontological Research, and published preferably in English, its scope and aims have entirely been redefined. The journal now accepts and publishes any international manuscript meeting the Society’s scientific and editorial standards. In keeping with the journal’s new target audience the Society has established a new category of membership (Subscribing Membership) which, hopefully, will be especially attractive to new and existing overseas members. 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(in Japanese with English abstract) In the article by Amano, Lutaenko and Matsubara (Paleontological Research, Vol.3, No.2), a sentence below should be included in the figure caption of Figure 4 on page 98. 6a, b : Macoma (Rexithaerus) hokkaidoensis Amano and Lutaenko, sp. nov., JUE no. 15654 (Par- atype), Oshamanbe (Recent). oe SHS lt, 2000 “FE 1 A 28 A (4)~1 A 30 H (A) tc [PRAY THEN +, -BEBHODHELUZEDTIN 141999 Æ 12 AS ACH, 10H 28 AizyyRYVA[G a HEN + SPORE RH He PAJILTERT AR © Pa ital A ARE RABI) DTbnEes, OS 149 [FIG (FETE : 2000 F0 6 ARE) cls, TÉLÉ EME] 2 à Ber LABS D ELK. 01999 FRZT, 2001 4ED 5 DES + KF E PISOPAERHAO A BARE à AE Le. EZ MR BIL6A PADS 7 HOSE FHEOPIZO AEH), BIS 1H F4 8 2HDNMDOE Ei EO FES REO) ESTES. BARE SRS 1 CSRS ELS, TER ETCBHLABZTEÄL, PROM LIAASE: T240-850 RT? RES 79-2 BREENLASAR AMES ABER HI (TER) Must FAIIBKE— : TEL 045-339-3349 [83 FAX 045-339-3264 FRÈRE E-mail majima @ ed.ynu.ac.jp &ll (TBARS): T 250-0031 ‚HET A EH 499 HSI [VITA AO Ee + HOB EPA TEL 0465-21-1515 FAX 0465-23-8846 E-mail taru @ pat-net.or.jp BCOFETICRS ZAHN, SÉDRÉDIHE, IRERFNRÄHN ER © UIC RBIS AD 5 DZAMZTENTOET, HEODBEHZARTELDEN TI, YEAYT BRAS te MRE MOR HREME AL TUN TIL À Te DB Heise th 7 4 ya 2 u ov ae El Wk sh et CBR ACAAORB MH 2-Y7LS-7RRRR (7 19741) AY Et à OMRBA FHA Hse KROME) Ick So ISSN 1342-8144 Paleontological Research le Slee S TT RL aly Beau 1999 £9274 El Ki] T113-8622 HR AP DC Et PCA BWIA 5-16 -9 1999 Æ 9 A 30 H FE ‘far HSE + YY - NW E & 03—-5814—5801 fn & fF W@W — kh - MEERE fn ES Ge M — Æ + HH RK oz ET A HE To8-001 Hé ATO Hr 8-45 2,500 F HRHRENNIKER ZH TR ee tt 022-288-5555 Hat 03-3455-4415 - tt tit LLP LDL LL LL LDL PL LL LOL LLL PLL LL OPS OOS Paleontological Research Vol. 3 No. 3 September 30, 1999 CONTENTS Alexander |. Kafanov, Konstantin B. Barinov and Louie Marincovich, Jr.: Papyridea harrimani Dall, 1904 (Bivalvia, Cardiidae) as a marker for upper Eocene and lower Oligocene strata of the:!North\Päßifie.- 2.4: ce oe 20 ete apr nent aie NN RON ST TE TA Rodney Watkins : Upper Paleozoic biostromes in island-arc carbonates of the eastern Klamath terrane;"Galifornia' „u... due we au a6 a2 ail we ee de nest we ne mount ee OTL Tatsuro Matsumoto and Yoshitaro Kawashita : The turrilitid ammonoid Mariella from Hokkaido —Part 2 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXVI) .... 162 Takashi Hasegawa: Planktonic foraminifera and biochronology of the Cenomanian-Turonian (Cretaceous) sequence in the Oyubari area, Hokkaido, Japan .................. .. ee Gr se WAS) Bunji Tojo and Fujio Masuda: Tidal growth patterns and growth curves of the Miocene potamidid: gastropod Vicarya yokoyamal :.....u.. seis ons ns wen anne woe ee NT 193 Cheol-Soo Yun: Ordovician cephalopods from the Maggol Formation of Korea .............. 202 Erratum: Article by Amano, Lutaenko and Matsubara in Vol. 3, NO. 2 ............................ 224 Paleontological Research ISSN 1342-8144 Formerly Transactions and Proceedings of the Palaeontological Society of Japan Vol. 3 No. 4 December 1999 The Palaeontological Society of Japan =. Co-Editors Kazushige Tanabe and Tomoki Kase = ; Language Editor Martin Janal (New York, USA) Ka Associate Editors Jan Bergstrôm (Swedish Museum of Natural History, Stockholm, Sweden), Alan G. Beu (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Satoshi Chiba (Tohoku University, Sendai, Japan), Yoichi Ezaki (Osaka City University, Osaka, Japan), James C. Ingle, Jr. (Stanford University, Stanford, USA), Kunio Kaiho (Tohoku University, Sendai, Japan), Susan M. Kidwell (University of Chicago, Chicago, USA), Hiroshi Kitazato (Shizuoka University, Shizuoka, Japan), Naoki Kohno (National Science Museum, Tokyo, Japan), Neil H. Landman (Amemican Museum of Natural History, New York, USA), Haruyoshi Maeda (Kyoto University, Kyoto, Japan), Atsushi Matsuoka (Niigata University, Niigata, Japan), Rihito Morita (Natural History Museum and Institute, Chiba, Japan), Harufumi Nishida (Chuo University, Tokyo, Japan), Kenshiro Ogasawara (University of Tsukuba, Tsukuba, Japan), Tatsuo Oji (University of Tokyo, Tokyo, Japan), Andrew B. Smith (Natural History Museum, London, Great Britain), Roger D.K. Thomas (Franklin and Marshall College, Lancaster, USA), Katsumi Ueno (Fukuoka University, Fukuoka, Japan), Wang Hongzhen (China University of Geosciences, Beijing, China), Yang Seong Young (Kyungpook National University, Taegu, Korea) Officers for 1999-2000 President : Kei Mori Councillors : Kiyotaka Chinzei, Takashi Hamada, Yoshikazu Hasegawa, Itaru Hayami, Hiromichi Hirano, Noriyuki Ikeya, Junji Itoigawa, Tomoki Kase, Hiroshi Kitazato, Itaru Koizumi, Haruyoshi Maeda, Ryuichi Majima, Makoto Manabe, Hiroshi Noda, Ikuo Obata, Kenshiro Ogasawara, Terufumi Ohno, Tatsuo Oji, Tomowo Ozawa, Yukimitsu Tomida, Tsunemasa Saito, Takeshi Setoguchi, Kazushige Tanabe, Akira Yao Members of Standing Committee : Hiroshi Kitazato (General Affairs), Tatsuo Oji (Laison Officer), Makoto Manabe (Finance), Kazushige Tanabe (Editor in Chief, PR), Tomoki Kase (Co-Editor, PR), Ryuichi Majima (Planning), Hiromichi Hirano (Membership), Kenshiro Ogasawara (Foreign Affairs), Haruyoshi Maeda (Publicity Officer), Noriyuki Ikeya (Editor, “Fossils’), Yukimitsu Tomida (Editor in Chief, Special Papers), Tamiko Ohana (Representative, Union of Natural History Societies). 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Phone: (978)750-8400, Fax : (978)750-4744, www.copyright.com Cover : Idealized sketch of Nipponites mirabilis Yabe, a Late Cretaceous (Turonian) nostoceratid ammonite. Various reconstructions of the mode of life of this species have been proposed, because of its curiously meandering shell form (after T. Okamoto, 1988). All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN c/o Business Center for Academic Societies, Honkomagome 5-16-9, Bunkyo-ku, Tokyo 113-8622, Japan Paleontological Research, vol. 3, no. 4, pp. 225-233, 6 Figs., December 30, 1999 © by the Palaeontological Society of Japan Formation in the Iwadono Hills area, Saitama Prefecture, central Japan YUKITO KURIHARA Doctoral Program in Geoscience, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8571, Japan Received 28 January 1999 ; Revised manuscript accepted 6 July 1999 Abstract. Twenty-five molluscan taxa were identified from three localities of the lower Middle Miocene Arakawa Formation in the Iwadono Hills area, Saitama Prefecture, central Japan. This fauna consists of two types of assemblage (protobranch-dominant and septibranch-dominant) and is inferred to represent a deep-water fauna (bathyal depths) on the basis of its taxonomic structure. Similarities in generic composition between the molluscan fauna of the Arakawa Formation and that of the bathyal zone in modern Sagami Bay suggest that the marine climate during the Arakawa deposition is comparable with that of the intermediate water of Sagami Bay. One new species, Neilonella tsukigawaensis, is described herein, and the stratigraphic relationship between the Arakawa and the overlying Goudo Formation is briefly mentioned. Key words: Arakawa Formation, deep-water molluscan fauna, Iwadono Hills, Miocene, intermediate water Introduction Mollusc-bearing marine Miocene strata are exposed in the lwadono Hills area, located in the eastern margin of the Kanto Mountains, Saitama Prefecture, central Japan (Figure 1-A). They are stratigraphically divided into the Arakawa, Goudo, Syougunzawa, Hatoyama, and Imazyuku Formations in ascending order (Majima, 1989). Molluscan fossils from the Goudo and Syougunzawa Formations have been listed and partly illustrated by Hatai and Masuda (1962) and Majima (1989), but there has not been any paleontological work on the molluscan fauna from the Arakawa Formation in the lwadono Hills area. During my field survey in the lwadono Hills area from 1993 to 1994, approximately one hundred specimens of molluscan fossils were collected from the Arakawa Formation, in which two types of deep-water assemblages were recognized. The purpose of this paper is to report the molluscan fauna of the Arakawa Formation in the Iwadono Hills area and to discuss the inferred paleobathymetry and marine paleo- climate of the formation based on the molluscan faunal analysis. Geologic setting and age Miocene strata distributed in the Iwadono Hills area are separated by a fault from Pre-Tertiary metamorphic rocks in the western part and are overlain by the Plio-Pleistocene Monomiyama Formation in the southern part (Figure 1-B). Koike et al. (1985) and Majima (1989) recently studied the geology of the lwadono area, but their stratigraphic divisions are slightly different from each other (Figure 2). In this paper, | follow Majima’s (1989) division because he made it clear that the lowermost Miocene stratigraphic unit in the Iwadono area belongs to the Arakawa Formation (Watanabe et al., 1950), which is widely distributed in the central part of Saitama Prefecture. The Arakawa Formation in the northern study area is exposed narrowly and sporadically (Figure 1-C). It consists mainly of diatomaceous siltstone and sandy siltstone, both of which commonly contain sand-sized fragments of schist. In this lithological feature, the Arakawa Formation can be distinguished from the other Miocene siltstone-dominant formations in the Iwadono area. Although partial sections were measured at the place where the megafossils were collected, structural complexities and poor exposures make it difficult to correlate these sections. The Arakawa Forma- tion is considered to be overlain by the Goudo Formation, which is Composed mainly of sandstone and conglomerate, but their stratigraphic relationship is unclear, as will be mentioned. The geologic age of the Arakawa Formation recently became better defined by means of diatom biostratigraphy. Kurihara (1994MS) obtained for the first time from the forma- tion (Loc. 1 of Figure 1-C and Table 1) a diatom assemblage, which he assigned to the early Middle Miocene Denticulop- sis lauta Zone (NPD 4A) of Akiba’s (1986) Neogene North Pacific Diatom Zonation (Horiuchi and Yanagisawa, 1994). 226 Yukito Kurihara Quaternary | Miocene Pre-Tertiary Yokohama te Pacific Sagami Bay ne / 7 D \ / F 139°20'E / 4 Senjido 5 h LEGEND for C synclinal axis _-". inferred boundary concealed fault fault fossil locality Quaternary Syougunzawa Fm. 4 || Goudo Fm. 1 Arakawa Fm. 1 Pre-Tertiary Kamikarako 36°2'20"N al m Toki-gawa & | Figure 1. (A) Index map showing the lwadono Hills area, and the geologic sketch map of eastern margin of the Kanto Mountains. (B) Geologic sketch map of the lwadono area. (C) Geologic map of the northern part of the Iwadono area with the fossil localities. Legend: 1, diatomaceous siltstone; 2, sandy siltstone; 3, conglomerate consisting mainly of sandy siltstone boulders ; 4, sandstone and conglomerate. ei = [e) = © © = © D> x< ° + 5 SE 5% = fr o i= © TD œ 2 Godo Cgl. Mm. unconformity unconformity? Kamikarako Fm. Arakawa Fm. Figure 2. Comparison of stratigraphic divisions of the Miocene in the Iwadono Hills area by recent workers. Fm., Formation ; Mm., Member; Cgl., Conglomerate ; Ss., Sand- stone ; Slt., Siltstone. According to Y. Yanagisawa (per. com.), the formation in the Iwadono area is assigned for the most part to NPD 4A, with the lowermost part extending to the latest Early Miocene Crucidenticula kanayae Zone (NPD 3A). Therefore, the Arakawa Formation in the lwadono area ranges from the uppermost Lower to lower Middle Miocene in age. The molluscan fossils treated in this paper cooccurred with a diatom assemblage assigned to the middle part of NPD 4A, which is characterized by the occurrence of the very short- ranging species Cavitatus lanceolatus. According to the latest age estimation of diatom datum levels by Yanagisawa and Akiba (1998), NPD 4A with C. lanceolatus ranges from 15.6 to 15.2Ma. The Goudo Formation yields larger for- aminifers including Lepidocyclina sp., which also suggest a lower Middle Miocene (Blow’s N. 8-9) age (Majima, 1989). Miocene molluscs from Arakawa Formation 227 Table 1. List of the diatom fossils from the Arakawa Formation (Loc.1) and from sandy siltstone boulders in the Goudo Formation (Loc. 3) (identified by Y. Yanagisawa). Num- bers indicate those of individuals for species that occur from 100 individuals selected at random. + indicate recognizable species. Sample locality Fo Loc. 3 Sample number Sg 3 lwd 9 Diatom zone 4A 4A Actinocyclus ingens f. ingens (Rattray) Whiting et Schrader 5 16 A. ingens f. nodus (Baldauf) Whiting et Schrader + 1 | A. ingens f. planus Whiting et Schrader 6 13 | A. octonarius Ehrengerg = 1 | Actinoptychus senarius (Ehrenberg) Ehrenberg + 3 | Cavitatus exiguus Yanagisawa et Akiba 1 2 in: jouseanus (Sheshukova) Williams + 2 | C. lanceolatus Akiba et Hiramatsu 5 1 C. linearis (Sheshukova) Akiba et Yanagisawa sr = (63 miocenicus (Schrader) Akiba et Yanagisawa 1 Cestodiscus Sp. (concave) + = Coscinodiscus lewicianus Greville + 1 | C. marginatus Ehrenberg 1 = | C. perforatus Ehrenberg = 1 Crucidenticula kanayae var. kanayae Akiba et Yanagisawa JH = Delphineis miocenica (Schrader) Andrews 1 — Denticulopsis ichikawae Yanagisawa et Akiba 8 8 D. lauta (Bailey) Simonsen 8 & D. cf. okunoi Yanagisawa et Akiba + — | Girdle view of D. lauta group U + Hemiaulus bipons (Ehrenberg) Grunow in Heurck ap = Ikebea tenuis (Trun) Akiba — Nitzschia challengeri Schrader + = Paralia sulcata (Ehrenberg) Cleve 13 11 Planifolia tribranchiata Ernissee = Stellarima microtrias (Ehrenberg) Hasle et Sims 1 — Stephanopyxis spp. 1 2 Thalassionema cf. hirosakiensis (Kanaya) Schrader Ar = Te nitzschioides (Grunow) H. et M. Peragallo 44 38 Thalassosira leptopus (Grunow) Hasle et Fryxell =F = Thalassiothrix logissima Cleve et Grunow Sr ar Total number of valves counted 100 100 | Resting spore of Chaetoceros 18 12 Remarks on the stratigraphic relationship between the Arakawa Formation and the overlying Goudo Formation The stratigraphic relationship between the Arakawa and Goudo Formations is unclear because of the lack of a boundary outcrop, except for a fault contact. Previous workers pointed out that the Arakawa Formation might be unconformably overlain by the Goudo Formation primarily on the basis of structural differences (Koike et al. 1985) or the presence of pebbles presumably derived from the Arakawa Formation in the Goudo Formation (Majima, 1989). Recently, | found new evidence by which to consider the stratigraphic relationships of the two formations. A conglomerate facies including abundant sandy siltstone boulders (more than 2 m in maximum diameter) is observed in the very coarse-grained sandstone matrix of the Goudo Formation at Loc. 3 (Figures 1-C and 3-C). The boulders are considered to have been derived from the Arakawa Formation, because: (1) the sandy siltstone boulders com- monly contain sand-sized fragments of schist; this lith- ofacies characterize the Arakawa Formation as mentioned before ; (2) the sandy siltstone lithology of the boulders resembles that of the Arakawa Formation exposed at Kami- karako (see Figure 1-C); (3) the boulders are too large to have been transported from outside the Iwadono area, and (4) the diatom assemblage in the boulders is assigned in age to Akiba’s NPD 4A, which is the same as the Arakawa Formation (Table 1). Although the exact boundary between 228 Yukito Kurihara the Arakawa and Goudo Formations could not be observed at Loc. 3, the facies including the boulders may represent a basal unit of the Goudo Formation which presumably covers the Arakawa Formation with an erosional contact. How- ever, it is difficult to conclude that the relationship between these two formations is an unconformity, because of the lack of chronological data indicating the time gap between them. Occurrence of molluscs Molluscan fossils treated in this paper were collected from the diatomaceous siltstone of the Arakawa Formation (Locs. 1,2) and from the sandy siltstone boulders in the Goudo Formation (Loc. 3) (Figure 1-C). The boulders are consid- ered to have been derived from the Arakawa Formation as mentioned before, thus the molluscan fossils contained in the boulders are treated as derived from the Arakawa Formation. Columnar sections showing the sampling hori- diatomaceous siltstone M@— Loc.2 diatomaceous siltstone i= S 2 oO E E © LL © 3 © x oO S < siltstone Figure 3. Columnar sections showing the sampling hori- zon of Locs.1 (A) and 2 (B). Field photo showing mode of occurrence of sandy siltstone boulders at Loc. 3 (C). zon of Locs.1 and 2 are shown in Figures3-A and B, respectively. Preservation of molluscs from the Arakawa Formation is generally poor and varies in relation to their enclosing lith- ology. Molluscan shells from the diatomaceous siltstone at Locs. 1 and 2 are completely dissolved and are preserved as molds, whereas those from the sandy siltstone at Loc. 3 often retain their shell material. Molluscan fossils from the diatomaceous siltstone have suffered more significant post- depositional deformation than those from the sandy siltstone. The mode of fossil occurrence remains almost constant at the three localities. Molluscan fossils are sporadically distributed in random orientation within the intensively biotur- bated massive silty matrix. The shells generally do not show signs of post-mortem wear or breakage. Most bivalve shells are disarticulated (Table 2). The intensively bioturbat- ed sediments suggest that burrowing animals reworked the shells, in which case the empty bivalve shells may have been disarticulated by bioturbation and not retained their life position. The sporadic occurrences of the shells and their showing no sign of abrasion and breakage suggest that the molluscan assemblage is essentially parautochthonous. Molluscan assemblages Six gastropods, one scaphopod and 18 bivalves were identified from the Arakawa Formation in the Iwadono area (Table 2). On the basis of occurrence of the characteristic species, two types of molluscan assemblages are recognized. The essentially parautochthonous nature of the molluscan fossils suggests that these assemblages may represent former benthic communities. Characteristics of specific composi- tions of each assemblage are described below. Type I: Myonera osawanoensis assemblage This assemblage is recognized in diatomaceous siltstone at Locs.1 and 2. It is characterized by the dominance of Myonera osawanoensis, which accounts for nearly 50% of the total number of the specimens. Commonly associated species are Portlandia sp. and Delectopecten cf. peckhami. Type Il: Neilonella tsukigawaensis assemblage This assemblage is recognized in massive sandy siltstone boulders at Loc. 3. It is characterized by the dominance of Neilonella tsukigawaensis sp. nov., which accounts for about 25% of the total number of the specimens. Subdominant species are Portlandia sp. and Orectospira sp. Paleobathymetry For the paleobathymetric interpretation of Cenozoic mol- luscan faunas, the taxonomic structure method is useful because it can discriminate between shallow- (less than 200 m) and deep-water (greater than 200m) faunas. This method was developed by Hickman (1974, 1984) and is based on the observation that the percent composition of species representing major taxonomic division of the molluscan group changes with depth in modern major regional faunas. Miocene molluscs from Arakawa Formation Table 2. List of the molluscan fossils from the Arakawa Formation. For bivalves, the numbers naked and in the parenthesis represent those of of individuals. i) N \O Numbers represent those disarticulated and articulated valves, respectively. Assemblage type | Il Locality Puncturella sp. | Bathybembix ? sp. | Bolma? sp. | Orectospira sp. | Epitonium sp. Ancistrolepis sp. Fissidentalium sp. | Acila sp. Bathymalletia chitensis Shikawa and Kase Neilonella isensis Shibata Neilonella tsukigawaensis sp. nov. Tindaria ? Sp. Nuculana (Testyleda) sp. N. (Crassoleda) aff. pennula (Yokoyama) | Portlandia sp. Acar sp. Delectopecten cf. peckhami (Gabb) Anomiidae gen. et sp. indet. Lucinoma sp. Conchocele sp. Macoma ? sp. Halicardia sp. Cuspidaria sp. Cardiomya mitsuganoensis Shibata Myonera osawanoensis (Tsuda) As Hickman (1984) has emphasized, the taxonomic structure method is a tool for analyzing not individual assemblages but entire faunas. | examined the taxonomic composition of the whole bivalve fauna of the Arakawa Formation in the lwadono area. The composition of the gastropod fauna was not examined because of the very low species diversity of gastropods in the Arakawa Formation. Figure 4 illustrates the taxonomic composition of the bivalve fauna of the Arakawa Formation and those from the modern shelf, bathyal, and abyssal zones for comparisons. As shown in this figure, the proportions of protobranchs and heterodonts in modern shallow- and deep-water faunas are remarkably reversed. Hickman (1984) used the predomi- nance of protobranchs over heterodonts as an indicator of deep water for paleobathymetric interpretation of Paleogene molluscan faunas. The Arakawa bivalve fauna is clearly indicative of deep water in the remarkable predominance of protobranchs. Another distinct feature in the taxonomic composition of the Arakawa bivalve fauna is the sub- dominance of septibranchs, which is also characteristic of deep water in modern faunas. Proportionally, the structure of the Arakawa bivalve fauna is most similar to that of the modern abyssal fauna. However, this similarity is superficial because the taxonomic structure method is not able to discriminate between bathyal and abyssal faunas. Next, | examined the compilations of modern bathymetric ranges of the constituent genera of the Arakawa fauna on the basis of the distribution data of Recent molluscs by Higo and Goto (1993). As a result, it became clear that both Type-I and -II assemblages contain genera restricted to bathyal depths such as Myonera and Halicardia, respectively and that the other genera have a wide range taking in the sublittoral to bathyal zones. Bathymetric ranges of Myonera and Halicardia in the modern northwestern Pacific are 400- 900 m and 400-1,500 m, respectively (Higo and Goto, 1993). There is no genus restricted to the sublittoral zone. There- fore, both Type-I and -Il assemblages can be considered to represent a fauna of bathyal depths. It is difficult to discuss in more detail the paleobathymetry of both assemblages and their bathymetric relationship with the present data. Both Type-I and -lIl assemblages are dominated by proto- branch bivalves in terms of species number and are compa- rable with the Protobranch Communities, one of the six Cenozoic deep-water molluscan community types of Hick- man (1984). There is, however, a difference between Type- | and -II in terms of major taxonomic groups of dominant species. The type-lIl assemblage clearly belongs to the Protobranch Communities in the dominance of a protobran- ch bivalve, Neilonella tsukigawaensis sp. nov. On the other hand, the Type-I assemblage differs from the typical Proto- 230 Yukito Kurihara % of total number of species Arakawa (n=18) Figure 4. Taxonomic composition of the bivalve fauna of the Arakawa Formation and those from modern shelf (less than 200 m), bathyal (200-2,000 m) and abyssal (greater than 2,000 m) zones for comparisons (after Hickman, 1984). Pr, Proto- branchs ; Pt, Pteriomorphs ; H, heterodonts ; S, septibranchs. Letter n represents the number of species. shelf bathyal abyssal branch Communities in the dominance of a septibranch bivalve, Myonera osawanoensis. Such an assemblage dominated by a septibranch bivalve may be distinguishable from Hickman's six Cenozoic deep-water molluscan com- munity types and may represent a new one, the Septibranch Communities. Marine paleoclimate The marine paleoclimatic aspect of the Arakawa fauna is Latitude N. 30 32 34 36 38 40 42 A Myonera Neilonella Orectospira Bathymalletia Conchocele C Ancistrolepis Figure 5. Latitudinal range of the selected genera of the Arakawa fauna in the modern northwestern Pacific. Over- lapped area of A, B and C-type genera is indicated by shade. Dotted line represents the latitude of the Iwadono Hills area. here inferred on the basis of the observed latitudinal ranges of the constituent genera in the modern northwestern Pacific by Kuroda and Habe (1952) and Higo and Goto (1993). The Arakawa fauna contains several genera that show distinct latitudinal distributions and which can be grouped into three types on the basis of their distribution patterns ; namely, A, B, and C-types (Figure 5). The A-type genera are widely distributed to the south of Lat. 36°N, the B-type are restricted between 33° and 36'N, and the C-type are widely distributed to the north of 33°N. The A-type genera, Myonera and Neilonella, can be regarded as southern ele- ments, and the B-type genera, Orectospira and Bathymalletia, are nearly equivalent to the Southwestern Japonic elements of Nobuhara (1993). The C-type genera, Ancistrolepis and Conchocele, are known as northern elements, because their main distribution is in northern sea areas (Okutani, 1968). In the Pacific coast of Japan, the cooccurrence of the three types of genera is now restricted to deep water of Lat. 33 to 36'N. According to Okutani’s (1968) study of the deep-water molluscan fauna in Sagami Bay (approximately Lat. 35.2'N ; see Figure 1-A), the cooccurrence of the three types of genera is typically recognized at depths of 400 to 1,000 m, where they would be bathed in the intermediate water at 6 to 8C, and where most of the constituent genera (about 80%) of the Arakawa fauna occur. Such similarities sp., Loc. 1, rubber cast, 11848. 3. Bolma ? sp., Loc. 3, rubber cast, «1.5, IGUT 11849. 4. Epitonium sp., Loc. 3, rubber cast, x 2.5, IGUT 11851. b. Orectospira sp., Loc. 3, 5. rubber cast, x 2, IGUT 11850-2; 6. — Figure 6. (For bivalves, RV and LV are used for abbreviation of right valve and left valve, respectively.) 1a-b. Puncturella < 4, (a) dorsal view, (b) lateral view, IGUT 11847. 2. Bathybembix ? sp., Loc. 1, rubber cast, x 2.5, IGUT 5, 6a- < 2.3, (a); lateral view, (b) basal view, IGUT 11850-1. 7a-b, 12. Neilonella isensis Shibata, Loc. 3, X 3.5, 7. RV (a) dorsal view, (b) lateral view, IGUT 11833 ; 12. LV, IGUT 11832. 8a-b, 9a- b, 10a-b. Neilonella tsukigawaensis sp. nov., Loc. 3, x 3.5, 8. LV, (a) dorsal view, (b) lateral view, IGUT 11834-1, holotype ; 9. LV (a) dorsal view, (b) lateral view, IGUT 11834-2, paratype ; 10. LV, (a) rubber cast, (b) internal mold, IGUT 11834-3, paratype. 1. Ancistrolepis sp., Loc. 3, X1.5, IGUT 11852. 13. Bathymalletia chitensis Shikama and Kase, Loc. 1, rubber cast of RV, 2.5, IGUT 11836. 14,15. Nuculana (Crassoleda) aff. pennula (Yokoyama), 14. Loc. 3, LV, x 3.5, IGUT 11839 ; 15. Loc. 2, rubber cast of RV, <3, IGUT 11840. 16. Nuculana (Thestyleda) sp., Loc. 3, LV, «3, IGUT 11838. 17. Tindaria? sp., Loc. 1, internal mold of LV, x4, IGUT 11835. 18,19. Portlandia sp., 18. Loc. 2, internal mold of RV, 1.5, IGUT 11841-1; 19. Loc.1, internal mold of RV, 1.5, IGUT 11841-2. 20. Delectopecten cf. peckhami (Gabb), Loc. 1, internal mold of RV, x 2, IGUT 11837. 21. Lucinoma sp., Loc. 3, RV, x 2, IGUT 11842. 22. Macoma? sp., Loc. 3, internal mold of RV, «1.5, IGUT 11843. 28a-b. Halicardia sp., Loc. 3, RV, 1.5, (ainal undulations and a depressed and triangle-shaped rostrum. The shell outline is somewhat variable in the examined specimens as illustrated. 24. Cuspidaria sp., Loc.1, rubber cast of RV, «3, IGUT 11844. 25, 26,27. Myonera osawanoensis (Tsuda), 25. Loc. 2, internal mold of LV, «3, IGUT 11845-3; 26. Loc.1, internal mold of LV, x3, IGUT 11845- 2; 27. Loc.1, internal mold of LV, x3, IGUT 11845-1. This species is closely related to Myonera dautzenbergi Prashad, 1932, which currentlyl mold of LV, x3, IGUT 11845-2 ; 27. Loc. 1, internal mold of LV, x 3, IGUT 11845-1. 28. IGUT 11854-1; 29. IGUT 11854-2. 28, 29. Cardiomya mitsuganoensis Shibata, Loc. 2, rubber cast of LV, X5, Miocene molluscs from Arakawa Formation 232 Yukito Kurihara in the generic composition between the molluscan fauna of the Arakawa Formation and of the bathyal zone in modern Sagami Bay suggests that the marine climate during the Arakawa deposition was similar to that of the intermediate water of modern Sagami Bay. Systematic paleontology A new species and another species in a new combination are described in this section. All the illustrated specimens are deposited in the Institute of Geoscience, University of Tsukuba, under the IGUT collection catalogue numbers. Family Malletiidae Genus Neilonella Dall, 1881 Neilonella tsukigawaensis sp. nov. Figures 6-8a, b, 9a, b, 10a, b ? Neilonella cf. soyoae Habe. Shibata in Itoigawa et al., 1974, p. 47-48, pl.1, fig. 18; Itoigawa et al., 1981, pl.1, fig. 7; Itoi- gawa et al., 1982, p. 7. Type.—The holotype is a left valve (IGUT 11834-1). The paratypes, IGUT 11834-2,3. All from Loc. 3: a riverside exposure along the Tsuki-gawa River, about 250 m down- stream of the Tsuki-gawa Bridge, Senjido, Ranzan-machi, Hiki-gun, Saitama Prefecture. Diagnosis.—Moderate-sized species of Neilonella, char- acterized by its elongate-ovate outline, broad umbo, and surface sculptured all over with densely spaced distinct commarginal ribs. Description.—Shell moderate in size for the genus, rarely exceeding 10mm in length, elongate-ovate, inequilateral, equivalve, moderately inflated ; umbo broad, not so promi- nent, located at about two fifths of the length ; antero-dorsal margin nearly straight, gradually bending down rounded anterior portion; postero-dorsal margin long, broadly con- cave, abruptly turned to posterior margin at rostrated poste- rior end ; ventral margin smoothly convex ; lunule indistinct ; escutcheon broadly concave, circumscribed by a blunt ridge from beak to posterior end; external surface sculpted all over with densely spaced distinct commarginal ribs ; anterior teeth about 11 in number, posterior teeth more than 10; muscle scar and pallial line unknown. Comparison.—This new species is most similar to Neilonella soyoae Habe, 1958, a Japanese living species, in shell size and form. However, N. soyoae is distinguished from this new species by its smoother surface. Neilonella isensis Shibata, 1970 differs from this new species in its smaller shell size and higher shell outline with coarser commarginal ribs. Judging from descriptions, this new species may be conspecific with Neilonella cf. soyoae of Shibata in Itoigawa et al. (1974) and Itoigawa et al. (1981, 1982) from the Oidawara Formation in Gifu Prefecture. It is, however, difficult to conclude that the two forms are conspecific because these authors illustrated only a poorly preserved internal mold. Measurements.—Holotype, Length 7.9 mm, height 4.6 mm, width 2.4 mm [Figure 5-8 ; IGUT 1184-1]. Paratypes, length 9.2 mm, height 4.8mm, width 2.2mm [Figure 5-9; IGUT 11834-2] ; length 81mm, height 4.6mm, width 2.0mm [Figure 5-10 ; IGUT 11834-3]. Family Cuspidariidae Genus Myonera Dall, 1886 Myonera osawanoensis (Tsuda, 1959) Figures 6-25, 26, 27 Cuspidaria osawanoensis Tsuda, 1959, p. 73, pl. 2, figs. 2a, b. Cuspidaria sp. Shibata in Itoigawa et al., 1974, p. 110, pl. 35, figs. 3, 4. Cuspidaria (Tergula) sp. Itoigawa et al., 1981, pl. 22, fig. 9; Itoi- gawa et al., 1982, p. 119. Remarks.—Many specimens referred to this species were obtained from Locs. 1 and 2, but most of them were damaged during the sampling. This species is characterized by having a well inflated disc with rough commarginal undula- tions and a depressed and triangle-shaped rostrum. The shell outline is somewhat variable in the examined speci- mens as illustrated. This species is closely related to Myonera dautzenbergi Prashad, 1932, which currently inhabits bathyal depths in Sagami Bay and Indonesian waters (Higo and Goto, 1993), but differs in surface ornamentation. The external surface of the disc of M. dautzenbergi is not sculptured with rough undulations. This species was originally described by Tsuda (1959) under the genus Cuspidaria from the Miocene Kurosedani Formation in Toyama Prefecture, but is treated herein as a Myonera by virtue of having an umbonal-ventral sharp step separating the rostrum from the disc, which is a diagnostic character of Myonera. Judging from their description and illustration, Cuspidaria sp. (n. sp.) of Shibata in Itoigawa et al. (1974) and Cuspidaria (Tergula) sp. of Itoigawa et al. (1981, 1982) from the Oidawara Formation in Gifu Prefecture seem to be included within the variation of this species. Measurements.—Length 11.0 mm, height 6.9 mm, width 2.4 mm | Figure 5-25 ; IGUT 11845-3] ; length 9.5 mm, height 7. 1mm [Figure 5-26 ; IGUT 11845-2] ; length 9.0 mm, height 7.0mm, width 2.4mm [Figure 5-27 ; IGUT 11845-1]. Acknowledgments | would like to express my sincere appreciation to Hiroshi Noda (University of Tsukuba) for his invaluable suggestions and discussions on the present study. Thanks are due to Kenshiro Ogasawara (University of Tsukuba) and Carole S. Hickman (University of California, Berkeley) for reading the early draft of this paper and giving helpful comments. | am also indebted to Leopoldo De Silva, Jr. (University of Tsu- kuba) for his correcting my English, and to Yukio Yanagi- sawa (Geological Survey of Japan) for his identifications and valuable suggestions on diatom fossils. Miocene molluscs from Arakawa Formation References cited Akiba, F., 1986: Middle Miocene to Quaternary diatom biostratigraphy in the Nankai Trough and Japan Trench, and modified Lower Miocene through Quaternary diatom zones for middle-to-high latitudes of the North Pacific. In, Kagami, H., Karig, D.E., Coulbourn, W.T. et al., Initial Report of Deep Sea Drilling Project, vol. 87, p. 393-481, pls. 1-30. U.S. Govt. Printing Office, Washin- gton, D.C. Dall, W.H., 1881: Reports on the results of dredging, under the supervision of Alexander Agassiz, in the Gulf of Mexico, and in the Caribbean Sea, 1877-79, by the U.S. Coast Survey Steamer Blake. 15. Preliminary report on the Mollusca. Bulletin of the Museum of Compara- tive Zoology at Harvard College, vol. 9, p. 33-144. Dall, W.H., 1886: Neaea. Nature, vol. 34, no. 867, p. 122. Habe, T., 1958: Report on the Mollusca chiefly collected by the S.S. Söyö-maru of the Imperial Fisheries Experimen- tal Station of the continental shelf bordering Japan during the year 1922-1930, Part 3. Lamellibranchia (1). Publications of the Seto Marine Biological Laboratory, Kyoto University, vol. 6, no. 3, p. 241-280, pls. 11-13. Hatai, K. and Masuda, K., 1962: Megafossils from near Higashi-Matsuyama City, Saitama Prefecture, Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 46, p. 254-262, pl. 40. Hickman, C.S., 1974: Characteristics of bathyal mollusk faunas in the Pacific Coast Tertiary. Annual Report of the Western Society of Malacologists, vol. 7, p. 41-50. Hickman, C.S., 1984: Composition, structure, ecology, and evolution of six Cenozoic deep-water mollusk commu- nities. Journal of Paleontology, vol. 58, no. 5, p. 1215- 1234. Higo, S. and Goto, Y., 1993: A systematic list of molluscan shells from the Japanese Islands and the adjacent area, 693 p. Eru-Kairui-Shuppan-Kyoku, Osaka. (in Japanese) Horiuchi, S. and Yanagisawa, Y., 1994 : Diatom biostratigra- phy of the Miocene sequence of Iwadono Hills, Saitama Prefecture, central Japan. Bulletin of Geological Sur- vey of Japan, vol. 45, no. 11, p. 655-675, pls.1-3. (in Japanese with English abstract) ltoigawa, J., Shibata, H. and Nishimoto, H., 1974 : Molluscan fossils of the Mizunami Group. Bulletin of the Mizunami Fossil Museum, no. 1, p. 42-203, pls. 1-63. (in Japanese) Hoigawa, J., Shibata, H., Nishimoto, H. and Okumura, Y., 1981: Miocene fossils of the Mizunami Group, central Japan. 2. Molluscs. Monograph of the Mizunami Fossil Museum, no. 3-A, p. 1-53, pls. 1-52. (in Japanese) Itoigawa, J., Shibata, H., Nishimoto, H. and Okumura, Y., LD w LU) 1982 : Miocene fossils of the Mizunami Group, central Japan. 2. Molluscs (continued). Monograph of the Mizunami Fossil Museum, no.3-B, p.1-330. (in Japanese) Koike, M., Takei, K., Shimano, T., Machida, J., Akimoto, K., Hashiya, I, Yoshino, H. and Hirakoso, S., 1985: Miocene formations of Iwadono Hills. Journal of the Geological Society of Japan, vol. 91, no. 10, p. 665-677. (in Japanese with English abstract) Kurihara, Y., 1994MS : Neogene stratigraphy in the environs of Iwadono Hills, Saitama Prefecture, central Japan. Graduation thesis, University of Tsukuba. (in Japanese with English abstract) Kuroda, T. and Habe, T., 1952: Check list and bibliography of the Recent marine Mollusca of Japan, 210 p. Leo. W. Stach, Tokyo. Majima, R., 1989: Neogene stratigraphy along the Arakawa River near Yorii, and of the Ogawa Basin, Hiki Hills, and Iwadono Hills, central Saitama Prefecture, central Japan. Geoscience Reports of Shizuoka University, no. 15, p. 1-24. (in Japanese with English abstract) Nobuhara, T., 1993: The relationship between bathymetric depth and climate change and its effect on molluscan faunas of the Kakegawa Group, central Japan. Trans- actions and Proceedings of the Palaeontological Society of Japan, New Series, no. 170, p. 159-185. Okutani, T., 1968: Systematics, ecological distribution and paleaeoecological implication of archibenthal and abys- sal Mollusca from Sagami Bay and adjacent areas. Journal of the Faculty of Science, University of Tokyo, Section 2, vol. 17, pt. 1, p. 1-98. Prashad, B., 1932 : The Lamellibranchia of the Siboga Expe- dition. Systematic part. Il. Pelecypoda. Siboga Expedition, Monograph 53C, p. 1-353, pls. 1-9. Shibata, H., 1970: Molluscan faunas of the First Setouchi Series, southwest Japan. Part1. Fauna of the Ichishi Group. The Journal of Earth Sciences, Nagoya Univer- sity, no. 18, p. 27-84, pls. 1-4. Tsuda, K., 1959: New Miocene molluscs from the Kuro- sedani Formation in Toyama Prefecture, Japan. Jour- nal of the Faculty of Science, Niigata University, Series 2, vol. 8, no. 2, p. 67-110, pls. 1-7. Watanabe, K., Kanno, S., Murayama, I. and Takano, T., 1950: Tertiary geology in northeastern marginal region of the Kwanto Mountainland. Bulletins of the Chichibu Museum of Natural History, no.1, p. 93-146. (in Japanese with English Resume) Yanagisawa, Y. and Akiba, F., 1998: Refined Neogene diatom biostratigraphy for the northwest Pacific around Japan, with an introduction of code numbers for selected diatom biohorizons. Journal of Geological Society of Japan, vol. 104, no. 6, p. 395-414. Paleontological Research, vol. 3, no. 4, pp. 234-248, 6 Figs., December 30, 1999 © by the Palaeontological Society of Japan Apparatus of a Triassic conodont species Cratognathodus multihamatus (Huckriede) TOSHIO KOIKE Department of Science Education, Faculty of Education and Human Sciences, Yokohama National University, 7-2, Tokiwadai, Hodogaya-ku, Yokohama 240-0067, Japan Received 24 February 1999 ; Revised manuscript accepted 17 August 1999 Abstract. A Triassic conodont Cratognathodus multihamatus (Huckriede) from the pelagic limestone of the Taho Formation in Ehime Prefecture, Southwest Japan is newly reconstructed as an octomembrate apparatus with segminate Pa, angulate Pb, breviform digyrate M, alate Sa, breviform digyrate Sb,, extensiform digyrate Sb., bifurcate bipennate Sc,, and bipennate Sc, elements. Among the elements, the Pb, M, and S series were regarded as those of a septimembrate or octomembrate species Gladigondolella tethydis (Huckriede) by previous authors. Cr. multihamatus may comprise a lineage of the Gondolellidae ; it occurs in the Tethyan realm and ranges from late Spathian or early Anisian to late Carnian. Key words: Cratognathodus multihamatus (Huckriede), Gondolellidae, octomembrate apparatus, Taho Formation, Triassic Introduction The form species of conodonts, Cratognathodus kochi (Huckriede, 1958), Cratognathodus posterognathodus Mosher 1968, Cypridodella venusta (Huckriede, 1958), Diplododella lautissima (Huckriede, 1958), Enantiognathus stoppeli (Ben- der, 1967), Cypridodella spengleri (Huckriede, 1958), Hin- deodella petrae-viridis Huckriede 1958, and Hindeodella multihamata Huckriede 1958 were recovered from the Trias- sic in various areas of Tethyan realm. These eight form species also occur abundantly in the limestone strata of the Taho Formation outcropped at Tahokamigumi, Shirokawa cho, Higashiuwa-gun, Ehime Prefecture in Shikoku. As a result of statistic analysis of conodont fauna with these form species from various levels of the upper Spathian or lower Anisian to middle Anisian and upper Carnian strata of the formation, it has been made clear that these form species are the elements of a conodont skeletal apparatus and Cr. kochi, Cr. posterognathodus, Cy. venusta, D. lautissima, E. stoppeli, Cy. spengleri, H. petrae-viridis, and H. multihamata are assigned to the Pa, Pb, M, Sa, Sb,, Sb,, Sc,, and Sc; elements, respectively. | propose Cratognathodus multihamatus (Huckriede) herein for this octomembrate apparatus and describe the elements of the apparatus. Furthermore, | scrutinize the phylogeny of this species and compare it with the previously reconstruct- ed Triassic and some Paleozoic conodont apparatuses. All of the described specimens are kept in the Department of Science Education, Faculty of Education and Human Sciences, Yokohama National University (YNU). Biostratigraphic setting The limestone strata of the Taho Formation attain approxi- mately 75 m in thickness and correspond to Griesbachian to middle Anisian and upper Carnian to lower Norian. Upper Anisian to lower Carnian strata are missing due to a fault (Koike, 1996). In the Taho Formation, Cratognathodus multihamatus ranges from the uppermost part of the Neospathodus homeri Zone in the upper Spathian or the basal part of the Chiosella timorensis Zone in the lower Anisian to the Metapolygnathus nodosus Zone in the upper Carnian. The elements of this species are particularly abundant in the lower Anisian where 930 specimens were recovered from approximately 5 kg of limestone from level 1197. On the other hand, they are very rare in number and poor in preservation in the upper Carnian (Table 1). Cratognathodus multihamatus is a Tethyan species and the elements of the species were reported as form species from various parts of the Tethyan realm by many authors. In the biostratigraphic study of conodonts in Austria, Huckriede (1958) proposed and described the form species Prioniodina kochi, Lonchodina venusta, Roundya lautissima, Lonchodina spengleri, Hindeodella petrae-viridis, and Hindeodella multi- hamata. These species are assigned to the Pa, M, Sa, Sb;, Sc,, and Sc, elements of the Cr. multihamatus apparatus, respectively. The form species Ozarkodina saginata de- Triassic conodont apparatus 235 Table 1. Occurrence of Pa, Pb, M, Sa, Sb;, Sb:, Sc;, and Sc: elements of Cratognathodus multi- hamatus (Huckriede) obtained from 3 to 5 kg of limestone of the Taho Formation. Stratigraphic Elements level Pa Pb M Sa Sb; Sb» Sc: SC2 Sc:? + Sc? Carnian 1133 18) 10 3 2 1 2 5 1 8} Anisian 1202 31 50 49 9 27 13 11 20 51 1199 14 9 9 2 9 8 2 2 4 1198 29 20 8 5 Ss 4 4 9 8 1197 242 126 150 18 82 51 19 164 79 1196 20 6 9 8} 6 14 5} 12 12 1195 38 18 28 6 8 9 6 29 13 1324 23 5 6 3 4 4 1 4 1 1132 18 5 14 2 10 11 10 10 8 1194 52 13 26 ts) 10 12 8 18 11 1323 63 31 35 3 17 29 7 30 15 016 29 28 21 8 9 31 8 50 19 1193 143 45 38 12 33 36 17 54 39 1130 74 40 7 5 21 27 10 29 30 1322 70 32 25 6 18 25 8 17 36 1129 95 32 45 Urf 34 49 13 27 38 1321 155 67 68 15 43 65 19 55 29 015 45 14 ite 3 12 13 2 29 13 1192 12 9 11 2 6 3 4 9 4 1128 34 16 16 8} 7% 9 4 10 16 014 37 19 14 2 3 12 3 14 9 1191 59 48 50 16 29 37 11 18 19 1127 265 113 135 39 72 113 48 63 86 1316 66 35 32 7 23 19 9 22 17 Spathian ? 013 42 26 26 9 i 11 3 19 12 1183 18 3 6 1 2 8 2 6 2 total 1687 821 845 203 615 495 237 72 583 ratio 8.3 4.0 4.2 1 3.0 2.4 1.2+ 3.6+ scribed by Huckriede (1958) was distinguished from the form species Cratognathodus posterognathus Mosher (Pb element of Cr. multihamatus apparatus) by its shorter posterior proc- ess (Mosher, 1968). The form species Ozarkodina saginata illustrated by Huckriede (1958) is, however, probably based on incomplete specimens of Cr. posterognathus lacking a part of the posterior process. The specimen of the form species Apatognathus sp. illustrated by Huckriede (1958) is poorly preserved but the features of the processes and denticula- tion agree well with those of the Sb, element of Cr. multi- hamatus. According to Huckriede (1958), most of the form species occur commonly in the upper Anisian to Carnian. Bender (1967) reported Spathian and early Anisian conodonts from Chios and other Greek islands in the Mediterranean Sea and described the Pa, Pb, M, Sb,, Sc,, and Sc, elements of Cr. multihamatus as the form species proposed by Huckriede (1958). The specimens of the form species Hindeodella stoppeli illustrated by Bender (1967) are incomplete but the features of the lateral processes agree with the Sb, element of Cr. multihamatus. The Pa and Pb elements occur first in the upper part of the middle Neospathodus homeri Zone (late Spathian or early Anisian) and other elements occur first in the lower or middle part of the lower N. homeri Zone (late Spathian). Mosher (1968) studied Triassic conodonts of Austria, North America, and Germany, and described the form species assignable to the Pa, Pb, M, Sa, Sb,, Sc,, and Sc; elements of Cr. multihamatus from the Middle and Upper Triassic limestones in Austria. In part the specimens illus- trated as the form species Prioniodina petrae-viridis by Mosher (1968, PI. 116, Figs. 30, 31) are referable to the Sb, element. Furthermore, Mosher (1968) reported the occur- rence of the Pb, Sb,, and Sc, ? elements in the Middle and Upper Triassic of North America, but did not report any occurrences of the elements of Cr. multihamatus in the Muschelkalk of Germany. According to Mosher (1968), all of the elements appear first in the late Anisian and the Pb, M, Sa, and Sc, elements range to early Ladinian, but the Pa, Sb,, Sb,, and Sc, elements range to Carnian or Norian in Austria. In their biostratigraphic study of the Lower to Upper Triassic conodonts in some areas of Europe in the Tethyan 236 Toshio Koike realm, Kozur and Mostler (1972) described the form species referable to the Pb, M, Sa, and Sb, elements of Cr. multi- hamatus. One of the specimens of the form species Hin- deodella spengleri (Huckriede) illustrated by Kozur and Mostler (1972, pl. 7, fig. 11) is referable to the Sc, element of Cr. multihamatus. Most of the specimens of the form species Enantiognathus petraeviridis (Huckriede) illustrated by Kozur and Mostler (1972, pl. 10, figs. 1,2; pl. 14, figs. 4, 5, 8,12) are the Sb, element of Cr. multihamatus. The form species Cratognathodus kochi, the Pa element of Cr. multi- hamatus, is regarded as the immature form of the “gladigon- dolelliform” (Pa) element of Gladigondolella tethydis (Huck- riede) by Kozur and Mostler (1972). According to them, the biostratigraphic ranges of the elements are within the Ladinian to early Carnian. In the report on Triassic conodonts from Turkey, Gedik (1975) described the form species referable to the Pa, Pb, M, Sb,, and Sc, elements of Cr. multihamatus. The speci- mens illustrated by Gedik (1975) as the form species Hibbar- della magnidentata (Tatge) (pl. 4, figs. 8-10), Enantiognathus ziegleri (Diebel) (pl. 5, fig. 3), and Prioniodina (Frabellignathus) latidentata (Tatge) (pl. 8, figs. 13-15) are probably referable to the Sa, Sb,, and Sc, elements of Cr. multihamatus, respec- tively. According to Gedik (1975), all of the elements appear first in the Zone A of the early Anisian just above the Chiosella timorensis Zone and range to the late Carnian. Summarizing the above-mentioned reports, Cr. multi- hamatus is a diagnostic species in the Tethyan realm and ranges from late Spathian or early Anisian to late Carnian as recognized in the Taho Formation. Appartus of Cratognathodus multihamatus (Huckriede) Cratognathodus multihamatus is reconstructed as an octomebrate skeletal apparatus in this study (Figure 1). The elements are Pa, Pb, M, Sa, Sb,, Sb;, Sc,, and Sc.. The Pa element is a segminate (neospathodiform) type having an arched anterior process with 3 to 10 relatively short and broad, discrete denticles, a large broad cusp, and an expanded basal cavity. One or two small denticles may be present behind the cusp. It is identical with the form species Cratognathodus kochi (Huckriede, 1958). The Pb element is an angulate (ozarkodiniform) type possessing a strongly and laterally bending unit, an anterior process with 3 to 6relatively large, discrete denticles, a posterior process with 4 to 6 short, slender, discrete denti- cles, a large cusp, and a slightly expanded basal cavity. It is identical with the form species Cratognathodus saginatus (Huckriede, 1958) and Cratognthodus posterognathus Mo- sher, 1968. The M element is a breviform digyrate (cypridodelliform) type having a short lateral process with 1 to 3 short denticles, a long lateral process with 8 to 10 short to long denticles, a large Cusp, and an expanded basal cavity. It is identical — Figure1. A hypothetically reconstructed apparatus of Cratognathodus multihamatus (Huckriede) from the Taho For- mation. M Sb1 Sb2 2 Sc2 Pb Pa Triassic conodont apparatus 237 with the form species Cypridodella venusta (Huckriede, 1958). The Sa element is an alate (diplododelliform) type possess- ing 2 long lateral processes with 3 to 5 short to long, discrete denticles, a long posterior process with more than 10 short, indiscrete denticles, a large cusp, and a slightly expanded basal cavity. It is identical with the form species Di- plododella lautissima (Huckriede, 1958). The Sb, element is a breviform digyrate (enantiognathi- form) type possessing subequal-sized slender lateral proces- ses with 7 to 10 short to long, discrete denticles, a slender long cusp, and a slitlike basal cavity. It is probably identical with the form species Enantiognathus stoppeli (Bender, 1967). The Sb, element is an extensiform digyrate (prioniodini- form) type having a short lateral process with 2 to 5 short denticles, a long lateral process with 10 to 13 short to long, indiscrete denticles, a slender long cusp, and a triangular basal cavity. It is identical with the form species Cypridodella spengleri (Huckriede, 1958) The Sc, element is a bipennate (hindeodelliform) type posessing a bifurcate long anterior process with 5 to 8 short to long, discrete denticles, a long posterior process with more than 5 short to long, discrete denticles, a slender long cusp, and a slitlike basal cavity. It is identical with the form species Hindeodella petrae-viridis Huckriede, 1958. The Sc, element is a bipennate (hindeodelliform) type having slender long anterior and posterior processes Carrying 5 to 12 short to long, discrete denticles, a slender long cusp, and a slitlike basal cavity. It is identical with Hindeodella multihamata Huckriede, 1958. The number of elements of Cr. multihamatus occurring in each level is shown in Table 1. The frequencies of the Pa, Pb, M, Sa, Sb,, Sb», Sc,, and Sc, elements from the sam- ples of the Spathian or Anisian to Carnian are 1687, 812, 845, 203, 615, 495, 237 +, and 721+, and an approximate ratio of the elements is 83:4.0:4.2:1:3.0: 2.4:1.2+ :36+4, respectively. The natural assemblage of Neogondolella sp. recovered by Rieber (1980) from the Middle Triassic of Swizerland and Gondolella pohli reconstructed by von Bitter and Merrill (1998) based on many natural assemblages from Illinois are com- posed of a single unpaired alate Sa, single pairs of segmini- planate Pa, angulate Pb, breviform digyrate M, breviform digyrate Sb,, and extensiform digyrate Sb., and two pairs of bipennate Sc elements. Orchard (1998) regarded, however, the Sc elements in Neogondolella as being composed of Sc, and Sc., and the Neogondolella apparatus as an octomem- brate type. As mentioned further on, Cr. multihamatus represents a close phylogenetic relationship with neogondolellids and is referable to the Gondolellidae. Therefore, Cr. multihamatus probably has as many elements as Neogondolella sp. (Rieber, 1980) and G. pohli. In that case, the abundance of seg- minate Pa elements is very high compared with other ele- ments in Cr. multihamatus. The reason is probably due to robustness of Pa elements. On the other hand, alate Sa elements are considerably low in abundance. This is pre- sumably due to their fragility. The same tendency in abun- dance of Pa and Sa elements is observed in apparatuses of G. pohli (von Bitter and Merrill, 1998, table 1). Cratognathodus multihamatus and previously reconstructed apparatuses Kozur and Mostler (1971) reconstructed a multielement species Gladigondolella tethydis (Huckriede) with 11 or 12 elements. The elements are identical with the form species Cr. posterognathus, Cy. venusta, D. lautissima, Cy. spengleri, H. petrae-viridis, H. multihamata, Cr. saginatus, Didymodella alternata (Mosher), Lonchodina hungarica Kozur and Mostler, H. pectiniformis (Huckriede), and G. tethydis. Among these form species, the first six correspond with the Pb, M, Sa, Sb;, Sc,, and Sc, elements of the Cr. multihamatus apparatus, respectively. Furthermore, one of the specimens demon- strated as Enantiognathus petraeviridis by Kozur and Mostler (1971, pl.1, fig.14) is referable to the Sb, element of Cr. multihamatus. Hirsch (1981, 1994) also reported a multielement species G. tethydis composed of eight elements. Judging from the simple illustration by Hirsch (1994), the eight elements are identical with the form species, Cr. posterognathus, Cy. venusta, D. lautissima, H. petrae-viridis, H. multihamata, Cr. saginatus, H. pectiniformis, and G. tethydis. As mentioned above, the first five form species correspond with the Pb, M, Sa, Sc,, and Sc, elements of Cr. multihamatus, respectively. The correlation coefficient of occurrence is very low between the Cr. multihamatus apparatus and the Pa element of G tethydis in the Taho Formation: Cr. multihamatus appears first at the upper part of the Neospathodus homeri Zone in the late Spathian or the basal part of the Cr. timoren- sis Zone in the early Anisian but the Pa element of G. tethydis appears later, at the base of the Paragondolella bulgarica Zone (Figure 2). Among the studied samples yielding Cr. multihamatus (Table 1), the occurrence of the Pa elements of G. tethydis is restricted within the levels 1197, 1198, and 1202 in the P. bulgarica Zone and the number of the elements found in about 3 to 5 kg of limestone is only 2, 2, and 25, respectively. According to Muttoni et al. (1998), the Pa elements of G. tethydis appear first near the base of the Paragondolella bifurcata-Neospathodus kockeli Zone in Pelsonian of Anisian of Italy. The first appearance of the Pa elements of G. tethydis in Italy is nearly the same in age as their first appearance in Japan. As mentioned previously, Cr. multi- hamatus appears first in the late Spathian or earliest Anisian in Tethyan realm. Therefore, the first appearances of Cr. multihamatus and the Pa element of G. tethydis are obviously different in the Tethyan realm. Kozur and Mostler (1972) regarded the form species Cr. kochi (=Pa elements of Cr. multihamatus) as immature forms of the “gladigondolelliform” (Pa) elements of G. tethydis. As mentioned above, mature forms of the Pa elements of G. tethydis, however, never occur in the N. homeri and Cr. timorensis Zones which yield the abundant form species Cr. kochi. Furthermore, Pa elements of Cr. multihamatus and immature forms of Pa elements of G. tethydis are easily distinguished from each other by the feature of lateral expansion of process, denticulation, and the shape of the basal cavity. As far as observed conodont faunas in Japan are con- 238 Toshio Koike E. Triassic . homeri Z. [Olenekian | N = 2 = S 2 S 2 Ss f= Ri À 8 Ee S à = pa x x 3 < S nm SS < 1133 3 1202 fault Le x & & “Ve 2.0 SS a > Ÿ ES aan N 4 5 sa = Pr à o 1201 = eS 77 © 2 So SS aS N = Soe À 8 S o 1199 nie Ss E Ÿ SER SES À 2 È o 1198 SS 8% D 8 . = LS ™ IS n <= 3 à o 1197 re S D R an © 1196 eS Q S = S © S x 50 = : S 28 © = N O 1195 1324 S 3 Ss S = 2 fo) 1132 x 2, eso = < O 1194 1323 016 § S =e © ae S o 1193 11301322 Bes 3 3 O 11291321 015 à SS 3 & © 1192 1128 1320 014 SS o 1191 1127 SS e) 1316 SES © 1183 013 SS S © x Figure 2. Stratigraphic section and vertical distribution of Cratognathodus multihamatus (Huckriede) and important pectiniform conodonts in the Taho Formation. cerned, the correlation coefficient of occurrence is very low among the Pa element of G. tethydis and other pectiniform and ramiform elements. For example, a late Anisian or early Ladinian limestone sample collected from Izuriha near Kyoto yields about 550 specimens of G. tethydis Pa elements, but other elements associated with them are mainly of the Cr. multihamatus apparatus with some “ozarkodiniform” Pb and a few “enantiognathiform” Sb, of unidentified apparatuses. The abundances of the Pa, Pb, M, Sa, Sb,, Sb., Sc,, and Sc, elements of Cr. multihamatus in the sample are 19, 56, 36, 17, 30, 59, 72+, and 33+, respectively. Thus, the G. tethydis apparatus reconstructed by Kozur and Mostler (1971) and Hirsch (1981, 1994) is problematical. Furthermore, it is difficult to reconstruct G. tethydis as a multielement appara- tus with Pa and any other elements at present. Phylogeny of Cratognathodus multihamatus As mentioned above, Cr. multihamatus is characterized by possessing segminate Pa, angulate Pb, breviform digyrate M, alate Sa, breviform digyrate Sb,, extensiform digyrate Sb;, bifurcate bipennate Sc,, and bipennate Sc, elements. Triassic conodont apparatus 239 Among these elements, Pa is one of the most important components for scrutinizing the phylogeny of Cr. multi- hamatus. The Pa element of Cr. multihamatus with a relatively large cusp and large discrete denticles is morphologically very different from not only the typical Spathian neospathodid species: Neospathodus homeri (Bender) and N. triangularis (Bender) but also from the immature forms of the typical Anisian neogondolellid, paragondolellid, and chiosellid species: Neogondolella regale Mosher, Paragondolella bul- garica (Budurov and Stefanov), and Chiosella timorensis (Nogami), all of which exhibit a small Cusp and subequal indiscrete denticles. The Pa element of Cr. multihamatus, however, represents some morphologic similarities to the immature forms of the Pa elements of Gladigondolella tethy- dis, which appeared later than Cr. multihamatus in Anisian time, and Paragondolella navicula (Huckriede) and P. hall- stattensis Mosher, which appeared in Norian time. Further- more, the Pa element closely resembles the “ozarkodiniform” element of Celsigondolella watznaueri watznaueri (Kozur) and the form species Pollognathus sequens (Kozur), which are regarded as the endemic Ladinian conodont species of the German Basin (Kozur and Mostler, 1972 ; Kozur, 1989). The presence of “enantiognathiform” Sb, element in Cr. multihamatus is also considerably important in establishing its phylogenetic relationship with the previously reconstruct- ed conodonts. The natural assemblage of Neogondolella sp. recovered by Rieber (1980) from the Middle Triassic of Switzerland is composed of as many as 15 elements belong- ing to Pa, Pb, M, Sa, Sb,, Sb., and Sc (von Bitter and Merrill, 1998). The Sb, element of Neogondolella sp. is of the typical “enantiognathiform” type (von Bitter and Merrill, 1998) and morphologically quite similar to the Sb, of Cr. multi- hamatus. The Pennsylvanian Gondolella pohli reconstruct- ed by von Bitter and Merrill (1998) based on natural assem- blages from Illinois also includes a single pair of “enantionathiform” Sb, elements accompanied by a single unpaired Sa, single pairs of Pa, Pb, M, and Sb,, and two pairs of Sc elements. Orchard (1998) reviewed all gondolellids and pointed out that Neogondolella is an octomembrate apparatus with an “enantiognathiform” type occupying the Sb, position adja- cent to the Sa element and a single pair of Sc elements always having a bifurcate anterior process. Orchard (1998) regarded the Sc element with a bifurcate anterior process as the Sc, but now is of the opinion that it is the Sc, (personal communication). In addition to the “enantiognathiform” element, the pres- ence of the Sc element with a bifurcate anterior process in Cr. multihamatus represents a phylogenetic relationship with Neogondolella. Furthermore, the Pb, M, Sa, and Sb, ele- ments of Cr. multihamatus also basically have the same morphology as those of Neogondolella sp. and Gondolella pohli. The skeletal apparatus of Pseudofurnishius murcianus reconstructed by Ramovs (1977,1978) based on many clus- ters in the upper Ladinian of Slovenia is setpimembrate with “enantiognathiform” elements. The “pollognathiform” ele- ment of P. murcianus shows some similarities to the Pa elements of Cr. multihamatus. The “pollognathiform” ele- ments were identified with Pollognathus sequence by Ramovs (1977). All elements except for the “pseudofurni- shiform” Pa and “chirodelliform” Sb, ? elements in P. mur- cianus are basically similar to their counterparts in Cr. multihamatus. The Ladinian Budurovignathus mungoensis (Diebel) appa- ratus reconstructed by Mietto (1982) based on clusters from Italy also includes “enantiognathiform” elements with the Pa, M, Sa, and Sc elements. The Xaniognathus and Cypridodella apparatuses statisti- cally reconstructed by Sweet (1981, 1988) are composed of six elements such as the Pa, Pb, M, Sa, Sb, and Sc, among which the Pb is regarded as the “enantiognathiform” digyrate type. The Pb element is closely similar to the Sb, element of Neogondolella sp. of Rieber (1980). Sweet (1988) regarded Neogondolella, Gondolella, Xaniognathus, and Cypridodella as belonging to the family Gondolellidae based on the common occurrence of “enantiognathiform” elements among their apparatuses, and as having a close phylogenetic relationship with Ellisonia of the family El- lisoniidae, which also bears “enantiognathiform” elements. Pseudofurnishius and Budurovignathus are as well included in the Gondolellidae by many authors (Sweet, 1988 ; Kozur, 1989, and others). Although Dzik (1991) recognized that Gondolella is char- acterized by the presence of lo (enantiognathiform) elements, he claimed the presence of enantiognathiform-like elements in some undescribed apparatuses of the Devonian Hibbar- dellidae which are unlikely to have any relationships to Gondolella. Sweet (1988) assumed the origin of both of the Gondolel- lidae and Ellisonidae to be /dioprioniodus or a closely related genus with “enantiognathiform” elements in the Missis- sippian. Von Bitter and Merrill (1998) also considered that the Mississippian /dioprioniodus is a likely ancestor of the Pennsylvanian Gondolella based on their recognition of an evolutionary trend of reduction of the posterior process in the anguliplanate Pa elements. Dzik (1991) pointed out that reduced posterior processes in the platform (p) elements are characteristic of Gondolella and a similar feature occurs in some Devonian Ozarkodina. On the basis of morphologic similarities in both platform and ramiform elements. Dzik (1991) regarded the Devonian Pinacognathus (?) sp. as the probable ancestor of the Gondolellidae. In summary, | conclude that Cr. multihamatus should be included in the Gondolellidae because Cr. multihamatus has segminate Pa elements similar to immature forms of some neogondolellid Pa elements and bears “enantiognathiform” Sb, elements which are common in the Gondolellidae, and Sc, and other elements which are basically similar in morphology to those of neogondolellid and gondolellid apparatuses. The segminate Pa elements in Cr. multihamatus represent close morphologic similarity with the anterior process of the angulate (ozarkodiniform) Pb elements, which are basically the same in morphology as those of Neogondolella sp. of Rieber (1980) and Gondolella pohli. This feature suggests 240 Toshio Koike that both elements in the P position have a mutual relation- ship in feeding mechanism, but while the Pa elements acquired broad variation in morphology (anguliplanate Gladigondolella, segminate Neospathodus, and segmini- planate Gondolella and Neogondolella), the Pb element remained angulate during the evolution of the Gondolellidae. The ancestral form of the Pa elements of the Gondolellidae may be referable to an angulate (ozarkodiniform) element like the Pb elements. In that case the ancestor of the Gondolellidae should be searched for in conodonts with “ozarkodiniform”-like Pa and “ozarkodiniform” Pb elements. The conodonts possessing such Pa and Pb elements were not included in the Or- dovician family-group of the order Prioniodinida Sweet, 1988 in which the family Gondolellidae was included by Sweet (1988). On the other hand, Ordovician conodonts Bryantodina? staufferi Bergstrom and Sweet and Plectodina of Sweet (1988) in the Spathognathodontidae of the order Ozarkodinida Dzik, 1976 possess “ozarkodiniform”-like Pa and “ozarkodiniform” Pb elements (Sweet, 1988). Dzik (1991) included the order Prioniodinida erected by Sweet (1988) within the order Ozarkodinida and regarded the Gondolellidae as having a phylogenetic relationship with the Spathognathodontidae. On the basis of morphologic similarity between the Pa and Pb elements in Cr. multihamatus and those of the species in the Spathognathodontidae, | would like to support the opin- ion of Dzik (1991) that the Gondolellidae is phylogenetically related to the Spathognathodontidae of the order Ozar- kodinida. Systematic Paleontology Phylum Conodonta Order Ozarkodina Superfamily Gondolellacea Family Gondolellidae Genus Cratognathodus Type species.—Hindeodella multihamata Huckriede, 1958, p. 148-149. Revised diagnosis.—Cratognathodus newly proposed herein contains species with octomembrate apparatus of as many as 15 elements: single pairs of segminate Pa, an- gulate Pb, breviform digyrate Sb,, extensiform digyrate Sb;, bipennate Sc, and Sc, elements, and a single unpaired alate Sa element. Pa elements characterized by relatively broad cusp with expanded basal cavity and large discrete denticles. Remarks.—Mosher (1968) enacted the genus Cratogna- thodus and included the following four form species in the genus, Prioniodina kochi Huckriede, Cr. posterognathus new- ly proposed, and two unidentified species, which are both characterized by the presence of a strong broad cusp with a widely expanded basal cavity, and relatively small number of discrete denticles. As mentioned previously, Cratogantho- dus kochi and Cr. posterognathus are respectively identical with the Pa and Pb elements of the Cr. multihamatus appara- tus. Among the three specimens illustrated as Cr. kochi by Mosher (1968), one specimen (pl. 113, fig. 7) is misidentified and another specimen (pl. 113, fig. 4) is not a typical Pa element of the Cr. multihamatus apparatus. Mosher (1968), however, regarded the form species Prioniodina kochi Huck- riede as the type species of his Cratognathodus. Later, Kozur and Mostler (1972) claimed that the genus Cratognathodus created by Mosher (1968) is not a valid taxon because the holotype and all other specimens previously described as the form species Cr. kochi are immature forms of the “gladigondolelliform” (Pa) elements of Gladigondolella tethydis (Huckriede). Based on my observation on Pa elements of G. tethydis from the Taho Formation and other limestone formations in Japan, the immature forms of the element are characterized by a narrow platform-like anterior process and gradually increasing denticles in length toward the anterior as obser- ved in the mature forms. The immature forms of the Pa elements of G. tethydis can be, therefore, easily distin- guished from the form species Cr. kochi (=Pa element of Cr. multihamatus). The Pa element of Cr. multihamatus represents various features in the shape and size of the cusp and denticulation on the anterior process (Figure 3). The holotype of the form species Cr. kochi (Huckriede, 1958, pl. 12, fig. 11) possessing a short broad cusp and subequal denticles is safely assigned within the range of morphologic variation of the Pa element of Cr. multihamatus and agrees well with the specimens illustrated in Figure 3-16, 26. Cratognathodus multihamatus (Huckriede) Figures 3-5 Pa element Prioniodina kochi Huckriede, 1958, p.159, pl. 11, fig. ?37, pl. 12, figs. 11, 12, pl. 14, fig. 4; Spasov and Ganev, 1960, p. 89, pl. 1, fig. 23, pl. 2, fig. 12; Catalov and Stefanov, 1966, pl. 1, fig. 3; Bender, 1967, p.527, non pl. 5, fig.12; Hirsch, 1969, pl. 1, fig. ?7. Neoprioniodus cf. kochi (Huckriede), Ishii and Nogami, 1966, non — Figure 3. 1-31, Pa elements of Cratognathodus multihamatus (Huckriede) from the Taho Formation. all x60. 1: YNUC15881 from Lev. 1316. 2: YNUC15882 from Lev. 1195. 3: YNUC15883 from Lev. 1197. 4: YNUC15884 from Lev. 1324. 5: YNUC15885 from Lev. 1196. 6: YNUC15886 from Lev. 1321. 7: YNUC15887 from Lev. 1316. 8: YNUC15888 from Lev. 1127. 9: YNUC15889 from Lev. 1197. 10: YNUC15890 from Lev. 1197. 11: YNUC15891 from Lev. 1191. 12: YNUC15892 from Lev. 1130. 13: YNUC15893 from Lev. 1323. 14: YNUC15894 from Lev. 1183. 15-16: YNUC15895-15896 from Lev. 1321. 17: YNUC15897 from Lev. 1323. 18: YNUC15898 from Lev. 1127. 19: YNUC15899 from Lev. 1321. 20: YNUC15900 from Lev. 1195. 21-24: YNUC15901-15904 from Lev. 1193. 25: YNUC15905 from Lev.1128. 26: NUC15906 from Lev.1321. 27: YNUC15907 from Lev. 1198. 28: YNUC15908 from Lev. 1195. 29: YNUC15909 from Lev. 1193. 30: YNUC15910 from Lev. 1127. 31: YNUC 15911 from Lev. 1320. Triassic conodont apparat 242 Toshio Koike pl. 1, fig. 12. Cratognathodus kochi (Huckriede), Mosher, 1968, p. 919, pl. 113, figs. 3, ?4, non fig. 7 ; Jenkins and Jenkins, 1971, non fig. 5, no. 29; Sahni and Chhabra, 1974, p. 263, 265, pl. 3, figs. D, ? E, F, non fig. |; Gedik, 1975, p. 111-112, pl. 5, fig. 23 ; Budur- ov, 1976, pl. 4, fig. 29 ; Sudar, 1977, pl. 5, fig. 4; Catalov and Budurov, 1978, pl.1, fig. 8; Koike, 1981, pl.1, fig. 21; Koike, 1982, p. 20, pl.9, fig. 15, non fig. 16 ; Onder, 1984, p. 76, pl. 22, figs. ?7, 78. non Prioniodina? kochi germanica Kozur, 1968a, p. 139-140, pl. 1, figs. 24,25; Kozur, 1968b, pl.3, figs. 15,19, 21; Kozur, 1968c, p. 1081. Cratognathodus cuspidatus Koike, 1982, p. 20-21, pl. 9, figs. 217, 18. Pb element Ozarkodina saginata Huckriede, 1958, p. 153-154, pl. 13, figs. 16, 17,20; Mosher, 1968, p. 932, pl. 115, fig. 214, non fig. 15. Pseudoozarkodina saginata (Huckriede), Vrielynck, 1987, p. 229- 230, pl. 14, figs. 9-11. Cratognathodus posterognathus Mosher, 1968, p. 919, pl. 113, figs, 10,14; Koike, 1973, p. 98, pl.17, figs. 30, 31; Budurov and Stefanov, 1975, pl.1, fig. 235; Koike, 1981, pl.1, fig. 30; Koike, 1982, p. 20, pl. 9, figs. 20, 21; Onder, 1984, p. 77, pl. 22, figs. 9-11. Lonchodina? posterognathus (Mosher), Kozur and Mostler, 1971, pl.1, fig. 10; Mock, 1971, pl.1, fig.9; Kozur and Mostler, 1972, p.19, pl. 10, figs. 6, 7, 11. Lonchodina angulata Budurov, 1971, p.28, pl.1, figs. 5-9, 12; Catalov and Budurov, 1975, p. 1248, pl. 1, fig. 8. Cratognathodus posterognathus posterognathus Mosher, Gedik, 1975, p. 112, pl. 5, figs. 19, 20, 22. Cratognathodus posterognathus angulatus 1975, p. 113, pl. 8, figs. 25, 26. Cratognathodus angulatus (Budurov), Budurov, 1976, pl. 4, figs. 17, 18; Catalov and Budurov, 1978, pl.1, fig. 2. (Budurov), Gedik, M element Lonchodina venusta Huckriede, 1958, p. 152-153, pl. 11, fig. 25; Spasov and Ganev, 1960, p.82, pl.1, figs. 15-17 ; Hirsch, 1969, pl. 1, fig. 5. Cypridodella venusta (Huckriede), Mosher, 1968, p. 922-923, pl. 114, figs. 1, 7,?13; Gedik, 1975, p. 115-116, pl. 7, figs. 16-18 ; Koike, 1982, p. 23, pl.7, fig. 47 ; Onder, 1984, p. 78-79, pl. 22, figs. 5, 6. Prioniodina (Cypridodella) venusta (Huckriede), Kozur and Most- ler, 1971, pl.1, figs. 3,4; Mock, 1971, pl. 2, figs. 5, 10, 11; Kozur and Mostler, 1972, p. 32, pl. 11, figs. 16, 24, pl. 12, fig. 11, pl. 15, fig. 3. , Prioniodina venusta (Huckriede), Catalov and Budurov, 1975, p. 1248, pl. 1, fig. 12; Budurov, 1976, pl. 4, figs. 23-26; Sudar, 1977, pl.5, fig. 9; Catalov and Budurov, 1978, pl.1, fig.1; Vrielynck, 1987, p. 226-228, pl. 10, fig. 15, pl. 11, figs. 1, 2. ? Cypridodella pronoides (Budurov), Koike, 1982, p. 22, pl. 7, figs. 48, 49. Sa element Roundya lautissima Huckriede, 1958, p. 160, pl. 11, fig. 41, pl. 13, figs. 13, 15 ; Spasov and Ganev, 1960, p. 90, pl. 2, figs. 15, 22. Diplododella lautissima (Huckriede), Ishii and Nogami, 1966, pl. 1, fig. 15 ; Mosher, 1968, p. 924, pl. 114, fig. 20 ; Koike, 1973, p. 101, pl.17, fig. 32; Sahni and Chhabra, 1974, p. 270, pl. 3, fig. ?S ; Budurov, 1976, pl. 4, fig. 36 ; Sudar, 1977, pl. 5, fig. 2. Hibbardella lautissima (Huckriede), Mosher and Clark, 1965, p. 561, pl. 65, figs. ?1, ?3, ?4 ; Kozur and Mostler, 1971, pl. 1, fig. 13; Mock, 1971, pl. 3, figs. 7,18 ; Kozur and Mostler, 1972, p. 12, pl. 9, fig. 10, pl. 12, figs. 10, 13 ; Vrielynck, 1987, p. 195-196, pl. 11, figs. 3-7. pars Hibbardella magnidentata (Tatge), Gedik, 1975, p. 122-123, pl. 4, figs. 8-10 (only). Sb, element Apatognathus sp. Huckriede, 1958, p. 147, pl. 11, fig. 29. ? Hindeodella stoppeli Bender, 1967, p. 510, pl. 2, figs. 6, 15-17. pars Prioniodina petrae-viridis (Huckriede), Mosher, 1968, p. 934- 935, pl. 116, figs. 30, 31 (only). pars Enantiognathus petraeviridis (Huckriede), Kozur and Mostler, 1972, p. 9, pl. 10, figs. 1, 2, pl. 14, figs. 4, 5, 8, 12 (only). Sb, element Lonchodina spengleri Huckriede, 1958, p.152, pl. 10, figs. 54, ? 55, 256, pl. 11, fig. 6, pl. 12, fig. 9, pl. 13, figs. 1, 6, 10, pl. 14, fig. 11; Budurov, 1962, p. 119, pl. 1, figs. ?5-8 ; Mosher and Clark, 1965, p. 562, pl. 66, fig. ?5; Bender, 1967, p. 513-514, pl. 3, figs. 12, 2713-15, non fig.17. _ Prioniodina spengleri (Huckriede), Catalov and Budurov, 1975, p. 1248, pl.1, fig. ?13, non fig. 14; Sudar, 1977, pl. 5, fig. ?11; Catalov and Budurov, 1978, pl. 1, fig. 5, non figs. 4, 6, pl. 2, fig. 20, non figs. 19, 21. Prioniodina spengleri (Huckriede), “dimitrovi” element, Budurov, 1976, pl. 3, figs. 8, 18. Prioniodina spengleri (Huckriede), “spengleri” element, Budurov, 1976, pl. 3, figs. ?9, 211-15, 16-18, non figs. 20-25, non pl. 4, figs. 37-39. Prioniodina (Flabellignathus) spengleri sapanlii Gedik, 1975, p. 146-147, pl. 7, figs. 22, 26, 27, 30. Cypridodella spengleri (Huckriede), Mosher, 1968, p. 922, pl. 113, figs. 19, 20, 25, non fig. 18 ; Koike, 1973, p. 100, pl. 16, fig. 31; Sahni and Chhabra, 1974, p. 269, fig. 3-20 ; Onder, 1984, p. 78, non pl. 22, figs. 3, 4. Hindeodella (Metaprioniodus) spengleri (Huckriede), Kozur and Mostler, 1971, pl. 1, fig. 12 ; Mock, 1971, pl. 2, fig. 213, non fig. 14; Kozur and Mostler, 1972, p. 16-17, non pl. 7, fig. 11, pl. 10, fig. 4, pl. 15, figs. 1, 5. — Figure 4. Pb, M, Sa, and Sb, elements of Cratognathodus multihamatus (Huckriede) from the Taho Formation, all x 60. 1-14, Pb elements, 1: YNUC15912 from Lev. 1191. 2: YNUC15913 from Lev. 1321. 3-5: YNUC15914-15916 from Lev. 1130. 6: YNUC15917 from Lev. 1321. 7: YNUC15918 from Lev. 1316. 8: YNUC15919 from Lev. 1321. 9: YNUC15920 from Lev. 1322. 10: YNUC15921 from Lev. 1193. 11: YNUC from Lev. 1130. 12: YNUC 15923 from Lev. 1316. 13: YNUC15924 from Lev. 1197. 14: YNUC15925 from Lev. 1192. 15-19, M elements, 15: YNUC15926 from Lev. 1321. 16: YNUC15927 from Lev. 1197. 17: YNUC15928 from Lev. 1323. 18: YNUC15929 from Lev. 1193. 19: YNUC15930 from Lev.014. 20-24, Sa elements, 20: YNUC15931 from Lev. 016. 21: YNUC15932 from Lev. 1127. 22: YNUC15933 from Lev. 1129. 23: YNUC15934 from Lev. 1193. 24: YNUC15935 from Lev. 1195. 25-32, Sb, elements, 25: YNUC15936 from Lev.1197. 26-27: YNUC15937-15938 from Lev. 1196. 28-29: YNUC15939-15940 from Lev. 1197. 30: YNUC15941 from Lev. 1196. 31-32: YNUC15942-15943 from Lev. 1197. n = > © > © Q Q (ay) + = o oO © = fe) Oo oO H Q SG = Fr 244 Toshio Koike Sc, element Hindeodella petrae-viridis Huckriede, 1958, p. 149-150, pl. 11, fig. ? 46, pl.13, figs. ?7, ?8, 9,11,12,14, pl. 14, fig.6, non fig. 7; Spasov and Ganev, 1960, p.81, pl.1, figs. 3,4; Budurov, 1962, p. 116, pl. 1, figs. 219, ?20 ; Mosher and Clark, 1965, p. 562, pl. 65, fig. ?9 ; Ishii and Nogami, 1966, pl.1, fig. ?14 ; Catalov and Stefanov, 1966, pl. 1, figs. 4, 7, 216; Hirsch, 1969, pl. 1, fig. 4. Prioniodina petrae-viridis (Huckriede), Mosher, 1968, p. 934-935, pl. 116, figs. 28, 29, non figs. 30,31; Sahni and Chhabra, 1974, p. 284-285, fig.5,?A, C, ?D, ?E; Sudar, 1977, pl. 5, figs. ?7, 712; Onder, 1984, p. 86-87, pl. 23, figs. 16-21. Prioniodina (Flabellignathus) petraeviridis (Huckriede), Gedik, 1975, p. 145-146, pl. 8, figs. 11, 27. Prioniodina spengleri (Huckriede), “petraeviridis” element, Budur- ov, 1976, pl. 4, figs. 38, 39, non fig. 37. Parachirognathus petrae-viridis (Huckriede), Bender, 1967, p. 524, pl. 5, figs. ?1, 2, 3, ?4, ?5, 6, non figs. 8, 9. Enantiognathus petraeviridis (Huckriede), Mock, 1971, pl. 1, fig. 3, non figs. 4, 10, pl. 2, fig. 17 ; Kozur and Mostler, 1972, p. 9, pl. 10, fig. ?3, non figs. 1, 2, pl. 12, fig. ?16, non pl. 14, figs. 4, 5, 8, 12 ; Kemper et a/., 1976, pl. 6, fig. 28 ; Vrielynck, 1987, p. 188, pl. 9, fig. 210, non figs. 11, 12. Diplododella petraeviridis (Huckriede), Koike, 1981, pl. 1, fig. 26; Koike, 1982, p. 26-27, pl. 7, fig. 25. Prioniodina (Flabellignathus) latidentata (Tatge), Gedik, 1975, p. 143-144, pl. 8, figs. 13-15, 716-18, ?20, 721, 223, 224. pars Hindeodella (Metaprioniodus) spengleri (Huckriede), Kozur and Mostler, 1972, p. 16-17, pl.1, fig. 11 (only). Sc, element Hindeodella multihamata Huckriede, 1958, p. 148-149, pl, 10, figs. 52, 58, pl. 12, fig. 23; Catalov and Stefanov, 1966, pl. ?1, fig. 15; Bender, 1967, p. 508-509, pl. 2, figs. ?18, 20 ; Mosher, 1968, p. 925, pl. 114, fig. 19; Kozur and Mostler, 1971, pl. 1, fig. 9; Koike, 1973, p. 104, pl. 17, figs. 26-29, non fig. 25 ; Sahni and Chhabra, 1974, p. 274-275, fig. 4, A, D; Budurov, 1976, pl. 4, fig. 40 ; Chhabra, 1981, pl. 1, figs. 14, 17 ; Koike, 1982, p. 30, pl.9, figs. 23, 25, non fig. 24; Vrielynck, 1987, p. 201 202, pl. 14, fig. ?6, non figs. 4, 5. Neohindeodella multihamata (Huckriede), Koike, 1981, pl. 1, fig. 17. Hindeodella (Metaprioniodus) pectiniformis (Huckriede), Kozur and Mostler, 1972, p. 15-16, pl. 5, figs. 1, 2, pl. 14, figs. 19, ?23, 24. Prioniodina (Flabellignathus) pectiniformis (Huckriede), Gedik, 1975, p. 144-145, pl. 8, fig. 22. Prioniodina libita Mosher, 1968, p.934, pl. 115, figs. 17, 26, 29; Önder, 1984, p. 86. pl. 23, figs. 13, 14. Description.—Pa and Pb elements have common mor- phologic characteristics such as stout unit, broad cusp, and discrete denticles. M, Sa, Sb,, Sb,, Sc,, and Sc, elements possess long cusp, and thin process with long denticles. All elements possess distinct basal cavity. Pa element: Paired segminate elements with arched and laterally curved process. Length of anterior process ranges from 250 to 720 um. Anterior process relatively low to high and carries 3 to 10 denticles. Denticles represent broad variation in denticulation and size: narrowly to broadly discrete and subequal to highly unequal in size. In the case of consisting of highly unequal denticles, they tend to become larger in central portion on anterior process in some specimens and become larger toward anterior in others. One or two denticles may be present behind cusp. Cusp shows a morphologic variation in relative size, shape, and degree of inclination: narrow to broad, short to long, and medium-angled to subparallel with anterior process. Basal cavity shallow, narrowly to widely expanded laterally. Basal cavity margin thin in immature form and tends to be thick in mature form. Basal groove narrow and extends from basal cavity to anterior end. Pb element: paired angulate element with subequal anterior and posterior processes in length. Both processes meet at an angle of about 120 to 160 degrees in both upper and lateral views. Posterior process may be convex inward. Length of anterior and posterior processes ranges from 160 to 400 um, respectively. Denticles on anterior process 3 to 6 in number, short, discrete, and tend to increase in length and inclination posteriorly. Denticles on posterior process 3 to 6 in number, short, slender, discrete, and tend to increase in length and inclination posteriorly. Cusp large and stands commonly on anterior process and uncommonly on posterior process. Basal cavity a laterally compressed lenticular shape flaring outward in lower view. Basal groove extends anteriorly and posteriorly from basal cavity to beneath processes. M element: Paired breviform digyrate elements with short and long lateral processes ranging from 60 to 140 «m and from 530 to more than 670 um in length, respectively. Both processes meet at an angle of about 80 to 100 degrees in antero-posterior views. Short lateral process may be con- vex inward and carries 1 to 3 short denticles or none in some specimens. Long lateral process projects strongly down- ward and slightly convex outward. Denticles on long lateral process 8 to 10 in number, curve inward, and tend to increase in size and inclination downward. Cusp large and curves posteriorly. Basal cavity expanded posteriorly and slightly depressed on anterior side. Small lip of basal cavity present on posterior side and rounded keel extends from basal margin of lip to halfway up cusp. Narrow basal groove beneath both processes extends into basal cavity. Sa element: Alate elements with two long lateral proces- ses and long posterior process. Length of each lateral process ranges from 160 to 250 um. Length of posterior process unknown due to its incompleteness and more than 330 um in moderately large specimens. Lateral processes form an angle of 60 to 90 degrees with each other in anterior — Figure 5. Sb,, Sc, and Sc, elements of Cratognathodus multihamatus (Huckriede) from the Taho Formation. all X 60. 1-8, Sb, elements, 1-2: YNUC15944-15945 from Lev. 1316. 3: YNUC15946 from Lev. 1321. 4: YNUC15947 from Lev. 1323. 5: YNUC15948 from Lev. 1321. 1322. 21: YNUC15964 from Lev. 1127. 6: YNUC15949 from Lev. 1191. 1183. 9-17, Sc, elements, 9-15: YNUC15952-15958 from Lev. 1197. Lev. 1197. 18-21, Sc, elements, 18: YNUC15961 from Lev. 1127. 7: YNUC15950 from Lev. 1321. 8: YNUC15951 from Lev. 16: YNUC15959 from Lev. 1193. 17: YNUC15960 from 19: YNUC15962 from Lev. 1191. 20: YNUC15963 from Lev. Triassic conodont apparatus 246 Toshio Koike view and 90 to 120 degrees with posterior process in lateral view. Denticles on each lateral process 3 to 5 in number, discrete, tend to be large in central portion. Inclination of denticles tends to increase toward cusp. Denticles on posterior process more than 11 in number, short, indiscrete and standing perpendicular. Cusp as long as largest denti- cle on lateral processes and slightly curves posteriorly. Basal cavity moderately expanded and narrow basal groove extends beneath lateral and posterior processes. Sb, element: Paired breviform digyrata elements with subequal, long, slender lateral processes. Length of each lateral process ranges from 170 to 450 um. Both processes meet at an angle of about 90 to 120 degrees in upper view and are convex anteriorly. Denticles on each lateral proc- ess 7 to 10 in number, indiscrete, slightly inclined posteriorly, and tend to increase in length distally, the largest being the distalmost 2nd or 3rd. Cusp slender and as large as largest denticle on lateral processes. Basal cavity slitlike, narrow basal groove extends from basal cavity toward lateral processes. Sb, element: Paired extensiform digyrate elements with short and long lateral processes. Length of short and long processes ranges from 130 to 200 um and from 460 to 640 um, respectively. Both processes meet at an angle of 100 to 130 degrees in antero-posterior views. Denticles on short lateral process 2 to 5 in number and tend to increase in length and inclination toward cusp. Denticles on long lat- eral process 10 to 13 in number, weakly curve posteriorly, and tend to increase in length distally, the largest being the distalmost 3rd or 4th. Inclination of denticles tends to increase toward cusp. Cusp slender, as large as large denticles on long lateral process, and slightly curves poster- iorly. Basal cavity forms triangular shape in lower view. Small lip of basal cavity present on posterior side and narrow keel extends from basal margin of lip to approximately halfway up cusp. Narrow basal groove extends from basal cavity to beneath both lateral processes. Sc, element: Paired bipennate elements with bifurcate long anterior process and long posterior processes. Length of anterior process ranges from 230 to 370 um. Length of posterior process cannot be measured because of its incom- pleteness. Anterior process bends at an angle of 30 to 80 degrees downward and 10 to 20 degrees inward. Denticles on anterior process 5 to 8 in number, tend to increase abruptly in size, being largest in anterior to middle portion, and then decreasing in size posteriorly. Bifurcation projects anterolaterally and forms an angle of about 160 degrees in both upper and lateral views and carries 1 to 3 small, discrete denticles. Posterior process may carry almost the same number of denticles as on anterior process. Cusp as long as longest denticle on anterior process. Basal cavity slitlike, narrow basal groove extends toward anterior and posterior processes. Sc, element: Paired bipennate elements with long, slen- der anterior and posterior processes with long, discrete denticles. Length of anterior and posterior processes ranges from 300 to 470 um and 380 to 750 um, respectively. Anterior process bends at an angle of 30 to 80 degrees downward and 10 to 30degrees inward. Denticles on anterior process 5 to 9 in number and tend to be largest in anterior to middle portion and increase in inclination poster- iorly. Denticles on posterior process 5 to 12 in number and tend to increase in size and inclination posteriorly. Basal Cavity slitlike, very small lip of basal cavity turned upward on inner side. Narrow groove extends from basal cavity toward anterior and posterior processes. Remarks.—The “ozarkodiniform” element of Celsigondolel- la watznaueri watznaueri (Kozur) is somewhat similar to the Pa element of Cr. multihamata. The former has, however, a conspicuously long cusp whose feature is out of the range of morphologic variation of the latter. The form species Pol- lognathus sequence (Kozur) and P. germanicus (Kozur) fairly resemble the Pa element of Cr. multihamatus but the former have a relatively long and slender cusp. The holotype and other specimens of the form species Ozarkodina saginata illustrated by Huckriede (1958) are all incomplete and lack most of their posterior processes, which has caused some confusion in determination among an- gulate elements. The stout unit with relatively long discrete denticles of O. saginata shares characteristics with the Pb element of Cr. multihamatus. The holotype and another specimen of the form species Cratognathodus posterognath- us (=the Pb element of Cr. multihamatus) shown by Mosher (1968) are of young forms of the form species Or. saginata. One specimen figured as the form species Lonchodina venusta (=the M element of Cr. multihamatus) by Huckriede (1958) is incomplete and lacks the distal half of the longer lateral process but well represents such characteristic morphology as long denticles on the lateral process and broadly expanded basal cavity. All specimens previously figured as the form species Diplododella lautissima and specimens determined by me as the Sa element of Cr. multihamatus lack most of their poste- rior processes. The Sa element can be distinguished, however, from the form species D. magnidentata (Tatge) by the anteriorly projecting lateral processes with long discrete denticles. The specimens illustrated as the form species Hindeodella stoppeli by Bender (1967) are all incomplete but they appear to correspond to the Sb, element of Cr. multihamatus because of their “enantiognathiform” digyrate type with a broad angled junction of the lateral processes. All specimens including the holotype of the form species Lonchodina spengleri (the Sb, element of Cr. multihamatus) are incomplete and lack most of the longer lateral process. The identification of this element is, however, not so difficult because of its extensiform digyrate type and the presence of a triangular basal cavity. The holotype of the form species Hindeodella petrae- viridis (=the Sc, element of Cr. multihamatus) illustrated by Huckriede (1958) is of a part of the anterior process and lacks the bifurcation on the anterior processes. Therefore, some workers regarded this form species as bipennate type without the bifurcate anterior process or breviform digyrate types. The holotype possesses, however, a faint trace of the bifurcation on the basal part of the anteriormost denticle. Huckriede (1958) claimed that the form species H. petrae- viridis is characterized by the presence of the bifurcation on Triassic conodont apparatus 247 the anterior process and four specimens figured by Huck- riede (1958) carry distinct bifurcation. It is very difficult to distinguish Sc. from Sc, elements of Cr. multihamatus if the Sc, elements are incomplete and lack the anterior portion of their anterior processes. The form species Prioniodella pectiniformis erected by Huckriede (1958) is based on the specimens of a part of the posterior process with long discrete denticles. The features agree well with those of Sc, elements of Cr. multihamatus. Acknowledgments | would like to express my sincere appreciation to Hisayo- shi Igo, Emeritus Prof. of Institute of Geoscience, University of Tsukuba, for critical review of the manuscript and valuable suggestions. My deep gratitude is expressed to Michael J. Orchard, Geological Survey of Canada, for critical reading of the manuscript and valuable comments on the reconstruc- tion of Cr. multihamatus. | am indebted to Ryuichi Majima, Department of Environmental Sciences, Faculty of Education and Human Sciences, Yokohama National University for fruitful discussion. References cited Bender, H., 1967: Zur Gliederung der mediterranen Trias Il. Die Conodontenchronologie der mediterranen Trias. Annales Geologiques des Pays Helleniques, vol. 46, p. 465- 540. 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(in Bulgarian with German abstract) Sudar, M., 1977: On the Triassic microfacies of the Uvac Canyon. Annales Geologiques de la Péninsule Bal- kanique, vol. 41, p. 281-291. Sweet, W.C., 1981: Family Xaniognathidae Sweet, 1981. In, Robinson, R. A. ed., Treatise on Invertebrate Paleontology. Pt. W, Miscellanea, Supplement 2, Conodonta, p. W154-W157. The Geological Society of America, Inc. and the University of Kansas Press, Boulder, Colorado and Lawrence, Kansas. Sweet, W.C., 1988: The Conodonta. Morphology, taxonomy, paleontology, and evolutionary history of a long-extinct animal phylum. Oxford Monographs on Geology and Geophysics, no. 10, Clarendon Press, Oxford, 212 p. von Bitter, P.H., and Merrill, G.K., 1998 : Apparatus composi- tion and structure of the Pennsylvanian conodont genus Gondolella based on assemblages from the Des- moinesian of northwestern Illinois, U.S.A. Journal of Paleontology, vol. 72, no. 1, p. 112-132. Vrielynck, B., 1987 : Conodontes du Trias perimediterraneen systématique, stratigraphie. Documents des Labor- atoires de Geologie Lyon. no. 97, 301 p. Paleontological Research, vol. 3, no. 4, pp. 249-258, 5 Figs., December 30, 1999 © by the Palaeontological Society of Japan Evolutionary history of the Cenozoic bivalve genus Kaneharaia (Veneridae) KAZUTAKA AMANO’ and YOSHINORI HIKIDA’ ‘Department of Geoscience, Joetsu University of Education, Joetsu City, Niigata Prefecture 943-8512, Japan “Nakagawa Museum of Natural History, Nakagawa Town, Hokkaido 098-2802, Japan Received 12 April 1999 ; Revised manuscript accepted 17 August 1999 Abstract. The evolutionary history of the bivalve genus Kaneharaia (Dosiniinae) is discussed. The genus Kaneharaia is restricted to the North Pacific region and contains four species : K. kaneharai (Yokoyama), K. kannoi (Masuda), K. ausiensis (Ilyina) and K. sp. K. ausiensis survived until the mid-Pliocene while the other three species became extinct at the end of the Miocene. In addition to these species, Dosinia mathewsonii from the upper Oligocene San Ramon Formation of California and D. whytneyi from the early middle Miocene Astoria Formation of Oregon most probably belong to the genus Kaneharaia. Kaneharaia evolved from the common ancestor with Dosinia because both genera share many common characteris- tics such as the subumbonal pit, the brown-coloured surface, and the finely crossed lamellar structure in the outer layer. Based on the fossil record, Kaneharaia first appeared in the northeastern Pacific during the late Oligocene and migrated westward during the early middle Miocene Climatic Optimum in the North Pacific. Key words: Bivalvia, evolution, Kaneharaia, Dosinia, Dosiniinae Introduction Kaneharaia is an extinct genus of Dosiniinae (Bivalvia: Veneridae) which was first proposed as a subgenus of Dosinia Scopoli, 1777 by Makiyama (1936), based on Dosinia kaneharai Yokoyama, 1926 from the Miocene Kanomatazawa Formation in Tochigi Prefecture as its type species. Species of Kaneharaia have been found in the Miocene deposits of Honshu and Hokkaido, Japan, Sakhalin and Kamchatka, Russia and northern Korea, and also in the lower Pliocene of Honshu (Masuda, 1967; Amano, 1983; Gladenkov et al., 1987 ; Amano and Sato, 1995). Other than K. kaneharai, the following species and subspecies of Kane- haraia have been described : K. kaneharai (Yokoyama, 1926), K. ausiensis (llyina, 1954), K. kaneharai ouchiensis (Kanno, 1955), K.kannoi (Masuda, 1963), K. kaneharai fujinensis (Masuda, 1967), K. kaneharai rumoiensis (Amano,1983), K. kaneharai uandiensis (Sinelnikova, 1987 in Gladenkov et al., 1987). Makiyama (1936) and Masuda (1967) pointed out that Kaneharaia is similar to Dosinidia Dall, 1902 (=Dosinia Scopoli, 1777) in the absence of escutcheon and lamellated concentric sculpture which are common characters in other Japanese dosiniine genera such as Phacosoma Jukes Brown, 1912, Dosinella Dall, 1902 and Dosinorbis Dall, 1902. However, no detailed comparison of hinge structure between Kaneharaia and Dosinia has been made. When they examined the shell microstructure of Kanehar- aia kaneharai and Phacosoma spp., Kobayashi et al. (1968) and Hikida (1996) showed that the shell microstructure is a useful character for diagnosing some genera within Dosiniinae and separated Kaneharaia from Phacosoma as a distinct genus based on the difference of microstructure of the outer layer: spherulitic structure in Kaneharaia and composite prismatic structure in Phacosoma. However, these authors did not examine the shell microstructure of dosiniine species from the Cenozoic of the North Pacific, including K. ausiensis. Thus, the lack of enough information on hinge structure and shell microstructure prevents us from understanding the detailed relationship among the Kaneharaia and other dosiniines from the Cenozoic of the North Pacific. Recently, it has become clear that some molluscan genera originated in the northeastern Pacific and then migrated to the northwestern Pacific during the early middle Miocene (Vermeij, 1991; Amano et al., 1993; Matsubara, 1994 ; Reid, 1996 ; Amano and Vermeij, 1998 ; Amano, 1998). If we can make clear the close phylogenetic relationship between Kaneharaia and the American Dosinia species, it should be possible to judge whether Kaneharaia is another example of a westward spreading genus or not. Fortunately, we were able to collect some well preserved specimens of Kaneharaia ausiensis (Ilyina) from the Miocene of Sakhalin and also examined previously undocumented specimens of K. ausiensis from the Pliocene of Hokkaido and of K. sp. from the Miocene of Kodiak Island. Here we 250 Kazutaka Amano and Yoshinori Hikida examine the morphology of this material in detail and the shell microstructure of K. ausiensis and the Recent Dosinia species as well in order to clarify the evolutionary history of Kaneharaia. Materials A number of fossil specimens identified as Kaneharaia ausiensis were collected from the following four localities (Figure 1): Loc. 1, river bank about 2 km upstream of Lesnaya River in southeastern Sakhalin; early middle Miocene Ausinskaya Formation: Loc. 2, roadside cliff about 2.5 km north of Baykovo in southwestern Sakhalin (the type locality of Dosinia ausiensis llyina, 1954); early middle Miocene Ausinskaya Formation: Loc. 3, roadside cliff about 500 m northwest of Kotobuki Bridge in Kamitokushibetsu, Hok- kaido ; middle Miocene Shibiutan Formation: Loc. 4, bank of the Horonitachibetsu River near Numata dai-go in Hok- kaido ; early Pliocene Horokaoshirarika Formation yielding the Pliocene index fossil, Fortipecten takahashii (Yokoyama). These specimens are housed at Joetsu University of Educa- tion (JUE). Five fossil specimens identified as Kaneharaia sp. were Si MAKAPOB ke MAKAROV N Hosocu6upcxde IR: + Novosibirakoye >< a ze | Ir < provided by Emeritus Professor Saburo Kanno of the Univer- sity of Tsukuba. These specimens are from the middle Miocene Ejoviy Horizon of Korf Bay in eastern Kamchatka and from the early middle Miocene Narrow Cape Formation on Kodiak Island, Alaska. Detailed information on these localities are unfortunately unknown. These are also stored in Joetsu University of Education (JUE). Besides these specimens, we examined the type specimens of Kaneharaia kannoi and K. kaneharai fujinensis stored in the Museum of Natural History of Tohoku Univeristy (IGPS). We examined the shell microstructure of two fossil and four Recent species (Table 1). Systematic notes on northern Pacific species Family Veneridae Rafinesque, 1815 Subfamily Dosiniinae Deshayes, 1853 Genus Kaneharaia Makiyama, 1936 Comparison.—As pointed out by Makiyama (1936), Hatai (1938) and Masuda (1967), Kaneharaia and Dosinia share many features such as absence of the escutcheon and lamellated concentric ribs, and presence of a wide triangular ese Kamitokushibetsu = TE 233.6 Figure 1. Collecting localities of Kaneharaia (using the topopgraphical maps “Occhube” and “Moseushi”, scale 1 : 50,000, published by Geographical Survey of Japan). Evolutionary history of the Cenozoic bivalve genus Kaneharaia Table 1. Shell structure of outer layer of Dosiniinae Species SSO** Age Localities and formations *Kaneharaia ausiensis (Ilyina) sph-+ fel Miocene Ausinskaya F., Sakhalin (Loc. 1) K. kaneharai (Yokoyama) sph-+fel Miocene Kubota F., Fukushima Pref. *Dosinia discus (Reeve) fcl Recent Florida in USA *D. dunkeri (Philippi) fcl Recent Panama “D. ponderosa (Gray) fcl Recent California in USA Phacosoma japonicum (Reeve) cpr Recent Ohita Pref. P. japonicum (Reeve) cpr Pleistocene Omma F., Ishikawa Pref. P. japonicum (Reeve) cpr Pliocene Tatsunokuchi F., Miyagi Pref. P. troscheli (Lishcke) cpr Recent Fukuoka Pref. P. tomikawensis (Takagi) cpr Pleistocene Omma F., Ishikawa Pref. P. tatunokutiensis (Nomura) cpr Pliocene Tatsunokuchi F., Miyagi Pref. P. hataii (Masuda) cpr Miocene Kubota F., Fukushima Pref. *P. akaisiana (Nomura) cpr Miocene Yatsuo G., Toyama Pref. P. kawagensis (Araki) cpr Miocene Mizunami G., Gifu Pref. P. nomurai (Otuka) cpr Miocene Mizunami G., Gifu Pref. Austrodosinia anus (Philippi) cpr Recent New Zealand *Pectunculus exoleta (Linnaeus) cpr Recent Galcia in Spain * Species treated in this study. The data of other species are based on Hikida (1996). ** Shell structure of outer layer (sph; spherulitic structure, fcl ; finely crossed lamellar structure, Cpr ; composite prismatic structure, see a/so Hikida, 1996) pallial sinus. In addition to these characters, we found that both genera have a subumbonal pit on the hinge plate (Figures 2 1-5,13b,3 1,3, 6b,11a) and sometimes have a brown-coloured shell surface. The above features are not observed in Phacosoma Jukes-Brown, 1912, Dosinella Dall, 1902, Dosinorbis Dall, 1902 and Austrodosinia Dall, 1902 (Figures 3-2, 4,5,10; see also Fischer-Piette and Delmas, 1967). Pectunculus Da Costa, 1778 lacks not only the escutcheon, but also the subum- bonal pit (Figure 3-8). Morphologically, Kaneharaia differs from Dosinia by having a narrower thin plate above the nymph, a thick middle cardinal tooth of both valves, and a long anterior cardinal tooth in the left valve extending to the basal line of hinge plate. As already pointed out by Kobayashi et al. (1968), Shimamoto (1986) and Hikida (1996), the inner layer through- out the Dosiniinae has the same microstructure (homogene- ous structure). According to Hikida (1996), the outer layer of Kaneharaia is spherulitic in structure while in Phacosoma, Austrodosinia, Pectunculus and Dosinella the outer layer has a composite prismatic structure (Table 1). We have found that the outer layer of K. ausiensis from Sakhalin (Loc. 1) has a spherulitic structure like K. kaneharai, but also was a finely crossed lamellar structure near the beak and ventral margin. On the other hand, the outer layers of Dosinia discus and D. ponderosa are composed totally of the finely crossed lamellar structure (Figure 4). On D. ponderosa, our observation supports the results by Carter and Lutz (1990), not by Taylor et al. (1973). Adding D. dunkeri to these two species, it has become clear that all the species of Dosinia here examined have the same finely crossed lamellar structure (Table 1). Thus, the outer shell microstructure of Kaneharaia has the features partly in common with Dosinia, but not with other dosiniines. From the above morphological and shell microstructure data, we conclude that Kaneharaia is close to Dosinia than any other genus within the Dosiniinae. Remarks on American species.—Dosinia mathewsonii Gabb, 1869 was described from the upper Oligocene San Ramon Formation of California (Figure 2-7a, b). This species is characterized by the absence of the escutcheon, and presence of many wide concentric ribs, a subumbonal pit (Figure 2-9) on the hinge plate, and a brown-coloured shell surface. It is especially allied to K. ausiensis in having an almost identical shell shape and number of concentric ribs (15 between 10 mm and 20 mm from beak). Although no information on the pallial sinus shape of “D.” mathewsonii could be obtained, it is most probably included in the genus Kaneharaia. When she examined the dosiniines from the early middle Miocene Astoria Formation in Oregon, Moore (1963) synonymized Dosinia mathewsonii with Dosinia whitneyi (Gabb, 1869). However, D. whitneyi is based on a single fragment. It is too difficult to obtain any information on the inner structure of D. whitneyi. For the above reasons, we do not use the species name D. whitneyi. The Astoria speci- mens would be better included in Kaneharaia rather than Dosinia, because the anterior cardinal tooth in the left valve extends to the basal line of the hinge plate and the plate above the nymph is narrow. However, there is also no information on pallial sinus shape in the Astoria specimens. Therefore, it is difficult to conclude whether the Astoria species can be accurately included in the genus Kaneharaïa. Kaneharaia ausiensis (\lyina, 1954) Figures 2—1-5, 8, 10-12, 14-16 ; 3—14 Dosinia ausiensis \lyina, 1954, p. 228, 229, pl. 18, figs. 7,8; Zhid- kova et al., 1968, p. 107, 108, pl. 5, fig. 2, pl. 18, figs. 7, 8. Kazutaka Amano and Yoshinori Hikida Evolutionary history of the Cenozoic bivalve genus Kaneharaia 253 Fujie et al., 1964, pl. 6, fig. 4. Masuda, 1967, Dosinia mirabilis Uozumi (MS). Dosinia (Kaneharaia) kaneharai kannoi Masuda. pl. 2, fig.9; Noda, 1992, p. 83, 84, pl. 4, fig. 1. Dosinia (Kaneharaia) kaneharai rumoiensis Amano, 1983, p. 50, 51, pl. 4, fig. 12, pl. 5, figs. 1, 5, 10. Dosinia (Kaneharaia) kaneharai uandiensis Sinelnikova in Gladen- kov et al., 1987, p. 35, pl. 7, figs. 4, 6. Dosinia (Kaneharaia) ausiensis Ilyina. Gladenkov et al., 1987, p. 35, fig.3; Amano and Sato, 1995, p.7, figs. 4-3, 6,12; Amano et al., 1996, p. 637, figs. 4-3, 8. Dosinia (Kaneharaia) kaneharai Yokoyama. Shimizu and Fujii, 1995, fig. 6. Type Locality—Klyuch Bezimyaniy (Japanese name, Ausi) in Chekhov district, southwestern Sakhalin (Loc. 2); early middle Miocene Ausinskaya Formation. Holotype, VNIGRI no. 7/6819. Description of Sakhalin specimens.—Shell medium in size (47.4 mm in maxmum length), suborbicular in outline, moder- ately inflated. Anterodorsal margin slightly concave, pass- ing into well rounded ventral margin ; posterodorsal margin broadly arcuate. Beak protruding, weakly prosogyrate, anteriorly situated. Surface sculptured by dense concentric ribs ; Concentric ribs 15-17 in number between 10 mm and 20 mm from beak, flattened near beak but becoming rounded and elevated near ventral margin. Lunule long, narrow, shallow, and not depressed by any distinct groove. Escutcheon lacking. Hinge plate consisting of one anterior lateral tooth and three cardinal teeth ; middle cardinal tooth of right valve thick and simple; anterior lateral tooth of left valve rather large. Subumbonal pit small, situated at upper- most part of nymph plate. Pallial sinus rather shallow and triangular in shape. Remarks.—The Sakhalin specimens have the same shell characters as the Hokkaido specimens other than shell size : the Pliocene Horokaoshirarika specimen attains 60.6 mm in maximum length while that of the type specimen is 55 mm. When they examined the fossil fauna from the Ausinskaya Formation in Novoselovo of southwestern Sakhalin, Amano et al. (1996) considered the following two subspecies to be junior synonyms of D.(K.) ausiensis: D.(K.) kaneharai rumoiensis Amano, 1983 and D. (Kaneharaia) kaneharai uan- diensis Sinelnikova, 1987. They also considered that the specimens illustrated by Masuda (1967, pl. 2, fig. 9) and Noda (1992, pl. 4, fig. 1) as D.(K.) kannoi can be assigned to D.(K.) ausiensis. Fujie et al. (1964) illustrated a specimen referred to Dosinia mirabilis Uozumi (MS) from the Miocene Tokushibetsu For- mation in Hokkaido. Judging from its subcircular shell, fine concentric ribs and dentition with a subumbonal pit, this specimen should be referred to K. ausiensis. Shimizu and Fujii (995) illustrated a specimen of D.(K.) kaneharai Yokoyama from the “Otogawa fauna (type Il)” of Toyama Prefecture. This specimen obviously has concen- tric ribs much more than the typical form of K. kaneharai and many elevated ribs near the ventral margin. Therefore, the Otogawa specimen should be referred to K. ausiensis rather than to K. kaneharai. Comparison.—Kaneharaia ausiensis resembles Kaneharaia kannoi Masuda, 1963 from the lower middle Miocene Heiroku Formation of North Korea in having fine concentric ribs. However, K. ausiensis differs from K. kannoi (Figure 2-6) in its less inflated shell and more numerous concentric ribs (usu- ally 12-13 between 10 mm and 20 mm from the beak in K. kannoi). K. ausiensis differs from K. kaneharai Yokoyama in its orbicular rather than ovate shell and has much more numer- ous concentric ribs (15-17 between 10 mm and 20 mm from the beak instead of 8-12 in K. kaneharai) Distribution.—Early middle Miocene Ausinskaya and Uan- dinskaya Formations in Sakhalin, and Chikubetsu Formation in Hokkaido ; middle Miocene Togeshita, Tachikaraushinai and Shibiutan Formations in Hokkaido; late Miocene (?) “Otogawa Formation” ; early Pliocene Horokaoshirarika For- mation in Hokkaido and Joshita Formation in Honshu. Kaneharaia sp. Figures 3—9, 11-13 Dosinia cfr. mathewsoni Gabb, Khomenko, 1933, p. 17, pl. 2, fig. 10, pl. 3, fig. 4. Dosinia margaritana Wiedy, Slodkewitsch, 1938, pl. 88, figs. 3, 4. ? Dosinia (Dosinia) whitneyi Gabb, Moore, 1963, p. 73-74, pl. 24, figs. 3-10. Dosinia (Kaneharaia) rumoensis Amano [sic], Gladenkov et al. 1987, p. 34-35, pl. 8, figs. 1, 2, 4, 7-11. Remarks.—Five specimens from eastern Kamchatka, Russia and Kodiak Island, Alaska resemble K. ausiensis in the absence of an escutcheon and lamellated concentric ribs and the presence of a wide pallial sinus and a narrow subumbonal pit. However, these specimens have more numerous (18-22) and more flattened concentric ribs than in K. ausiensis, and therefore they can easily be separated from the latter at the species level. Khomenko (1933) recorded Dosinia cfr. mathewsoni Gabb, 1869 from Korf Bay of eastern Kamchatka, with which our specimens discussed here are identical. Thereafter, Slodk- ewitsch (1938) reasigned Komenko’s specimens to Dosinia margaritana Wiedey, 1928. When they described the fauna from Korf Bay, Gladenkov et al. (1987) identified their speci- — Figure2. 1-5,8,10-12,14-16: Kaneharaia ausiensis (Ilyina). Loc. 1, Ausinskaya F.; white arrow indicating a subumbonal pit. 1; x14, JUE no.15670-1: 3; x1.2, JUE no. 15670-2; 2; 1.05, JUE no. 15666-3: 15; 1.41, JUE no. 15666-2 ; Loc. 3, Shibiutan F. 4; 1.2, JUE no.15667-2: 5; 115, JUE no. 15667-3: 14; x1, JUE no 15667-4: 16; x1, JUE no. 15667-5; Loc. 4, Horokaoshirarika F. 8; x1, JUE no.15664-5: 10; 1, JUE no. 15664-1: 12; x1, JUE no. 15664-3; Loc. 1, Ausinskaya F. 11; «1, JUE no. 15665-1, topotype, Loc. 2, Ausinskaya F. 6,13: Kaneharaia kannoi (Masuda). 6; 0.9, IGPS no. 73203: 13a-b; «0.8, IGPS no. 64682, holotype, Heiroku F. 7a-b, 9: “Dosinia” mathewsoni Gabb. 7a-b; x1, UCMP no. 11173, San Ramon F.: 9; 1, UCMP no. 11149, reproduced from pl. 7, fig. 5 of Clark (1918), San Ramon F. White arrows in 1, 2, 3,5, 9,13b shows the subumbonal pit. 254 Kazutaka Amano and Yoshinori Hikida Evolutionary history of the Cenozoic bivalve genus Kaneharaia a 3 AN @ Wie NUE 2 NR UNE HARAS N oli \ ARE on FES MAUR N NOTES 0.6% (v/v) HCl; 10 sec.) section. a: Spherulitic structure of the outer layer of Kaneharaia ausiensis showing spherical to subspherical configuration of 3-12 um in diameter. The elongated structural subunits grow radially in all directions from central parts of the spherulite. The central parts appear to be etched more quickly than the surroundings. b: Finely crossed lamellar structure recognized near the beak of K. ausiensis. Acicular crystals aggregate to form a higher structural unit (first order lamella), and they are inclined in opposite directions in the adjacent first order lamellae. Long axes of the first order lamellae are arranged perpendicularly to the outer shell surface (upper right). c: Finely crossed lamellar structure of the outer layer of Dosinia ponderosa. The first order lamellae are arranged in a feathery, radial manner toward the ventral margin (shell surface). d: Finely crossed lamellar structure recognized near the beak of Dosinia discus. Individual first order lamellae are sometimes branched, their long axes being arranged perpendicularly to the outer shell surface. “= Figure 3. 1,7: Kaneharaia kaneharai (Yokoyama). 1; 1, JUE no.15671-2: 7; 0.8, IGPS no. 90511 ; Loc. Tanagura, KubotaF. 2: Phacosoma japonicum (Reeve), “1, JUE no. 15672, Loc. Tomikawa, Recent. 3: Dosinia ponderosa (Gray), x 0.8, UC Davis, Loc. Puerto Penasco, Sonora, Mexico, Recent. 4: Dosinella penicillata (Reeve), x1, JUE no. 15673, Loc. Okayama, Recent. 5: Phacosoma tatunokutiensis (Nomura), 1, JUE no. 15674, Loc. Tatsunokuchi, Tatsunokuchi F. 6a-c: Dosinia discus (Reeve), «1, JUE no. 15675, Loc. Virginia Beach, USA, Norfork F. 8: Pectunculus exoleta (Linnaeus), <1, JUE no. 15676, Loc. Galicia, Spain, Recent. 9,11-13: Kaneharaia sp. 9; 1, JUE no.15668-2: 18a-b, x1, JUE no. 15668-1; Loc. Kodiak Is., USA, Narrow Cape F. tla; «1.2; 11b; «1, JUE no. 15669-1: 12a-b; x1, JUE no. 15669-2 ; Loc. Korf Bay, Russia, Ejobyi Horizon. 14: Kaneharaia ausiensis (Ilyina), x1, JUE no.15665-2, topotype, Loc. 2, Ausinskaya F. 10: Phacosoma tomikawensis (Takagi), X 1, JUE no. 15679, Loc. Kakuma, Omma Formation. White arrows in 1, 3, 6b, 11a show the subumbonal pit. 256 Kazutaka Amano and Yoshinori Hikida mens as Dosinia (Kaneharaia) rumoensis Amano [sic]. Our specimens seem to constitute a new species, but poor preservation of the Kamchakta and Kodiak specimens prevents us from establishing a new species. Allison (1978) and Marincovich and Moriya (1990) only listed Dosinia and D. whitneyi respectively from the Narrow Cape Formation in Kodiak Island. Judging from the loca- tion, we suspect that their specimens are identical with the present species. Distribution —Early middle Miocene Ejoviy Horizon, Korf Bay, eastern Kamchatka, Russia; early middle Miocene Narrow Cape Formation, Kodiak Island, Alaska. Revision of Kaneharaia Dosinia (Kaneharaia) kaneharai ouchiensis was described by Kanno (1955) from the Miocene Yoshigasawa Formation in Miyagi Prefecture. Acccording to him, this subspecies can be dicriminated from K. kaneharai (s.s.) by its higher shell. However, the holotype and topotype specimens of D.(K.) kaneharai ouchiensis were slightly compressed laterally, jud- ging from Kanno’s (1955) figures and topotype specimens stored at IGPS. As mentioned by Masuda (1967), it is sometimes hard to distinguish D.(K.) kaneharai ouchiensis from K. kaneharai (s.s.). Therefore, there is no reason to follow this separation. D.(K.) kaneharai fujinensis was established by Masuda (1967) from the Miocene Fujina Formation in Shimane Prefec- ture. This subspecies was separated from K. kaneharai (s.s.) based on an elongated shell. However, the shell outline of K. kaneharai (s.s.) in our specimens from the Kanomatazawa Formation shows a wide range of variation from subcircular to elongate ovate shell. The surface of the holotype of D. (K.) kanaharaia fujinensis is sculpted by 11 concentric ribs between 10 mm and 20 mm from the beak just the same as in K. kaneharai (s.s.). For the above reasons, we also do not accept the separation of D.(K.) kanaharaia fujinensis from K. kaneharai kaneharai (S.S.). Evolutionary history of Kaneharaia To sum up the discussion above, the genus Kaneharaia consists of four species in the North Pacific region, : K. kaneharai (Yokoyama)(middle-late Miocene), K. kannoi (Masuda) (early middle Miocene), K. ausiensis (llyina) (early middle Miocene-early Pliocene) and K.sp (early middle Miocene). Moreover, as described above, the Astoria species of “Dosinia” and “D.” mathewsonii most probably belong to the genus Kaneharaia. There is no Oligocene record of Kaneharaia in the north- western Pacific region. On the other hand, one species most probably included in Kaneharaia and two species of Dosinia have been reported from the upper Oligocene of northwest and central America. “Dosinia” mathewsoni from the upper Oligocene of California is most probably a Kane- haraia as discussed above. Woodring (1982) recorded D. aff. delicatissima Brown and Pilsbry, 1913 from the upper Oligocene Bohio Formation of Panama. On the Atlantic coast, Palmer (1927) illustrated D. chipolana Dall, 1903 from the Oligocene Silex beds of Florida. Taking the phylogenetic relationship and fossil records into consideration, Kaneharaia first appeared in the north- eastern Pacific during the late Oligocene. Among the northwestern Pacific species, K. kannoi is confined to the early middle Miocene in northeastern Honshu and North Korea while K. kaneharai might be directly derived from K. kannoi and occurs from the middle to late Miocene in Honshu (Figure 5). K. ausiensis is related to K. kannoi and first appeared in the early middle Miocene in Sakhalin and Hokkaido. This species also occurs in the early Pliocene of Hokkaido and central Honshu. K. sp. is locally restricted to eastern Kamchatka and Kodiak Island in the early middle Miocene. From the early middle Miocene Astoria Formation in Oregon, Kaneharaia-like species have been reported. Judging from the above distribution, Kaneharaia migrated to the northwestern Pacific region during the early middle Miocene time, corresponding to the Neogene Climatic Optimum. Thus, Kaneharaia represents another example of a mollusc that shows westward spreading in the North Pacific and is an exceptional in being an extinct genus among this group. When she discussed the evolution of Mercenaria Schuma- cher, 1817, Harte (1998) pointed out that all Japanese “Mer- cenaria” should be placed in Securella Parker, 1949 because aia 2 f / Cat un $ eK. ausiensis (Miocene) 4 K. ausiensis (Pliocene) J AK. kannoi AK. kaneharai N K. sp. if : / Figure 5. Distribution of Kaneharaia. Evolutionary history of the Cenozoic bivalve genus Kaneharaia they lack a rugose nymph. According to her, Mercenaria arose from the early Oligocene S. mississippiensis during the late Oligocene. Securella first appeared in the northeastern Pacific in the late Oligocene while the oldest record of Securella in the northwestern Pacific date from the Miocene (Harte, 1998). Such an evolutionary pattern is very similar to that of Kaneharaia and Dosinia. It is reasonable to conclude that both genera have a common ancestor. Then, after the late Oligocene, Kaneharaia fluorished in the North Pacific region like Securella. On the other hand, Dosinia radiated in the Atlantic coast region like Mercenaria. Besides Kaneharaia and Securella, Amano (1998) listed Compsomyax (Veneridae) as another example of a west- ward-spreading group. More examples of this type of migration will no doubt be found in other venerids. Acknowledgements We are greatful to Geerat J. Vermeij (Univ. California, Davis) for his critical reading of this manuscript. We thank Saburo Kanno (Univ. Tsukuba), Vladimir D. Khudik (Far East Geol. Inst. Russian Acad. Sci), Yuri B. Gladenkov (Geol. Inst. Russian Acad. 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(in Russian) Paleontological Research, vol. 3, no. 4, pp. 259-267, 5 Figs., December 30, 1999 © by the Palaeontological Society of Japan A new Foraminifera from the upper Middle Eocene of the Ebro Basin, Spain KUNITERU MATSUMARU Department of Geology, Faculty of Education, Saitama University, Urawa 338-8570, Japan Received 17 January 1999 ; Revised manuscript accepted 31 August 1999 Absiract. Serraia cataloniensis gen. et sp. nov. is differentiated from other pellatispiracean Foraminifera by the presence of one or more intercalary whorls of median chambers winding in the same direction as the primary whorl, and by frequent protoconchal and deureroconchal diverticula and a short spire of chambers around the deuteroconch. S. cataloniensis is described from the La Tossa Formation of the Bartonian regressive cycle of sedimentation in the Ebro Basin, Barcelona region, Spain. Key words: Bartonian regressive cycle, Ebro Bassin, La Tossa Formation, Late Bartonian, Serraia cataloniensis, Spain Introduction At the second meeting of the IGCP 393, “Neritic Events at the Middle-Upper Eocene Boundary”, in Vic, Spain, 2-6 September 1997, the field trip guided by Serra-Kiel et al. (1997) took us to different outcrops of Lutetian and Bartonian sediments in the Ebro Basin, southeastern Pyrenean Fore- land Basin, Catalonia, Spain. The Puig Aguilera outcrop lies at 4135/N. Lat. 139’E. Long, on the Puig Aguilera, a mountain 5km northeast of the town of Igualada, 50 km northwest of Barcelona (Figure 1). The geologic section in the Puig Aguilera outcrop (Serra-Kiel et al., 1997, p. 43, fig. 38; Figure 1) begins with marls alternating with sandstone beds in the lower sequence. Above this sequence, there is an interval of marls and sandstones alternating with lime- stone beds. Serra-Kiel et al. (1997) interpret the former as belonging to the upper part of the Bartonian transgressive facies of the La Tossa Formation (Ferrer, 1971), while the latter belongs to the Bartonian regressive facies of the same formation. Sample 4 at the Puig Aguilera outcrop is from the marls corresponding to the Bartonian regressive facies and is rich in larger foraminifers. Especially common are Asterocyclina stellaris (Brunner, 1848 MS., in Rütimeyer, 1850), Discocyclina pratti (Michelin, 1946), D. sella (d’Archiac, 1850), Heterostegina reticulata Rutimeyer, 1850, Operculina schwageri Silvestri, 1928, Pellatispira madaraszi (Hantken, 1875), Orbitocliypeus sp., and Nummulites sp. The regressive facies of the Bartonian cycle occurs in the Igualada and Vic areas, eastern Ebro Basin, Barcelona region, and changes laterally. The facies of the La Tossa Formation in the Igualada area is correlated to the Saint Marti Xic Limestone Formation (Reguant, 1967) represented by deltaic and reef sediments in the Vic area. On top of the deltaic-reef complex of the Bartonian regressive cycle and below the evaporitic sediments of the Cardona Formation (Riba, 1975) in the Igualada and Vic areas, there is a Terminal Complex, named by Trave (1992), which reflects the change from marine to continental sedimentation. The Terminal Complex corresponds to the magnetostratigraphic scale from 17.2 to 17.1, and to planktonic foraminiferal Zone P.15 of Berggren et al. (1995). Thus the age of the Bartonian regressive facies of the Bartonian marine sediments in the Igualada and Vic areas is regarded as Late Bartonian. One of the major achievements of project IGCP 393 was the identification of additional larger foraminifers. Serraia cataloniensis gen. et sp. nov. occurs in marls in sample 4, which Dr. Serra-Kiel kindly sent to the author for study, and is found there in association with Biplanispira mirabilis (Umb- grove, 1937) and the foraminifers listed above. Systematic paleontology Order Foraminiferida Suborder Rotaliina Superfamily Nummulitacea Family Pellatispiridae Hanzawa, 1937 Remarks.—I|n addition to the type genus, Matsumaru (1996a, p. 110-118) assigned the genus Biplanispira Umbgrove, 1937 to the family Pellatispiridae Hanzawa, 1937, because of its Characteristic planispiral to low trochospiral coiling, sub- sutural and intraseptal radial canals, vertical canals or fis- sures, and no marginal cord, following Loeblich and Tappan’s (1987) classification. Also Matsumaru (1996a) emended the diagnosis of the family such that the secondary and surface chambers are differentiated from the spiral and umbilical sides of the test. Moreover Matsumaru (1996b) transferred the genus Bolkarina Sirel, 1981 to the family 260 Kuniteru Matsumaru 0° 40° Le z Ba rcelona er “WR Sample 4 TE Puig Aguilera to Barcelona Igualada O 5km case LIMESTONE Puig d’Aguilera to Odena 4 626m Collet del Bumsquet °Cal Lledo SANDSTONE MARL N 6) to Igualada Figure 1. Geographic and stratigraphic position of sample locality (sample 4) from Puig Aguilera outcrop, Igualada City, northwest of Barcelona, Spain. A new Foraminifera, Serraia cataloniensis 261 Discocyclinidae Galloway, 1928 from the family Pellatispiri- dae. Genus Serraia gen. nov. Type species.—Serraia cataloniensis sp. nov. Diagnosis—A pellatispiriid genus characterized by remarkable development of secondary and tertiary spiral chambers of intercalary whorls in early growth stage of planispiral to low trochospiral whorl of primary spiral cham- bers, and by frequent presence of protochoncal and deutero- conchal diverticula and short spiral chambers around deuter- oconch. Description—Test lenticula, bilaterally symmetrical in outline with granules extending to pillars distributed rather spirally over surface of test ; bilocular embryo of protoconch and deuteroconch frequently containing protoconchal and deuteroconchal diverticula, and a short spire of small cham- bers around deuteroconch, followed by a primary coil of loosely evolute, later becoming involute whorls of large spiral chambers (i. e. primary spiral chambers), together with secon- dary and tertiary intercalary whorls of small spiral chambers (i. e. secondary and tertiary spiral chambers) added between whorls of primary coil; all chambers connected by a basal foramen with intraseptal, subsutural and rather canals, winding in same direction as primary whorls towards periph- ery of test; later primary spiral chambers subdivided into irregularly arranged spiral chambers at peripheral part of test as seen in Biplanispira. Lateral layers thickest at center and gradually attenuated towards periphery of test, pierced by numerous vertical pores opening between numerous pillars embeded in lateral layers, and by numerous vertical and radial canals; vertical pores opening covered by thin and finely cribrate roofs of small surface chambers. Test wall calcareous, thick, fibrous and lamellar with two layers of fibrous structure, inner one thin and compact, and outer one thick and coarsely perforate. Etymology.—The genus name is after Dr. Josep Serra-Kiel, who provided the pellatispiracean-bearing sample in this study. Stratigraphic horizon.—Upper part of the La Tossa Forma- tion. Comparison.—The present genus resembles the genus Biplanispira Umbgrove by the presence of a single median layer of primary spiral chambers, and later bifurcating layers of spirally disposed chambers. However, Serraia is distin- guished from Biplanispira in having the second and third median layers of chambers developed from the third and fourth chambers of the primary spiral chambers, respectively, which wind in the same direction as the primary whorl, and also in having frequent protoconchal and deuteroconchal diverticula and a short single layer of chambers around the deuteroconch. Serraia resembles Dictyoconoides Nuttall, 1925 and Dictyokathina Smout, 1954 in having median cham- bers formed by repeated doubling (originated from bilocular embryonic and median chambers) and in having a test wall with fibrous, lamellar structure that is pierced by vertical canals. However, this new genus is distinguished from them in having double median chambers originated from the primary spiral chambers in an early nepionic stage, in having median layers of fibrous structure, and in lacking an umbilical mass of numerous pillars. Moreover, Serraia is distinguished from the genus Boninella Matsumaru, 1996a in having cham- ber layers with fibrous and lamellar structure. Serraia cataloniensis sp. nov. Figures 2-1—3; 3-1—5; 4-1—3; 5-1—3 Material.—Holotype : a megalospheric specimen in a half test, Saitama University coll. no. 8841 (Figures 2-1; 3-1); Paratype : equatorial sections of megalospheric specimens, Saitama University coll. no. 8842 (Figures 2-2 ; 3-5), Saitama 3 Figure 2. Serraia cataloniensis gen. et sp. nov. Drawings of megalospheric specimens. 1. Holotype, Saitama University coll. no. 8841 (see also Figure 3-1). 2. Paratype (see also Figure 3-5), Saitama University coll. no. 8842. 3. Paratype (see also Figure 5-2), Saitama University coll. no. 8843. Abbreviations: p=protoconch ; pd=protoconchal diverticulum ; d=deuter- oconch ; 3,4=third and fourth primary spiral chambers ; psc=primary spiral chambers ; ssc=secondary spiral chambers ; tsc=tertiary spiral chambers ; sscd=short spiral chambers around deuteroconch. Scale bars=100 um. Kuniteru Matsumaru A new Foraminifera, Serraia cataloniensis 263 University coll. no. 8843 (Figures 2-3; 5-2), Saitama Univer- sity coll. no. 8846 (Figure 5-1), Saitama University coll. no. 8847 (Figures 5-3a-b), and Saitama University coll. no. 8850 (Figure 3-4); Paratype: test surface and/or equatorial views of megalospheric or microspheric specimens, Saitama Uni- versity coll. no. 8844 (Figures 4-1a-c), Saitama University coll. no. 8845 (Figures 4-2a-b), Saitama University coll. no. 8848 (Figure 3-2) and Saitama University coll. no. 8851 (Figures 4- 8a-b); Paratype: vertical sections of megalospheric speci- men, Saitama University coll. no. 8849 (Figure 3-3). Description—Test thin (0.6 to 0.9mm in thickness), lenticular (2.0 to 4.0mm in diameter) with rather thick marginal periphery ; form ratio (diameter/thickness) 4.0 to 7.7 in megalospheric form; and 9.0 in single microspheric form observed which is 4.5 mm in diameter. Megalospheric embryonic chambers biloculine ; subspherical to spherical protoconch ranging from 160 x 140 to 370 x 370 um in diam- eter in seven specimens, and reniform deuteroconch 200 x 160 to 430 x 370 um in diameter in seven specimens ; whole embryonic chambers 320 to 600 um in diameter across both protoconch and deuteroconch in seven specimens ; outer wall of embryonic chambers 20 to 30 um thick in seven specimens ; third primary spiral chamber 100 x 120 to 265 x 350 um in radial and tangential diameters in seven speci- mens ; and fourth primary spiral chamber 60120 to 240 x 215 «m in radial and tangential diameters in seven speci- mens. Other primary spiral chambers developed into a planispirally to low trochospirally evolute whorl in mature stage and into involute whorl in gerontic stage ; first whorl divided by septa into 7 to 10 chambers, first whorl and a half with 15 to 20 chambers, and second whorl with 25 ? to 33? chambers in seven specimens. Secondary spiral chambers of second median layer in planispiral to low trochospiral whorl 60100 to 220x240 «m in maximum radial and tangential diameters in seven specimens. Tertiary spiral chambers of third median layer in planispiral to low tro- chospiral whorl 100 x 200 to 200 x 130 um in maximum radial and tangential diameters in five specimens ; both secondary and tertiary spiral chambers wind in same direction as primary spiral chambers. Median layer of primary spiral chambers subdivided into irregularly arranged, spiral cham- ber layers towards periphery. Protoconchal diverticula ar- cuate, 28 x 42 to 30x62 um in radial and tangential diame- ters in three specimens, and deuteroconchal diverticula arcuate 807140? um and 83145 um in radial and tangential diameters in two specimens. Short spiral cham- bers around deuteroconch frequently present and arcuate, 25x62 to 40x93 um in maximum radial and tangential diameters in two specimens. Lateral layers thickest at center and attenuated towards periphery of test, and pierced by numerous open pores or vertical canals of 8 to 20 um diameter. Pore openings covered by thin roofs of small surface chambers with 135 x 38 to 14540 um in maximum tangential diameter and height in three specimens. Test wall thick, fibrous, and perforate; canal system showing radial, simple and marginal, and intraseptal canal present. Dorsal and umbilical pillars present over lateral walls ; smal- ler ones 85 to 100 wm in diameter, and larger ones 135 to 185 um in diameter. Aperture with longitudinal grooves on base of apertural face; in present material, measurements of seven megalospheric forms given in Table 1. Etymology.—The species name is derived from the prov- ince of Catalonia, Spain. Type locality —Sample locality (Sample 4) of Puig Aguilera outcrop, Igualada, 50km northwest of Barcelona, Spain (Figure 1). Remarks.—Serraia cataloniensis sp. nov. resembles Bi- planispira mirabilis (Umbgrove, 1936), but is easily distin- guished from the latter in having the secondary and tertiary spiral chambers developed in the same direction as the primary spiral chambers, and in posessing frequent protoconchal and deuteroconchal diverticula and short spiral chambers around the deuteroconch. The author considers that this new species may have evolved from Biplanispira mirabilis (Umbgrove) by developing secondary and tertiary spiral chambers directly from the spiral chambers. Acknowledgments The author thanks Josep Serra-Kiel, Universitat de Bar- celona, for his kindness in sending sample materials for study. He also thanks Edward Robinson, Department of Geography and Geology, the University of the West Indies, Jamaica, Alphonse Blondeau, Maitre de Conference honor- aire, Université Pierre et Marie Curie (Paris VI), and Earl E. Brabb, Geologist Emeritus, U. S. Geological Survey, Men- lopark, California, for their kind reading of the manuscript, and Ministry of Education, Japan, for financial assistance toward presenting results at the 2nd Meeting of IGCP 393. — Figure 3. Serraia cataloniensis gen. et sp. nov. ta. External view (spiral side) of megalospheric specimen (holotype), showing large- and small-sized granules, and rather thick marginal periphery of test. 1b. Equatorial and internal view of holotype showing embryonic chambers with half-broken deuteroconch ; primary spiral chambers with 5th, 9th and 12th broken chambers, and secondary and tertiary spiral chambers, all coiling in same direction except for peripheral chambers. x 26. 2. External view of spiral side of test in microspheric specimen, paratype, Saitama University coll. no. 8848, x22. 3. Vertical section of megalospheric specimen, paratype, Saitama University coll. no. 8849, showing spiral and surface chambers, lateral layers thickest at center and attenuated towards periphery, large and small pillars, pore openings, and canals, x43. 4. Egautorial section of broken specimen, paratype, Saitama University coll. no. 8850, showing irregularly-arranged primary spiral Chambers towards periphery of test, coiling opposite direction to primary whorl as seen in Biplanispira, and also coiling in same direction as primary whorl, «43. 5. Equatorial section of megalospheric specimen, paratype, Saitama University coll. no. 8842, showing embryonic chambers, primary spiral chambers, and secondary and tertiary spiral chambers, all coiling in same direction, X 40. Kuniteru Matsumaru A new Foraminifera, Serraia cataloniensis Table 1. Measurements of internal equatorial view and equatorial sections of Serraia cataloniensis sp. nov. Holotype Paratype Paratype Paratype Paratype Paratype Paratype Specimen no. 8841 no. 8842 no. 8843 no. 8846 no. 8847 no. 8844 no. 8845 (Fig.3-1) (Fig.3-5) (Fig.5-2) (Fig.5-1) (Fjg.5-3) (Fig.4-1) (Fig. 4-2) Diameter (mm) 3.6 Bal PE) 3.0 3.0 4.0 2.0 Thickness (mm) 0.9 0.6 0.3 0.4 0.5 0.9 0.3 Form ratio (diameter/thickness) 4.0 5.2 Tah 19 6.0 4.4 6.7 Embryonic chambers protoconch diameter (4m) 370x370 350x290 302x272 235x265 360x250 220x140 160x140 deuteroconch diameter (4m) 374x212 320x208 350x230 235x170 430x340 220x160 200x160 distance across both 600 498 502 435 600 320 320 chambers (4m) wall thickness (4m) 30 30 20 28 30 28 22 Protoconchal diverticula radial diameter (4m) 30 30 28 tangential diameter (4m) 62 42 42 Deuteroconchal diverticula radial diameter (4m) 80? 83 tangential diameter (4m) 140 ? 145 Spiral chambers around deuteroconch radial diameter (4m) 33 40 40 25 33 tangential diameter (4m) 72 52 93 62 40 Primary spiral chambers Third chamber radial diameter (um) 145 265 208 100 220 135 100 tangential diameter (4m) 280 350 290 140 290 165 120 Fourth chamber radial diameter (um) 200 165 240 140 180 60 80 tangential diameter (4m) 160 145 215 140 220 120 110 number in 1st whorl 8 8 if 9 10 it 9 number in 1+1/2 whorl 16 18 15 17 18 15 18 number in 2nd whorl 30? 33? 28? 29 29? 29 25? Secondary spiral chambers radial diameter (um) 230 220 230 190 140 60 60 tangential diameter (4m) 160 240 230 200 186 100 100 Tertiary spiral chambers radial diameter (4m) 200 120 100 100 100 tangential diameter (um) 130 95 200 200 200 tN in — Figure4. Serraia cataloniensis gen. et sp. nov. 1a. External view of megalospheric specimen, paratype, Saitama University coll. no. 8844, in umbilical side of test, showing dextral distribution of large- and small-sized granules. 1b. Equatorial and internal view of same specimen of Figure 4-1a, showing embryonic chambers, and primary, secondary and tertiary spiral chambers, all coiling in sinistral direction, «26. 1c. Central part of internal view of Figure 4-1b, showing embryonic and primary spiral chambers, and secondary and tertiary spiral chambers, «43. 2a. Equatorial and internal view of megalospheric specimen, paratype, Saitama University coll. no. 8845, x43. 2b. Central part of internal view in Figure 4- 2a, showing embryonic and primary spiral chambers, and secondary spiral chambers connected by intraseptal, subsutural and radial canals from third chamber and 7 th chamber of primary spiral chambers, «107. 3a. External view of megalospheric specimen, paratype, saitama University coll. no. 8851, showing spiral side of test. 3b. External view of same specimen as Figure 4-3a showing umbilical side of test, x 26. Kuniteru Matsumaru 266 A new Foraminifera, Serraia cataloniensis References Archiac, E. J. A. d., 1850: Description des fossiles du group Nummulitique recueillis par M.S. P. Pratt et M. Delbos aux environs de Bayonne et de Dax. Mémoires de la Société Géologique de France, vol. 3, p. 397-456, pls. 8-13. Berggren, W.A., Kent, D.V., Swisher, C.C. and Aubry, M.P., 1995: A revised Cenozoic geochronology and chrono- stratigraphy. In, Berggren, W. A. Kent, D. V., Aubry, M. P. and Hardenhol, J. eds., Geochronology, Times Scale and Global Correlations : a Unified Temporal for an Historical Geology. Society of Economic Paleontologist and Miniralogists. Special Publication, no. 54, p. 129-212. Ferrer, J., 1971: El Paleoceno y Eoceno del borde surori- ental de la Depresion del Ebro (Cataluna). Memoires suisses del Paleontologie, vol. 90, p. 1-70. Galloway, J. J., 1928: A revision of the family Orbitoididae. Journal of Paleontology, vol. 2, p. 45-69. Hantken, M. von, 1875: Die Fauna der Clavulina Szaboi Scgichten. |. Teil: Foraminiferen. Magyar Kiralyi Foldtani Intezet Evkonyve, vol. 4, p. 1-93, pls. 1-16. Hanzawa, S., 1937: Notes on some interesting Cretaceous and Tertiary Foraminifera from the West Indies. Jour- nal of Paleontology, vol. 11, p. 110-117, pls. 20-21. Loeblich, A.R. and Tappan, H., 1987 : Foraminiferal Genera and their Classification. 970p., 847 pls. Van Nord- strand Reinhold Company Inc., New York. Matsumaru, K., 1996a: Tertiary larger Foraminifera (For- aminiferida) from the Ogasawara Islands, Japan. Paleontological Society of Japan, Special Papers, no. 36, p. 1-239, pls. 1-88. Matsumaru, K., 1996b: Discussion on Bolkarina Sirel, 1981 (Foraminiferida). /n, Noda, H. and Sashida, K., eds., Professor Hisayoshi Igo Commemoration Volume on Geology and Paleontology of Japan and Southeast Asia. p. 163-164. Gakujutsu Tosho Insatsu Co., Tokyo. Michelin, H., 1846 : Iconographie zoophytologique, 348 p., P. Bertrand, Paris. Nuttall, W. L. F., 1925: Two species of Eocene Foraminifera from India: Alveolina elliptica and Dictyoconoides cooki. Annals and Magazine of Natural History, Ser. 9, vol. 16, p. 378-388. Reguant, S., 1967: El Eoceno marino de Vic (Barcelona). Memorias del Instituto Geologico y Minero de Espana, vol. 68, p. 1-350. Riba, O., 1975: Introduction. /n, Le basin Tertiaire Catalan Espagnol et les gisements de potasses. /X Congress International de Sedimentologie, Livret-Guide, Excur- sion. no. 20, p. 9-13. Rutimeyer, L., 1850: Über das Schweizerische Nummuliter- rain mit besonderer Berücksichtigung des Gebirges zwischen den Thunersee und der Emme. Denks- chriften Schweizerischen Naturforschenden Gesell- schaft, vol. 11, p. 1-120. Serra-Kiel, J., Busquets, P., Trave, A., Mato, E., Saula, E., Tosquella, J., Samso, J. M., Ferrandez, C., Barnolsa, A., Alvarez, G., Franques, J. and Romero, J., 1997 : Field Trip Guide, “Marine and Transitional Middle/Upper Eocene Sediments of the South-Eastern Pyrenean Forland Basin”. UNESCO Project IGCP 393 Neritic Events at the Middle-Upper Eocene Boundary, 2nd Meeting, Vic (Spain), 2-6 September, 1997. p. 1-52. Silvestri, A., 1928: Di alcune facies litho-paleontologiche del Terziario di Derna, nella Cirenaica. Bollettino Societa Geologica Italiana (Roma), vol. 47, p. 109-113, p. 6. Sirel, E., 1981: Bolkarina, new genus (Foraminiferida) and some associated species from the Thanetian limestone (central Turkey). Eclogae Geologicae Helvetiae, vol. 74, p. 75-95. Smout, A. H., 1954 : Lower Tertiary Foraminifera of the Qatar Peninsula, 96 p., 15 pls. British Museum (Natural His- tory), London. Trave, A., 1992: Sedimentologia, petrologia i geoquimica (elements traca i isotops) dels Estomatolits de la Conca Eocena Sudpirinenca. Ph. D. Thesis, Universitat de Barcelona, p. 1-396. Umbgrove, J. H. F., 1936: Heterospira, a new foraminiferal genus from the Tertiary of Borneo. Leidsche Geologis- che Mededeelingen, vol. 8, p. 155-157, pl. 1. Umbgrove, J. H. F., 1937: A new name for the foraminiferal genus’ Heterospira. Leidsche Geologische Mededeelingen, vol. 8, p. 309. — Figure 5. Serraia cataloniensis gen. et sp. nov. 1. Equatorial section of megalospheric specimen, paratype, Saitama University coll. no. 8846, showing embryonic chambers, primary spiral chambers, and secondary and tertiary spiral chambers, all coiling in same direction, «43. 2a. Equatorial section of megalospheric specimen, paratype, Saitama University coll. no. 8843, showing embryonic and primary spiral chambers, secondary spiral chambers, protoconchal diverticulum, and short spiral chambers arranged deuteroconch, “453. 2b. Central part of equatorial section in Figure 5-2a, showing protoconchal diver- ticulum and short spiral chambers around deuteroconch connected by deuteroconchal stolons and probably intraseptal, subsutural and radial canals from third chamber, «107. 3a. Equatorial section of megalospheric specimen, paratype, Saitama University coll. no. 8847, showing embryonic, primary and secondary spiral chambers, deuteroconchal diverticulum, and short spiral chambers around deuteroconch, «43. 3b. Central part of equatorial section in Figure 5-3a, showing deuteroconchal diverticulum, and short spiral chambers connected by deuteroconchal stolons and intraseptal, subsutural and radial canals or stolons? 95. 267 Paleontological Research, vol. 3, no. 4, pp. 268-286, 8 Figs., December 30, 1999 © by the Palaeontological Society of Japan The Late Bathonian gastropod fauna of Kutch, western India-a new assemblage SHILADRI S. DAS', SUBHENDU BARDHAN° and TAPES C. LAHIRI’ ‘Indian Statistical Institute, Geological Studies Unit, 203 Barrackpore Trunk Road, Calcutta- 700035, India “Department of Geological Sciences, Jadavpur University, Calcutta- 700032, India “Palaeontology Division 1, Geological Survey of India, 15 Kyd Street, Calcutta- 700016, India Received 2 December 1998 ; Revised manuscript accepted 7 September 1999 Abstract. The Middle Jurassic sediments of Kutch have been known all over the world as a veritable storehouse of diverse fauna, particularly ammonites. The present investigation has brought to light a rich haul of gastropods hitherto unknown in Kutch. The present assemblage includes eleven new species belonging to nine genera. They are: Colpomphalus jumarense sp. nov.; Emarginula karuna sp. nov. ; Helicacanthus chanda sp. nov.; Riselloidea tagorei sp. nov.; R. elongata sp. nov.; Onkospira kutchensis sp. nov.; Proconulus jadavpuriensis sp. nov.; Neritopsis (Neritopsis) patchamensis sp. nov.; N. (Hayamiella) sankhamala sp. nov.; Hayamia mitra sp. nov. and Globularia spathi sp. nov. The assemblage shows strong Tethyan affinity at generic level, but species display marked endemism since Kutch belongs to a distinct Indo-Madagascan Faunal Province. The present finding refines and widens the spatiotemporal distribution of these genera. Key words: Gastropoda, Kutch, Middle Jurassic, systematics, western India Introduction The marine Jurassic sediments of Kutch were deposited in a newly emerging basin that developed as an extension of the Tethys during separation of Africa and India consequent to the rifting of the Gondwana Superplate (Biswas, 1982, 1991). The Jurassic rocks yield many diverse shallow marine taxa. The fossils are numerous and remarkably well preser- ved. Amongst them the ammonites attract the most atten- tion of palaeontologists. Among the ammonites many are time-diagnostic forms that provide finer time resolution and help in establishing regional standard biozonations and inter- continental correlation with Europe and other areas. The faunal horizons that yield gastropods, may be assigned to an age ranging from the Late Bathonian to Tithonian. Many classic studies on this biota, e.g., Cephalopoda (Waagen, 1873-75 ; Spath, 1927-33), Bivalvia (Kitchin, 1900 ; Cox, 1940, 1952), Brachiopoda (Kitchin, 1900) and corals (Gregory, 1898, 1900) were made by great masters of the last and this centuries. It is rather surprising that the vast gas- tropod fauna from the different sections of the mainland and ‘islands’ of Kutch escaped their notice, notwithstanding the scanty reports of a few gastropod species (Maithani, 1967 ; Mitra and Ghosh, 1979). In this present endeavour, we describe 11 new species of the Bathonian, some of which continue to the base of the Middle Callovian. The present study covers a large number of specimens systematically collected in the field with a precise stratigraphic background by us and other members of the Palaeontological Laboratory, Department of Geologi- cal Sciences, Jadavpur University. These species belong to nine genera of seven families. They are Colpomphalus jumarense sp. nov.; Emarginula karuna sp. nov. ; Helicacanthus chanda sp. nov.; Riselloidea tagorei sp. nov.; À. elongata sp. nov. ; Onkospira kutchensis sp. nov.; Proconulus jadavpuriensis sp. nov.; Neritopsis (Neritopsis) patchamensis sp. nov.; N. (Hayamiella) sank- hamala sp. nov.; Hayamia mitra sp. nov.; and Globularia spathi sp.nov. They show strong Tethyan affinity at generic level, especially with Europe (see Knight et al. 1960). Biogeographic distributions of the other Kutch biota suggest prevalence of faunal migrational pathways across the Tethys particularly with Europe (Hallam, 1982 ; Krishna and Cariou, 1990 ; Kayal and Bardhan, 1998). The faunas are, however, marked by strong provincialism at species level. The sedi- ments developed due to repeated marine transgression- regression cycles in a basin that emerged from the breakup of Gondwana Superland and was surrounded by East Africa, Madagascar and western India (see also Fürsich et al., 1991). This newly formed basin acted as the Eden of evolution for many immigrant faunas that invaded it (Dutta et al., 1996). Rapid diversification of various taxa marks a strong ende- mism of fauna which constitutes what is called the Indo- Madagascan or Ethiopian Faunal Province. This record of Jurassic Gastropoda from India 269 new taxa widens our knowledge about spatiotemporal distri- bution of the Jurassic gastropod fauna, which are less comprehensively known and poorly documented in the existing literature. lt should be noted here that recent advances in the studies of suprageneric classification of gastropods have drawn attention to some lacunae in the earlier traditional classifications (e.g. Wenz, 1938—44 ; Knight et al., 1960). Many higher taxonomic categories are now considered to be paraphyletic, e.g., the Archaeogastropoda (e.g. Hickman and McLean, 1990), and poorly delineated. Major revisionary works are now available for many important groups including their extinct taxa, e.g., on Naticidae and Trochidae (see Kabat, 1991; Hickman and McLean, 1990). Some new schemes have deployed cladistic methodology emphasising the role of derived (apomorphic) conditions and included large character sets. But excessive weight has been given to the characters related to soft parts. The systematic position of many extinct lineages remain still problematic since shell characters may be convergent (Hickman and McLean, 1990). Thus a large amount of uncertainty still prevails in respect of the classification of fossil gastropods. Under such circumstances our endeavour has been to large- ly retain the general framework (subordinal level and above) of classification given in the Treatise on Invertebrate Paleontology (Knight et al., 1960) while effecting some family or subfamily level changes with regard to certain Kutch taxa in the light of modern classification. In this context the following brief discussion would clarify the taxonomic hierar- chies followed in the present study. Particular attention should be drawn to our categorisation of the genera Risel- loidea and Onkospira under the family Trochidae instead of Amberleyidae of the earlier classification and the genus Helicacanthus under Turbinidae instead of Nododel- phinulidae following Hickman and McLean (1990). Dealing in detail with the shell characters of Amberleyidae, Hickman and McLean (1990) have been very explicit in pointing to the trochid innovations in its shell morphology that are shared with the living species. Of the many trochid subfamilies recognised by them the subfamily Eucyclinae is of particular interest ; it covers erstwhile Amberleyidae (Family) and Am- berleyinae (Subfamily) and has been divided into three tribes among which the Tribe Eucyclini comprises only the fossil trochids of Middle Triassic to Oligocene age. While discus- sing this subfamily they have also dealt with those shell characters of the three tribes that separate them from other trochid subfamilies. The historical treatment presented by them clearly demonstrates the weak foundation on which the Amberleyidae of Wenz (1938) and Cox's (in Knight et al. 1960) eucycline taxa and superfamily Amberleyacea stand. Similar detailed character analyses that include hard part features have resulted in the placement of erstwhile Nododelphinulidae in the subfamily Angariinae (family Tur- binidae) and Proconulinae tentatively under Calliostomatinae (Trochidae) taking into account the assignments which have also been followed here. The scheme used here is logical under rather conflicting positions presently prevailing in fossil gastropod taxonomy and leaves room for more detailed work on an improved, widely acceptable classification. Stratigraphy The Mesozoic rocks occupy nearly half of the area in Kutch, covering the mainland as well as three Rann ‘islands’, and lie nonconformably on the Pre-Cambrian basement (Biswas and Deshpande, 1968). On the mainland the Mesozoic rocks are represented by: Patcham Formation, Chari Formation, Katrol Formation, Bhuj Formation and Deccan Trap in ascending order (for details see Mitra et al. 1979). The thick pile of sediments exceeds more than 3,000 m (Biswas, 1991) and has been regionally folded into three parallel anticlines running northwest-southeast. The Jurassic rocks are best developed in the central anticline (Wynne, 1872; Rajnath, 1932; Poddar, 1959). A set of zones of culmination is observed along the anticlines. These zones of culmination crop out as topographical domes at Jara, Jumara, Nara, Keera etc. (Figure 1) where the inliers of older rocks belonging to the Patcham and Chari Formations mainly occur at the core. The present gastropod faunas come mainly from the different levels of the Patcham Formation which is partially exposed at Jumara, the locality for the stratotype of the Chari Formation. The Middle Jurassic sediments of the ‘islands’ belts are included in the formations equivalent to the Pat- cham Formation and even older ones (Biswas, 1977 ; Fursich et al., 1994). Here gastropods occur sporadically, becoming locally abundant at Kuar Bet near Patcham ‘island’. The gastropod assemblage of this area appears to be quite distinct from that of Jumara and is dominated mainly by Katosira Koken. This level, judged by the associated fauna and stratigraphic position, may represent the Bajocian (See also Fürsich et al., 1994) and these gastropods are therefore not included in the present study. The exposed sequence of the Patcham Formation at Jumara, which is about 47 m thick, consists of alternations of two distinct lithofacies (Beds 24-26 of Rajnath, 1932 ; Beds 1-2 of Bardhan et al., 1994) (Figure 2). The lower facies is an alternation between coralline rudstone and cream-coloured H A CN oem 2. £ "BHUJ a Figure 1. Jumara, the type area of the Chari Formation. area is the Rann of Kutch. Geographic location of Kutch with Keera and The patterned 270 Shiladri S. Das et al. Oxycerites sp. Stvajiceras congener oo ) zZ a 2 Le x mule Sale See zic See = ee o ; E Dit = Epistrenoceras sp. Te an ES j © |- + i C Macrocephalites lu, lie triangularis(0&0) aq a y se] = 4 2 = Procerites hi a rocerites hians ob x IT jz a CS a ER Ga Renee! x ly (8) aq HI TT? Epimorphoceras a re 55; decorum 5m (hye || Redraw coon mes ees a Se = Figure 2. Stratigraphic distribution of key ammonite taxa within the Patcham Formation of Jumara. Key: 1, Coralline limestone (rudstone) alternating with white to brown-coloured limestone(wackestone). Arrows indicate occurrences of dif- ferent gastropod species. 2, Repeated alternations between white and cream-coloured limestone (wackestone and marl). wackestone. Biostromes of diverse corals appear at sev- eral levels where gastropods are most abundant. The coral biostromes occur in the form of parallel-sided, thin tabular beds. They dominantly consist of largely intact fossils with or without interstitial mud (Dutta et a/., 1996). There are large varieties of corals (Gregory, 1900 ; Pandey and Fursich, 1993), most of them being in life attitude. Besides corals and gastropods, many other taxa including ammonites also characterise this horizon. The facies is marked by the first appearance of Macrocephalites Zittel in Kutch. Judging by its faunal content and a recently found excellent time- diagnostic ammonite, Epistrenoceras Bentz (Kayal and Bard- han, 1998), this lower part of the Patcham Formation can safely be assigned to the late Bathonian. The upper facies is, on the other hand, an alternation between cream-colour- ed wackestone and mud. It supports sparse fauna includ- ing gastropods. Only some _ fragmentary perisphinctid Lower | Middle | > Callovian |Callovian | ® Chari — Formation Upper Balkhaniam Patcham = na1ysoosAsyy snsowJo4j sispj)nBbundisy DPnpgusopuj Species Proconulus jadavpuriensis Emarginula | karuna Colpomphalus jumarense Neritopsis(N.) atchamensis Neritopsis (H.) sankhamala Hayamia mitra Globularia spathi Riselloidea tagorei | R.elongata Onkospira kutchensis He licacanthus [Ananas Figure 3. Range chart of different species of gastropods in Kutch. Zones are modified after Dutta (1992). ammonites belonging to Procerites Siemiradzki have been reported from it. This also suggests a late Bathonian age (see also Callomon, 1993; Dutta et a/., 1996). Recently, Dutta (1992) made a substantial revision of the standard zonations within the Bathonian-Callovian Stages of Kutch. We follow here the biostratigraphic scheme of Dutta (1992) with modification, and stratigraphic distribution of the present gastropod species is shown in Figure 3 (after Bardhan et al. 1994 with modification). Systematic Paleontology All the materials studied are deposited in the Department of Geological Sciences, Jadavpur University, Calcutta, India (JU). Measurements are not provided since specimens are plentiful for most of the species, over three hundred in the case of Riselloidea tagorei. These can be provided upon request. Subclass Prosobranchia Order Archaeogastropoda Suborder Macluritina Superfamily Euomphalacea Family Helicotomidae Genus Colpomphalus Cossmann, 1916 Type species.—Straparollus altus d'Orbigny, 1853 ; original designation. Jurassic Gastropoda from India 271 Colpomphalus jumarense sp. nov. Figure 4-1, 2 Material—Seven specimens. JUM/g 19-22, 594-596. Specimen JUM/g 19 is designated holotype ; the rests are paratypes. JUM/g 19-22 were collected from Bed 1, Jumar- a and JUM/g 594-596 from Bed 2, Keera (see Bardhan et al., 1994). Diagnosis —Average-sized Colpomphalus (6 to 10mm high); whorls 4 to 5 in number, gradate with wide sloping concave ramp ; ornamentation of three strong spiral carinae, irregularly spaced and middle one relatively weaker, close to first one ; prominent collabral ridges prosoclinal on ramp. Description.—Shell small in size, maximum height about 10 mm; thick, phaneromphalous ; highly depressed and tur- biniform with height about half of shell diameter. Apical angle ranges between 120° and 130°. Whorls 4 to 5 in number including protoconch and separated in early stage by weakly grooved suture which becomes conspicuous in later ontogeny. Protoconch poorly preserved, seemingly consists of one and a half smooth, planispiral whorls. Spire very low, conical, obtusely pointed owing to near-planispiral coiling of early whorls. Spire occupies one-fourth of shell height. Body whorl very large, width slightly greater than twice of height; shell rapidly increases in diameter. Whorls gradate with wide sloping ramp, which is concave at upper whorl surface. Outer whorl surface inclined abapically. Body whorl consists of three revolving carinae, which are irregularly spaced. First one situated in ramp margin while third carina at base of whorl forms umbilical border, second carina is close to first. First and third are stronger than second. Umbilical wall steep. Transverse, prosoclinal ridges fine to sharp, intersect carinae and form pointed tubercles at junctions. Tubercles are variable in number, 20 to 25 on body whorl. Aperture subquadrangular, width of aperture is greater than height. Columellar and basal lips form an angulation at their junction. Discussion.—Relatively low spire, concave upper whorl surface, tuberculate periphery and angular peristome place the present species securely within the genus Colpomphalus. It however, differs from Colpomphalus exsertus (Hudleston, 1893) (Knight et al., 1960, fig. 106, 7) from the Bajocian of England mainly in shell ornamentation. C. exsertus is or- namented with two revolving carinae and fine collabral threads ; conversely, the present species has three strong revolving carinae and strong collabral ridges which are prosocline on ramp. Besides, the present species has fewer whorls and a relatively more protruded spire. The general shell outline, apertural shape, little raised spire and number of whorls of the present species are comparable with those of the Lower Jurassic (Middle Aalenian) Colpom- phalus baugieri (d’Orbigny) (1853, p. 307, pl. 321, figs. 13-16) (see also Fischer, 1997, p.121, pl.24, figs. 1a-c) of Niort, France. But the European form is stratigraphically older and relatively smaller in size. It is less coarsely ornate and is characterised by numerous fine spiral striae, which are lacking in the present species. Colpomphalus altus (d’Orbigny) (1853, p. 314, pl. 332, figs. 5-8) (also see Fischer, 1997, p. 124, pl. 22, figs. 5a-c), the type species, is a contemporaneous species from France and is based on a monotypic holotype which is broken and im- mature and hence comparison is very difficult. Its restored diameter is about 8mm and thus appears to be smaller. It appears similarly but less strongly ornate, basal ornamenta- tion consisting of numerous striae which are conspicuous by their absence in the Kutch species. Etymology.—After Jumara area of Kutch, Gujarat, where the species occurs. Suborder Pleurotomariina Superfamily Fissurellacea Family Fissurellidae Subfamily Emarginulinae Genus Emarginula Lamarck, 1801 Type species.—Emarginula conica Lamarck, 1801 ; original designation. Emarginula karuna sp. nov. Figure 4-3—5 Material.—Five specimens. JUM/g 71-75. Specimen JUM/g 71 is designated holotype; the rest are paratypes. Specimens are mostly broken, but their original shells are preserved. All were collected from Bed 1 of Jumara. Diagnosis.—Averaged-sized Emarginula (8 to 13 mm high) ; shell short ; apex slightly curved; narrow, raised selenizone extending more than three-fourths of shell height from base ; in transverse section, shell nearly flattened along selenizone. Shell ornamented with strong, closely spaced axial ribs intersected by relatively weaker spiral cords; weaker axial rib intercalates between two stronger ribs ; very fine, dense, transverse and crescent-shaped ribs with concavity towards aperture subdivide selenizone. Description.—Shell short, maximum height achieved 13 mm ; cap-shaped. Apex curved pointing to rear, protocon- ch missing. Shell convex, slightly flattened along seleni- zone. Narrow, slightly raised selenizone between two ridges extending more than three-fourths of shell height from base. Shell ornamented with strong axial ribs intersected by relatively weaker spiral cords resulting in reticulation. Weaker axial rib intercalates between two stronger ribs. This secondary axial rib is similar in strength or may be sometimes weaker than spiral cords. Very fine, dense and transverse ribs subdivide selenizone to form lunula. They are crescentic in shape with a concavity towards the aper- ture. All collabral and longitudinal elements are weak in early ontogeny. Peristome ovate. Discussion.—Emarginula karuna sp. nov. is similarly ovate and elevated as Emarginula (Emarginula) conica Lamarck (Knight et al., 1960, figs. 140, 1a-c), the type species, which is a Recent form. But it differs mainly in ornamentation being characterised by axial ribs of variable strength. Moreover, selenizone is not depressed. Emarginula (Tauschia) orthogonia Tausch, 1890 (Knight et al., 1960, figs. 140, 11a-b), resembles the present form in Shiladri S. Das et al. Jurassic Gastropoda from India 273 having similarly raised selenizone, but can be distinguished by stronger collabral ribs and absence of fine axial threads between the two stronger ones. Apex of the E. (7). orth- ogonia is also more strongly curved. Emarginula (Altomarginula) desnoyersi Eudes-Deslong- champs, 1842 (Knight et al. 1960, figs. 140, 7a-b), is a Bathonian form that differs in shell size and ornamentation. The present species is larger in size, less elevated with raised selenizone and bears spiral elements, which the European form lacks. The present species differs from Emarginula (Emarginula) vadanaei Toni, 1912 (Szabo, 1980, pl. 4, figs. 10-11 ; Conti and Monari, 1991, pl. 7, figs. 7-14), in shell size, ornamentation and curvature of the apex. The Bakony and Turkey specimens are smaller in size. Although they have similar slightly elevated selenizone, it extends for only about one-third of the shell height while in the present form it extends more than three-fourths of the shell height from the base. Furthermore, the present species is ornamented with strong longitudinal ribs and its apex is less curved. Emarginula lepsuisi Gemmellaro, 1878 is another compa- rable Jurassic form. It can, however, be differentiated from the Kutch form by its convex shell along the selenizone and fewer ribs (See also Szabo, 1980). Etymology.—The species is named in honour of late Karun Chandra Mitra, a renowned palaeontologist of the Depart- ment of Geological Sciences of Jadavpur University. Suborder Trochina Superfamily Trochacea Family Turbinidae Subfamily Angariinae Genus Helicacanthus Dacqu in Wenz, 1938 Type species.—Turbo thurmanni Pictet and Campiche, 1863 ; original designation. Helicacanthus chanda sp. nov. Figures 4-6,7; 5-1,2 Material—Ten specimens, JUM/g 35-44. JUM/g 35 is designated holotype; the rest are paratypes. All speci- mens have their original shell preserved. Only two speci- mens are intact and the rest are lacking mostly their apical parts. All were collected from Bed 1, Jumara. Diagnosis.—Average-sized Helicacanthus (about 18mm high); height greater than diameter; a broad nearly flat ramp on upper surface, outer whorl concave ; dense, fine prosoclinal striae on whorls and within umbilicus; both carinae and cords may be granulated. Description.—Shell of medium size, maximum height about 18mm; thick, phaneromphalous turbiniform with height slightly greater than diameter. Apical angle ranges between 47 and 54. Whorl at least 4 in number including protocon- ch and separated by strongly grooved suture. Protoconch dome-shaped, consisting of one and a half smooth whorls. Spire low, conical occupying about one-third of shell height. Body whorl large, rapidly increases in diameter, width slightly greater than height. A broad, nearly flat ramp on upper surface of whorls. Outer face of whorls narrow, slightly concave, bordered by two strong spiral carinae, first one being stronger. Prominent spiral cords3 to 4 in number appear after second angulation and are restricted at base. Cords and occasionally carinae show regular granulation. Dense prosoclinal striae present on whorls and also within umbilicus. Aperture orbicular in outline, both outer and inner lips thick and base rounded. Discussion. The characteristic shell outline, presence of two strong carinae on outer whorls and apertural shape assure its generic position. The present species is distin- guishable from the type species Helicacanthus thurmanni (Pictet and Campiche, 1863), (Knight et al., 1960, fig. 204, 2) from the Aptian of Switzerland by its slender form and in ornamental features. The type species is ornamented with numerous spiral cords, which are present between the carinae and also within the umbilicus, whereas in the present species spiral cords are restricted only at the base and umbilicus is ornamented with dense axial threads. Cox and Arkell (1948-50) mentioned but did not describe one species of this genus, Helicacanthus tegulatus (Lycett) (1863, p. 102, pl. XLV, figs. 17, 18), from the Bathonian Forest Marble of England. Besides this, the present form is the second oldest species of the genus which otherwise ranges from the Upper Jurassic to Lower Cretaceous (see Knight et al., 1960). Etymology.—The species is named in honour of late S.K. Chanda, a famous sedimentologist of the Department of Geological Sciences, Jadavpur University Family Trochidae Subfamily Eucyclinae Genus Riselloidea Cossmann, 1909 Type species.—Risellopsis subdisjuncta Cossmann, 1908 ; original designation. — Figure 4. 1,2. Colpomphalus jumarense sp. nov. 3. and basal views. lateral view showing selenizone (see arrow). view. 6,7. Helicacanthus chanda sp. nov. from Bed 1, Jumara abapertural views. abapertural views. Note strong collabral ridges and presence of three spiral carinae on body whorl (1b). Bed 2, Keera, JUM/g 595, apical, apertural and basal views. Holotype, JUM/g 71, protoconch missing ; apical and two lateral views. 5. Paratype, both apical part and peristome damaged, JUM/g 73, oblique lateral <3. 6a,b. Holotype, complete shell, JUM/g 35, apertural and 7a, b. Paratype, complete shell, umbilicus showing axial ornamentation (7a), JUM/g 36, apertural and 1a-c. Holotype, from Bed 1, Jumara, JUM/g 19, apical, abapertural 2a-c. Paratype, from 3-5. Emarginula karuna sp. nov. Bed 1, Jumara, x4. 3a-c. 4. Paratype, apical part damaged, JUM/g 72, oblique 274 Shiladri S. Das et al. Jurassic Gastropoda from India 275 Riselloidea tagorei sp. nov. Figure 5-3—6 Material —Over 300 specimens. JUM/g 148 is designat- ed holotype ; JUM/g 145-147 and JUM/g 149-166 are para- types. Most of the specimens have their original shell preserved. All were collected from Bed 1, Jumara. Diagnosis.—Medium to large-sized Riselloidea (10 to 15 mm high). Species shows wide intraspecific variation in shell profile with height greater than diameter changing to diameter greater than height; whorls cyrtoconoid to straight; axial elements stronger than spiral ones; three spiral tuberculate carinae of variable strength and 3 to 4 basal cords with granulation. Description.—Shell medium to large in size, maximum height being achieved 15mm; weakly cyrtoconoid to straight; trochiform and anomphalous. Apical angle ranges between 55 to 95. Shell diameter may be greater or smaller than height. Whorls 4 to 5 in number including protoconch, which consists of two smooth, rounded whorls. Spire conical, low to moderately high, occupying one-fourth to one-third of shell height. Whorls regularly expanded, may be separated by relatively deep-channelled suture. Shell ornamented with three revolving carinae, third one is stronger than other two. First inter area forming a ramp, larger than that of second one which may sometimes be depressed. Relatively weak, prosoclinal riblets intersect carinae and produce pointed tubercles at crossing points. Axial elements running suture to suture, 20 in number on body whorl. Base weakly convex with 3 to 4 strong spiral cords with regular granulation resulting from interception of fine axial growth lines. Peristome is prosocline with thick- ened columellar lip. Aperture quadrangular to subquadran- gular with angulations at middle carina and suture ; outer lip thin. Discussion.—Cossmann (1909) proposed the genus Risel- loidea and designated his Risellopsis subdisjuncta Coss- mann, as the type species. The present species resembles the type species in ornamentation and other general features but is relatively larger and has a rounded base. The present species is very close to Riselloidea biarmata (Münster, 1844) (Cox and Arkell, 1948-50, p. 58 ; Knight et al. 1960, fig. 203, 8) from the Great Oolite Series, England and the Middle Jurassic of Germany. However, it has a wide range of variation particularly in shell outline and larger shell size, quadrangular apertural outline, prosoclinal peristome and convex base. Moreover, it is ornamented with three tuberculate Carinae whereas R. biarmata bears only two rows of tubercles. Conti and Fischer (1982) described two new Riselloidea species from the Middle Jurassic sequence of Italy. These species are very small in size and differ in some mor- phological aspects from the present species. Riselloidea martariensis Conti and Fischer (1982, pl. 3, figs. 11a-d, 12) differs, besides being small, in having a convex whorl outline and more depressed suture and in variation in number of axial elements. Riselloidea subreticularis Conti and Fischer (1982, pl. 3, figs. 18a-d, 14), a smaller species than À. martariensis, resembles the present form in shell outline, but has a larger aperture, less dense axial ribs and convex whorl outline. In R. su- breticularis, spiral cords appear only in the last whorl, while they are present right from the early whorls except for the protoconch, in the present species. R. reticularis (Cossmann in Piette, 1864-91) (also see Conti and Fischer, 1982), a Bathonian species, has a close corre- spondence with the present species. It has comparable radial elements but differs mainly in having 4 spiral carinae instead of three and 5 to 7 basal cords instead of 3 to 4 in the present species. Further, we are not aware of any kind of intraspecific variation within R. reticularis. Riselloidea multistriata (Böckh) (1874, p.110, pl. VI, fig. 5) (also see Szabo, 1982, pl. 3, figs. 3-6) has a comparable size, but its convex whorls and dense, fine collabral cords distin- guishes it from the Kutch form. Moreover, in R. multistriata basal cords are fine and more numerous, about 8 against 3 to 4 in the present population Etymology.—After the great Indian poet, R.N. Tagore. Riselloidea elongata sp. nov. Figure 6-1—3 Material. Seven specimens, JUM/g 138-144. Specimen JUM/g 138 is designated holotype ; the rest are paratypes. The specimens have their original shell preserved. The present collection has been made from Bed 1, Jumara. Diagnosis.—Large-sized Riselloidea (about 15 mm high); shell slender, height being twice shell diameter ; whorls straight conical and numerous ; base flat to weakly convex ; two spiral, tuberculate carinae of equal strength, 3 to 4 basal cords with no granulation. Description.—Shell slender, large, maximum height achieved 15 mm; anomphalous, trochiform ; straight conical in outline, with height about twice the shell diameter. Apical angle ranges from 20° to 25°. Whorls numerous, seven in number including protoconch, which consists of two smooth and rounded whorls. Spire moderately long, occupying about half of shell height. Shell ornamented with two spiral carinae, more or less of equal strength, each bordering suture. Axial elements are weakly prosocline, running suture to suture. They are 20 in number on body whorl. Feeble tubercles are formed at intersecting points of trans- — Figure 5. 1,2. Helicacanthus chanda sp. nov from Bed 1, Jamara, 3. abapertural view ; abapertural view (1b) showing dense axial striae. Note granulated basal cords in apertural view (2a). and abapertural views. ta, b. Paratype, JUM/g 38, apertural and 2a, b. Paratype, almost complete, JUM/g 39, apertural 3-6. Riselloidea tagorei sp. nov. from Bed 1, Jumara, X3. 3a-c. Holotype, complete shell, JUM/g 148, apertural, abapertural and basal views. 4a-c. Paratype, complete shell, JUM/g 157, apertural, abapertural and basal views. views. 5a, b. Paratype, complete shell, JUM/g 147, abapertural and basal 6a, b. Paratype, complete shell, JUM/g 159, abapertural and apical views. Shiladri S. Das et al. Jurassic Gastropoda from India 277, verse and longitudinal elements. Base flat to weakly con- vex with 3 to 4 faint spiral cords. No granulation on cords at crossing points when intersected by very feeble axial growth lines. Aperture almost circular to subquadrangular ; columellar lip thickened by callus ; base narrow and slightly rounded. Discussion.—Riselloidea elongata sp. nov. comes from the same stratigraphic level and geographic locality as Risel- loidea tagorei sp. nov. These two species are comparable in having more or less similar size, conical and straight- walled shell outline, and nearly flattened base. R. elongata however, differs from R. tagorei in being more slender and high-spired. It has also more whorls and less shell rugosity, with only two rows of tubercles instead of three in R. tagorei. Besides, basal cords of R. elongata lack granulations, which are typical of R. tagorei. The Kutch species has a close resemblance with Risel- loidea biarmata (Münster, 1844), described from the Great Oolite Series, England and the Middle Jurassic, Germany (Cox and Arkell, 1948-50, p. 58, Knight et a/., 1960, fig. 203, 8). The present species, however, can be distinguished by its larger size, slender shape and absence of granulation on the basal cords. The present species resembles Riselloidea periniana (d'Orbigny) (1853, p. 266, pl. 310, figs. 12, 13) (also see Fischer, 1997, p.103, pl. 21, fig. 24) from the Plansbachian of France. Both species have a similar higher shell outline, high spire and surface ornamentation with two rows of tuberculate carinae. However, the older European form is smaller in height, having deeply grooved suture and more oblique axial riblets. Moreover, it has granulation at the basal cords, a feature which is absent in the present species. Etymology.—Atfter its elongated shape. Genus Onkospira Zittel, 1873 Type species.—Turbo ranellatus Quenstedt, 1858 ; Origi- nal designation. Onkospira kutchensis sp. nov. Figure 6-4—6 Material—Twenty-six specimens. JUM/g 45-70. JUM/ g 45 is designated holotype ; the rest are paratypes. All the specimens have their original shell preserved. Only two specimens are intact with the rest lacking their apical part. All were collected from Bed 4, Jumara. Diagnosis.—Average-sized Onkospira (13 to 25 mm high) ; whorls 5 in number including protoconch; spire short; strong spiral cords, 3 to 4 in number throughout ontogeny, basal cords 7 to 8; axial threads very fine, may be absent in some variants ; two strong prosoclinal varices on each whorl, showing slight offset in successive whorls. Description.—Shell medium in size, maximum height achieved about 25 mm; thick, anomphalous and turbiniform with shell diameter about half of shell height. Apical angle ranges between 25° and 32°. Whorls 5 in number including protoconch. Protoconch consists of two smooth and rounded whorls. Spire highly elevated and about half of shell height. Whorls regularly expanding, strongly to slightly convex with sloping ramp. Suture impressed. Surface ornamented with 3 to 4 strong spiral cords throughout ontogeny and fine prosoclinal threads. Both are cancellate at their junction. Second and third cords from suture rela- tively stronger. Two strong prosoclinal varices located on each whorl and show slight offset on successive whorls. Last varix situated just behind outer lip. Basal cords are relatively fine and closely spaced, 7 to 8 in number. Aperture oval with its height slightly greater than width. Outer lip rounded and inner lip arcuate and reflected. Both lips are thick. Discussion.—The turbiniform shell outline, Convex whorl sides, predominance of spiral ornamentation and presence of varices are the characteristic features of Onkospira. From the above morphological description the generic posi- tion of the present species seems secure. So far, species of Onkospira have been reported from Europe and Japan ranging in age from the Upper Jurassic to Lower Cretaceous. The discovery of the present species brings down the lower limit of stratigraphic range of Onkospira as far as the Upper Bathonian. The present form resembles Onkospira gracilis Zittel, 1873 (Knight et al., 1960, fig. 203, 1) reported from the Tithonian of the Czech Republic. But O. gracilis is characterised by strongly convex, more numerous whorls, prominent collabral riblets and varices showing alignment on successive whorls. The present species differs from Onkospira haipensis described by Kase (Kase, 1984, pl. 11, figs. 9-12) mainly in shell ornamentation. In some variants of O. haipensis, spiral cords are strong and tubercles are present at the intersec- tion. Etymology.—After Kutch, western India, from where the specimens have been collected. ? Subfamily Calliostomatinae Genus Proconulus Cossmann, 1918 — Figure6. 1-3. Riselloidea elongata sp. nov. from Bed 1, Jumara, 3. apertural, abapertural and basal views ; note two rows of spiral carinae and basal cords lacking granulation. apical part damaged, JUM/g 139; apertural and abapertural views. basal views. ta-c. Holotype, JUM/g 138, apical part damaged ; 2a, b. Paratype, 3a, b. Paratype, complete shell, JUM/g 141, apertural and 4-6. Onkospira kutchensis sp. nov. from Bed 1, Jumara, «3. 4a-c. Holotype, apical part damaged, original shell preserved, JUM/g 45, apertural, abapertural and basal views ; note slight offset of varices in last two whorls (4b). 5a, b. Paratype, complete shell, JUM/g 46, apertural and adapertural views. preserved, JUM/g 47, apertural and abapertural views. 6a, b. Paratype, apical part damaged, original shell 7a-c. Proconulus jadavpuriensis sp. nov. from Bed 1, Jumara, x3, Holotype, complete shell, JUM/g 76, apertural, abapertural and basal views; note abapertural view showing very fine opisthocline threads near aperture. 278 Shiladri S. Das et al. Type species.— Trochus guillieri Cossmann, 1885 ; original designation. Proconulus jadavpuriensis sp. nov. Figures 6-7; 7-1,2 Material.—Sixty-two specimens. JUM/g 76-137. Speci- men JUM/g 76 is designated holotype; the rest are par- atypes. Most of the specimens are intact and have the original shell preserved. JUM/g 81-86 were collected from Bed 7 and the rest are from Bed 1 of Jumara. Diagnosis.—Average-sized Proconulus (15 to 20 mm high) ; smooth shell; whorls less numerous; flat in early stage, feebly concave later, periphery marked by angular keel; base feebly convex. Description.—Shell small, maximum height 20 mm; anom- phalous, thick, conical; acute juvenile whorls ; trochiform with height slightly greater than diameter. Apical angle ranges between 50° and 60’; whorls less numerous, five in number including protoconch, separated by impressed suture. Protoconch conical, consists of two smooth, rounded whorls. Spire moderately high, occupying about one-third of shell height. Whorls flat or feebly concave in early stage, concavity increases during ontogeny. Periphery is sharply angulate like a carina, which occurs just above suture. Body whorl large with diameter slightly greater than height. Shell smooth except for some fine prosocline threads, especially prominent near aperture of adult speci- mens; base rounded. Aperture circular to subquadran- gular, width of aperture slightly greater than height, base of aperture rounded. Both outer and inner lips thick, collumel- lar part has a thick callus. Discussion.—The shell shape of the present species has a close correspondence with some species of Epulotrochus Cossmann, especially E. epulus (d'Orbigny, 1850). Szabo (1981), while describing the Hungarian Lower to Middle Jurassic gastropods, also observed the same similarites. Some smooth variants of his Proconulus epuliformis Szabo (1981, pl.1, figs.6-8) shows a striking resemblance to E. epulus. Szabo (1981) and Kase (pers. comm., 1992) acknow- ledged the need for a revision of these genera. The present species has thick callus and from the nature of the nucleus whorl and ornaments it is retained within Proconulus. Present study includes numerous specimens, which enable us to examine both ontogenetic and intraspecific variations. The population shows low intraspecific variabil- ity. The present species shows a resemblance in shell shape to Proconulus rimosus Szabo (1981, pl. 1, figs. 9-13), though the latter species has a wide range of variation in this respect. However, P. rimosus is an ornamental form with prominent spiral elements, which are even tuberculated in the early stage. The present species has a smooth shell except for some fine, faded axial threads which appear only at the adult stage in some variants. It is further character- ised by slightly concave whorl and marked angular keel just above the suture. Proconulus jadavpuriensis sp. nov. closely resembles Proconulus brutus (d’Orbigny) (1853, p. 283, pl. ccxv, figs. 13- 16) (Cossmann, 1885, p.285, pl. vii, figs. 28,24; Cox and Arkell, 1948-50, p. 59 ; also see Fischer, 1997, p. 112, pl. 19, figs. 6, 7) described from the Great Oolite of England. The latter species has a similar shell and apertural shape with a convex base, but differs in shell ornamentation, being char- acterised by five strongly tuberculate spiral bands and a very obscure suture while the present species has a smooth shell and very impressed suture. Besides, the present species has a concave whorl outline. Proconulus epuliformis has a more or less similar whorl outline and smooth or feebly ornamented shell but differs in having a high conical shell, more numerous whorls and flattened base. Moreover, the present species is character- ised by a well marked angular keel and impressed suture. P. jadavpuriensis sp. nov. exhibits some degree of resem- blance to the upper Bajocian species Proconulus acanthus (d’Orbigny) (1853, p. 273, pl. 312, figs. 9-12) (also see Fischer, 1997, p.107, pl.19, figs. 4a, b, 5) described from Port-en- Bessin (Calvados) in overall shell outline with angular periph- ery, size and apical angle. However, the present species differs from the latter in having a distinctly concave whorl outline, impressed suture and smooth shell except for some prosocline threads near the aperture, while the latter is distinguished by straight whorl outline and finely granular spiral cords. Etymology.—After Jadavpur University. Suborder Neritopsina Superfamily Neritacea Family Neritopsidae Subfamily Neritopsinae Genus Neritopsis Grateloup, 1832 Subgenus Neritopsis s. str. Type species.—Neritopsis moniliformis Grateloup, 1832 ; original designation. Neritopsis (Neritopsis) patchamensis sp. nov. Figure 7-3—5 Material.—Eight specimens. JUM/g 1-3, 5, 8-11. Holotype, JUM/g1; the rest are paratypes. The specimens have their original shell preserved and were collected from Bed 1 of Jumara. Diagnosis.—Small Neritopsis (8 to 11mm high); whorls rounded with wide, gently sloping ramp; spire slightly protruding ; whorls cancellated, both axial and spiral cords of equal strength, axial cords numerous (12 to 16) on body whorl ; aperture very large, axially ovate with slight angula- tion near suture. Description.—Shell small in size, maximum height about 11 mm, moderately thick, subglobose ; height of shell about three-fourths of shell diameter. Apical angle ranges between 110° and 120°. Whorls rounded with wide gently sloping ramp, slightly angulate at suture. Protoconch not well discernible, but appears to be smooth and consisting of about two whorls. Spire short, body whorl very large and Jurassic Gastropoda from India 279 increases rapidly in diameter. Suture impressed, running along a furrow. Whorls cancellated throughout later ontogeny, resulting from intersection of axial and spiral cords of equal strength. Axial cords 12 to 16 in number on body whorl, prosocline in beginning but becoming gentler during ontogeny. Spiral cords 10 to 14 in number on body whorl and irregularly spaced. Aperture very large, axially ovate and slightly angulate near suture ; inner lip slightly thickened by callus accompanied by a shallow furrow running parallel to it and resulting in a pseudoumbilicus. Discussion.—Neritopsis (Neritopsis) patchamensis sp. nov. shows some degree of resemblance to the Lower and Middle Jurassic forms from Europe (Szabo, 1982 ; Conti and Szabo, 1989). It differs from Neritopsis (Neritopsis) papodensis Szabo (1982 pl.1, figs. 6-9) in having a less protruded spire and less convex whorl surface with relatively broader ramp. It is coarsely ornate with stronger axial elements than in N. (N). papodensis. The present species, although it resembles strongly Neri- topsis abbas Huddleston (1894, p. 341, pl. XXVII, figs. 11a-c) (also see Conti and Szabo, 1989, pl.1, figs. 10-11) in shell shape, is much smaller in size with a less protruded spire. In N. abbas, spiral cords dominate with very faint axial growth lines near the aperture, but in the present species, axial elements are equally prominent and cut across the spiral cords resulting in a conspicuous cancellate ornamentation. Neritopsis (Neritopsis) spinigera Szabo (1982, pl. 1, figs. 10- 18) has been described on the basis of mostly damaged specimens. It, however, can be distinguished by its bicar- inate ornamentation, long spine and fewer and stronger axial elements. The Middle Jurassic (Bajocian—Bathonian) form Neritop- sis (Neritopsis) bajocensis d'Orbigny (1852, p.223, pl. 300, figs. 8—10 ; Fischer, 1997, p. 86, pl. 17, figs. 14a—c, 15a—c) can be compared with the present form in general globose shape and apertural outline. Close examination reveals that in the present species the height is less than the diameter while in the European form it is just the reverse. Further, the Kutch species has strongly cancellated ornamentation in the later ontogeny resulting from intersection of equally strong axial and spiral cords, but the European form has dominant spiral cords with very feeble axial elements. Besides, the Kutch species is less than half the size of N. (N.) bajocensis. Etymology.—Refers to the Patcham Formation in which the species is exclusively confined. Subgenus Hayamiella Kase, 1984 Type species.—Neritopsis (Hayamiella) japonica Kase, 1984 ; original designation. Neritopsis (Hayamiella) sankhamala sp. nov. Figure 7-6, 7 Material. Ten specimens, JUM/g 4,6, 7,12-18. JUM/g 6 is designated holotype; the rest are paratypes. The specimens have their original shell preserved. The present collection has been made from Bed 1 of Jumara. Diagnosis.—Small size for genus (6 to 8 mm high); narrow ramp, whorls bordered by subcarinate angulation; spire slightly protruding, suture impressed with a subsutural chan- nel; cancellate ornamentation, axial element developed into varices, irregularly spaced, 6 to 9; spiral cords 9 to 13; prominent tubercles at intersection of spiral and axial ele- ments ; aperture circular to slightly axially ovate. Description.—Shell small in size, maximum height achieved 8mm; low-spired and naticiform. Shell diameter greater than height. Apical angle ranges between 105° and 122°. Narrow ramp, whorls bordered by subcarinate angula- tion. Protoconch seemingly smooth but number of whorls not discernible, may consist of more than one whorl, spire slightly protruding. Body whorl large, rapidly widening. Suture impressed with a prominent subsutural channel. Cancellate ornamentation with much stronger axial ele- ments. Varices become stronger and interspace increases ontogenetically. Varices 6 to 9 in number on body whorl and orthocline. Spiral cords 9 to 13, strength varies, stronger ones irregularly intercalate with finer cords. Fine but promi- nent tubercles appear at intersection of spiral cords and varices. Aperture very large, near circular to slightly ovate axially ; inner lip with narrow callus. Furrow running parallel to inner lip, resulting in a pseudoumbilicus. Discussion.—Kase (1984) erected a subgenus Hayamiella within the genus Neritopsis and described N. (H.) japonica Kase (p. 84, pl. 8, figs. 6a-c, 17) from the Upper Aptian of Japan as type species. He distinguished Neritopsis s. str. from Hayamiella on the basis of the presence of spiral cords, larger shell size and wider shell outline. He also admitted that distinction may not be very clear as there exist some intermediate forms (see also Hayami, 1960). The present species is characterised by small shell size, globose shape and coarsely cacellated ornamentation with much stronger axial elements, but it has a wider shell outline. Because of the similarities in many diagnostic characters we place the present species within the subgenus Hayamiella. The present species has similarities with the type species N. (H.) japonica in many important morphological characters like small shell size, globose shape and cancellated orna- mentation, so that their inclusion within the same subgenus is justified. However, N. (H.) sankhamala is still smaller in size, wider in outline and having fewer but stronger axial elements than N. (H.) japonica. Moreover, the type species comes from a higher stratigraphic horizon (Aptian). The present species is closer to Neritopsis (Neritopsis) patchamensis sp. nov., but is relatively smaller in diameter with a narrower ramp area. Its axial elements are stronger and fewer on body whorl. Besides, it differs in having subcarinate angulation, tubercles, a circular aperture and a subsutural channel. Neritopsis (Hayamiella) sankhamala sp. nov. is comparable to some European forms. It is close in size to Neritopsis dumortieri Conti and Szabo (1989, pl. 1, figs. 12-13) from the Southern Alps. This European species is based on the monotypic holotype, which is a damaged specimen. N. dumortieri bears three rows of spiral carinae and transverse elements of equal strength. Long hollow spines are present at the intersection point. The present species, on the other Shiladri S. Das et al. 280 Jurassic Gastropoda from India 281 hand, possesses strong varices and small tubercles. Neritopsis (Neritopsis) spinigera Szabo (1982, pl. 1, figs. 10- 18) differs mainly in having a more closely ornate form with long spines and more protruded spire. The present species shows a remarkable correspondence in size, shape and ornamentation to Neritopsis (Neritopsis) elegantissima Hörnes (1853, p. 763) (Szabo, 1982, pl. 1, figs. 1- 3), but closer examination reveals that the Kutch form has a circular aperture, varices6 to 9 in number, subcarinate angulation and tubercles. Moreover, N. (N). elegantissima comes from a much older horizon of the Lower Jurassic (U. Sinemurian). Neritopsis (Hayamiella) sankhamala sp. nov. has a close resemblance to Neritopsis guerrei Hebert and Deslong- champs (1860, p.185, pl.|, figs. 4a-d) described from the Great Oolite of England (see also Cox and Arkell, 1948-50, p. 64). One variant even appears to be more close in having similar distant and unevenly placed axial elements. The present species, however, can be distinguished by its rela- tively distant spiral cords, stronger varices and presence of prominent tubercles. Etymology.—Refers to an Indian ornament—a chain of small and globular gastropod shells Genus Hayamia Kase, 1980 Type species.—Hayamia rex Kase, 1980 (in Kase and Maeda, 1980) ; original designation. Hayamia mitra sp. nov. Figure 8-1—3 Material —Five specimens, JUM/g 31-34, 597. JUM/g 31 is designated holotype, the rest are paratypes. JUM/g 32, 33 are internal moulds, the holotype and one of the par- atypes (JUM/g 597) represent composite state of preserva- tion. JUM/g 34 with shell remains. JUM/g 31,33 were collected from Bed 1, JUM/g 597, from Bed 6, JUM/g 32, from Bed 7 of Jumara; JUM/g 34 from Bed 2, Keera (see Bardhan et al., 1994). Diagnosis.—Medium-sized Hayamia (about 24 mm high); height less than diameter, spire slightly protruding, suture impressed with prominent subsutural channel, aperture large ; prominent, numerous spiral cords with finer subordi- nate ones in between. Description.—Shell medium-sized, maximum height achieved 24mm; phaneromphalous ; moderately — thick, ovate and naticiform in outline with height of shell is about three-fourth of shell diameter. Apical angle ranges between 120° and 160°. Whorls rapidly expanding, convex in outline ; whorls make two and a half volutions. Protoconch is not well discernible. Spire slightly protruding, about one- eighth of shell height. Body whorl very large, increases rapidly in diameter with a wide and weakly convex sutural ramp. Suture impressed with subsutural channel. Shell is ornamented with prominent and widely spaced spiral cords and several subordinate ones in interspaces; spiral ele- ments are intercepted by very faint axial growth lines obser- ved particularly near peristome; internal mould smooth. Aperture very large, elliptical in outline and expanded in direction oblique to axis. Height of aperture slightly greater than width. Both outer and inner lips thin and entire. Thin and somewhat obscure callus covers inner lip. Operculum thick, solid and elliptical in outline, its outer surface or- namented with both radial and concentric elements, abaxial part broken, but its adaxial margin has a curvaceous chevron shaped-outline. Discussion.—Kase (1980) introduced the genus Hayamia (Kase and Maeda, 1980, pl. 35, figs.3—10) in the family Neritopsidae from the Lower Cretaceous of central Japan to distinguish it from Neritopsis. The genus also includes some previously described Jurassic and Cretaceous species of Neritopsis. The main features which characterise Hayamia are spiral striae with or without costellae, absence of parietal tubercles and an elliptical operculum lacking any quadrangular process at the adaxial edge ; although there is a certain amount of similarity with Neritopsis, these features probably confer an independent status to the genus. While Hayamia is included in the subfamily Neritopsinae, it has opercular feature resembling that of Naticopsis belonging to the subfamily Naticopsinae. Thus, it appears that Hayamia occupies an intermediate position between Neritopsis and Naticopsis. The actual phylogenetic relationship among the three genera is not yet clear (Kase. pers. comm., 1999) and has to be worked out by detailed study of properly weighted characters linking and separating them. In consonance with its genus the Kutch species Hayamia mitra sp. nov. has also a similar status and presently we place the species provisionally under the subfamily Neritopsinae. The Kutch species displays some resemblance to the type species Hayamia rex Kase (in Kase and Maeda, 1980, pl. 35, figs. 5—10) in size and surface ornamentation. But it differs from the latter in its overall shape with shell diameter measuring more than height, less protruded spire and slightly asymmetric elliptical operculum. Hayamia chosiensis Kase (in Kase and Maeda, 1980, pl. 35, figs. 3—4) also bears some similarity with the present species, but differs in having more dense spiral striae, more protruded spire and circular aper- ture with curved angulation at the adapical part. Etymology.—The species is named in honour of late K.C. Mitra, a renowned palaeontologist in the Department of — Figure 7. 1,2. Proconulus jadavpuriensis sp. nov. from Bed 1, Jumara, 3. 2a, b. Paratype, peristome slightly damaged, JUM/g 79, apertural and abapertural views. 3- g 77, apertural and basal views. la, b. Paratype, broken at apical part, JUM 5. Neritopsis (Neritopsis) patchamensis sp. nov. from Bed 1, Jumara, <3. 3a-c. Holotype, JUM/g 1, apertural, abapertural and apical views ; apical view showing closely spaced axial cords. 4. Paratype, JUM/g 3, apical view. 5. Paratype, body whorl broken, JUM/g 9, abapertural view. 6,7. Neritopsis (Hayamiella) sankhamala sp. nov. from Bed 1, Jumara, X4. 6a, b. Holotype, JUM/g 6, apical and abapertural views showing distant and strong axial cords. g 16, apertural, abapertural and apical views. 7a-c. Paratype, young shell, JUM 282 Shiladri S. Das et al. CRETE Jurassic Gastropoda from India 283 Geological Sciences of Jadavpur University. Order Caenogastropoda Superfamily Naticacea Family Naticidae Subfamily Globulariinae Genus Globularia Swainson, 1840 Type species.—Ampullaria sigaretina Lamarck, 1804 ; orig- inal designation. Globularia spathi sp. nov. Figure 8-4—6 Material—Eight specimens. JUM/g 23-30. Holotype, JUM/g 23; the rest are paratypes. Three specimens are intact and rest are broken. Mostly internal moulds, in three specimens (JUM/g 23, 24, 25) part of the original shell is preserved. JUM/g 23 was collected from Bed 1, JUM/g 24, 26-30 from Bed 7 of Jumara and JUM/g 25 from Keera. Diagnosis.—Medium-sized Globularia (about 30 mm high) ; spire relatively high; suture impressed throughout; um- bilicus narrowly open, sheath narrow ; aperture subelliptical ; ornamented with fine prosoclinal growth lines conspicuous near aperture. Description.—Shell of medium size, maximum height about 30 mm; globose, moderately thick, phaneromphalous and naticiform in outline with height slightly smaller than diame- ter. Apical angle ranges from 95° to 106. Whorls at least five in number, separeted by deeply channelled suture bordered by sharp periphery. Protoconch not discernible. Spire relatively high, obtusely conical, occupying about one- fourth to one-sixth of shell height. Body whorl with height slightly higher than diameter. Whorls convex, angulation present near suture. Whorl surface ornamented with fine prosoclinal growth lines conspicuous near aperture. Aper- ture wide, subelliptical in outline, with height nearly twice width, acute above and broadly rounded below. Parietal area covered by thick callus. Umbilicus narrowly opens ; sheath narrow. Discussion.—In a recent major taxonomic revision of the family Naticidae, Kabat (1991) has stabilised many family and genus level names. He removed Natica fluctuata G.B. Sowerby, 1825 from Globularia and designated it as the type species of Cernina Gray, 1847. This is the largest naticiform species collected from Kutch. Globularia (Nanggulania) puruensis (Martin, 1914) (Wenz, 1941, fig. 2933) has a very short spire, both axial and spiral threads and a large aperture. In the present species, the spire is comparatively long, only prosoclinal growth lines are present as surface ornamentation and the aperture is smaller than that of G. (N.) puruensis. The present species can be compared with Globularia (Globularia) izumiensis Kase (1990, figs. 216-22, 2.25). Kase's species has a shell diameter greater than the height, low spire, and weakly impressed suture in early whorls. Further, it has a flattened upper whorl surface and subovate aperture. In contrast, the present species has a shell diameter smaller than its height, a more protruding spire, and a strongly impressed suture all through during growth. Aperture is subelliptical and whorls have a convex upper surface with angulation near the suture. The present species resembles Globularia rupellensis (d’Orbigny) (1852, p. 203, pl. 293, figs. 1-3) (see Fischer, 1997, p. 77, pl. 16, figs. 1a, b, 2) from the Oxfordian—Kimmeridgian of Europe in general shell outline, apical angle, apertural shape etc. But the European form is much larger, the largest being about three times that of the present species. However, the obvious difference lies in the nature of the ornamentation. G. rupellensis is characterised by spiral striae with punctuation along their alignment, whereas the Indian species is ornamented with fine prosoclinal growth lines. Moreover, the suture of the present species remains deeply impressed all through ontogeny. The present species is comparable with Globularia zangis (d’Orbigny) (1852, p. 198, pl. 291, figs. 10-11) (also see Fischer, 1997, p. 74, pl. 15, fig. 9) from the Callovian of France but differs in having a smaller shell size, higher apical angle and flatter outer whorl surface in early ontogeny. The ornamen- tal aspects, however, cannot be compared since the holotype of the European form is an internal mould. A close correspondence can be observed between the present species and Globularia? sp. described by Sohl (1965, pl. 4, figs. 10-15) from the Middle Jurassic Carmel Formation of Utah, North America. Sohl’s specimens are undoubtedly G/obularia with the diagnostic narrow sheath. Sohl compared them with some British Jurassic gastropods (Cox and Arkell, 1948-50, p. 83). His form is similarly high- spired like the present species, but is smaller and less globose. The smoothness of the American specimens, however, may be attributed to complete silicification, which might have destroyed the finer details of ornamentation. Etymology.—Named in honour of L.F.Spath, a famous palaeontologist. Acknowledgements The authors wish to express their deep gratitude to Tomoki Kase, National Science Museum, Tokyo, Japan for his critical reading of an earlier version of the manuscript and valuable suggestions. Dr. Kase also helped in making — Figure 8. 1-3. Hayamia mitra sp. nov. “2. 1a-c. Holotype, JUM/g 31, from Bed 1, Jumara, apertural, abapertural and apical views ; mostly internal mould, part of shell remains near aperture, apical part damaged, well preserved operculum. 2a, b. Paratype, internal mould, from Bed 1, Jumara, JUM/g 33, abapertural and apical views. 3. Paratype, from Bed 2, Keera, JUM/g 34, with shell remains, showing spiral ornaments of variable strength, abapertural view. 4-6. Globularia spathi sp. nov. x2. 4a, b. Holotype, from Bed 1, Jumara, JUM/g 23, mostly shell remains, showing axial ornamentation ; apertural and abapertural views. 5. Paratype, from Bed 7, Jumara, JUM/g 24, abapertural view. 6a, b. Paratype, young shell, internal mould, from Bed 7, Jumara, JUM/g 26, apertural and abapertural views. 284 Shiladri S. Das et al. critical comments on the final version of the manuscript and providing valuable reference materials that helped in improv- ing the paper. The authors also thank the late Sukomal K. Chanda, Jadavpur University, Calcutta, India, for his useful discussion. Deep appreciation is also due to Debabrata Pramanick who kindly made available his material for the present study. Amitava Kayal, Debahuti Mukherjee, Sudipta K. Jana and Kalyan Haldar, Jadavpur University helped at various stages in both field and laboratory works. One of us (S.B.) received financial aid from the Department of Science and Technology, India. 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Paleontological Research, vol. 3, no. 4, pp. 287-293, 5 Figs., December 30, 1999 © by the Palaeontological Society of Japan Hilgendorf’s planorbid tree-the first introduction of Darwin’s Theory of Transmutation into palaeontology HORST JANZ Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, D-70191, Stuttgart, Germany Received 31 March 1999 ; Revised manuscript accepted 16 September 1999 Abstract. Franz Hilgendorf (1839-1904)’s palaeontological studies on the Miocene planorbid snails of the Steinheim basin (Germany) frame his scientific work from his dissertation in 1863 to his last publication on this subject in 1901. Hilgendorf discovered that the different planorbids are not mixed in each layer, and noticed gradual transitions between different morphs of successive layers. These findings led to his hypothesis of species transmutation illustrated by his planorbid tree. This was the first phylogenetic tree reconstructed on the basis of real fossil evidence, and therewith it was the first palaeontological example of Darwin’s Theory of Transmutation. Although Hilgendorf did not refer to Darwin emphatically, he can be called the first one who introduced Darwin’s Theory of Transmutation into palaeontology. Key words: Hilgendorf, phylogenetic tree, planorbids, Steinheim, theory of transmutation Introduction Franz Hilgendorf is famous mainly for his zoological work, of which the Hilgendorf Exhibition (Yajima, 1997, 1998) focused on his merits for ichthyology and fishery sciences in Japan. However, his palaeontological work is no less important. Hilgendorf started his scientific career with a palaeontological study on the Miocene planorbid snails of the Steinheim basin. This was the subject of his disserta- tion (Hilgendorf, 1863) and of his first publication (Hilgendorf, 1866), and although he was later on mainly concerned with zoological subjects, the Steinheim snails remained on his mind for the rest of his life. His last paper on the Steinheim snails was published three years before his death (Hilgendorf, 1901). Thus, the planorbid studies frame his scientific work. Already in his first study Hilgendorf recognised gradual transitions between the snails of successive layers. He documented and interpreted these findings in his first publi- cation with a phylogenetic tree, which is the first palaeontological documentation of species transmutation. His hypothesis, heavily disputed at that time, was largely confirmed over the last two decades (Mensink, 1984 ; Gorth- ner, 1992; Povel, 1993; Nutzel and Bandel, 1993; Finger, 1998). Although Hilgendorfs findings were most important for the discussion of Darwin’s Theory, which was published only few years before (Darwin, 1859), Hilgendorf did not refer emphati- cally to Darwin in his papers. On the other hand, Darwin himself mentioned Hilgendorf in his sixth edition of the ‘On the origin of species. ., published in 1872, within Chapter 10 (On the imperfection of the geological record), subchapter ‘On the absence of numerous intermediate varieties in any “ single formation’, as follows: “... Hilgendorf has described a most curious case of ten graduated forms of Planorbis multiformis in the successive beds of a fresh-water forma- tion in Switzerland” [wrong geographic information by Dar- win]. Hilgendorfs historical role has been already recognised by Abel (1929), and the significance of Hilgendorf's studies from a Neo-Darwinian point of view is discussed in detail by Reif (1983a, 1983b, 1985, 1986). To assess whether Hilgendorf was familiar with Darwin’s Theory, the present paper gives a brief chronological survey of Hilgendorf’s planorbid studies, paying special attention to remarks on Darwin and Darwinism. Finally, a brief account of the research on the Steinheim snails after Hilgendorf's death with emphasis on the connection between Hilgendorf’s contribution and the latest work at Steinheim is added. Before that, some information about the Steinheim basin, and also the state of knowledge of the Steinheim snails before Hilgendorf are given. The Steinheim basin-a meteorite crater The Steinheim basin is situated on the Swabian Alb in southern Germany (Figure 1). Today it is known that the basin was formed by a meteorite impact, about 15 million years ago, which is, expressed in geological time, the Middle Miocene of the Tertiary. The Steinheim basin is a complex impact crater structure with an almost circular outline, and a central uplift, called the central hill. The basin has a diameter of about 3.5 km, and is 120m deep today. Soon after the impact the crater filled with water and became a lake. It is supposed that the water supply came mainly from the subterranean karst system and from precipitation. How 288 Horst Janz na | long the lake actually existed is not exactly known. | wa Je N fl | Between some hundreds of thousands to two million years f = SN ( | are suggested. This is what we today call a long-lived lake | en 6) (Gorthner, 1994). At the end of the lake period the basin I. 5: 2% © 9 | was completely filled with lake sediments. The fact that we LS GP (RD AT? D | can recognise the basin again today is due to partial erosion \ N a ye during the Quaternary, the last two million years. However, N g os RE | the lake sediments preserved reach a thickness of 30 to 40 33) eset \s) \ | meters, and are very rich in well preserved fossils. About A I) 100 species of fossil plants and more than 250 species of ° G Berlin e fossil animals have been found so far. The snails comprise ER ) | about 100 species, of which the planorbids are the most \ abundant group. ê > London” / | RS) IS A SS as ‘at ee Sy ) RE a - erh At A = A — | Rx le eae Ss The knowledge of the Steinheim snails IS x ; | before Hilgendorf 3 Steinheim Basin Stuttgart eet Vac Ss. In 1862 when Hilgendorf started his studies not much was 182 wo CS ARS Vire & known about the Steinheim basin, neither about its origin nor 4 a , al its palaeontology. However, the occurrence of amazing BEE EE STE ON quantities of calcareous shells within the Steinheim sands e Woy ae EN was documented for the first time already about 150 years © RN CR before, by the physician Lentilius (1711). Lentilius was fas- N > cinated by the amount and multiformity of these shells, and 100 km £ N it seemed to him enigmatic for what reason God had created VAR such a variety of tiny shells (Figure 2). At that time it was Ye not yet known that these shells are remains of once living = - - À animals, what we call today fossils, but it was believed that Figure 1. Location of the Steinheim basin. all species were created by God and remained unchanged since their creation. This dogma of the fixity of species was still universal when the study of von Klein (1847) was publi- Figure 2. Ensemble of Steinheim snails within the sediment (photo: H. Lumpe, Staatliches Museum fur Naturkunde Stuttgart). The width of the shells is about 4 to 5mm. Hilgendorfs planorbid tree 289 shed. Von Klein's study is one of the first scientific studies of the Steinheim snails and reflects the latest knowledge about this subject at the time when Hilgendorf started with his studies. Von Klein distinguished five planorbid species, four of which he allocated to the genus Planorbis, and one to the genus Valvata. From the latter species, called Valvata multiformis, he distinguished five varieties. According to von Klein all of these species and varieties occurred always mixed within each layer of the Steinheim deposits. Hilgendorfs dissertation and first publication Before Hilgendorf went to Tübingen he had studied in Berlin for two years. He came to Tubingen in 1862, attract- ed by Friedrich August Quenstedt, in order to study palaeontology. Quenstedt was a professor of geology and palaeontology at the University of Tubingen, and became famous by his comprehensive stratigraphical investigations of the Jurassic Swabian Alb by means of ammonites. In the autumn of 1862, Hilgendorf accompanied Quenstedt on an excursion to Steinheim, during which he first became ac- quainted with the Steinheim basin and its snails. By collecting snails in Pharion’s sand pit on this excursion, as well as during the following weeks, Hilgendorf discovered that the different varieties of Valvata multiformis are never mixed, but that they occur separately in the different layers. From the lowermost beds onwards he noticed a sequence of flat or planispiral shells to trochispiral shells and again to planispiral ones in the upper parts of the section. Moreover, the different morphs were connected by transitional morphs. Most surprising was the discovery that transitions were not only found between the different varieties of Valvata multifor- mis but also between species of Planorbis and some of the varieties of Valvata - in other words: he found gradual transitions between two different genera. These findings, of course, were not compatible with the dogma of the fixity of species. Hilgendorf stated these findings in his dissertation which was submitted in spring, 1863. His dissertation comprises 42 pages, and does not include any figures. In the 1980s Prof. Wolf-Ernst Reif from the Palaeontological Institute of the University of Tubingen discovered a collection of 25 cards of thick paper with Steinheim snails glued onto it which could be clearly identified as Hilgendorf's, because of hand-written captions on the cards (Reif, 1983a). While each of the cards from no. 1 to no. 17 contains snails of different beds, the cards no. 18 to no. 25 illustrate transi- tions from one taxon to another, and card no. 24 gives a complete phylogenetic diagram of Hilgendorf's results. Reif (1983a) reconstructed a phylogenetic diagram according to card no. 24 (Figure 3). It corresponds fairly well with Hilgen- dorfs interpretation given in his dissertation, and shows three modes of species transformation in course of time: 1. grad- ual transformation, 2. splitting into two daughter species, and 3. fusion of two species. Actually, Hilgendorf never seriously suggested fusion of lineages, but merely raised it as a doubtful possibility. Considering the planorbid varieties of the third layer (see Figure 3, layer D), he raises the question of whether fusion of Figure 3. Reconstructed phylogenetic diagram of Hil- gendorf's dissertation according to card no. 24. Circled num- bers: either not identifiable (underlined) or missing. Exam- ples for species transformation are: 1. gradual transforma- tion: sequence from no.1 to no.5; 2. splitting into two daughter species: no. 5 splits into no. 9 and no. 10; 3. fusion of two species: no.8 and no.10. Reproduced from Reif (1983a, fig. 3) with permission of Palaontologische Gesell- schaft. two varieties could have led to this situation (Hilgendorf, 1863, p. 26). However, on the last page of his dissertation, there is an additional note to this subject (Hilgendorf, 1863, p. 42): “Darauf würde das schöne Bild, das Darwin uns vom Zusam- menhange der Spezies in einem Zweige-reichen Baume vorfuhrt, nicht passen, die Zweige eines Baumes wachsen nicht wieder zusammen.” [This does not fit the nice picture of a tree with many branches which Darwin presented to illustrate the descent of the species - the branches of a tree never fuse again]. This note also exemplifies that Hilgen- dorf was already acquainted with Darwin’s Theory during his first study. Already after one year at Tubingen Hilgendorf went back to Berlin and continued his studies of natural sciences, especially organic chemistry, but subsequently he concen- trated more and more on zoology. He got a position at the Humboldt Museum, and in 1865 he again started an investi- gation of the Steinheim snails, which was supported by the Royal Prussian Academy of Sciences. This new field work at Steinheim took two months and led to his first publication (Hilgendorf, 1866), which is still today the crucial publication on the Steinheim snails. This paper is based on a study of a large amount of 290 Horst Janz material collected thoroughly bed by bed from three sand pits around the central hill, as well as from the western margin of the basin. Already the title of this paper : “Planor- bis multiformis im Steinheimer Süsswasserkalk” |Planorbis multiformis within the calcareous freshwater deposits of Steinheim], reveals Hilgendorfs solution of the taxonomic problems, which confronted him through his findings. He considered all planorbid snails found to belong to one species, P. multiformis. And the subtitle: “Ein Beispiel von Gestaltveränderung im Laufe der Zeit” [An example of morphological change during time], so to say, gives an explanation for his solution. Moreover, this is also a clear confession of belief in Darwin's Theory of Transmutation. However, Hilgendorf did not refer to Darwin in this paper. The first part of the publication comprises a detailed strati- graphical description of the sections, and a morphological characterisation of the 19 varieties or subspecies of P. multiformis which he distinguished. Using the biostratigra- phical distribution of these subspecies, Hilgendorf subdivided the Steinheim deposits into ten zones or beds. In the second part of the paper he discussed the transitions between subspecies of successive beds. By arranging the sub- species in a stratigraphical scheme and marking transitions between two subspecies by a connecting line, Hilgendorf's phylogenetic tree became graphical. The planorbid tree is illustrated in the middle of the lithographic plate at the end of the paper, surrounded with illustrations of all subspecies, including also cross-sections of the snails. Figure 4 shows a reconstructed and magnified version of this tree. The whole tree arises from a small and planispiral planorbid, called aequeumbilicatus, which is considered the founder population. The branch at the right hand comprises ten bigger morphs. Today, this branch is called the ‘main branch’, and is the most studied and discussed part of the tree so far. Especially the transition between the trochispir- al form trochiformis and the planispiral form oxystommus later became a subject of controversial discussions. While the second branch, in the middle of the tree, splits from the steinheimensis form, and comprises only two forms, the third branch, at the left hand, splits from the founder population, and comprises seven forms. Today, these two branches are called the ‘side branches’. In contrast to the diagram reconstructed by Reif (1983a), according to Hilgendorf's cards and dissertation, this new tree involves only two modes of speciation: gradual trans- formation and splitting, but no fusion. Additionally, the whole tree arises from one founder species. This interpre- tation was compatible with Darwin's Theory. The controversy with Sandberger There was no critical reaction to Hilgendorf’s publication for the first few years, but during the time Hilgendorf was in Japan, Fridolin von Sandberger started to controvert Hilgen- dorf. Sandberger was a professor of geology at Wurzburg, and he was reputed to be an authority on fossil snails. By three very short articles (Sandberger, 1873, 1874a, 1874b), he totally rejected Hilgendorf's interpretation. Sandberger nei- ther accepted the allocation of all Steinheim planorbids to (Gr | 18 8. costatus © 16. crascens 7. oxystomus =@ © ©) 19. denudatus ) Me 9. supremus my YA 11. stegans 6. trochiformis 13. pseudotenuis Cc Ÿ 10. rotundatus @ 17. triquetrus > TG 18. costatus © 4 © 12. kraussii © © 4. sulcatus | 6) 3 tous % Qu (GO) swore oe | €) 1. aequeumbilicatus Figure 4. Reconstructed version of Hilgendorfs 1866 planorbid tree. 15. minutus one species, nor the occurrence of the different varieties of Valvata in a stratigraphically orderly fashion, nor the transi- tions, but sustained von Klein’s concept, and thus the fixity of species. Hilgendorf got wind of Sandberger's criticism in Tokyo, and commented on it in November 1874, with a letter to his friend Eduard von Martens, which was published in the “Zeitschrift der Deutschen Geologischen Gesellschaft” (Hilgendorf, 1875). The controversy lasted till 1877 and reached its summit at the ‘Meeting of Natural Scientists and Physicians’ in Munich. Although the dispute exemplifies Hilgendorf's excellent attitude of being always obliged to the facts, | do not want to discuss it in detail (see Hilgendorf 1877a, 1877b, 1877c, 1877d). Summarising, the following assessment can be given: 1. The background of Sandbergers attacks had been only to a minor extent a dispute against the validity of Darwin's Theory. Unfortunately, the dominant motivation for his rigid attitude apparently was his antipathy toward the Prussians (See Hilgendorf, 1879, p. 90). 2. However, responding to Sandbergers accusation, Hilgendorf had checked his findings again and again by field Hilgendorfs planorbid tree 291 investigations, and had found more evidence of his hypothe- sis. 3. Despite the trouble that Hilgendorf had to suffer from this controversy, another positive effect was that his findings became well known in professional circles, and finally most of the experts accepted his hypothesis. In order to demonstrate the stratification, as well as the transitions, at the Munich Meeting, Hilgendorf had collected new material and had taken photographs during his third season of field activities in Steinheim, which took nine weeks. One of these photos, actually assembled from two photos, is a panoramic view of the western side of the central hill. At that time, the sand pit had still a large expanse. Another photo taken by Hilgendorf himself shows a detail of Pharion’s sand pit, obviously taken to demonstrate the stratification, because it shows the same part of Pharion’s sand pit as a sketch drawn by Hilgendorf. Hilgendorfs planorbid papers after 1877 Concerning Hilgendorf's familiarity with Darwin’s Theory, his publication of 1879 (Hilgendorf, 1879) provides most clear evidence. This paper was published in the journal “Kos- mos” which was founded only two years before, in 1877, for the purpose of promoting the concept of natural evolution. On the editorial board appear the names of Charles Darwin and Ernst Haeckel. Haeckel was the most prominent exponent of Darwinism in Germany, and had coined the term “Phylogenie” in 1866. Hilgendorf (1879) gives a full account of his data and his theoretical concepts. The paper contains a newly drawn phylogenetic tree, showing most of the snails in cross- sections (Figure 5). The tree is almost identical with that of 1866, except that the founder population is missing. Already in 1866 Hilgendorf was in doubt whether there was only one planorbid form in the lowermost beds from which all the other forms had been developed. Now he withdrew this hypothe- sis, because it seemed to him that too little was known about the deposits on the western margin of the basin where this form occurs. In this paper Hilgendorf also formulated a concept for the recognition of evolutionary lineages in palaeontology including the practical method of bed-by-bed investigation. Finally, he summarised his data and his inter- pretations in 27 theorems. These theorems also contain problems and hypotheses, which became a subject of discussion only later, for example the law of irreversibility of evolutionary changes. Nevertheless, Hilgendorf did not speculate on the reasons for the species transmutation in the Steinheim basin. This seemed to him still too early, but he gave some hints for further investigations, for example to check the embryonic part of the gastropod shells, which should provide evidence for speciation, and to check other groups of Steinheim fossils for transmutation (Hilgendorf, 1879, p.94 and 98). Hilgendorf mentioned in his paper of 1879 also the findings of Neumayr and Paul (1875) who had also found gradual transformations in Tertiary gastropods of Slovenia. In a footnote of their paper they credited Hilgen- dorf as the first one who had provided evidence for gradual transformation by a detailed palaeontological study. oD trig RD | dE cos par GS STD stein \ Ye N / + Figure 5. Planorbid tree of Hilgendorf (1879). Re- produced with permission of Kosmos. After 1879, two additional papers of Hilgendorf (1881, 1901) on the Steinheim snails were published. In 1881 he com- mented on the paper of Hyatt (1880). Hyatt was an Amer- ican scientist, who had been studying the Steinheim snails since 1872. Then, Sandberger had claimed that Hyatt’s view would support his statements and would disprove Hilgendorf’s interpretation. But in fact, Hyatt was a Dar- winian, and was attracted to this study by Hilgendorf's first publication. Generally speaking, Hyatt’s findings support Hilgendorf's interpretation, except for some differences in the question of the stem species and the transition between the trochispiral and the planispiral form. Moreover, Hyatt promoted Hilgendorf's subspecies to species rank. In his last paper Hilgendorf (1901) once again took care of the most disputed transition between the trochispiral and the planispiral form, and illustrated the transitions by a series of photographs. The planorbid tree after Hilgendorf’s death From 1901 to the present day more than 30 papers on the Steinheim planorbids have been published. Till the begin- ning of the last decade the most important steps confirming Hilgendorf’s findings were made by Gottschick (1920) and Wenz (1922), as well as Mensink (1984). Gottschick and Wenz have been the first who examined again the Steinheim 292 Horst Janz snails of all beds in detail. Although, in contrast to Hilgen- dorf, they regarded the morphological changes of the planor- bids as ecophenotypic, they fully confirmed the occurrence of the different morphs within the different beds. Mensink also studied the planorbids of all beds, and additionally he checked the occurrence of Hilgendorf's main branch planor- bids at a large number of sites spread over the whole Steinheim basin. Moreover, Mensink demonstrated the gradual transitions of the main branch planorbids by means of biometrical investigations. The significance of Gott- schick’s and Mensink’s results are discussed in detail by Reif (1985), and recently, Mensink’s data set was reconsidered by means of multivariate methods (Povel, 1993). In connection with Hilgendorfs (1879) hints for further investigations mentioned above, i.e., to study the embryonic part of the shells and to check other groups of Steinheim fossils, both approaches were carried out only during the last decade, more than 100 years after Hilgendorf’s publication. With respect to the embryonic part of the gastropod shells (protoconch), Gorthner (1992) and Nützel and Bandel (1993) were able to show by means of SEM analyses of the protoconch structures that both Hilgendorf's main branch and side branch planorbids are valid species. Moreover, the most recent study shows by such protoconch analyses that Hilgendorf's aequeumbilicatus, which is called Gyraulus kleini today, did not consist of three different species giving rise to three lineages as Gottschick (1920) suggested, but that Gyraulus kleini was the only founder species of the whole planorbid lineage (Finger, 1998). Hilgendorf’s second hint, to check other Steinheim fossils for morphological changes, was taken up in a detailed bed by-bed study of the Steinheim ostracods (Janz, 1992, 1997). Ostracod shells are the most abundant fossils among the Steinheim deposits, and there are also some species which show morphological changes through the profile. In the genus Leucocythere, speciation by a splitting event was detected (Janz, 1992), and the splitting hypothesis could be supported by a detailed study of the microfeatures of Leucocythere shells by Viehofen (1997). Moreover, the ostracod assemblage shows a pattern of shell alteration through the profile similar to that of the planorbids (Janz, 1993, Janz, in press). As to the reasons for these alterations, on which Hilgendorf did not speculate, there are two major factors possibly provoking evolutionary changes in both snails and ostracods : long-term ecological changes, as well as the longevity of the lake. While the long-term ecological changes were mainly due to lake level fluctuations, the longevity of the former Lake Steinheim was postulated by Gorthner and Meier-Brook (1985) because of the similarity of the heavily sculptured planorbids with endemic species of extant ancient lakes. Conclusions Summing up this brief chronological survey of Hilgendorf's studies on the Steinheim snails, it can be concluded : 1. By looking at Hilgendorf’s palaeontological work more closely, it becomes evident that Hilgendorf was already a convinced Darwinian from the beginning of his studies. 2. Hilgendorf set a high value on demonstrating the objectivity of his methods of working based on an inductive approach, and perhaps for this reason did not refer to Darwin in his papers. 3. Nevertheless, he applied Darwin’s Theory of Trans- mutation by his interpretation of the Steinheim snails, and therefore he can be called the first one to introduce Darwin's Theory into palaeontology. 4. Hilgendorfs interpretation has been generally con- firmed by further studies, and hints he had given have led to findings supporting his hypothesis. However, there are still many questions to be answered, in order to fully understand the Steinheim planorbid tree. Acknowledgements | am much indebted to Michiko Yajima for stimulating me to write this paper by organising an exhibition as well as a symposium on Franz Hilgendorf in Japan. | also thank her very much for her continuous interest and helpfulness. The two referees, Wolf-Ernst Reif and Roger D. K. 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Journal of Geography vol. 107, p. 872-878. (in Japanese with English abstract) Paleontological Research, vol. 3, no. 4, pp. 294-302, 6 Figs., December 30, 1999 © by the Palaeontological Society of Japan Keraocarpon gen. nov., magnolialean fruits from the Upper Cretaceous of Hokkaido, Japan TAMIKO OHANA', TATSUAKI KIMURA’ and SHYA CHITALEY’ Institute of Natural History, 24-14-3 Takada, Toshima-ku, Tokyo 171-0033, Japan Cleveland Museum of Natural History, 1 Wade Oval Drive, University Circle, Cleveland, Ohio 44106-1767, U.S.A. Received 12 March 1999 ; Revised manuscript accepted 20 September 1999 Abstract. Upper Yezo Group are described in this paper. Two new permineralized magnolialean fruits derived from the Coniacian-Santonian strata of the Each fruit consists of floral head, convex receptacle and woody peduncle. Floral head consists of many conduplicate follicles with adaxial opening. Follicle is long stalked, unilocular and many seeded. Since the fruits differ from the already known ones of Magnoliales, a new genus Keraocarpon is proposed to include two new species, K. yasujii and K. masatoshii. A brief comparison of Keraocarpon to other magnolialean taxa is made. These two new species are distinguished from each other by the differences in size of various elements, number of follicles in the aggregate fruits, number of seeds per follicle, and other minor characters. The genus is character- ized by aggregate fruits of many-seeded apocarpous stalked follicles on a slightly convex receptacle. Key words: Aggregate fruits, follicle, Hokkaido, Japan, Keraocarpon, Magnoliales, Upper Cretaceous Introduction In 1980, Yasuji Kera collected a permineralized specimen of a magnolialean fruit from an ammonite-bearing floated nodule in the Kumaoizawa (brief map, see Ohana and Kimura, 1993, fig. 1), Mikasa City, Hokkaido. Around this locality, the fossiliferous Yezo Group of marine origin is exposed, and the coexisting ammonites indicate a Coniacian-Santonian age (Ohana and Kimura, 1991). This specimen was briefly described by Ohana and Kimura (1987) as an unnamed magnolialean flower. Masatoshi Kera collected later a smaller specimen of the same kind along the bank in the upper course of the Ikushunbetsu River, which might be derived from the Upper Yezo Group. After an extensive study of these specimens, this paper now describes them in detail as new fruits under a new name Keraocarpon gen. nov. Ohana, Kimura and Chitaley, with description of two new species K. yasujii and K. masatoshii. The genus and species described here have seeds inside the follicles and thus a new generic name Keraocarpon is better suited, instead of Keranthus. Materials and methods Both the fruits are permineralized. Their cells and minor structures are partly disintegrated by the subsequent crystal- lization of calcite. Two permineralized specimens are cut as indicated by arrows in Figure 2-2 and Figure 5-2. Cutting surfaces were polished with carborundum abrasive and then etched with diluted HCI for half a minute. Peels on cellulose-acetate film were taken from the etched surfaces after washing off the acid with water. Cellulose-acetate film 0.034 mm thick (‘Bioden, R. F. A.', Oken Co., Tokyo) was used to make the peel sections. The specimens and their peel sections are kept at the Institute of Natural History, Tokyo (INH). Systematic description Class Magnoliopsida Order Magnoliales (Family unknown) Keraocarpon Ohana, Kimura and Chitaley gen. nov. Etymology.—After Y. Kera who collected the type speci- men of Keraocarpon yasujli. Type species.—Keraocarpon yasujii Ohana, Kimura and Chitaley sp. nov. Generic diagnosis.—Keraocarpon is a member of the woody polycarpous aggregated group of magnolialean fruit. Follicles stalked, many-seeded and spirally arranged on the receptacle. Keraocarpon is unique in external form but vegetative parts and male organs are unknown. In transverse section, stalks have a large central pith, collateral bundles, and thin inner and thick outer cortices. The bundles consist of vascular elements with scalariform thicknings. Seeds: The follicle unilocular with many seeds alternately arranged in two rows. Seed coat thick with micropyle facing the adaxial suture of the follicle. Remarks.—The new magnolialean genus Keraocarpon is Keraocarpon gen. nov. 295 distinguishable from other magnolialean fossil genera with apocarpous and conduplicate follicles (e. g. Archaeanthus ; Dilcher and Crane, 1984) in having a long receptacle. Lesqueria (Crane and Dilcher, 1984) has an ovoid receptacle and bifid distal end of the follicle. Protomonimia has a concave receptacle and sessile follicles (Nishida and Ni- shida, 1988). Recently, a magnolialean fructification was reported by Nishida et al. (1996) from the Upper Cretaceous of Hokkaido. According to them, it has more than 170 short-stalked apocarpous and adaxially sutured follicles on the slightly concave receptacle. Follicle has a single dorsal and a pair of ventral strands. The authors created a new genus Hidakanthus on the basis of their single specimen. Exter- nally Keraocarpon differs from Hidakanthus with longitudinally compressed floral head and with short, strongly falcate follicles in the latter. In addition we could not make a detailed comparison of Keraocarpon with Hidakanthus, because in the latter no seeds are preserved in the follicle, and printed scales were omitted in all photographic figures (see Nishida et al., 1996, Figures 2-13). Keraocarpon yasujii Ohana, Kimura and Chitaley, sp. nov. Figures 1A, 2, 3, 4 Unnamed magnolialean flower with apocarpous follicles in Ohana and Kimura, 1987 p. 175, figures 1A-J. Specimen.—INH-020 (holotype). Locality —Kumaoizawa (roughly 142°27’E, 42°42’N), Mikasa City, Hokkaido. Horizon.—Coniacian-Santonian, Upper Yezo Group. Etymology.—After Yasuji Kera, collector of the holotype. Specific diagnosis.—Aggregate fruits large-sized. Receptacle slightly convex, disk-like. Follicles around 470, helically arranged; each follicle 2.4cm long and 2.0mm wide. Seeds numerous, 21-24 in each follicle. Description.—Peduncle : The preserved part is 2.2 cm long and 1.2 cm or more in diameter (Figure 2-2A) consisting of a parenchymatous central pith, 5.0 mm in diameter, sur- rounded by collateral vascular bundles, 1.7 mm each, and cortex, about 1.7 mm wide. The vascular bundles are arran- ged concentrically, and include secondary xylem with scalar- iform vessels, and annular or pitted tracheids. The outer cortex consists mainly of sclerenchymatous cells which are in vertical ribs about 10 rows deep (Figure 2-3, arrows; Figure 4-7). Large cells (possibly resin cells) elliptical in cross section, 0.5 mm in major diameter, are scattered in the cortex ; lining cells are not observed (Figure 4-7). Receptacle: The receptacle is disk-like, slightly convex centrally, 2.7 cm in diameter and more than 6.5 mm thick, consisting mainly of parenchymatous cells and a number of slender fibrous bundles running vertically and horizontally (Figure 2-2B ; Figure 4-8, 9). Follicles : The follicles are numerous and helically arran- ged (Figure 2-2D; Figure 2-5, 6). Parastichy is uncertain, because nearly half of aggregate fruits is missing. The estimated number of follicles is 470 or fewer. The follicles Figure 1. yasujii Ohana, Kimura and Chitaley, gen. et sp. nov. Longitudinally broken fruits. 1A: Keraocarpon Drawn from Figure 2-1 (holotype). 1B: Keraocarpon masatoshii Ohana, Kimura and Chitaley, sp. nov. Drawn from Figure 5-1 (holotype). are apocarpous and conduplicate, typically 2.4 cm long and 2.0 mm wide (Figure 2-2), and circular or oblong, 1.5-2.0 mm in diameter, in transverse section (Figures 2-5, 6 ; Figure 3- 5). Terminal of follicle with obtuse end is polygonal in transverse section (Figure 3-4). Wall of follicle consists of outer and inner layers and has a distinct adaxial median suture which is flanked on either side by a ridge, 150 um high, forming an adaxial crest pair with minor projections (Figure 3-5). Each follicle has a single abaxial vascular bundle (Figure 2-5,6; Figure 3-5). A pair of bundles is present in the adaxial crest. In addition, subordinate lateral bundles are present on the outer layer of the follicle wall (Figure 3-5). Spine-like projections are observed on the outer surface of inner follicles where walls are thinner (Figure 2-6). Stalks : Each follicle has a stalk, 6.0-8.0 mm long and 0.6 mm in diameter (Figure 2-2C ; penetrates inside). In longi- tudinal section, this stalk is inserted into the receptacle (Figure 3-1). In transverse section, it has a large central pith, collateral bundles, and thin inner and thick outer cortices (Figures 3-3, 4). The bundles consist of vascular elements with scalariform thickenings (Figures 4-4, 5, 6). 296 Tamiko Ohana et al. 5mm RE 3 MO DL CT a - = eee. ie cD, ; N £ N N 5 “ah à |) Pa \ à \ J 2 Oe ay Wee . Vlas = As 2 & oy A YS ı rau ; - RM SO MT Sa Ren. bn ee ZH : Ser Ce Le Figure 2. Keraocarpon yasujii Ohana, Kimura and Chitaley, gen. et sp. nov. 1. A permineralized fruit (holotype). Its counter part is missing. 2. A nearly radial longitudinal section of peduncle (A), poorly preserved receptacle (B), stalk of follicles (C) and apocarpous follicles (D). Surface of receptacle is slightly convex (composite photographs). 3. A part of a transverse section of the peduncle, cut at ‘a’-level in Figure 2-2 showing two sclerenchymatous ribs (arrows). 4. Transverse section cut slightly above the receptacle (at ‘b’-level in Figure 2-2). Vacant areas show the spaces among the proximal parts of stalks. 5. Transverse section cut at ‘c’-level in Figure 2-2, showing proximal parts of follicles (right side) and stalks (left side). In this section, stalks (C) correspond to the convex centre of receptacle. Centre of this fruit in this section is marked by the star. 6. Transverse section of follicles each with adaxial suture, cut at ‘d’-level in Figure 2-2. The centre of this fruit in this section is also indicated by a star. Keraocarpon gen. nov. 500um Figure 3. Keraocarpon yasujii, Ohana, Kimura and Chitaley, gen. et sp. nov. 1. Longitudinal section of stalks. 2. Tranverse section of stalks. 3. Enlarged from Figure 3-2. Each stalk consists of thick outer cortex (oc) with large cells and oil-glands, inner cortex (ic) with small cells, vascular bundle (vb) and pith (p). Pith cells are similar to those of inner cortex. Cells of outer cortex are similar to those of receptacle. 4. Transverse section of apical parts of two follicles (arrows). Seeds are absent. 5. Transverse section of middle part of follicles with adaxial sutures facing upper side (arrow a), and abaxial thick bundles (arrow b). Two thin layers are seen in the transverse section of follicle walls. 6. Transverse section of middle part of follicles with remains of seed coats inside. 7. Transverse section of proximal part of follicles, showing the follicle walls and seed coats. 8. Longitudinal section of a follicle with two thick seed coats. 9. A thick seed coat, enlarged from Figure 3- 8. Tamiko Ohana et al. ef, PR ia ea % In ary Med % [2 Le Ve ae Figure 4. Keraocarpon yasujii Ohana, Kimura and Chitaley, gen. et sp. nov. 1. Longitudinal section of proximal part of follicles, each with disintegrated seeds. 2. Longitudinal section of the follicle wall (outer layer; arrow a, inner layer; arrow b). 3. Longitudinal section of a stalk (arrow s) and the base of follicle Chamber (arrow f). 4. Longitudinal section of an enlarged stalk, showing scalariform bundles. 5. Enlarged from the boxed area of Figure 4-4. Scalariform bundles are clearly seen (arrow). 6. Tangential section of basal part of peduncle with eustele bundles (arrow a), showing the alternation of bundles and parenchymatous tissues (including oil glands) (arrow b). Pith is located to the right side. Phloem is not preserved. 7. Transverse section of the basal part of peduncle, enlarged from Figure 2-3. Arrows indicate the eustele bundles. 8. Transverse section of a part of receptacle, showing fibrous and crowded bundles. 9. Enlarged from a part of Figure 4-8, showing vertically (arrow a) and horizontally oriented (arrow b) bundles. Keraocarpon gen. nov. Figure 5. Keraocarpon masatoshii, Ohana, Kimura and Chitaley, sp. nov. 1. Preserved parts of small aggregate fruit (holotype ; compare with Keraocarpon yasujii shown in Figure 2-1). 2. Radial longitudinal section of an aggregate fruit, consisting of poorly preserved peduncle, receptacle and apocarpous follicles each with distinct stalk. 3. Transverse section of peduncle, showing large pith (p), collateral vascular bundles, inner cortex (ic) and thick outer cortex (oc). 4. Enlarged from Figure 5-3, showing pith and collateral vascular bundles (arrows). 5. Transverse section of stalks. x-y; zone lost by cutting (using a 0.4-mm-thick saw). 6. Enlarged from Figure 5-5, showing polygonal or irregular outline of stalks. Arrows indicate openings filled with rock matrix. 7. Transverse section of apocarpous follicles. Wall thickness varies according to the cutting plane. The adaxial suture faces the supposed centre of the fruit (star). 8. Tangential section of edge of receptacle, showing horizontal vascular bundles (arrows). Tamiko Ohana et al. 300 Keraocarpon gen. nov. 301 Seeds: The follicle is unilocular with seeds alternately arranged in two rows, 21-24 in number in each follicle (Figure 3-6—9). Seed coat is thick with micropyle facing the adaxial suture of the follicle (Figure 3-6—9). Keraocarpon masatoshii Ohana, Kimura and Chitaley, sp. nov. Figures 1B, 5, 6 Specimen.—INH-021 (Holotype). Locality—Upper course of the Ikushunbetsu River bank, Mikasa City (4km south of the Kumaoizawa locality where Keraocarpon yasujii was collected.) Horizon.—Same as K. yasujli. Etymology.—After Masatoshi holotype. Specific diagnosis.—An aggregate fruit of follicles, small. Receptacle slightly convex. Number of follicles around 70. Stalk and wall of follicle thick. Seeds in each follicle, 15-18. Description.—Preserved parts of this fruit are a permineral- ized peduncle, receptacle and apocarpous conduplicate follicles (Figures 1B, 5-1). Peduncle : Peduncle is 5.5 mm in diameter, consisting of pith, collateral vascular bundles and cortex (Figure 5-2—4). Receptacle: Receptacle is slightly convex disk-like, 1.0 cm in diameter and 3.5 mm thick. Follicles : The follicles are helically arranged ; their esti- mated number is 70. Since half of them are missing, the parastichy is uncertain. The follicles are apocarpous and conduplicate, 1.1 cm long, with transverse section circular or sometimes polygonal, 1.5-2.0 mm in diameter (Figure 5-7). Stalk : 1.0-1.5 mm long and 0.8-1 mm thick, and is inserted into the receptacle to a depth of about 1.8 mm (Figure 5-2). It is circular to polygonal in transverse section, having a pith, vascular bundles and cortex (Figure 5-5, 6). The bundles consist of scalariform vessels and pitted tracheids (Figure 6- Kera, collector of the 1—5). The follicles are adaxially sutured (Figure 5-7 ; Fig- ure 6-7—10). The follicle wall consists of two layers of cells, the outer thick and the inner thin. In each follicle, a thick vascular bundle is on the abaxial side, and a pair of adaxial bundles are on either side of the suture. No suture is observed at the proximal part of the follicle (Figure 6-7). Most of the sutures are not fully open, Suggesting that its seeds are not fully matured. Seeds: Seeds are 15-18 in number in each follicle. The seed coat is of two layers (Figure 6-1, 7). There is almost no space between the seed and the inner wall of the follicle. Remarks.—This species is distinguished from K. yasujii, the type species of Keraocarpon, by the smaller sizes of pedun- cle, receptacle, and follicle and the smaller numbers of follicles, and seeds in each follicle. The transverse section of follicle is not rhomboidal as illustrated by Nishida et al. (1996) in their Hidakanthus, but elliptical or polygonal (in this work). In both fruits no male organs or other vegetative parts have been found in organic connection. The Upper Yezo Group of marine origin contains many varied type of fossil plants. It is, however, difficult to get entire or nearly entire plant specimens, because these ter- restrial plants were disaggregated in the course of ta- phonomy. Acknowledgements We thank Yasuji Kera and Masatoshi Kera who offered their specimens for our study. This study was financially supported by the Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan to Kimura and Ohana, 07640629 and from the Fuji- wara Natural History Foundation to Ohana. We also thank the Cleveland Museum of Natural History, Cleveland, Ohio, U. S. A. for making available the services of S. Chitaley. — Figure 6. Keraocarpon masatoshii Ohana, Kimura and Chitaley, sp. nov. 1. Longitudinal section of a thick stalk. Its upward extension forms follicle wall to wrap a proximal seed. No adaxial suture is present below the position of the proximal seed. 2. Scalariform vessels in the stalk enlarged from Figure 6-1. Same, enlarged from Figure 6-1. Figure 6-1. follicle. Some perforation plate of vessels are scalariform. 3. 4. An annular tracheid (arrow a) and scalariform vessels (arrow b) in stalk enlarged from 5. Pitted tracheid. Pits are in two rows (arrow) enlarged from Figure 6-1. of a stalk, showing pith (p) and small collateral bundles (arrows). Figure 5-2, showing thick and irregularly formed follicle walls. 6. Transverse section of proximal part 7. Transverse section of follicles, cut along the p-q line in 8. Transverse section cut along the middle part of a marginal Follicle is transversely rhomboidal and the seed is disintegrated. The position of the adaxial suture is indicated by an arrow. 9. Transverse section of a follicle cut slightly above the section as in Figure 6-8, showing adaxial suture (arrow a). The vascular bundles are seen at each crest (arrow b). 10. Transverse section of a central follicle, cut at the same level as in Figure 6-8, showing the wall. 11. Enlarged from the boxed area of Figure 6-10, showing the abaxial bundle (arrow) and thick- layered follicle wall. 12. Transverse section of apical part of two follicles with distinct adaxial sutures (arrows). irregular in form. The walls are 302 Tamiko Ohana et al. References cited Crane, P.R. and Dilcher, D.L., 1984: Lesqueria : An early angiosperm fruiting axis from the mid-Cretaceous. Annals of the Missouri Botanical Garden, vol. 71, no. 2, p. 384-402. Dilcher, D.L. and Crane, P.R., 1984: Archaeanthus : An early angiosperm from the Cenomanian of the Western Interior of North America. Annals of the Missouri Botanical Garden, vol. 71, no. 2, p. 351-383. Nishida, H. and Nishida, M., 1988: Protomonimia kasai- nakajhongii gen. et sp. nov.: A permineralized magnolialean fructification from the mid-Cretaceous of Japan. Botanical Magazine, vol. 101, p. 397-426. Nishida, M., Ohsawa, T., Nishida, H., Yoshida, A. and Kanie, Y., 1996: A permineralized magnolialean fructification from the Upper Cretaceous of Hokkaido, Japan. Research Institute of Evolutionary Biology, Tokyo, Sci- ence Report, no. 8, p. 19-30. Ohana, T. and Kimura, T., 1987: Preliminary notes on the multicarpelous female flower with conduplicate carpels from the Upper Cretaceous of Hokkaido, Japan. Pro- ceedings of the Japan Academy, vol. 63 (B), p. 175-178. Ohana, T. and Kimura, T., 1993: Permineralized Brachyphyl- lum leafy-branches from the Upper Yezo Group (Coniacian-Santonian), Hokkaido, Japan. Bulletin of the National Science Museum, Tokyo, ser. C, vol. 19, no. 2, p. 41-64. 303 The Palaeontological Society of Japan has revitalized its journal. Now entitled Paleontological Research, and published preferably in English, its scope and aims have entirely been redefined. 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Charges : If a paper exceeds 24 printed pages, payment of page charges for the extra pages is a prerequisite for acceptance. Illustrations in color can also be published at the authors’ expense. For either case, the Editors will provide information about current page charges. Return of published figures: The manuscripts of the papers published will not be returned to the authors. However, figures will be returned upon request by the authors after the paper has been published. Ager, D.V., 1963: Principles of Paleoecology, 371p. McGraw-Hill Co., New York. Barron, J.A., 1983: Latest Oligocene through early Middle Miocene diatom biostratigraphy of the eastern tropical Pacific. Marine Micropaleontology, vol. 7, p. 487-515. Barron, J.A., 1989: Lower Miocene to Quaternary diatom biostratigraphy of Leg 57, off northeastern Japan, Deep Sea Drilling Project. In, Scientific Party, Initial Reports of the Deep Sea Drilling Project, vols. 56 and 57, p. 641- 685. U.S. Govt. Printing Office, Washington, D.C. Burckle, L.H., 1978: Marine diatoms. In, Hag, B.U. and Boersma, A. eds., Introduction to Marine Micro- paleontology, p. 245-266. Elsevier, New York. Fenner, J. and Mikkelsen, N., 1990: Eocene-Oligocene diatoms in the western Indian Ocean: Taxonomy, stratigraphy, and paleoecology. In, Duncan, R.A., Backman, J., Peterson, L.C., et al., Proceedings of the Ocean Drilling Program, Scientific Results, vol. 115, p. 433-463. College Station, TX (Ocean Drilling Program). Koizumi, |., 1972: Marine diatom flora of the Pliocene Tatsunokuchi Formation in Fukushima _ Prefecture. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 86, p. 340-359. Kuramoto, S., 1996 : Geophysical investigation for methane hydrates and the significance of BSR. Journal of the Geological Society of Japan, vol. 11, p. 951-958. (in Japanese with English abstract) Zakharov, Yu. D., 1974: Novaya nakhodka chelyust- nogo apparata ammonoidey (A new find of an ammonoid jaw apparatus). Paleontologicheskii Zhurnal 1974, p. 127-129. (in Russian) ye rt ‘a fae ge de) TE PA Pr ar dr we RY 2 1 a +! m Pr er S none er ae = 7a a és Ach = \ = ve PM LE : | ; d err . By : a ; n'en ON i f ine P \ 5 an Re co a Ue nee en ' OF 149 HFISX, 2000 Æ 6 A 28H (+) 5 24H (A) ic SHR AA RB yee) CH ESTES, iGO LidAMM Is 2000 Æ 5 A 40 CH. OË 150 IPI (2001 EI AP ARARE TE) CU, [SR ABER | 2 OBER LiAADSH D LZ. 2001 FES MSIL, 21 HHRMOES CIO, REX *& EDE REE C VYRD TARDE URBA CHEER COEDS, HERBESS CHEPA SAN H TI. CRAM SNISTHRE CHA? FSU. ©2002 “FAES RZ (2002 Æ 6 A PaBAET AE) CURE RÉ © BAER LIA ADH D # Lie, 33151 IBIS (2002 FIATARETE ORB LIAAlL, SFOLECAZHIV EVA, ObEMZES Cid, \AMCHHSNSZI-PvayT7RVYa—ba-REEELTHV ET, © ZWAERZEURNETRITEDTESEIOT, MHZKHSOAITSRE TB Tran, BEOHLAAF: T240-0067 HRT ASKER 79-2 REET ASaR ARES aA RARES HIS (TA) Att FIBME—: TEL 045-339-3349 I FAX 045-339-3264 “anes E-mail majima @ ed.ynu.ac.jp É Aal (TES): T250-0031 /\ HET A4ER 499 Ha | [URI AR a OD SE > HHEREEPIRE TEL 0465-21-1515 FAX 0465-23-8846 E-mail taru @ pat-net.or.jp Pere rere re rer er ere rere eres eser ere secorere+eoco+s eee ee rere rere re rere sere rere rere rere rere re cere ee ere rere re ee en ee rn, rs rn nn nn OO POC SOHO HPO OOOO neuerer ee ee ee er re er re re ee ee 0 0 7 ee. AGEOFAT ICES SAAS, ZADAR, MESO ER 5 VOLKES AS DEAMBZTOENTOET, HEDEHZARTLOBEUTT, AVERYS ARASH MHARLEROE + WE LIANKTZBRÄREMER BHWARRMBRASH FAV AVY +N bb À E À ih tk AS tt KERVALHAROEME = 0.7 F PACIFIC 1 206 1 Ë ; ; 1 ES Ba | | a Er ] = [ @ 04h | : ° ] = ß T T ° 3 [ e na! .| 2 03 - I Pal ! A 02 | | & es ST Ei oe. - oo “ A x Figure 7. Geographic distributions of height/diameter ratio of Planoglabratella opercularis morphogroup around the Japanese Islands from various samples taken during different seasons. Black circles mask average height/diameter ratio at different localities. Bars straddling circles indicate the range of one standard deviation of data at each locality. 0.7 [ Tome = m en = we = [ © Omaezaki Shimoda 2 06 | m ENS 3 Poe © f | | 5 0.5 i : = | 3 $ | e e ® | e © 04 F | | | n | oO 4 = 2 | 9 4 = I 1 © 03 + : =o aE 0.2 eae 1 (er Nl fi En fi 1 — N =] Oct. Nov. Dec. Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. 1987 1988 Month Figure 8. Seasonal differences of average height/diame- ter ratios of Planoglabratella opercularis both at Omaezaki Cape and Shimoda Bay, in Shizuoka Prefecture. Black circles show the data from Omaezaki Cape. Open circles show the data from Shimoda Bay. Bars indicate the range of one standard de- viation of data at each locality. Glabratella are mostly the same as those described by Le Calvez (1950) for Discorbis mediterranensis. The results of the interbreeding experiments are summa- rized in Figure 10. Individuals that belonged to the same morphogroup mated, but those that belonged to separate morphogroups did not (Figure 10A). These results suggest that the species reclassified by morphology can probably be considered to be breeding populations. However, there are individuals within the same population of a morphogroup that did not mate. Although they touched each other, they did not go further in forming a pair; instead, the rhizopods were disconnected and the individuals moved independently. The results indicate that some kinds of sex- ual differentiation may exist in Glabratella, as suggested by Le Calvez (1950), Grell (1957, 1958a, b, 1959), Weber (1965) and Berthold (1971) for several species that formed gamontogamous aggregates during fertilization. Gamont individuals from the same parental agamont sometimes formed pairs; however, there was no exchange of gametes. This could mean that autogamy may not occur in Glabratella, even though autogamy has been found among species of the genus Aotaliella as described in Grell (1973). Individuals from different morphogroups never reacted to each other, even if their rhizopodia were close enough to touch. As described above, two morphological variations occur in P. opercularis, i. e., presence/absence of peripheral spines and height/diameter ratio. Both individuals with and without peripheral spines were able to form gamontogamous pairs and reproduced during culture experiments (Figure 10B). SEM photographs of a gamontogamous pair formed by a spinose and a nonspinose individual are shown in Figure 11. Both high and low trochospiral individuals also formed gamontogamous pairs (Figures 10B, 12.1, 12.2) and also re- Hiroshi Kitazato et al. 10 Breeding populations in foraminifera 11 A _ INTERSPECIFIC BREEDING EXPERIMENTS P. nakamurai G. patelliformis P. opercularis P. nakamurai P. opercularis G. patelliformis 7/18 B INTRASPECIFIC BREEDING EXPERIMENTS Planoglabratella opercularis (d'Orbigny) spinose 0/48 0/22 11/30 0/33 1/4 non-spinose highH/Dratio low H/D ratio spinose non-spinose high H/D ratio low H/D ratio 7/9 2K EK 35/58 OK Kr 11/30 9/14 47/73 C INTERPOPULATIONAL BREEDING EXPERIMENTS Planoglabratella opercularis (d'Orbigny) Echizen-Matsushima Oshika Peninsula Shimoda Omaezaki Figure 10. Results of interbreeding experiments with both inter- and intraspecific populations. Numerals to the left of the slash show combinations that actually formed a gamontogamous breeding experiments are also shown. Echizen- Matsushima Oshika Peninsula Shimoda Omaezaki 0/3 2/6 Ber 0/6 47/73 10/61 16/41 Results of interpopulational pair. Numerals to the right of the slash indicate the number of experiments for each combination. ***: no experimental data. A. Interspecific breeding experiments, B. Intraspecific breeding experiments, C. Interpopulational breeding experiments. produced (Figure 12.3, 12.4). These results clearly show that all variants belong to the same population and can inter- breed. Both spines and H/D ratio were formerly used as key morphological characters for defining Glabratella spe- cies. We have not yet examined how these morphological Characters appear in daughter or granddaughter cells. Interbreeding experiments among P. opercularis popula- tions from different localities indicate that geographically re- mote populations do not make gamontogamous pairs (Figures 10C, 13). Gamont specimens between Omaezaki Cape and Shimoda Bay made gamontogamous pairs and reproduced. However, individuals between Omaezaki Cape and Oshika Peninsula, Miyagi Prefecture and between Omaezaki and Echizen-Matsushima Coast, Fukui Prefecture did not make gamontogamous pairs with each other, even though morphological characteristics of P. opercularis popu- lations at the three localities are very similar. These inter- breeding experiments of individuals of remotely separated populations show that the interbreeding abilities of popula- tions are closely related to geographic distances between Figure 9. Series of photographs showing the process of forming a gamontogamous pair of Glabratella patelliformis (Brady) on September 1, 1987. Photographed in 1. 1548 hours, 2. 1549 hours, 3. 1550 hours, 4. 1554 hours, 5. 1555 hours, 6. 1556 hours, 7. 1557 hours, 8. 1600 hours. Collected at Shimoda Bay, Shizuoka Prefecture. Hiroshi Kitazato et al. Figure 11. Gamontogamous pair between individuals with peripheral spines and without spines of Planoglabratella opercularis (d'Orbigny). Scale bars for 1 a, b, c and for 2 indicate 100 um and 50 pm respectively. 1a. Specimen without peripheral spines, 1b. Speciments with peripheral spines, 1c. Side view of gamontogamous pair. 2. Enlargement of peripheral spines. Figure 12. Photographs showing the reproductive process of Planoglabratella opercularis (d’Orbigny) from a gamontogamous pair during culture experiments. 1. Gamontogamous pair between individual showing high height/diameter ratio of Omaezaki popu- lation and individual showing low height/diameter ratio of Shimoda population. Agamont juveniles are visible within one pair. Photographed at 2130 hours, November 4, 1988. 2. Side view of gamontogamous pair. Upper right individual shows higher height/ diameter ratio than that of lower left individual. Photographed on November 4, 1988, 2140 hours. 3. Spreading of agamont offspring from the parental pair. Photographed on November 5, 1988. Juvenile agamonts have two chambers when they leave. 4. Juvenile agamont individuals with three chambers. Photographed on November 7, 1988. Breeding populations in foraminifera Figure 12. 14 Hiroshi Kitazato et al. | N o ® =| Japan Sea Echizen-Matsushima ia Pacific Ocean 1°" Am | | | 130°E 140°E Figure 13. Results of interbreeding experiments of indi- viduals among geographically remote populations. Map shows localities from which individuals actually tried to interbreed. Circle and cross marks in the figure refer the populations that can and cannot interbreed, respectively. The results show that individuals from proximate localities can interbreed. them. Individuals that succeeded in interbreeding belong to proximate populations. For instance, Omaezaki Cape is only 100 km from Shimoda Bay at the closest distance along the shoreline. In contrast, individuals from distant localities failed to interbreed. Oshika Peninsula is about 500 km from Omaezaki Cape. The Echizen-Matsushima Coast is more than 1000 km from Omaezaki Cape. Thus geographic dis- tance is critical in determining interbreeding abilities among populations of a single morphospecies in Glabratella. This phenomenon suggests that populations of this glabratellan morphospecies have characteristics of ring species, with chains of local populations that can interbreed between neighboring populations. Summary Four Glabratella morphospecies were reclassified into three morphogroups, according to stable morphological characters. There are several key morphological charac- ters that are stable with ontogenetic stages, life cycle, and/or geographic distance. Certain morphological characters changed during ontogeny. Interbreeding experiments show that reclassified morphospecies can breed within one morphogroup. Several morphological characters are not stable during ontogeny. This shows that we cannot use every morphological feature to define Glabratella species. Interbreeding experiments using individuals collected from geographically remote populations demonstrate that indi- viduals of closely located populations can breed with each other, whereas individuals from distant populations cannot interbreed. These results suggest that glabratellan popula- tions are chains of small, reproductively isolated popula- tions. Interbreeding experiments are a powerful tool to elucidate populational structure of morphologically defined species in foraminifera. Acknowledgments We are grateful to the late K. G. Grell and late W. -U. Berthold for their warm encouragement during the course of this study. Y. Matoba pointed out several taxonomic incon- sistencies among Glabratella species in Japan, which gave us the idea to perform this study. H. Kanesaki-Suzuki kindly provided us with important samples. S. Hasegawa kindly showed us holotypes of Discorbis subopercularis Asano and Discorbis nakamurai Asano, both of which are registered in the Institute of Geology and Paleontology, Tohoku University, Sendai; he also discussed taxonomic problems with us. Both Ch. Hemleben and R. M. Ross im- proved the manuscript by their criticisms. Two anonymous reviewers made helpful comments for improving this manu- script. We are also indebted to the staff of the Shimoda Marine Research Center of the University of Tsukuba for their kind help while using their laboratory. This research was supported by Grants-in-Aid from the Ministry of Education, Science, and Culture of Japan (nos. 61480027, 02454028, 06454002 and 09554025). This is contribution no. 643 of the Shimoda Marine Research Center, the University of Tsukuba. Reference cited Asano, K., 1951: Illustrated Catalogue of Japanese Tertiary Smaller Foraminifera. Pt. 14, Rotaliidae, p. 2-3. Berthold, W.-U., 1971: Untersuchungen über die sexuelle Differenzierung der Foraminifere Patellina corrugata Williamson mit einem Beitrag zum Entwicklungsgang und Schalenbau. Archiv für Protistenkunde, vol. 113, p. 147-184. Bock, W., Hay, W. and Lee, J. J., 1985: Order Foraminiferida D’Orbigny, 1826. In, Lee, J. J., Hutner, S. H. and Bovee, E.C. eds., An Illustrated Guide to the Protozoa, p. 252- 273, Society of Protozoologists, Allen Press, Kansas. Boltovskoy, E., 1954: The species and subspecies concepts in the classification of the foraminifera. The Micropaleonto- logist, vol. 8, no. 3, p. 52-56. Boltovskoy, E. and Wright, R., 1976: Recent Foraminifera, 515p., W. Junk, The Hague, Netherlands. Brady, H. B., 1884: Report on the foraminifera dredged by H. M. S. Challenger during the years 1873-1876. Report of the Scientific Results of the Voyage of H. M. S. Challenger, Pt. 22, vol. 9, 647 p. Culver, S. J., 1993: Foraminifera. In, Lipps, J. H. ed., Fossil Prokaryotes and Protists, p. 203-247, Blackwell Scientific Publications, London. Grell, K. G., 1957: Untersuchungen über die Fortpflanzung Breeding populations in foraminifera und Sexualität der Foraminiferen. |. Rotaliella rosco- fensis. Archiv für Protistenkunde, vol. 102, p. 147-164. Grell, K. G., 1958a: Untersuchungen Uber die Fortpflanzung und Sexualität der Foraminiferen. Il. Rubratella inter- media. Archiv für Protistenkunde, vol. 102, p. 291-308. Grell, K. G., 1958b: Untersuchungen über die Fortpflanzung und Sexualität der Foraminiferen. Ill. Glabratella sulcata. Archiv für Protistenkunde, vol. 102, p. 449-472. Grell, K. G., 1959: Untersuchungen über die Fortpflanzung und Sexualität der Foraminiferen. IV. Patellina cor- rugata. Archiv für Protistenkunde, vol. 104, p. 211-235. Grell, K. G., 1973: Protozoology, 554p., Springer-Verlag, Berlin, Germany. Kanesaki, H., 1987MS: Geographic distributions of rocky shore foraminifera adjacent to the Japanese Islands. Undergraduate Thesis, Institute of Geosciences, Shizu- oka University, 86p. (in Japanese with English abstract) Kitazato, H., 1984: Microhabitats of benthic foraminifera and their application to fossil assemblages. In, Oertli, H. J. ed., Benthos ’83, 2nd International Symposium on Benthic Foraminifera (Pau, April 1983), p. 339-344, Pau and Bordeaux, Elf Aquitaine, ESSO REP and Total DEP. Kitazato, H., 1988: Ecology of benthic foraminifera in the tidal zone of a rocky shore. Revue de Paléobiologie, Spec. vol. 2, p. 815-825. Kitazato, H., 1992: Pseudopodia of benthic foraminifera and their relationships to the test morphology. In, Saito, T. and Takayanagi, Y. eds., Studies in Benthic Foramini- fera, p. 103-108, Tokai University Press, Tokyo. Kitazato, H., 1994: Foraminiferal microhabitats in four marine environments around Japan. Marine Micropaleontology, vol. 24, 29-41. Le Calvez, J., 1950: Recherches sur les foraminiferes. 2. Place de la meiose et sexualité. Archives de Zoologie Experimentale et Generale, vol. 87, p. 211-243. Loeblich, A. R. Jr. and Tappan, H., 1988: Foraminiferal Genera and Their Classification, v. 1-2, 970p., Van Nostrand Reinold Company, New York. Matoba, Y., 1970: Distribution of Recent shallow water foraminifera of Matsushima Bay, Miyagi Prefecture, North Japan. Science Report of Tohoku University, 2nd ser. (Geol.), vol. 42, no. 1, p. 1-85. Mayr, E., 1969: Principles of Systematic Zoology, 428p., McGraw-Hill, New York. Myers, E. H., 1943: Life activities of foraminifera in relation to marine ecology. Proceedings of the American Philosophical Society, vol. 86, p. 439-459. Nyholm, K. -G., 1961: Morphogenesis and biology of the foraminifer Cibicides lobatulus: Zoologiska Bidrag fran Uppsala, vol. 33, p. 157-196. Orbigny, A. D.’, 1839: Foraminiferes, in Ramon de la Sagura. Histoire physique, politique et naturelle de l'île de Cuba, p. 93. Schnitker, D., 1974, Ecotypic variation in Ammonia beccarii (Linne). Journal of Foraminiferal Research, vol. 4, p. 217-223. Sonneborn, T. M., 1957: Breeding systems, reproductive methods, and species problems in Protozoa. In, Mayr, E. ed., The Species Problem. Publications from American Association for the Advancement of Science, vol. 50, p. 155-324. Tendal, O. S., 1990: Why are foraminiferida foraminifers? /n, Hemleben, Ch., Kaminski, M. A., Kuhnt, W. and Scott, D.B. eds., Paleoecology, Biostratigraphy, Paleoceano- graphy and Taxonomy of Agglutinated Foraminifera, p. 13-18, Kluwer Academic Publishers, Netherlands. Weber, H., 1965: Uber die Paarung der Gamonten und Kerndualismus der Foraminifere Metarotaliella parva Grell. Archiv für Protistenkunde, vol. 108, p. 217-270. ACT br AA, aan: | aoe a SMa “ses Bett. Yer me à AT ai Aa ar 7 a rar LD (cet uve | can ae ET EN ee | Br . ur ee à ve) ARES gg nit, © ee fe km = one Paleontological Research, vol. 4, no. 1, pp. 17-31, April 28, 2000 © by the Palaeontological Society of Japan Foraminal structures of some Japanese species of the genera Ammonia and Pararotalia, family Rotaliidae (Foraminifera) RITSUO NOMURA’ and YOKICHI TAKAYANAGI’ ‘Foraminiferal Laboratory, Faculty of Education, Shimane University, Matsue, 690-8504, Japan “c/o Institute of Geology and Paleontology, Faculty of Science, Tohoku University, Sendai, 980-8578, Japan Received 6 July, 1999; Revised manuscript accepted 10 October, 1999 Abstract. Rotaliid foraminifera have a complicated foraminal structure that has been recognized as the so-called toothplate. As to the interpretation of this toothplate, however, there has been confusion among foraminiferologists as to whether it is the same as the buliminid toothplate or not. In order to elucidate the apertural and foraminal structure, we examined some Japanese species of the genera Ammonia and Pararotalia. The apertures of Ammonia and Pararotalia show fundamentally the same style of construction, but the resultant structures are different among species. We recognized two main components in- stead of the indefinite toothplate in the aperture: foraminal plate and umbilical coverplate. The foraminal plate constructed out of a foramen is a free structure of the bilamellar wall. This plate is originally formed in the final chamber where it delimits the posterior side of the final aperture. The umbilical coverplate closes the umbilical side of the preceding foramen. This coverplate is originally bilamellar and is continuous from the foraminal plate. Both the foraminal plate and um- bilical coverplate are formed when the final chamber is constructed. The umbilical coverplate in- terconnects the new and preceding foraminal plate, which may lead to the original concept of toothplate. However, the umbilical coverplate is not associated with the final chamber wall, but as- sists in closing the umbilical side of the preceding chamber wall. Such a chamber construction is restricted to rotaliids, thus we reject the term toothplate as only indicating modified structures that pass through the aperture. Descriptions of the rotaliid aperture are of value when we note the foraminal plate and umbilical coverplate. Thus two types of foramen, Ammonia-type and Pararotalia-type, were developed in the rotaliids. Key words: aperture, foraminal plate, rotaliid foraminifera, taxonomy, toothplate. Introduction The toothplate is a characteristic structure developed in some taxa of benthic foraminifera (originally called “tooth pl ate”, recently “toothplate”; e. g., Loeblich and Tappan, 1964, 1987). Ithas a varied morphology, usually manifested as a protruded free structure passing through the aperture. Before Hofker (1950, 1951a, b) recognized this structure as a useful systematic criterion of hyaline calcareous foramini- fera, various distinctive parts of the aperture were called lip, tongue, tooth, partition and flap. Hofker’s toothplate was re- garded as a homologous structure with these variously nam- ed structures. Many forms having these apertural decora- tions have been classified into a number of families based on their apertural morphologies. Thus most hyaline cal- careous foraminifera were included in Hofkers order Dentata (Hofker, 1951a). However, morphologically, some of these structures should be grouped together in the same category and some should be clearly differentiated from it. The toothplate concept includes so many forms of apertural complexity that rigid application of this term leads to ambigu- ous comparisons in systematics. In particular, the apertural complex of Hofkers Protoforaminata, the group having protoforamen, is different from that of his Deuteroforaminata, the group having both protoforamen and deuteroforamen. In addition to such a confused recognition of the toothplate and related structures, development of the scanning electron microscopes (SEM) permitted the lamellar structure of the toothplate to be examined. The toothplate has been recog- nized as a bilamellar structure consisting of an inner lining and an outer lamella (Hansen and Reiss, 1971). However, the lamellarity is not consistent, since Revets (1993) 18 Ritsuo Nomura and Yokichi Takayanagi suggested that the buliminid toothplate is made from the inner lining. Thus, the concept of toothplate is still confused among foraminiferal researchers in its structural and mor- phological aspects. The rotaliid toothplate is the best exam- ple of this, it being unclear whether it should be recognized as homologous with the buliminid toothplate or not on the basis of morphology and structure. We describe the apertural and foraminal structures based on artificially dissected specimens and suggest the neces- sity of recognizing the morphological variation of the aper- ture. Methods Internal structure of foraminiferal test was examined by a scanning electron microscope using a hardened canada bal- sam (Nomura, 1983c). Some authors stress the impor- tance of lamellar structure, particularly to the understanding of toothplate structure (e. g., Revets, 1989, 1993). In recon- structing the lamellar structure for the sectioned and etched specimens that have been embedded in epoxy resin we en- countered difficulties, particularly for thinner walls. Alternatively, we etched the sectioned specimens with 0.5% phosphoric acid to observe the internal structure before re- moving the canada balsam. This method gives better re- sults in interpreting the three-dimensional lamellar structures within walls. Previous observations on the aperture of Ammonia Earlier workers examined thin sections of foraminifera or examined the test with naturally broken walls to observe the toothplate. In this way, the toothplate of Ammonia beccarii (Linné), type species of the genus Ammonia, has been rec- ognized as a free structure asymmetrically folded longitudi- nally and convex towards the umbilical side of the chamber (Hofker, 1950, 1951a, b; Reiss and Merling, 1958). Reiss and Merling (1958) showed various figures of the toothplate and related structures, and introduced several terms for its specific structures. They described the toothplate to “run al- ways from the intercameral foramen towards the umbilical side for part of the way, turning through torsion towards the dorsal side at their distal ends.” Thus the toothplate is con- vex towards the umbilical center. The rotaliid septal flap, originally proposed by Smout (1954), is also regarded by those authors as an extension of the toothplate, although they retain the term septal flap. Cifelli (1962) suggested the toothplate of A. beccarii was not homologous with the origi- nal toothplate and he separately called it an axial plate and a lip. He observed that the axial plate is imperforate and the umbilical extension of the plate passes into a chamber flap, without any openings into the umbilical area. The lip, in the different sense of Reiss and Merling (1958), is formed by the axial plate anteriorly projecting through the aperture at the bottom of the septum, except for the final one. Before the recognition of these apertural modifications by these workers, Ishizaki (1943) first noted the morphological difference between the aperture (as the final opening) and the foramen (as the preceding opening). However, he did not refer to any specific anatomical observations. Based on SEM examination, Seibold (1971) recognized the axial wall as forming a different part of the toothplate in Ammonia. Seibold’s axial wall and lip correspond to Cifelli’s axial plate and chamber flap. Hansen and Reiss (1971) first introduced the concept of a foraminal plate and an umbilical coverplate instead of the toothplate for the rotaliid foraminifera, suggesting the presence of this plate in all chambers, including the final one. They interpreted the septal flap which forms not only the foraminal plate on an axial chamber wall (=previous coil), but also the umbilical coverplate, as showing a continuous lamellar structure. Their observations corroborate Reiss and Merling’s explana- tion. The septal flap consists of an inner lining, which cov- ers the preceding bilamellar septal wall. This lamellar model has been adopted in Lykke-Andersen (1976). Thus the foraminal plate and the coverplate are bilamellar in the original construction. They suggested that the so-called fis- sure and intraseptal passage are formed as an imperfect ad- hesion of the septal flap to the preceding chamber. They referred to this fissure as an interlocular space. Müller- Merz (1980) supplied detailed anatomical information on rotaliids and she discussed the apertural structure based on the foraminal plate and cover plate (same sense of umbilical coverplate) model. Lévy et al. (1986) suggested the suprageneric similarities of some rotaliids, including Ammonia, to discorbids. They pointed out a similarity in internal structure for which they used the term paries proximus instead of the toothplate. They describe “It (=paries proximus=toothplate) is a thin plate which divides from the septum towards the umbilical face and which constitutes an oblique groove-like fold, in- stead the chamber, joining the preceding coil. This plate also spreads backwards, that is, in a proximal direction, clos- ing the edge of the folium of the preceding chamber. In equatorial section we give the name 'retroparies’ to the back part of the paries proximus.“ Their paries proximus and the retroparies correspond to the foraminal plate and umbilical coverplate respectively. Although their proposal to sub- sume the rotaliids within the discorbids at the family level is rejected by Haynes and Whittaker (1990), based on ontogenetic analyses of umbilical modifications, including canals and fissures, there is a similarity in the structure of paries proximus in both taxonomic groups. The complexity of the internal structure of Ammonia is re- flected in these different terms. On the other hand, differing recognition of the internal structure among researchers makes for uneasy interpretations. Hottinger et al. (1991) redefined the toothplate, particularly in relation to that of Pararotalia (see below). They stressed the presence of their toothplate (s.s.) in Pararotalia and its absence in Ammonia, indicating a difference in suprageneric classifica- tion. Revets (1993) questioned whether the rotaliid tooth- plate was homologous to the buliminid toothplate. He mentioned “The internal structures in rotaliids are not equivalent to toothplates, rather they all seem to conform to the foraminal plate coverplate concept.” His argument origi- nated from the difference between the bilamellar structure of rotaliid walls and the single-layer inner lining origin of the buliminid toothplate. Simple usage of the toothplate thus leads to confusion among researchers. The situation is Ammonia and Pararotalia apertures 19 similar in cassidulinids. Nomura (1983a, b) showed that simply the presence or absence of a toothplate is of little taxonomic value. We should describe the apertural decora- tion with careful attention to the various parts. Previous observations on the aperture of Pararotalia The detailed apertural structure of Pararotalia has been discussed by Loeblich and Tappan (1957, 1964) and Reiss and Merling (1958), based on its type species Pararotalia inermis (Terquem) from the Eocene of Paris Basin. Loeblich and Tappan (1987) described the aperture as interiomarginal and extraumbilical-umbilical, and the fora- men as areal with the attachment of the toothplate at the proximal margin of the penultimate chamber. Loeblich and Tappan’s toothplate is seemingly used in a broad sense, but they distinguished an umbilical plate (=umbilical coverplate here) and an internal septum from the chamber wall (Loeblich and Tappan, 1957). The umbilical coverplate and the internal septum were recognized as secondary struc- tures which can be broken away in the final chamber. Reiss and Merling (1958) stressed that the toothplate (internal sep- tum and umbilical plate of Loeblich and Tappan) is a primary formed structure, but they regarded the umbilical plate as chamber wall. As to the toothplate of the Japanese Pararotalia, Ujiié (1966) described P. nipponica as follows: “tooth plate imper- posterior final aperture hy ı ALLIITTT TI LULU forate, extending from proximal margin of last intercameral foramen to distal (peripheral) margin of aperture, adhering its basal (umbilical) margin on proximal margin of spirothecal wall of last chamber throughout whole chamber-length, de- veloping its upper (dorsal) free part broadly but very thinly in form of spatula with concave face turned to axial side and its upper anterior margin bent inwardly.” Interestingly, the spat- ula-shaped portion of the upper toothplate has been inter- preted as dissolved in the penultimate chamber based on a secondary wall which closes up an umbilical slit. His obser- vation is similar to Loeblich and Tappan’s umbilical plate for- mation model. However, a real image of the umbilical slit has not been clearly indicated. It may correspond to the interiomarginal slit of the aperture. Hansen and Reiss (1971) indicated that the original wall structure of Pararotalia is identical to that of Ammonia. The umbilical coverplate (umbilical plate of Loeblich and Tappan, 1957) extends back from the foraminal plate to the preced- ing foraminal plate. Hottinger et al. (1991) showed SEM micrographs of their defined toothplate of P. inermis. They describe the tooth- plate as “originating from the septal flap and connected to the inner ventral chamber wall, an imperforate toothplate ex- tends to the distal chamber wall, attached to the dorsal corner of the primarily interiomarginal, extraumbilical aper- ture, and protruding with a free, serrated edge into the latter.” Their toothplate is associated with a canal, which antepenultimate chamber distal/peripheral proximal/umbilical Schematic illustration of internal structure in the genus Ammonia. The aperture is an interiomarginal long slit extending from the peripheral side to the umbilicus. The final chamber continues to the foraminal plate and the umbilical coverplate of the penultimate chamber on the umbilical side. Thus, the coverplates around the umbilicus are delayed for one chamber lumen. The so-called toothplate corresponds to the ensemble of foraminal plate and umbilical coverplate. Abbreviations: a.fp=antepenultimate foraminal plate; a.uc=antepenultimate umbilical coverplate; cf=chamber flap; f.fp=final foraminal plate; f.uc=final umbilical coverplate; fo=foramen; p.fp=penultimate foraminal plate; p.uc=penultimate umbilical coverplate; sf=septal flap; sw=septal wall. Figure 1. 20 Ritsuo Nomura and Yokichi Takayanagi communicates with the chamber and with the furrow around an umbilical plug. Descriptive terms for aperture and its related structure In order to avoid confusion with respect to the aperture and foramen and their related structures, we use the follow- ing terms (Figure 1). Chamber flap.—Original extension of chamber wall, cov- ering umbilical sutural fissure, decorated with small spines. Pararotalia forms an umbilical shoulder associated with nodes on this portion (Loeblich and Tappan, 1957), instead of forming a free chamber flap. [chamber flap: Cifelli, 1962] [chamber lobe: Parvati, 1971; Haynes and Whittaker, 1990] [folium: Hottinger et al., 1991] [lip: Hofker, 1950, 1951a, b; Reiss and Merling, 1958; Seibold, 1971; Müller-Merz, 1980] [umbilical lip: Ujiié, 1965]. Foramen.—Opening connecting chamber lumina through septa, having a rounded, oval shape. Its shape is different from the final aperture. There are two types of foramen: the Ammonia-type and Pararotalia-type, based on the position and inclination of the foraminal plate to the walls of previous whorl (Figures 2, 3). [intercameral foramen: Smout, 1954][ areal intercameral foramen: Parvati, 1971][septal foramen: Hofker, 1950, 1951a, b] Foraminal plate.—Anterior plate extended from an umbili- cal coverplate (Figures 1, 2). It is formed on the proximal side of the aperture, leaving a foramen rounded or oval in shape. The foraminal plate is curled to the posterior out of the foramen, forming a hook-like structure in horizontal sec- tion (Figure 2), sometimes it is completely bent, resulting in Ammonia -type foramen septal flap umbilical coverplate hinge (preceding) previous whorl Drom 4) . Ma] à foraminal plate JE Side umbilical coverplate Figure 2. Schematic illustration of Ammonia-type fora- men. The hinge, junction of the umbilical coverplate and the foraminal plate, butts against the previous whorl. The umbilical coverplate adheres to the preceding foraminal plate or the pre- ceding umbilical coverplate. a columnar shape. This plate usually appears as an iso- lated plate adjoining the foramen of each chamber, including the final chamber, thereby some authors regarded it as a free structure of the toothplate. Our understanding of this plate agrees with the description of Hansen and Reiss (1971). They suggested that the chamber wall, septal flap, foraminal plate and umbilical coverplate are formed as one continuous structure. The foraminal plate of Pararotalia obliquely leans onto the chamber wall of the previous whorl and changes it to a protruded lip (lower lip) (Figure 3) [ante- rior projection of umbilical plate: Parvati, 1971][(apertural) lip: Cifelli, 1962] [foraminal plate: Hansen and Reiss, 1971; Muller-Merz, 1980; Revets, 1993] [internal septum: Loeblich and Tappan, 1957] [paries proximus: Lévy et al., 1986] [toothplate: Reiss and Merling, 1958; Ujiié, 1965, 1966] [part of toothplate: Hottinger et al., 1991] Hinge.—Junction of the foraminal plate and the umbilical coverplate. It delimits the proximal border or basal border of the foramen. In the Ammonia-type foramen, the hinge adheres to the umbilical/proximal side of the apertural open- ing on the previous whorl (Figure 2), and in the Pararotalia- type it adheres to the distal side of the aperture (Figure 3). Labial aperture.— Opening usually formed on the posterior side of the chamber, except for the final one. Originally this foramen was denoted a protoforamen to distinguish it from a deuteroforamen (Hofker, 1950, 1951a, b). Reiss and Merling (1958) recognized three parts of this aperture, namely, anterior, umbilical, and posterior. However, we recognized it as a single opening in the umbilical coverplate into the upper side of deeply incised sutures or sometimes into the umbilicus. The labial aperture is usually devoid of small spines around its opening. [protoforamina: Hofker, Pararotalia -type foramen umbilical 2 ë umbilical % overplate Sey, : coverplate preceding) Figure 3. Schematic illustration of Pararotalia-type fora- men. The hinge, junction of the umbilical coverplate and the foraminal plate, is much inclined toward the peripheral side of the aperture. Thus the foraminal plate appears as a protruded lip on the lower side. foraminal plate = lower lip Ammonia and Pararotalia apertures 21 1950, 1951a, b] Lip.—Plate-like or tube-like structure formed in aperture and foramen. It is distinguished from the lower lip of Pararotalia. Sometimes the lip is referred to as the apertural rim. Lower lip.—Lip usually associated with the foramen of Pararotalia and never seen in final aperture. It is formed by an adhesion of the basal part of the foraminal plate to the other, distal side of the final aperture, thereby the foramen of Pararotalia is areal. The lower lip is intrinsically the same as the foraminal plate, but structurally different. A tooth- Figure 4. Walls of Ammonia sp. etched with 0.5 % phosphoric acid solution showing lamellar structures. plate in the sense of Hottinger et al. (1991, 1993), which is a different concept from the so-called toothplate, corre- sponds to our lower lip. To avoid the confused usage of “toothplate,” we do not use their toothplate. Septal attachment.— Attachment of final septal wall to pre- vious whorl, dividing the final aperture into two openings. Umbilical coverplate.—Wall formed on the umbilical side of each chamber except for the final one, covered with chamber flap, usually forming a labial aperture in A. japonica and A. tepida, but usually without a labial aperture in A. beccarii and P. nipponica. This coverplate constitutes the 1. Detail of the final chamber showing the outer layer (ol) and inner lining (il) divided by the incised median layer (m). Scale bar: 5 um. 2. Detail of the pe- nultimate septal wall (closeup of no. 4) showing the multiple layers (I) developed on the main bilamellar structure (1st) with the median layer (m). bilamellar with median layer (m) and secondary layer (I) (closeup of no. 5). Scale bar: 5 um. 3. Detail of the penultimate umbilical coverplate showing a trilamellar structure consisting of the primary Scale bar: 5 um. 4. Detail of the penultimate septal wall, the penultimate foramen (fo), the final foraminal plate (fp), and the final umbilical coverplate (uc). Scale bar: 23.1 um. 5. Opened um- bilical side of the final and the preceding chamber walls. fa=final aperture. nultimate septal wall, the foraminal plate, and the umbilical cover plate (closeup of no. 5). Scale bar: 75 um. 6. Detail of the junction of the antepe- m=median layer. Scale bar: 7 um 22 Ritsuo Nomura and Yokichi Takayanagi main part of the umbilical side of the chamber lumen and en- closes the preceding foraminal plate. The foraminal plate should be an anterior projection of this coverplate. The foraminal plate lies within every chamber lumen, but the um- bilical coverplate is located in the umbilical side of the pre- ceding chamber. The umbilical coverplate is inclined to the previous whorl of the test, making a canal between the plate and the previous whorl in Pararotalia. [axial plate: Cifelli, 1962] [cover plate: Müller-Merz, 1980] [umbilical coverplate: Hansen and Reiss, 1971; Revets, 1993] [part of umbilical plate: Parvati, 1971] [retroparies: Lévy et al., 1986] [umbilical plate: Loeblich and Tappan, 1957] Lamellar structure The final chamber wall of Ammonia sp. etched with phos- phoric acid solution is typically bilamellar, consisting of inner and outer calcareous lamellae, and a middle incised lamella (in the sense of a primary organic membrane where calcifi- cation takes place; Hemleben et al., 1977) (Figure 4.1, 4.5). Both the inner and outer calcareous lamellae extend back to cover the penultimate wall, but only the inner lining of the bilamellar structure is superimposed on the outer lamella of the penultimate septal wall, forming a septal flap (Smout, 1954). Such a lamellar structure has been illustrated by Hansen and Lykke-Andersen (1976). In addition to this model, we found multiple lamellae (originally bilamellar with an additional two calcareous lamellae) in the penultimate penultimate chamber new layering Figure 5. Schematically illustrated lamellar structure in the various parts of the last four chamber walls. / penultimate Per COverpiatc septal wall near foramen (Figure 4.2, 4.4, 4.5), indicating that the preceding septal wall is not always three calcareous lamellae consisting of original bilamellar plus secondary la- mella (= inner lining). This feature is not in agreement with the statements of Hansen and Lykke-Andersen (1976) and Hottinger et al. (1991), who noted a trilamellar structure for the preceding septal wall. Their demonstrations follow a typical model of layering. However, the secondary lamellae of the preceding septal walls are variable in different por- tions. Thus, it matters whether the section looked at was from the umbilicus or spiral side of the test. Our demonstra- tion of multiple lamellae is based on a section from umbilical side of the test (Figure 4.5). The final foraminal plate is very thin but clearly shows the bilamellar structure. The additional layering does not occur on the final and preceding foraminal plate, which keeps the wall in thin condition. The umbilical coverplate is originally bilamellar, connecting to the foraminal plate in the hinge, but this coverplate has additional layering. Figure 4.3 shows the trilamellar wall of the rudimentary umbilical coverplate consisting of the original bilamellar wall covered with a new secondary lamella. Although we morphologically defined the two apertural types in Ammonia and Pararotalia, the lamellar structure of the foraminal plate and umbilical coverplate of the Pararotalia nipponica is the same as ob- served in Ammonia. The lamellar structure at the junction of the foraminal plate, umbilical coverplate and preceding septal wall is very antepenultimate chamber a.O preceding chamber N \ a.ol a.m antepenultimate coverplate Abbreviations: a.il=ante- penultimate inner lining; a.m=antepenultimate median layer; a.ol=antepenultimate outer lamella; f.il=final inner lining; f.m=final median layer; f.ol=final outer lamella; p.il=penultimate inner lining; p.m=penultimate median layer; p.ol=penultimate outer lamella; fp=foraminal plate. Ammonia and Pararotalia apertures 23 complicated (Figure 4.5, 4.6). The inner lining of the fora- minal plate connects to the septal flap and the inner lining of the umbilical coverplate connects to the preceding inner lin- ing of the septal wall. In Figure 5, the continuity and discon- tinuity of each lamella in various portions of the last four chambers are schematically illustrated. This lamellar model is similar to that of Hansen and Lykke-Andersen (1976), ex- cept for the median layer of the septal wall illustrated as a discontinuous layer at the junction area. Description of apertural structures Ammonia sp. Figures 2, 4.1-4.6, 6.1-6.8, 7.1 Materials. — Over 10 specimens of Ammonia sp. from Recent sediment of brackish Lakes Shinjiko and Nakaumi, Japan. This form has been recognized as a major form of Ammonia in Japan, and is identical to A. beccarii forma A (Takayanagi, 1955, p. 44, text-figs. 31a-c, in part) and to A. beccarii forma 1 (Matoba, 1970). Diagnosis of test.— The specimens are characterized by having nine to ten chambers in the final whorl, with an open umbilicus without a distinct plug, but with numerous spines in and around the umbilicus. Umbilical side of the test is flat Or somewhat concave; spiral side is gently inflated. Periphery rounded, very slightly lobulate. Sutures are limbate and slightly inflated on the spiral side, but limbate and incised on the umbilical side. Imperforate chamber flap, associated with spines for each chamber, is developed and each flap is imbricated, covering the incised suture near the umbilicus. Chambers are transparent with numerous fine pores. Apertural structures.—The final interiomarginal apertural opening is large without any free structure outside the aper- ture (Figure 6.1, 6.3). Thus the new foraminal plate is only formed between the foramen and proximal side of the finally formed chamber (Figure 6.2-6.4). When the new chamber is formed, the foraminal plate is usually covered with a new umbilical coverplate, which also covers the apertural open- ing (Figures 6.4-6.7, 7.1). Both the foraminal plate and um- bilical coverplate are formed in a series of proximal side walls of the preceding chamber (Figure 6.5, 6.6). The foraminal plate is left, without further development in the chamber lumen, which shows a hook-like structure when ob- served in horizontal section (Figure 6.5). The umbilical coverplate is less perforate (Figure 6.4), sometimes forms a very small labial aperture (Figure 6.8). However, this is not significant for this species. Chamber flaps are decorated with small spines, imbricated around the depressed umbili- cal center, and they are not fused with each other (Figure 7.1). Sutures are always incised, having a fissure shape, but they do not form canals. Remarks.—The examined species has been previously identified as Ammonia beccarii (Linné) by Japanese micropaleontologists. We doubt the taxonomic status of this species. Ammonia beccarii was originally collected from beach sands of the Adriatic Sea at Rimini, Italy. The type description given by Linné (1758) is not very helpful. In many subsequent works, A. beccarii has been broadly in- terpreted as possessing wide variations in the test morphol- ogy. Cushman (1928) recognized three forms in Ammonia beccarii, which represent the different generations of this species. Thereafter Japanese micropaleontologists have used this taxonomic name for widely varied forms of A. beccarii. However, we cannot accept such forms in the Japanese beccarii. Typical Ammonia beccarii is character- ized by a large test with well developed sutural knobs and fluted sutures on both dorsal and ventral sides. The num- ber of chambers in the final whorl is about 13 chambers in A. beccarii, while the Japanese form has a smooth test surface without sutural knobs and usually less than 10 chambers in the final whorl. Thus the Japanese form is quite different from the typical form of A. beccarii. With respect to such morphological variation, Walton and Sloan (1990) recog- nized three different morphotypes in Ammonia beccarii. The Japanese form without the umbilical plug falls within the morphological range of their forma tepida and the form with the umbilical plug falls within the range of forma parkinsoniana. Schnitker (1974) based on the culturing of Ammonia and Walton and Sloan (1990) based on geo- graphic distribution suggested a possible morphologic gra- dation between forma tepida and forma parkinsoniana, but no such clear gradation has been found between forma beccarii and the morphotypes tepida and parkinsoniana. Ecological observations show that A. beccarii (s.s.) and A. tepida have different morphofunctional adaptations to their habitats and environments (Debenay et al., 1998). Accord- ing to Debenay et al. (1998), A. beccarii (s.s.) lives on some algae as epiphytic life, whereas A. tepida lives in brackish sediments as endopelic life. The Japanese A. beccarii is similar to their A. tepida. Poag (1978) and Walton and Sloan (1990) mentioned that the geographic distribution of the typi- cal form of A. beccarii (s.s.) appears to be limited to the Mediterranean, the eastern Atlantic coast and the western Atlantic coast from Florida to Nova Scotia. Whittaker (per- sonal comm.) suggested that true A. beccarii lives only in the Mediterranean Sea and does not occur outside of it. These views are biogeographically supported, as no similarities exist between the Mediterranean fauna and the Indo-Pacific fauna (Rögl and Steiniger, 1984). Thus, no typical live or fossil A. beccarii occurs in and around Japan. This means the Japanese form does not represent Ammonia beccarii (S.S.). Another problem in the systematics of Ammonia beccarii is introduced from DNA analysis. Pawlowski et al. (1995) showed a high similarity of the ribosomal DNA sequences between A. beccarii (s.s.) and the Japanese “A. beccarii.” The Japanese form they examined in their DNA study is the same as we morphologically examined. Our morphologic comparison, however, indicates a taxonomic difference be- tween the two entities. The different results arrived at by morphological comparison and molecular analysis cannot be reconciled at this time. For these reasons, we hesitate to identify the Japanese form as A. beccarii, despite its being a well known species in brackish and shallow waters. Ritsuo Nomura and Yokichi Takayanagi 24 Ammonia and Pararotalia apertures 25 Ammonia japonica (Hada) Figure 7.2-7.5 Type reference.—Rotalia japonica Hada, 1931, p. 137, text-figs. 93a-c. Materials.—A. japonica (Hada) from Recent sediment of the Sakai Suido Strait near Miho Bay, the Sea of Japan. Diagnosis of test.—Examined specimens are character- ized by an inflated test with nine to ten chambers. Chambers are wedge-shaped toward the umbilicus. An umbilical plug is not usually developed in this species. The chamber flaps are less developed than in Ammonia sp. Radiate sutures on both the umbilical and spiral sides are straight. Umbilical sutures are incised and decorated with fine spines. Apertural structures.—The final aperture is divided into two openings by the septal attachment (Figure 7.2-7.5). The anterior aperture is interiomarginal, with an arch-shaped opening and the posterior one is not easily seen, as it is cov- ered by the chamber flap, but its shape is arched (Figure 7.4). The lip is somewhat protruded. The foraminal plates are curled and protrude out of the foramen when observed in horizontal section (Figure 7.3, 7.5). The foraminal plate without a free structure extends to form the ventral chamber wall in the final chamber (Figure 7.4). The umbilical coverplate is formed under the chamber flap when a new chamber is formed, but remains open in the upper part of the final aperture, forming a rounded labial aperture for each chamber but the final one (Figure 7.5). The chamber flap is triangular and points to the umbilicus and becomes larger as a new chamber is added, covering the labial aperture. Ventral sutures with small spines are deeply incised toward the umbilicus, like a fissure. Remarks.— Ammonia japonica is morphologically distin- guished from Ammonia sp. by having straight, radiate su- tures on the dorsal side and a more inflated test. Development of the septal attachment is another character- istic feature of this species which distinguishes it from allied species. Ammonia inflata should be allied to A. japonica in having straight radiate sutures. Ammonia sp.cf. A. parkinsoniana (d’Orbigny) Figure 7.6-7.8 Type reference.—Cf. Rosalina parkinsoniana d’Orbigny, 1839, p. 99, pl. 4, figs. 25-27. Materials.—Several specimens of Ammonia sp. cf. parkin- soniana from Recent sediment of brackish Lake Nakaumi. Diagnosis of test.—Examined specimens are character- ized by a thick lenticular test, having a distinct umbilical plug (Figure 7.6). The size is smaller than the examined form of Ammonia sp. The umbilical area is less decorated by spines and compact. The umbilical and spiral sides are inflated and the nonlobulate periphery is subacute. Chambers are eight to nine on the umbilical side and less inflated. Sutures on umbilical side are less incised and the ones on the spiral side are distinctly limbate for the test size. Walls are trans- parent with numerous fine pores and the test walls are brown in color. Apertural structures.—The test morphology of Ammonia sp. cf. A. parkinsoniana differs from that of Ammonia sp. in having an umbilical plug and a small and more compact test. However, the apertural structure is very similar to that of Ammonia sp. (Figure 7.7, 7.8). The major difference is found in the less developed chamber flap (Figure 7.7). The final aperture is interiomarginal, mostly covered with a small chamber flap (Figure 7.7). The base of the foraminal plate adheres to the previous whorl and extends rearward to con- tact the umbilical coverplate. The umbilical coverplate cov- ers the final apertural opening, leaving a rounded foramen (Figure 7.7). No labial aperture is formed in this species. Thus the foraminal plate is concealed by the umbilical coverplate, and remains in a plate-like structure in the pre- ceding chamber lumen. Remarks.—This form is identical to the form having the umbilical plug in A. beccarii forma 2 (Matoba, 1970, p. 48, pl. 5, figs. 11a-c, in part). Despite having the umbilical plug, this form is different from Ammonia. beccarii (s.s.) on ac- count of its small test and smooth test walls. According to Walton and Sloan (1990), this form falls within the range of morphotypic variation of Ammonia beccarii forma parkin- soniana. We tentatively identified this examined form with Ammonia. sp. cf. A. parkinsoniana, pending further compari- son with the type species. Ammonia tepida (Cushman) Figure 8.1-8.3 Type reference.— Rotalia beccarii (Linné) var. Cushman, 1931, p. 61, pl. 13, figs. 3a-c. Materials. — Ammonia tepida (Cushman) from Recent sediment of the Sakai Suido Strait near Miho Bay, the Sea tepida Figure 6. External and internal apertural structure of Ammonia sp. Scale: 50 um. 1. Umbilical side view. This form mostly has an open umbilicus. Fine umbilical plug is shown, but it is usually indistinct in optical observation. 2. Oblique view of the umbilical side. The final chamber is removed, thus the penultimate foramen and the foraminal plate can be seen. The umbilical coverplates cannot be seen because they are concealed by the chamber flaps. 3. Oblique view of the umbilical side. The final aperture is an interiomarginal slit from the peripheral side to the umbilicus. Note long slit of the apertural opening is different from rounded intercameral opening. 4. Internal features of the final and penultimate chambers. Spiral side of walls is removed. Walls of the foraminal plate and the umbilical coverplate are smooth. 5. Opened umbilical side showing the foraminal plates and the umbilical coverplates convex towards the umbili- cus. The umbilical coverplate adheres to the hinge of the preceding foraminal plate and umbilical coverplate. 6. The umbilical coverplate convex toward the umbilicus. The umbilical coverplate is curled and butts against the previous chamber whorl. 7. External view of the opened umbilicus. 8. Spiral side walls removed. Foraminal plate and umbilical coverplate shown in the penultimate cham- ber. Very small labial aperture may be seen in this specimen, but it is usually rare. Abbreviations: cf=chamber flap; fa=final aperture; fp=foraminal plate; h=hinge; fo=foramen; la=labial aperture; sw=septal wall; uc=umbilical coverplate. 26 Ritsuo Nomura and Yokichi Takayanagi Ammonia and Pararotalia apertures 27 of Japan. Diagnosis of test.— This species has a small test for this genus and has six to seven chambers in the final whorl. The umbilicus is depressed, without a plug. Sutures incised and decorated with small spines on the umbilical side and flush with surface on the spiral side. Ventral chambers are broad and oval. Chamber flaps are developed, imbricated, and cover the sutures near the umbilicus. Apertural structures.—The final aperture is interiomarginal and consists of a single opening extending to the umbilicus, with the developed chamber flap (Figure 8.1). The foraminal plate is formed on the proximal side of the foramen (Figure 8.2), and the hinge is much inclined and curled to connect to the posterior part of the chamber flap. Thus the posterior part of the chamber flap is concave where the la- bial aperture is formed except for the final chamber (Figure 8.1). The labial aperture is rather large and rounded in shape, which can be seen from a posterior oblique view (Figure 8.3). The umbilical coverplate is completely cov- ered with the chamber flap, but always developed except in the final chamber (Figure 8.2). Remarks. — Seibold (1971) put A. tepida in the genus Discorbis, based on differences of the internal structure such as the relationships between the toothplate (=foraminal plate), axial wall (=umbilical coverplate here), and septal lamellarity (that is, single or double). That idea is invalid, because these internal structures are not characteristic of Discorbis, but of Ammonia. Lévy et al. (1986) pointed out no critical differences in the internal structure between A. beccarii and A. tepida. How- ever, the development of the large labial aperture of A. tepida is not only significant in distinguishing this species from A. beccarii, but also from our examined Ammonia sp. herein. All examined specimens are in accordance with Cushman’s original concept of Ammonia beccarii var. tepida (s.s.) and represent the typical Ammonia beccarii forma tepida of Walton and Sloan (1990). Although there are externally gradational morphologies in Walton and Sloa n’s forma tepida, our tepida is different from the other end member form (e. g., Ammonia sp. herein) in the presence of the labial aperture. Ammonia tepida may represent a defi- nite species as suggested by Pawlowski et al. (1995). We are of the opinion that forma tepida of Walton and Sloan (1990) needs further consideration based on observations of the internal structure. Ammonia tochigiensis (Uchio) Figure 8.8, 8.9 Type reference.— Rotalia tochigiensis Uchio, 1951, p. 374, pl. 5, figs. 1a-c. Materials.— One examined specimen from the type local- ity of this species, the Momiyama Formation, Tochigi Prefecture; five specimens from the Miocene Bihoku Group, Southwest Honshu, Japan. This species is very common in early middle Miocene shallow deposits of Japan. Diagnosis of test—Most examined specimens are natu- rally broken, without the final chamber, but well preserved specimens show the interiomarginal aperture. An umbilical plug is distinctly developed. Chamber flaps are less devel- oped, thus chambers around the umbilical plug are serrated. 13-15 chambers in the final whorl. Sutures distinct and limbate on both sides of test and less incised on umbilical side. Sutures on spiral side are raised. Apertural structures.—The final aperture is interiomargin- al, mainly open on the umbilical side, but covered with a less developed chamber flap. The hinge is columnar in shape, formed at a high angle to the preceding whorl near the um- bilicus, with a less developed free margin of the foraminal plate (Figure 8.8). The base of the foraminal plate on the previous whorl is strongly bent toward the posterior. The umbilical coverplate adheres to the edge of the preceding foraminal plate, leaving a concave space between the um- bilical coverplate and the foraminal plate (Figure 8.9). Labial apertures are found in an incised suture near the um- bilicus. Remarks.—The internal structure with emphasis on the aperture has been discussed by Ujiié (1965). He described exactly the final aperture as showing an interiomarginal- basal narrow slit, but the description with respect to the fora- men is unclear. We did not observe such a structure indicating “interiomarginal foramen converted from aperture, probably by partial resorption of apertural face slightly before addition of new chamber.” His toothplate structure is not clearly distinguished from the chamber wall or the umbilical coverplate. His description says the free structure (foraminal plate?) is added after the formation of the new chamber. In our view the umbilical coverplate positioned in the penultimate chamber is formed simultaneously with the foraminal plate as well as the final chamber wall. Figure 7. External and internal apertural structure of Ammonia sp., Ammonia japonica (Hada, 1931), and Ammonia sp. cf. A. parkinsoniana (d’Orbigny, 1836). Scale: 50 um. 1. Closeup figure of the chamber flaps and the umbilical coverplates in Ammonia sp. 2. Umbilical side view of A. japonica. 3. A. japonica with artificially removed chamber walls of the umbilical side. 4. Oblique view of the umbilical side of A. japonica. Proximal part of the septal wall adheres to the previous whorl in its final chamber (septal attachment in here), thus the anterior and posterior apertures are shown. The foraminal plate with its thickened rim represents the posterior end of the final chamber. 5. Oblique view of the umbilical side of dissected A. japonica. The posterior aperture changes into the labial aperture with development of the umbilical coverplate. 6. Umbilical side view of A. sp. cf. A. parkinsoniana. 7. Oblique view of the umbilical side of A. sp. cf. A. parkinsoniana without the final chamber. The umbilical coverplates seal the previous interiomarginal apertures. 8. Oblique view of the umbilical side of A. sp. cf. A. parkinsoniana showing opening of final aperture. No labial apertures are shown. Abbreviations: aa=anterior part of aperture; cf=chamber flap; fa=final aperture; fp=foraminal plate; fo=foramen; la=labial aperture; pa=posterior part of aperture; sa=septal attachment; uc=umbilical coverplate. 28 Ritsuo Nomura and Yokichi Takayanagi à = Ammonia and Pararotalia apertures 29 Pararotalia nipponica (Asano) Figures 3, 8.4-8.7 Type reference.—Rotalia nipponica Asano, 1936, p. 614, pl. 31, figs. 2a-c. Materials. — Pararotalia nipponica (Asano) from Recent sediment of the Sakai Suido Strait near Miho Bay, the Sea of Japan. Diagnosis of test—The specimens examined are charac- terized by a well developed umbilical plug. Eight chambers on the umbilical side, inflated without a chamber flap, and having a rounded triangular shape around the umbilical plug. Sutures on the umbilical side are mostly radiate, deeply in- cised, but those on the spiral side are tangential. Umbilical spiral suture is covered with overhanging chambers (=um- bilical shoulder), but it is never sealed up by the umbilical shoulders. Apertural structures.—The final aperture is an interio- marginal slit, extending from the midbase of the apertural face to the umbilicus (Figure 8.4). The lip is thick and pro- truded. The chamber flap is undeveloped, thus the umbili- cal canal and sutural grooves are well shown as deep fissures on the umbilical side. The foraminal plate is only associated with the foramen and the base of its hinge ad- heres to the distal end of the preceding apertural opening, thereby forming the protruded lip (Figure 8.5-8.7), which is here called the lower lip (Figure 3). Thus the foramen is areal in position (Figure 8.5). The umbilical coverplate is developed around the umbilical plug except in the final chamber and connects to the foraminal plate (Figure 8.6, 8.7). No openings corresponding to a labial aperture are found in the umbilical coverplate, indicating the foramen is the main passage between the chambers. Remarks.—The previously described toothplate of this species is morphologically very ambiguous and confused. The toothplate of Ujiié (1966) may correspond to the umbili- cal coverplate, according to his description and sketched fig- ures (see above). He noted the umbilical slit (=aperture in original form) is closed with secondary calcification, and then the free toothplate disappears. Because of the absence of such a free structure in the penultimate and preceding chamber, he considered this to indicate partial dissolution of the toothplate. However, such an ingenious explanation is unnecessary. Originally, there are no free structures com- parable to his suggested structure in P. nipponica. External test shape of Pararotalia nipponica is similar to that of P. inermis. We can observe the protruded structure demonstrated by Hottinger et al. (1991) on the umbilical side of nipponica’s foramen. This free part of the walls, which is called a toothplate by them, is structurally the same as the lower lip. We find also this type of foramen in Neorotalia, as can be seen in the detailed figures of Hottinger et al. (1991, 1993). Discussion Our observations suggest that the foraminal plate and um- bilical coverplate complexes are variable at species level. Moreover, the interrelationships of these plates with neigh- boring structures are too complicated to easily understand without detailed anatomical observations. Thus, the simple application of the presence or absence of the so-called toothplate to taxonomic decisions is not a reliable criterion. The foraminal plate and umbilical coverplate are a speci- fied part of the chamber wall formed simultaneously in asso- ciation with the preceding foramen. On this point, the final aperture is connected with the preceding foramen via the foraminal plate, which may be apparently correlated with the original toothplate concept of Hofker (1950, 1951a, b). Nevertheless, the critical point is that the foraminal plate in- volves both the final aperture and the preceding foramen. The umbilical coverplate serves only to seal the preceding apertural opening and is not associated with the formation of the final chamber wall. Such foraminal plate and umbilical coverplate structures are characteristic of the rotaliids, not of other taxa with a toothplate. The buliminid toothplate ex- tends within the chamber lumen and no parts of it are con- cerned with the preceding chamber (e. g., Hofker, 1950, 1951a, b; Revets, 1989). We regard this difference of the toothplate as of primary importance in distinguishing the rotaliid aperture from others. Thus we follow the foraminal plate and umbilical coverplate concept of Hansen and Reiss (1971) and Revets (1993), who stressed the significance of applying only the terms foraminal plate and coverplate to rotaliid taxonomy rather than accepting the general toothplate concept. Figures 8. External and internal apertural structure of Ammonia tepida (Cushman, 1931), Ammonia tochigiensis (Uchio, 1951), and Pararotalia nipponica (Asano, 1936). Scale: 50 um. 1. Umbilical side view of Ammonia tepida . Note well developed chamber flaps. 2. Oblique view of the umbilical side of dissected A. tepida. The umbilical coverplates adhere to the preceding umbilical coverplate, apart from the hinge in this species. 3. Umbilical side view of A. tepida indicating the foraminal plate, umbilical coverplate, and labial aperture. 4. Umbilical side view of P. nipponica. The final aperture is an interiomarginal slit extending from the peripheral side to the umbilicus. 5. Oblique view of the umbilical side of dissected P. nipponica. The antepenultimate aperture is an oval surrounded by the lip and the lower lip (=foraminal plate). The remnant of the dissected penultimate chamber wall shows the lower lip linking to the umbilical coverplate. 6. P. nipponica with removed chamber walls of the umbilical side showing the lower lips and the umbilical coverplates. The lower lips represent the foraminal plates as a continuation to the umbilical coverplates. 7. Umbilical side view of P. nipponica with the final three chambers removed. The continuous structure of the lower lip (=foraminal plate) and the umbilical coverplate is clearly shown. The umbilical coverplates adhere to the previous whorl at a low angle. 8. Peripheral view of dissected A. tochigiensis. Columnar- shaped foraminal plate is due to a posterior bend of the plate. The umbilical coverplate adheres to the bent edge of the preceding plate. 9. Oblique view of the umbilical side of dissected A. tochigiensis. The complex of foramen, foraminal plate and umbilical coverplate is shown in the antepenultimate chamber. Abbreviations: cf=chamber flap; fa=final aperture; fp (Il)=foraminal plate (lower lip); fp=foraminal plate; fo=foramen; la=labial aperture; uc=umbilical coverplate; I=lip. 30 Ritsuo Nomura and Yokichi Takayanagi On the other hand, different opinions appeared in the dis- cussion and description of the rotaliids by Hottinger et al. (1991, 1993). They are consistent in using the term tooth- plate by revising its concept. In addition to the original con- cept, their toothplate includes a new point of view such as an association with a canal. They defined the toothplate as “A toothplate separates partly or entirely the main chamber lumen from an axial space....Interconnected toothplates pro- duce a primary canal.” According to their definition, Pararotalia is associated with a toothplate as it has an um- bilical canal, while Ammonia is not associated with a toothplate as it has no umbilical canal. The presence or ab- sence of their toothplate is due to whether the canal is formed or not. Their toothplate concept in relation to struc- tures such as foraminal plate, umbilical coverplate and um- bilical plate is subordinate in significance. As we observed in the aperture of Pararotalia, the umbilical coverplate obliquely leans to the walls of the previous whorl. The incli- nation of the foraminal plate is much the same as the umbili- cal coverplate and changes to a lip in this type of foramen (Figure 3). Thus we usually observe the canal between the umbilical plate/foraminal plate and the previous whorl of the test. This structural reconstruction is similar to that of Neorotalia demonstrated by Hottinger et a/. (1991, p. 29, fig- ure 7) and Pararotalia (Hottinger et al., 1993, p. 141, pl. 200, figs. 10, 11). This means that their toothplate is noth- ing but our foraminal plate, which is here called the lower lip in order to emphasize the structural difference from the Ammonia-type foramen. The same view can be seen in Revets (1993), who stated “The internal structures delimiting the canals are the perfect homologues of the foraminal- and coverplate of Ammonia.” In addition to different interpretations for the toothplate among these authors, there are also discrepancies with re- spect to the lamellar structure. Hansen and Reiss (1971) observed that the foraminal plate is bilamellar. Later, Revets (1993) confirmed the bilamellar structure of the rotaliid genus Neorotalia, along with the taxonomic signifi- cance of the buliminid toothplate consisting only of a modification of the inner lining. Hottinger et al. (1991) state that the septal flap, consisting of the inner lamella (=inner lin- ing), may extend into the foraminal plate, coverplate, and toothplate. Thus an additional inner lamella is imposed on the original bilamellar walls, producing trilamellar walls. A similar view of lamellar structure was suggested by Revets (1993) when he stated “As the coverplate butts into the foraminal plate of the prepenultimate chamber, it covers its outside by a secondary lamella, so that this foraminal plate cum coverplate is trilamellar.” Our observations of Ammonia sp. indicate, however, that the foraminal plate is always bilamellar and the preceding umbilical coverplate is covered with an outer lamella of newly formed coverplate (Figure 5). The foraminal plates never receive additional lamella from the new umbilical coverplate. We need further comparisons to ascertain the variation in the lamellar structure. Conclusions We studied the internal structure of some Japanese spe- cies of the genera Ammonia and Pararotalia to validate Hofker’s original concept of the toothplate (Hofker, 1950; 1951a, b). Two major structures, the foraminal plate and the umbilical coverplate (Hansen and Reiss, 1971), are dis- tinguished instead of the general term toothplate. The lamellar structure of the foraminal plate and umbilical coverplate is originally bilamellar. Two types of aperture ex- cept for the final one, Ammonia-type and Pararotalia-type fo- ramen, are recognized, according to the position of the foraminal plate constructed in the aperture. The description of the foraminal plate/umbilical coverplate structure is signifi- cant to rotaliid taxonomy in understanding intraspecific mor- phological variation. However, the structural complex should not be treated as a unit in order to make generic-level distinctions. Acknowledgments We are deeply indebted to Dr. S. A. Revets of the Univer- sity of Western Australia, Prof. Y. Matoba of Akita University and Prof. H. Kitazato of Shizuoka University, for their con- structive comments and suggestions. Dr. B. Hayward of Auckland University, New Zealand, carefully read the earlier version of this paper. Dr. J. Whittaker of the British Muse- um of Natural History and Dr. M. Kaminski of University College London responded to our inquiry. Prof. C. Benja- mini of Ben Gurion University gave R.N. a chance to exam- ine the Mediterranean fauna. We extend our thanks to Prof. J.-P. Debenay of Université D’Angers for reviewing the final version of this paper. References Asano, K., 1936: Fossil foraminifera from Muraoka-mura, Kamakura-göri, Kanagawa Prefecture. The Journal of the Geological Society of Japan, vol. 43, no. 515, p. 603 -615, pls. 30-31. Cifelli, R., 1962: The morphology and structure of Ammonia beccarii (Linné). 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Journal of Micropalaeontology, vol. 12, no. 2, p. 155-169, pls. 1-3. Rögl, F. and Steiniger, F. F., 1984: Neogene Paratethys, Mediterranean and Indo-Pacific seaways: Implications for the paleobiogeography of marine and terrestrial biotas. In, Brenchley, P. J., ed., Fossils and Climate, p. 171-200, Wiley, Chichester. Schnitker, D., 1974: Ecotypic variation in Ammonia beccarii (Linné). Journal of Foraminiferal Research, vol. 4, p. 217-223. Seibold, L., 1971: Ammonia Brünnich (Foram.) und verwandte Arten aus dem Indischen Ozean (Malabar-Küste, SW- Indien). Paläontologische Zeitschrift, vol. 45, p. 41-52, pls. 1-7. Smout, A. H., 1954: Lower Tertiary Foraminifera of the Qatar Peninsula, 96 p. and 15 pls. British Museum (Natural History), London. Takayanagi, Y., 1955: Recent foraminifera from Matsukawa- ura and its vicinity. Contributions from the Institute of Geology and Paleontology, Tohoku University, no. 45, p. 18-52, pls. 1, 2. (in Japanese with English description of new species) Uchio, T., 1951: New species of foraminifera of the Miocene age in Tochigi Prefecture, Japan. The Journal of the Geological Society of Japan, vol. 56, no. 661, p. 369-377, pl. 5. Ujiié, H., 1965: Shell structure of Japanese smaller foramini- fera Part 1. Ammonia tochigiensis (Uchio, 1951). Trans- actions and Proceedings of the Palaeontological Society of Japan, New Series, no. 60, p. 156-165, pls. 19-20. Ujiié, H., 1966: Shell structure of Japanese smaller foramini- fera Part 2. Pararotalia nipponica (Asano, 1936). Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 60, p. 191-200, pls. 24, 25. Walton, W. R. and Sloan, B. J., 1990: The genus Ammonia Brünnich, 1772: Its geographic distribution and morphol- ogic variability. Journal of Foraminiferal Research, vol. 20, no. 2, p. 128-156, pls. 1-3. 31 wi eee pa Baars sn tritt We PT Roe ee ee i ROMANE San Tan Bi key: = D a hey by ER Er e E r Ci a i = —— ‘ 5: re ( u re Ala fi firmed, gv eed 4 a Ge aap (Ol, 4) nr Paleontological Research, vol. 4, no. 1, pp. 33-38, April 28, 2000 © by the Palaeontological Society of Japan The turrilitid ammonoid Mariella from Hokkaido-Part 3 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin LXXXVII) TATSURO MATSUMOTO!’ and TOSHIO KIJIMA’ " c/o Kyushu University 33, Fukuoka, 812-8581, Japan * Kita-4 Joh, Nishi 17-1-1, lwamizawa, Hokkaido, 068-0044, Japan Received 14 June 1999; Revised manuscript accepted 13 October 1999 Abstract. south-central Hokkaido, is described. dorsetensis (Spath, 1926). Mariella (Mariella) lewesiensis (Spath, 1926) from the Cretaceous of the Hobetsu district, It is represented by a large specimen, from which a question may arise about the previous view of dimorphism. It has some affinities with M. (M.) cenomanensis (Schlüter, 1876). This species is not directly related to M. (M.) Key words: Cretaceous, dimorphism, Hokkaido, Mariella (Mariella) lewesiensis, Turrilitidae Introduction Altogether eight species of the genus Mariella from Hokkaido have been described successively in Part 1 (Matsumoto et al., 1999) and Part 2 (Matsumoto and Kawashita, 1999) under the same title as this paper. They are based primarily on a number of specimens from the mid- Cretaceous members of the Middle Yezo Subgroup in the Soeushinai area [=Shumarinai-Soeushinai area by some authors] of northwestern Hokkaido and on supplementary material from the correlative part in the Yubari Mountains of central Hokkaido. An additional species of Mariella described here is repre- sented by a large specimen which was found by T. K. from the Hobetsu district of south-central Hokkaido. At the re- quest of the Mikasa City Museum [MCM] the specimen was temporarily put on public display there without, however, its being assigned specific name. With the consent of MCM we have recently investigated it to settle its systematic allo- cation. The described specimen is now officially registered at the National Science Museum [NSM] in Tokyo as a dona- tion by T. K. Paleontological description (continued) Mariella (Mariella) lewesiensis (Spath, 1926) Figures 2-4 Turrilites bergeri Sharpe, 1857, p. 65 (pars), pl. 26, fig. 10 only. Turrilites lewesiensis Spath, 1926, p. 429. Mariella lewesiensis (Spath). Spath, 1937, p. 512. Mariella (Mariella) dorsetensis (Spath, 1926). Renz in, Renz et al., 1963, p. 1095, pl. 1, fig. 3; Klinger and Kennedy, 1978, p. 31, pl. 9, fig. F, text-figs. 3A, 8A; Kennedy et al., 1979, p. 18, pl. 1, fig. 9. Mariella (Mariella) lewesiensis (Spath, 1926). Kennedy, 1971, p. 27, pl. 8, figs. 1, 4, 5, 8; Juignet and Kennedy, 1976, p. 62, pl. 3, fig. 17; Atabekian, 1985, p. 37, pl. 7, fig. 1; pl. 8, fig. 1; Wright and Kennedy, 1996, p. 339, pl. 100, figs. 4, 13, 23, 27; pl. 101, figs. 2, 3; pl. 103, figs. 6-8. Type.—Holotype, by monotypy, is BMNH 3355B, the origi- nal of Sharpe, 1857, pl. 26, fig. 10 (reillustrated by Wright and Kennedy, 1996, pl. 101, fig. 3). It was studied by T.M. at the British Natural History Museum (BMNH) in 1979. Material. —NSM PM16123. This specimen was collected by T. K. on 19 September 1973 at his locality no. 21 from the mudstone outcrop on the right side of a stream called the Matsukashimapu, about 600m NW of Sanushi Bridge, Inasato area in the Hobetsu district, south-central Hokkaido (Figure 1). The geologic structure is complicated in the Inasato area, where strata seem to be much disordered by folding and thrusting. Description.—The specimen (Figures 2, 3) is in the state of half-ammonoid preservation (see Maeda, 1987 for this technical term). It is, however, magnificent in its large size, nearly 270mm in total height consisting of 7 preserved whorls and roughly 120mm in diameter at the last whorl (i.e., part of the body chamber). It would be nearly 400mm in tower height, if the missing younger whorls were added. The estimated apical angle is 21°. The late part (at the fifth whorl from the preserved top in Figure 2) is secondarily dis- placed from the main part, whereas the middle whorl (the third whorl from the preserved top) is almost undeformed. The septal suture is partly exposed on this whorl (Figure 4). The upper part of the exposed whorl face is broadly con- vex and smooth. It slopes down to the gently convex or nearly vertical main flank, which in turn slopes down 34 Tatsuro Matsumoto and Toshio Kijima Map showing the location of T. Kijima’s Loc. 21 Figure 1. where Mariella (Mariella) lewesiensis (Hobetsu specimen) was obtained. HD=Hobetsu Dam; IS=Inasato; MK=Matsuka- shimapu-zawa; PW=Penke-wakka-tannenai-zawa; RH=River Hobetsu; SB=Sanushi Bridge across the River Sanushibe; TK=Takikawa-no-sawa; US=Uesugi-zawa. The term sawa or zawa means a rivulet. Broken line: highway. considerably inward. Thus the interwhorl junction is deeply impressed. Each whorl is ornamented by tubercles in four rows. The tubercles of the upper two rows are coarse and fairly strong, although those of the second row are slightly smaller than those of the first row. On the whorls of the early to middle growth stages the tubercles are somewhat transversely and obliquely elongated. In later growth stages the tubercles of the upper two rows are very coarse, showing a subelliptical base, a domelike shape and a spinose peak. The tubercles of the third row are somewhat smaller than those of the sec- ond row in the early to middle growth stages. In the later growth stages they become much smaller, weaker and obliquely clavate (i.e., spirally elongated) in contrast to the enlarged tubercles of the upper two rows. The three rows on the exposed whorl face are disposed at subequal but slightly decreasing intervals downward (Figures 2, 3). The tubercles of the fourth row are close to those of the third and run along the lower whorl seam, giving crenulation to the interwhorl junction. They are scarcely visible in ear- lier growth stages, but become more obvious on the lower whorl face in later stages. The tubercles of the first to fourth rows are aligned in an obliquely adoral orientation, but they do not form clear ribbing. Although the basal surface is not fully exposed, distinct ribs do not seem to run from the tuber- cles of the fourth row. A series of shallow dimplelike de- pressions is discernible between the upper two rows of tubercles, but it does not form a wide and deep furrow like that of Mariella (Wintonia). Comparison.—The middle part of this specimen is compa- rable with the septate holotype and some other example of M. (M.) lewesiensis (e.g., Wright and Kennedy, 1996, pl. 101, figs. 3, 2; Atabekian, 1985, pl. 8, fig. 1). In its less de- formed whorl, i.e., the third whorl from the top, the height [H] is 32mm at diameter [D] 72mm, hence, H/D is 0.47. These proportions conform with those of the holotype at a corre- sponding stage, where H=30.5mm, D=67.0mm and H/D= 0.47. Similarity is also observable in the ornament. There are 21 tubercles in each row per whorl in the holotype. The Hobetsu specimen shows eleven tubercles in the exposed half of the whorl at the middle growth stage, although the number seems to decrease to 7 or 8 at the last stage. The smooth surface in the upper part of the exposed whorl face immediately below the upper seam is a diagnostic character of this species. This feature is clearly observed in the Hobetsu specimen. The faint ribbing on the basal surface in this species also occurs in our specimen. To sum up, the described specimen is certainly identified with M. (M.) lewesiensis. Discussion.—The Hobetsu specimen attains enormous size for Mariella (M.) lewesiensis. This raises the problem of dimorphism. Wright and Kennedy (1996, p. 340) have pointed out a dimorphic pair in this species, namely they re- garded SMC B35910 (Wright and Kennedy, 1996, pl. 103, fig. 7) as an adult macroconch and SMC B35905 (Wright and Kennedy, 1996, pl. 100, fig. 27) as an adult microconch. The former is about 200mm in estimated original tower height with an inferred apical angle of 22°, whereas the latter is about 150mm in tower height with an apical angle of 21°. The specimen from Hobetsu is almost twice as large as the so-called macroconch example (SMC B35910) from England in regard to the total whorl height (400mm) and also to the diameter (120mm) of the last whorl. This fact throws doubt on the previous evidence of dimorphism in M. (M.) lewesiensis. Further investigation, including the statistical examination on a sufficient number of specimens, is re- quired for a definite conclusion. Mariella (M.) lewesiensis has been often confused with M. (M.) dorsetensis (Spath). This is shown by the synonymy given in the description of the latter in Part 1 (Matsumoto et al., 1999, p. 107) and that of the former in Part 3. Here we would like to comment that the two specimens illustrated by Benavides-Cäceres (1956, p. 108, pl. 40, figs. 8, 9) under “Paraturrilites lewesiensis (Spath)” should both be revised to M. (M.) dorsetensis (Spath), although one of them (Benavides-Caceres, 1956, pl. 40, fig. 8 only) was consid- ered so by many authors. Likewise, what was called M. (M.) lewesiensis (Spath) by Marcinowski (1974, pl. 32, fig. 13 without description), from the Lower Cenomanian of the Polish Jura Chain, is probably M. (M.) dorsetensis, because of the distinct ribs on the upper whorl face and the rows of granular tubercles on the convex flank at subequal intervals. The morphological distinction between the two species has been already discussed in Part 1 (Matsumoto et al., 1999). We offer here remarks on their affinities. M. (M.) Mariella from Hokkaido-Part 3 Figure 2. Mariella (Mariella) lewesiensis (Spath). Lateral view of NSM PM16123, X 2/3. Shinohara, without whitening) (Photo courtesy of Katsumi 35 36 Tatsuro Matsumoto and Toshio Kijima Figure 3. Mariella (Mariella) lewesiensis (Spath). NSM PM16123. Specimen turned about 60° clockwise from the posi- tion in Figure 2, X2/3. (Photo courtesy of Katsumi Shinohara, without whitening) Mariella from Hokkaido-Part 3 231 Figure 4. Mariella (Mariella) lewesiensis (Spath). External suture partly exposed on the preserved third whorl of NSM PM16123. E: external lobe; L: lateral lobe. Bar scale: 5 mm. dorsetensis is closely allied to M. (M.) bergeri (Brongniart) of latest Albian age. The affinities of M. (M.) lewesiensis have not been much discussed, but recently Wright and Kennedy (1996, p. 344) have pointed out a close relationship between M. (M.) lewesiensis and M. (M.) cenomanensis (Schlüter, 1867). We would agree with them, although well preserved examples of M. (M.) cenomanensis have not been described from Hokkaido. Based on the description and plentiful illus- trations by Wright and Kennedy (1996, p. 342, with a full synonymy, and pl. 100, figs. 3, 24, 26; pl. 101, figs. 1, 4; pl. 102, fig. 14; pl. 103, fig. 9; pl. 110, fig. 3; pl. 111, figs. 1, 3; text-figs. 136A and 141B; also Wright and Kennedy, 1995, text-fig. 129E for the suture), the following points are evi- dent. In M. (M.) cenomanensis the upper part of the exposed whorl face is convex and smooth as in M. (M.) lewesiensis. The tubercles of the upper two rows are coarse in both spe- cies, but in the former the tubercles of the second row are clavate (i.e., spirally elongated) and disposed in the lower part of the flank, being separated from the first row by a broad, smooth zone. Some examples of M. (M.) cenomanensis (e.g., Wright and Kennedy, 1996, pl. 101, figs. 1, 2) are nearly as large as the Hobetsu specimen of M. (M.) lewesiensis. Incidentally, “Mariella (Mariella) n. sp. aff. lewesiensis (Spath),” was mentioned by Kanie et al. (1977, p. 113, pl. 1, fig. 8) in their Madagascar paper. Actually it is one of the specimens (TKD 30080A from Loc. 71204 in the Shumarinai area) of M. (M.) dorsetensis, as has been recently described by Matsumoto et al. (1999, p. 108). Distribution.— Mariella (M.) lewesiensis has been reported to occur in the Lower Cenomanian of southern England, France, Germany, Switzerland, Poland, Turkmenistan, Iran, Zululand (South Africa) and Madagascar (see synonymy for the references). Now its distribution is extended to Japan in the northwestern Pacific region. Acknowledgments We are much indebted to Hiroshi Hayakawa of the Mikasa City Museum for his kind help in various ways. Thanks are extended to Katsumi Shinohara for his photography, to Masashi Kawano (deceased) and Yoshitaro Kawashita for this cooperation in T.K.'s fieldwork and also to Kazuko Mori for her assistance in preparing the manuscript. References cited Atabekian, A. A., 1985: Turrilitids of the late Albian and Cenomanian of the southern part of the USSR. Academy of Sciences of the USSR, Ministry of Geology of the USSR, Transactions, vol. 14, p. 1-112, pls. 1-34. (in Russian) Benavides-Caceres, V. E., 1956: Cretaceous System in north- ern Peru. Bulletin of the American Museum of Natural History, vol. 108, p. 353-494, pls. 31-66. Juignet, P. and Kennedy, W. J., 1976: Faunes d’Ammonites et biostratigraphie comparée du Cénomanien du nord-ouest de la France (Normandie) et du sud de Il’Angleterre. Bulletin trimenstriel de la Societe Géologique de Normandie et des Amis du Museum du Havre, vol. 63, no. 2, p. 1-193, pls. 1-34. Kanie, Y., Hirano, H. and Tanabe, K., 1977: Lower Cenomanian mollusks from Diego - Suarez, northern Madagascar. Bulletin of the National Science Museum, Series C (Geology), vol. 1, p. 109-132, pls. 1-4. Kennedy, W. J., 1971: Cenomanian ammonites from southern England. Special Papers in Palaeontology, vol. 8, p. 1- 133, pls. 1-64. Kennedy, W. J., Chahida, M. R. and Djafarian, M. A., 1979: Cenomanian cephalopods from the Glauconitic Lime- stone, southeast of Esfahan, Iran. Acta Palaeontologica Polonica, vol. 24, no. 1, p. 3-50, pls. 1-8. Klinger, H. C. and Kennedy, W. J., 1978: Turrilitidae (Cretaceous Ammonoidea) from South Africa, with a dis- cussion of the evolution and limits of the family. Journal of Molluscan Studies, vol. 44, p. 1-48, pls. 1-9. Maeda, H., 1987: Taphonomy of ammonites from the Cretaceous Yezo Group in the Tappu area, northwestern Hokkaido, Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 148, p. 285-305. Marcinowski, R., 1974: The transgressive Cretaceous (Upper Albian through Turonian) deposits of the Polish Jura Chain. Acta Geologica Polonica, vol. 24, no. 1, p. 117- 217, pls. 1-34. Matsumoto, T., Inoma, I. and Kawashita, Y., 1999: The turrilitid ammonoid Mariella from Hokkaido - Part 1. Paleon- tological Research, vol. 3, no. 2, p. 106-120. Matsumoto, T. and Kawashita, Y., 1999: The turrilitid ammonoid Mariella from Hokkaido - Part 2. Paleon- tological Research, vol. 3, no. 3, p. 162-172. Renz, O. in, Renz, O., Luterbacher, H. and Schneider, A., 1963: Stratigraphisch-paläontologische Untersuchungen im Albien und Cenomanien des Neuenburger Jura. Eclogae Geologicae Helvetiae, vol. 56, no. 2, p. 1073- 1116, pls. 1-9. Schlüter, C., 1876: Cephalopoden der oberen deutschen Kreide. Palaeontographica, vol. 24, p. 121-164, pls. 36-55. 38 Tatsuro Matsumoto and Toshio Kijima Sharpe, D., 1857: Description of the fossil remains of Mollusca found in the Chalk of England. Cephalopoda, part 3. Monograph of the Palaeontographical Society, London, no. 36, p. 37-68, pls. 17-27. Spath, L. F., 1926: On the zone of the Cenomanian and the uppermost Albian. Proceedings of the Geologists Association, vol. 37, p. 420-432. Spath, L. F., 1937: A monograph of the Ammonoidea of the Gault, part 12. Monograph of the Palaeontographical Society, London, no. 409, p. 497-540, pls. 37-58. Wright, C. W. and Kennedy, W. J., 1995: The Ammonoidea of the Lower Chalk, part 4. Monograph of the Palaeon- tographical Society, London, no. 599, p. 295-319, pls. 87-94. Wright, C. W. and Kennedy, W. J., 1996: The Ammonoidea of the Lower Chalk, part 5. Monograph of the Palaeontographical Society, London, no. 601, p. 320- 403, pls. 95-134. Paleontological Research, vol. 4, no. 1, pp. 39-52, April 28, 2000 © by the Palaeontological Society of Japan Dicotyledonous leaf macrofossils from the latest Albian-earliest Cenomanian of the Eromanga Basin, Queensland, Australia. MIKE POLE Department of Botany, University of Queensland, St Lucia, Brisbane, QLD 4072, Australia. Received 10 May 1999; Revised manuscript accepted 14 October 1999 Abstract. Ten types of dicotyledonous angiosperm cuticle are described from bore core samples from the Early Cretaceous (latest Albian-earliest Cenomanian) of the Eromanga Basin, central Queensland. To date, these are the oldest organically preserved angiosperm macrofossils in Australia. Most of this material is found as small dispersed fragments, but two more intact lobed leaves were found. The affinities of some specimens are suggested to lie with the Chloranthaceae and Illiciales, and possibly the Platanaceae, but the rest are unknown. None of the cuticles show the paracytic stomatal arrangement which is common in extant plant families often regarded as ‘primitive’. However, one of the cuticle forms exhibits a ‘plastic,’ variable form of subsidiary cell arrangment, which has previously been suggested as the most primitive condition. These angio- sperms were a small component of an overwhelmingly gymnosperm (mostly conifer) dominated flora. They grew in clastic swamps, but may also have occured in coal swamps or sandy levees. The notably thin cuticle of some forms is consistent with an understory or deciduous habit. Key words: angiosperm, Australia, Cretaceous, cuticle, stomate Introduction The first angiosperms appeared in Australia during the Barremian-early Aptian, and by the end of the Albian over 20 angiosperm(id) pollen types are known (Burger, 1990). Based on pollen records the angiosperms had originated somewhere distal to Australia by the Valanginian (Brenner and Bickoff, 1992; Brenner, 1996). The oldest angiosperm macrofossils in Australia are impressions from the Aptian of the Otway Basin in Victoria (Douglas, 1994). These impres- sions include a dicot identified as Hydrocotylophyllum lusitanicum Teixeira (Douglas, 1965). A further specimen, previously interpreted by Drinnan and Chambers (1986) as a possible fern, was later claimed as the world’s oldest flower (Taylor and Hickey, 1990; although this distinction is now claimed by Late Jurassic material from China, Sun et al. 1998). The Australian Late Cretaceous angiosperm macrofossil record is very poor, probably due to a lack of outcrop. Scattered impressions and some cuticular debris are known from drill core material from the later part of the Victorian Cretaceous but have not been formally docu- mented. McLoughlin et al. (1995) illustrated several dico- tyledonous leaf impressions of probable Cenomanian age from the Eromanga Basin of central Queensland. Their ma- terial came from surface outcrop of the Winton Formation (Vine and Day, 1965; Exon and Senior, 1976) which has undergone considerable weathering. Below this zone, in samples obtained from bore cores for this study, weathering and lithification have been minimal and anatomical details (including cuticle) of fossil plants are preserved (Pole, 1999; Pole and Douglas, 1999). This material has been dated palynologically as close to the Albian-Cenomanian boundary (Dettmann and Playford, 1969; Helby et a/., 1987; Dettmann et al., 1992). The purpose of this paper is to document the dicotyledonous macrofossils from bore core samples of the Eromanga Basin. Dicotyledon leaf fragments were recognised by having net venation comprising more than one order, or thickness of veins, and confirmed with epidermal characters. Angio- sperm cuticle was recognised partly by its robustness, i. e. it is strong enough to survive processing and handling. This eliminates from consideration the ferns, which in any case, are generally distinct on morphological characters (van Cotthem, 1970a). The Early Cretaceous fern Weichselia, which does have relatively thick cuticle, is singularly unique in morphology. Weichselia is more similar to Equisetum and some gymnosperms (Alvin, 1974), having relatively large, randomly oriented guard cells, which are not sunken or over arched by subsidiary cells, but have an outer stomatal ledge. On these criteria there is little else in the Early Cretaceous which could be confused as dicotyledon- ous, with the possible exception of the Caytoniales. Harris 40 Mike Pole eg PTIT [| ergs gine Thargomindah-3 | | Grace 140° 141° 142° 143° 144° 145° Longitude 22° 23° Latitude D (o>) ö 21° Queensland 28° 30° Figure 1. Locality map. The position of the study area within Queensland, Australia, is shown at left, and the po- sition of all drill cores sampled within the study area is shown at right. Names of drill cores which provided dicotyledonous cuticle are in bold. (1940) described Sagenopteris cuticle which had guard Table 1. Stratigraphic details of samples with cells, apparently (according to his sketch) without outer dicotyledonous macrofossils. stomatal ledges, no distinct subsidiary cells, and trichomes SAMPLE DEPTH/M FORMATION with basal cells. A cuticle type from the Winton Formation with possible affinities to the Caytoniales is described in Pole MAC- 3 155.44 Winton and Douglas (1999). Monocotyledon cuticle is generally MAC- 7 193.49 Winton distinct and is dicussed in Pole (1999). MAC-11 319.7 Mackunda My separation of fossil cuticles into morphological groups is based on my experience with the cuticle of extant plants. MAN- 6 28.8 Winton In my opinion the forms described below represent individual MAN- 7 29.4 Winton species. MAN- 8 29.7 Winton MAN- 9 29.8 Winton Materials and methods MAN-11 29.95 Winton MAN-12 30.0 Winton Seven bore cores were selected from the Eromanga MAN-20 39.4 Winton Basin in central Queensland (Figure 1); GSQ Blackall-1, MAN-22 42.0 Winton GSQ Eromanga-1, GSQ Quilpie-1, GSQ Machattie-1, GSQ MAN-23 42.3 Minten Maneroo-1, GSQ Thargominda-3, and GSQ Tickalara- 1 MANSES 205 Much (these cores are stored in a Geological Survey of MAN-30 86.8 Winton Queensland (GSQ) warehouse at Zillmere, Brisbane). MAN-34 161.6 Mackunda Each core penetrates fluvial sediment of the Winton MAN-42 326.4 Mackunda Formation and the underlying marine sediment of the Allaru | and Mackunda Formations. Samples of approximately 5 THA-24 218.0 Winton cm’ each were selected for macrofossil preparation, based THA-32 240.3 Winton on a visual appraisal of the sediment. Each sample was THA-41 292.3 Winton numbered consecutively and prefixed with the first three let- THA-47 313.3 Wen ters of the bore core name. Stratigraphic details of samples which contained dicotyledonous macrofossils are given as Cretaceous dicotydonous macrofossils 41 Table 1 (details of all samples are given in Pole and Douglas, 1999). Carbonaceous muds were preferred, sands were avoided unless they contained prominent carbo- naceous horizons, and lignites were also generally avoided (previous experience and some tests indicated these usually do not preserve cuticle). Carbonaceous material was sparse in the marine sediment. Only two nearly intact leaves were recognised in hand specimen, the rest were small fragments of leaf lamina exhibiting some net venation or cuticle. In total, 235 samples were taken. Samples were numbered consecutively from the top of the core and given a prefix of the first three letters of the core name. Most of the sample was processed for cuticle, leaving a small amount as a voucher specimen. Samples usually broke down into a sludge with the addition of warm water, but sometimes addition of a little hydrogen peroxide was needed. Sludge was washed through 500 and 125 um mesh sieves, with most workable cuticle being retained on the 500 um. Further clearing of cuticle involved increasing concentrations of warm peroxide. This treatment was con- trolled so that fragments retained veins or resin glands. Further clearing so that only cuticle remained used aqueous chromium trioxide. Any adhering silicates were removed Figure 2. sil found. Stipple = margin, dashes = broken lamina. with hydrofluoric acid. Samples were scanned under a binocular microscope, the dominant floristic components were estimated, and speci- mens were removed with tweezers for transmitted light mi- croscopy (TLM) or (when sufficient extra material was available) scanning electron microscopy (SEM). Crystal Violet was used to stain when necessary. There are insufficient data for the dicotyledonous cuticles to formally diagnose new taxa and an informal system of no- menclature is used. Macrofossils and slides are catalogued with the prefix ‘SL’ and are stored in the Department of Botany, University of Queensland. Specimens mounted on Electron Microscope stubs are catalogued with the prefix ‘S’. Specimens for TLM viewing were mounted on micro- scope slides with glycerine jelly, and those for SEM viewing on stubs with double-sided tape and coated with gold. Results Dicotyledon sp. A Figures 2, 3 cm Dicotyledon sp. A, SL797. Line drawing of the only near-intact dicotyledon fos- See Fig. 3 for photographs. 42 Mike Pole Figure 3. Dicotyledon sp. A. A. Intact leaf on bedding surface of drill core sample, SL797, scale: 1 cm. B. Counterpart of SL797, scale: 1 mm. C. SEM of outer surface of stomate, S761, scale: 10 um. D. SEM of outer surface of stomate, S763, scale: 10 um. E. SEM of inner surface of stomate, S763, scale: 20 um. F. SEM of outer surface of stoma showing ridges ex- tending from lateral margin, S761, scale: 20 um. G. SEM of outer upper leaf surface showing ridges, S773, scale: 20 um. H. TLM of stomate, SL678, scale: 10 um. Cretaceous dicotydonous macrofossils 43 Reference specimen.—SL797 (almost intact leaf on bed- ding surface, MAN-11). Referred specimen and occurrence. — SL996; MAC -3 (dispersed cuticle). Description.—Leaf lobed, length about 40 mm, width about 50 mm (midrib-margin 24 mm), hypostomatic; on abaxial surface stomatal orientation random; outline of guard cell pair ovate, outer stomatal ledge broad, T-piece thicken- ings at poles prominent; subsidiary cells not visible under TLM, under SEM typically 6 isodiametric contact cells visi- ble; cuticle very thin, epidermal cell flanges not visible under TLM; on surface ridges of cuticle sometimes present over outer walls of guard cells, also bands of fine ridges promi- nent, extending laterally from guard cells; glabrous; adaxial surface epidermal cell flanges visible under TLM, isodiametric, polygonal, straight-walled; finely and evenly ridged on surface; glabrous. Figure 4. Dicotyledon sp. B. A-D. TLMs of leaf fragments with net-venation, scale: 1 mm. A.SL776. B.SL777. C. SL774. D.SL773. E. TLM of cuticle showing widely separated, aligned stomata (arrowed), SL787, scale: 50 um. F. TLM detail of single stomate, note narrow, elliptical rim, SL787, scale: 10 pm. 44 Mike Pole Dicotyledon sp. B SL777, MAN-23; SL788, MAN-34. Fi À Description. —Leaf shape unknown, small fragments of igure lamina exhibit net-venation; stomata scattered, infrequent, Reference specimen.—SL787 (dispersed cuticle, MAN- visible under TLM as very thin, aligned (at least over small 23). areas), elliptical, outer stomatal ledges; cuticle otherwise Referred specimens and occurrence.—SL997, MAN-9; very thin, no clearly distinguished subsidiary cells, epidermal SL774, MAN-11; SL773, MAN-20; SL771, MAN-22; SL776, cell flanges generally not visible, isodiametric, smooth, Figure 5. Dicotyledon sp. C. A. TLM, SL738, scale: 100 um. B. TLM with numerous dark resin bodies still attached, SL735, scale: 100 um. C.TLM of single stomate, SL738, scale: 25 um. D. SEM of inner surface of single stomate, note T-piece thickening, S765, scale: 20 um. E. SEM of outer surface of single stomate, S759, scale: 20 um. F. SEM of outer surface of sin- gle stomate, S765, scale: 20 um. Cretaceous dicotydonous macrofossils 45 slightly thicker over veins; glabrous. Dicotyledon sp. C Figure 5 Reference specimen.—SL738 (dispersed cuticle, MAN- 30). Referred specimens and occurrence.—SL731, MAN-6; S760, MAN-7; SL733, MAN-8; S765, MAN-9; S759, MAN- 11; SL735, MAN-12; SL739, MAN-42; SL676, THA-32. Description.—Stomatal orientation random, outer stomatal ledges broad; distinct, thin T-piece thickenings at guard cell poles; peristomatal thickening sometimes present; no clear or consistent subsidiary cell arrangement but lateral contact cells often divided tangentially to give irregular-shaped sub- sidiary cells; normal epidermal cells polygonal, smooth; major veins (midrib?) visible as more elongate, rectangular epidermal cells; outer cuticular surface smooth; typically glabrous but sparse poral trichome bases sometimes pre- sent; resin bodies from within leaf lamina often adhering to cuticle (e. g. SL735). Note.—The resin bodies are similar to those widespread throughout the extant magnoliids (Metcalfe, 1987; pers. obs.). Dicotyledon sp. D Figure 6 Reference specimen.—SL676 (dispersed cuticle, THA- 32) Referred specimens and occurrence.—SL895, MAC-7; SL677, THA-41 Description. — Stomatal distribution over leaf unknown; stomata randomly oriented; guard cell pair outline ovate, central portion covered by broad outer stomatal ledge; T- piece thickenings present at guard cell poles; subsidiary cell pattern variable, polar and lateral subsidiary cells typically recognisable, but sometimes not; lateral subsidiary cells pre- sent in up to three layers (including the hexacytic arrange- ment of van Cotthem, 1970b), apparently formed by Figure 6. Dicotyledon sp. D, all SL676, TLMs of stomata of varying type, scale: 25 um. A. Stomata with single lateral sub- sidiary cells on either side, some have divided radially. B. Stoma with 3 lateral subsidiary cells on one side, and two on the other which have both divided radially. C. Stomata with two lateral subsidiary cells. side. D. Stoma with six lateral subsidiary cells on one 46 Mike Pole elongate, tangential divisions of contact cells, sometimes also radially divided (i. e. giving six lateral subsidiary cells on one side of stoma); polar subsidiary cells irregular (probably just unmodified contact cells) or sometimes elongate, form- ing from tangential division of contact cell; veins not reflected in epidermal cells; glabrous. Dicotyledon sp. E Figure 7 Reference specimen.—SL772 (only specimen, small leaf with apex and base missing, two teeth present, MAN-34). Description.—Leaf toothed or lobed, preserved lamina length 6 mm, up to 4 mm wide, teeth/lobes 0.8 mm wide and high; first order venation externodromous; tooth vasculari- sation central; stomata visible only as thin, elliptical outer stomatal ledges; aligned with midrib when close, or aligned with lateral venation further away; resin bodies numerous within lamina. Dicotyledon sp. F Figure 8 Reference specimen.—SL678 (dispersed cuticle, only specimen, THA-24). Description. — Stomatal distribution over leaf unknown; stomata randomly oriented; outer stomatal ledges promi- nent, elliptical, sometimes narrowing abruptly before poles; prominent T-piece thickenings at stomatal poles; subsidiary cells not visible; cuticle very thin, epidermal cell flanges not visible in TLM, faint under SEM; outer epidermal surface or- namented by swirling bands of fine ridges sometimes start- ing at right angles from lateral subsidiary cells, but also with no consistent orientation to stomates; sometimes peristomal ridges present along edges of guard cells. Note.—The general appearance of the cuticle, particularly the surface ornamentation, appearance of the outer stomatal ledge, and the prominent T-piece thickenings are compara- ble with two extant genera of the Illiciales, Kadsura (Schisandraceae; cf. fig. 24F Metcalfe, 1987) and Illicium (Illiciaceae; cf. fig. 22B Metcalfe, 1987), suggesting a rela- tionship with this order. The same features are comparable with Eucalyptophyllum oblongifolium Fontaine from the Potomac Group, which was suggested by Upchurch (1984, p. 544 and cf. his figure 7) to represent “an extinct group of at least ordinal rank... that is related in some way to Chloranthaceae and Illiciales.” Figure 7. Dicotyledon sp. E, all SL772. A. TLM of complete specimen, note teeth and broken apex, scale: 1 mm. B.TLM detail of tooth showing numerous resin bodies, scale: 1 mm. C. TLM detail showing stoma (arrowed) and resin bodies, scale: 100 um. D. TLM detail of single stomate, scale: 25 um. Cretaceous dicotydonous macrofossils 47 Figure 8. Dicotyledon sp. F. A-C. SEMs of outer surface of single stomate, all S764, scale: 20 um. D. TLM of outer sur- face of single stomate, SL768, scale: 10 um. Dicotyledon sp. G Figure 9 Reference specimen.— SL894 (dispersed cuticle, only specimen, MAC-11). Description.— Stomatal distribution over leaf unknown; stomata randomly oriented; normal stomata sunken under and occluded by frilled, radiating rim of cuticle; giant stomata common, exposed, with thin, elliptical, outer stomatal ledge, surrounded by low tangentially oriented ridges; major veins only reflected in epidermal cells; glabrous. Dicotyledon sp. H Figure 10A, B Reference specimen.— SL987 (dispersed cuticle, only specimen, MAC-3). Description. — Stomatal distribution over leaf unknown; stomata randomly oriented; normal stomata dense; outer stomatal ledge broad, narrowing at poles, not extending full length of guard cells; moderate T-piece thickenings at stomatal poles; peristomal thickenings sometimes present; giant stomata present; no distinct subsidiary cells; contact cells of separate stomata often abut, sometimes shared; outer stomatal ledge wide; normal epidermal cell shape ir- regular, rounded, generally slightly elongate; fine ridges on outer surface of cuticle oriented parallel to stomatal pore; major veins reflected in more rectangular, slightly papillate epidermal cells; glabrous. Dicotyledon sp. | Figure 10C, D Reference specimen. — SL737 (only specimen, poorly preserved leaf fragment near apex, bases of teeth present, MAN-28). Description.—Leaf margin with small teeth; stomatal distri- bution over leaf hypostomatic; stomata randomly oriented; guard cell pair outline ovate; outer stomatal ledge narrow, not extending full length of guard cells; no obvious subsidi- ary cells; epidermal cell flanges prominent; normal outline polygonal, isodiametric; midrib reflected in epidermal cells. Dicotyledon sp. J Figure 10E, F 48 Mike Pole Figure 9. Dicotyledon sp. G, all SL894. A. TLM showing exposed giant stomata and normal stomata obscured by cuticle ridges, scale: 50 um. B. TLM detail of giant stomate, scale: 10 um. C, D. TLM of two normal stomates. D. Higher focus, scale: 10 um. Reference specimen.— SL679 (dispersed cuticle, only specimen, THA-47). Description. — Stomatal distribution over leaf hyposto- matic; on abaxial surface stomata generally aligned but some oblique, striations aligned with stomates, elliptical, thickened outer stomatal ledge, epidermal cell flanges not visible under TLM; glabrous; adaxial surface also with paral- lel striations, glabrous. Identification Worldwide, most described angiosperm leaf fossils of Albian-Cenomanian age are impressions only, lacking cuti- cle. However, in this study, although cuticular preservation is good, most material is found as small, dispersed frag- ments in amongst a large amount of coniferous material (the chances of a bore core sampling a complete leaf are slim). This situation is frustrating, as a combination of gross leaf morphology and venation combined with anatomical detail would be a great help in identification. Nevertheless, these C. Lower focus. are the best preserved angiosperms from the Australian Cretaceous to date, and the cuticle is amongst the oldest from angiosperms in the world. The few Cenomanian re- cords of cuticle include Upchurch (1984, 1995) and Kvacek (1983, 1992), and for the Albian that of Crane et al. (1993). The current knowledge of mid-Cretaceous angiosperms is based on pollen, flowers, and leaves, and includes several identifications of extant taxa. For instance, the Upper Albian Potomac Group of North America has yielded repro- ductive material regarded as of probable chloranthoid, hamamelididean, magnoliidean, platanoid, and rosidean af- finities (Friis et al, 1986; Crane et al, 1986). The Cenomanian, or possibly late Albian Dakota Formation has yielded possible Magnoliales (Dilcher and Crane, 1984). These inferred affinities are at high taxonomic levels (but have still raised dispute, e. g. Hughes, 1994), nevertheless they may form a starting point for comparing fossil cuticle. Upchurch and Wolfe (1993) summarised the data from Cretaceous leaf fossils, including the latest Albian to middle Cenomanian period. Similar to the reproductive material Cretaceous dicotydonous macrofossils Figure 10. A, B. Dicotyledon sp. H, both SL987. A. Scale: 50 um. B. Scale: 10 um. C, D. Dicotyledon sp. I, both SL737. C. scale: 50 um. D. Arrows point to opposite poles of a single stomate, scale: 10 um. E, F. Angiosperm sp. J, both SL679. E. Scale: 50 um. F. Scale: 10 pm. 49 50 Mike Pole the affinities included the Magnoliales, Laurales, Hamamelidales (aff. to Platanaceae) and the Rosidae. Thus, even at this relatively early stage, several of the major clades of angiosperms recognised by Chase et al. (1993), were present. Despite having some indication of ‘where to look’ for the affinities of the Eromanga material, taxonomic placement is far from obvious. For one taxon (Dicotyledon sp. F) an af- finity with the Chloranthaceae and Illiciales has been sug- gested, but for the others their identity remains completely unknown. This situation may result from a combination of inadequate material for comparison with extant plants as well as the likelihood that plants of this age had combina- tions of cuticle characters unknown today (e. g. Upchurch, 1984). Certainly none of the cuticle has any of the charac- teristic features of extant Australian families such as Lauraceae, Myrtaceae, or Proteaceae which are well known in the Tertiary record (and which would not be expected for this time). Platanus or extinct relatives were widespread in the mid-Cretaceous, including New Zealand (Pole, 1992), but none of the fossil cuticle is comparable to extant Platanus (documented by Brett, 1979). However, cuticle of Albian Sapindopsis, regarded as Platanaceae by Crane et al. (1993), compares favourably with Dicotyledon spp. A, F, and H in the presence of surface striations and form of the outer stomatal ledge. Curiously, where subsidiary cells can be seen, none of the Eromanga cuticle shows the paracytic subsidiary cell arrangement which is common in extant plant families often regarded as ‘primitive’, i. e. the ‘paleoherbs’ of Donoghue and Doyle (1989). However, Upchurch (1984) reported a plastic, variable condition of the subsidiary cell ar- rangement for Lower Cretaceous Potomac Group cuticles and suggested it to be an even more primitive style, al- though Baranova (1992) remarked that several extant taxa also show such plasticity. This plasticity is shown by Dicotyledon sp. D from the Eromanga. As for whole leaf form, the single larger leaf fragment of Dicotyledon sp. A is not comparable with any of the material illustrated by McLoughlin et a/. (1995) from younger Winton Formation de- posits, although its lobed form would not be out of place in their assemblage. Distribution All samples containing dicotyledonous fossils come from the Winton Formation, except three (MAC-11; MAN-34, 42), which came from the underlying Mackunda Formation. Angiosperm cuticle was not found in sandy samples. This could be a result of its not surviving in that environment (i. e. fluvial abrasion destroyed the cuticle), or because physical distortion by sand grains during compaction may have rendered the cuticle unrecognisable. It may also be a real absence, suggesting angiosperms were typically absent along relatively high-energy sedimentary environments such as river margins or levees. However, the three Mackunda Formation samples come from marine sediments to where the fossils contained must have been transported by fluvial activity. Out of the 144 fossiliferous samples which were fine-grained or muddy, only 20 of them contained dicotyle- donous remains and these were restricted to three of the seven cores; GSQ Machattie-1, GSQ Maneroo-1, and GSQ Thargominda-3 (Appendix 1). This suggests that, at least in the lower-energy floodplain environments, dicotyledons were either patchy in their distribution, or were relatively small plants, producing little biomass. They were evidently a small component of what was, on a regional scale, an overwhelmingly gymnosperm (mostly conifer) dominated flora (Pole, in prep.). Burger (1990), on the basis of palynological data, also concluded the angiosperms were patchily distributed. One sample (MAC-11) comes from a thin unit of Winton Formation bounded above and below by marine sediments which probably accumulated very close to sea level, perhaps as a delta lobe. The other samples are interpreted as accumulating essentially in an overbank/ floodplain environment (see facies analysis of the Eromanga core by Fielding, 1992). Although no dicotyledon fossils were recovered from coal, some samples were stratigraphically close. Sample THA- 47 comes from a mud immediately below the prominent coal seam of Thargomindah-3. Samples MAN 6, 8, 9, 11, 12 (closely spaced, all coming from a 4.5 m-thick muddy unit) are close to the prominent coal seam of Maneroo-1 but separated from it by a 3.5 m-thick sandy bed. The most reasonable assumption is that the angiosperms grew in clastic swamps, but growth on sandy levees or in coal swamps cannot be discounted. The plants were probably woody rather than herbaceous, as herbs are unlikely to be- come fossilised and their very delicate cuticle would not be expected to be preserved, or to survive the preparation proc- ess. Even so, some of the fossil cuticle is notably thin, con- sistent with understorey plants or deciduousness. Summary Latest Albian-earliest Cenomanian assemblages from the Eromanga Basin, Australia include sporadic fragments of dicotyledonous leaf cuticle, and rare semi-intact leaves. Ten types can be distinguished with the affinities of at least one possibly being with the Chloranthaceae and Illiciales. Acknowledgements | am most grateful to the Geological Survey of Queensland, particularly Kinta Hoffmann, and the staff at the Zillmere core store for providing access to the drill cores. Assistance from the staff of the Centre for Microscopy and Microanalysis, University of Queensland was greatly appre- ciated, and | thank A. N. Drinnan, H. T. Clifford, and J. N. A. Hooper for their helpful comments on the manuscript. This research was completed with funding from an ARC grant to M. E. Dettmann and G. Stewart. References Alvin, K. L., 1974. Leaf anatomy of Weichselia based on fusainized material. Palaeontology, vol. 17, 587-598. Baranova, M., 1992: Principles of comparative stomatographic studies of flowering plants. The Botanical Review, vol. 58, p. 49-99. Cretaceous dicotydonous macrofossils Brenner, G. J., 1996 : Evidence for the earliest stage of angio- sperm pollen evolution: a paleoequatorial section from Israel. In, Taylor, D. W. and Hickey, L. J. eds., Flowering Plant Origin, Evolution and Phylogeny, p. 91-115. Chapman and Hall, New York. Brenner, G. H. and Bickoff, I., 1992: Palynology and age of the Lower Cretaceous basal Kurnub Group from the coastal plain to the northern Negev of Israel. Palynology, vol. 16, p. 137-185. Brett, D. W., 1979: Ontogeny and classification of the stomatal complex of Platanus L. Annals of Botany, vol. 44, p. 249-251. Burger, D., 1990: Early Cretaceous angiosperms from Queensland, Australia. Review of Palaeobotany and Palynology, vol. 65, p. 153-63. Chase, M. W., Soltis, D. 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Paleontological Research, vol. 4, no. 1, pp. 53-55, April 28, 2000 © by the Palaeontological Society of Japan A new pseudorthoceratid cephalopod from the Kazanian (middle Late Permian) of Japan SHUJI NIKO’ and TAMIO NISHIDA’ ‘Department of Environmental Studies, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashihiroshima, 739-8521, Japan (niko @hiroshima-u.ac.jp) Department of Earth Science, Faculty of Culture and Education, Saga University, Saga, 840-8502, Japan (nishidat @ cc.saga- u.ac.jp) Received 23 July 1999; Revised manuscript accepted 8 November 1999 Abstract. A new cephalopod species, Dolorthoceras nakazawai (Orthocerida: Pseudortho- ceratidae), is described from the Permian Mizuyagadani Formation, Centrai Japan. age, based on a fusulinid species, makes this the youngest record of Dolorthoceras. first undoubted occurrence of the genus in Japan. Its Kazanian This is the Key words: Dolorthoceras nakazawai sp. nov., Orthocerida, Mizuyagadani Formation, Permian, Kazanian Introduction and geologic setting A new pseudorthoceratid cephalopod species, Dolortho- ceras nakazawai, is described from a float block of limestone in the upper reaches of Ichinotani Valley in the Fukuji area, Gifu Prefecture, Central Japan. The vicinity of the collecting site is underlain by the Mizuyagadani Formation (Igo, 1956), which consists mostly of clastic sediments and has a “lenti- cular’ limestone in its upper part (see fig. 2 in Niko et al. 1987). The cephalopod-bearing limestone consists of bioclastic wackestone and has a characteristic appearance that is dark gray micrite, with sporadic crinoid fragments as the main allochemical constituent, and is identical in lithology with the “lenticular” limestone noted above. With the exception of apparently reworked fossils, the age of this formation has been discussed on the basis of foraminifers (Okimura et al., 1984), radiolarians (Niko et al, 1987; Umeda and Ezaki, 1997), corals (Kamei, 1957; Igo, 1959), brachiopods (Kamei, 1957) and cephalopods (Niko and Nishida, 1987; Nishida and Niko, 1989). Among them, ra- diolarians in tuffaceous mudstone and acidic tuff range from Sakmarian (middle Early Permian) to Midian (middle Late Permian), and ammonoids reported by Nishida and Niko (1989) are the only fossils known from the “lenticular” lime- stone excepting crinoid fragments. Although the precise age of the limestone is a pending question, we found the index fusulinid Parafusulina cf. kaerimizensis (Figure 1), as- sociated with the pseudorthoceratid cephalopod Dolortho- ceras nakazawai sp. nov., from the same locality and in limestone of similar lithology (but from another float block). It is possible that this limestone is a redeposited olistolith or has been introduced by faulting, but its age can be determined by the presence of Parafusulina cf. kaerimizensis. Based on the assembled evidence, we con- clude that the specimen of D. nakazawai was derived from the “lenticular” limestone in the Mizuyagadani Formation, and that its age is Kazanian (middle Late Permian). The abbreviation UMUT for the repository stands for the University Museum of the University of Tokyo. Systematic paleontology Order Orthocerida Kuhn, 1940 Superfamily Pseudorthocerataceae Flower and Caster, 1935 Family Pseudorthoceratidae Flower and Caster, 1935 Subfamily Spyroceratinae Shimizu and Obata, 1935 Genus Dolorthoceras Miller, 1931 Type species.—Dolorthoceras circulare Miller, 1931. Dolorthoceras nakazawai sp. nov. Figure 2 Diagnosis.—Species of Dolorthoceras with circular shell cross section; sutures oblique, attaining 16° to rectangular direction of shell axis; siphuncular position nearly central with asymmetrical septal necks; cameral deposits form circumsiphuncular ridge and mamiform growth; endosiphun- cular deposits form thick lining on ventral siphuncular wall. Description.—Orthoconic shell with circular cross section, reaches 7.4 mm in diameter near adoral end; shell expan- sion moderate with approximately 5° angle; shell surface 54 Shuji Niko and Tamio Nishida Figure 1. Parafusulina cf. kaerimizensis (Ozawa) from the Fukuji area, thin sections. 1. Axial section, X 10. 2. Sagittal sec- tion, X 10. smooth, obvious ornamentation not recognized. Sutures not observed, but with relatively strong obliquity, ranging from 12° to 16° to rectangular direction of shell axis, as rec- ognized in dorsoventral section, toward aperture on venter; septal curvature moderate to relatively deep, steeper in venter than dorsum; camerae relatively long for genus in api- cal phragmocone, with maximum width/length ratio 1.7 at shell diameter approximately 5.4 mm, being increased to 3.3 near adoralend. Siphuncle nearly central in position; septal necks asymmetrical in form, suborthochoanitic to rarely cyrtochoanitic in ventral siphuncular wall, and strongly curved cyrtochoanitic in dorsal siphuncular wall; length of septal necks short, ranging from 0.31 mm to 0.56 mm; brims short with length nearly equal to septal necks in adoral and ventral siphuncular wall, but in other portions they are shorter than septal necks; adnation area very narrow; con- necting rings weakly inflated, subcylindrical with constric- tions at septal foramina; ratio of maximum external diameter of connecting ring/corresponding shell diameter is approxi- mately 0.2. Ventral cameral deposits well developed, episeptal-mural or episeptal and mural on rare occasions, al- ways form circumsiphuncular ridge and mamiform growth; dorsal cameral deposits episeptal-mural indicating L-shaped longitudinal profile, relatively thin. Endosiphuncular depos- its restricted to ventral siphuncular wall, where they form a thick lining with crescentic transverse profile. Discussion. — With the exception of Dolorthoceras, the relatively simple shell morphology of the present species has much in common with Late Paleozoic Spyroceratinae such as Adnatoceras (Flower, 1939), Euloxoceras (Miller et al., 1933), Mitorthoceras (Gordon, 1960) and Shikhanoceras (Shimanskiy, 1954). However, the combination of an un- compressed shell with a smooth surface, the very narrow adnation area and the short brims confirms the assignment Figure 2. Dolorthoceras nakazawai sp. nov., holotype, UMUT PM 27826, from the Fukuji area. 1. Ventral view, X2. 2. Dorsoventral thin section, venter on right, <5. 3. Dorsoventral thin section, showing the details of the siphuncular structure. Arrows indicate septal necks, 14. 4. Transverse polished section at position indicated by arrow in Figure 2.1, venter down, *5. New Permian cephalopod from Japan of the species to Dolorthoceras, which was proposed by Miller (1931) from the Upper Carboniferous in the Aghil- Depsang (Central Range) of Central Asia. Its previously known range was Early Devonian to Early Permian, with an upper limit represented by two Artinskian species from the Urals, namely Dolorthoceras siphocentrale (Krotov, 1885, pl. 1, fig. 3; Shimanskiy, 1954, pl. 1, figs. 11, 12a, b) and D. stiliforme Shimanskiy (1948, figs. 1a, b; Shimanskiy, 1954, pl. 1, figs. 1-10, pl. 2, figs. 1-6). Thus, the present discov- ery of Dolorthoceras in the Mizuyagadani Formation extends the stratigraphic range of this genus upwards to the Kazanian. The somewhat similar Dolorthoceras stiliforme is distin- guished from D. nakazawai sp. nov. in having a subcentral siphuncular position, the usually simple mural cameral de- posits and the unfused endosiphuncular deposits. Niko and Nishida (1987, fig. 3.3-3.5) assigned a specimen from the same formation to an indeterminate genus and species of the Pseudorthoceratidae having the surface annulation clearly separate from D. nakazawai at the generic level. A poorly preserved specimen of Dolorthoceras? sp. from the Early Carboniferous Hikoroichi Formation in the southern Kitakami Mountains (Niko, 1990) was the only record of this genus in Japan until the present report. Material.—Holotype and only known specimen, UMUT PM 27826, is an incomplete phragmocone 37.2 mm in length. Etymology.—The specific name honors Dr. Keiji Naka- zawa, in recognition of his contributions to the study of Permian mollusks. Acknowledgments We are indebted to Yuji Okimura, who made suggestions in fusulinid identification. Toshiaki Kamiya kindly assisted in the field work. References Flower, R. H., 1939: Study of the Pseudorthoceratidae. Palaeontographica Americana, vol. 2, p. 1-214, pls. 1-9. Flower, R. H. and Caster, K. E., 1935: The stratigraphy and paleontology of northeastern Pennsylvania. Part Il: Paleontology. Section A: The cephalopod fauna of the Conewango Series of the Upper Devonian in New York and Pennsylvania. Bulletins of American Paleontology, vol. 22, p. 199-271. Gordon, M. Jr., 1960: Some American Midcontinent Carbo- niferous cephalopods. Journal of Paleontology, vol. 34, p. 133-151, pls. 27, 28. Igo, H., 1956: On the Carboniferous and Permian of the Fukuji district, Hida Massif,with special reference of the fusulinid zones of the Ichinotani Group. The Journal of the Geologi- cal Society of Japan, vol. 62, p. 217-240. (in Japanese with English abstract) Igo, H., 1959: Note on some Permian corals from Fukuji, Hida Massif, Central Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 34, p. 79-85, pl. 8. Kamei, T., 1957: On two Permian corals from the Mizu- yagadani Formation. Journal of the Faculty of Liberal Arts and Science, Shinshu University, no. 7, p. 29-35, pls.1-3. Krotov, P., 1885: Artinskii yarus (The Artinskian stage). Trudy Obshchestvo Estestvoispytatelei pri Kazanskom Univer- sitete, vol. 13, p. 1-314, pls. 1-4. (in Russian) Kuhn, O., 1940: Paläozoologie in Tabellen, 50 p. Fischer, Jena. Miller, A. K., 1931: Two new genera of Late Paleozoic cepha- lopods from Cental Asia. American Journal of Science, Fifth Series, vol. 22, p. 417-425. Miller, A. K., Dunbar, C. O. and Condra, G. E., 1933: The nautiloid cephalopods of the Pennsylvanian System in the Mid-Continent region. Nebraska Geological Survey, Bulletin 9, Second Series, p. 1-240, pls. 1-24. Niko, S., 1990: Early Carboniferous (Viséan) cephalopods from the Hikoroichi Formation, southern Kitakami Moun- tains. Transactions and Proceedings of the Palaeontolo- gical Society of Japan, New Series, no. 159, p. 554-561. Niko, S. and Nishida, T., 1987: Early Permian cephalopods from the Mizuyagadani Formation, Fukuji district, Central Japan. Transactions and Proceedings of the Palaeon- tological Society of Japan, New Series, no. 146, p. 35-41. Niko, S., Yamakita, S., Otho, S., Yanai, S. and Hamada, T., 1987: Permian radiolarians from the Mizuyagadani Formation in Fukuji area, Hida Marginal Belt and their sig- nificance. TheJournal of the Geological Society of Japan, vol. 93, p. 431-433, pl. 1. (in Japanese) Nishida, T. and Niko, S., 1989: Ammonoids from the Mizuyaganani Formation in Hida Marginal Belt. Abstracts of the 1989 Annual Meeting of the Palaeontological Society of Japan, p. 94. (in Japanese) Okimura, Y., Niko, S. and Nishida, T., 1984: Discovery of michelinoceratine nautiloids (Orthocerida) and calcareous imperforate foraminiferal assemblage from the Permian Mizuyagadani Formation of Fukuji district, Hida Marginal Belt. The Journal of the Geological Society of Japan, vol. 90, p. 211-214. (in Japanese) Shimanskiy, V. N., 1948: K voprosu o rannikh stadiiakh razvitiia verkhnepaleozoiskikh ortotserakonovykh nauti- loidei (Problems on the early growth stages of the Upper Palaeozoic orthoconic nautiloids). Doklady Akademii Nauk SSSR, vol. 60, p. 871-874. (in Russian) Shimanskiy, V. N., 1954: Pryamye nautiloidei i baktritoidei sakmarskogo i artinskogo yarusov Yuzhnogo Urala (Straight Nautiloidea and Bactritoidea of the Sakmarian and Artinskian Stages of the Southern Urals). Akademiia Nauk SSSR, Trudy Paleontologicheskogo Instituta, vol. 44, p. 1-156, pls. 1-12. (in Russian) Shimizu, S. and Obata, T., 1935; New genera of Gotlandian and Ordovician nautiloids. The Journal of the Shanghai Science Institute, Section 2, Geology, Palaeontology, Mineralogy and Petrology, vol. 2, p. 1-10. Umeda, M. and Ezaki, Y., 1997: Middle Permian radiolarian fossils from the acidic tuffs of the Kanayama and Fukuiji areas in the Hida “Gaien” Terrane, Central Japan. Fossils (Palaeontological Society of Japan), no. 62, p. 37-44. (in Japanese with English abstract) 55 ae La ses yr & u u & EN RO MT DIS MT ; NM ar I ETS Paleontological Research, vol. 4, no. 1, pp. 57-67, April 28, 2000 © by the Palaeontological Society of Japan Early Carboniferous miospores from the southern Kitakami Mountains, northeast Japan WEI-PING YANG and JUN-ICHI TAZAWA’ ‘USPS Fellow in the Department of Geology, Faculty of Science, Niigata University, 8050 Igarashi-ninocho, Niigata, 950-2181, Japan; Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing, 210008, P. R. China “Department of Geology, Faculty of Science, Niigata University, 8050 Igarashi-ninocho, Niigata, 950-2181, Japan Received 7 July, 1999; Revised manuscript accepted 17 December, 1999 Abstract. The first authenticated Early Carboniferous miospores in Japan are described from the upper part of the lower Hikoroichi Formation (HK2 Member) in the Hikoroichi area, southern Kitakami Mountains, northeast Japan. The stratigraphically significant miospores are Auroraspora sp. cf. A. macra, Crassispora trychera, Schopfites sp., Spelaeotriletes crustatus, and S. sp. cf. S. pretiosus, which suggest a late Tournaisian to early Viséan age and the “Vallatisporites Microflora” provincialism. Key words: Hikoroichi Formation, late Tournaisian to early Viséan, miospores, southern Kitakami Mountains Introduction Because of their poor preservation and scarcity late Paleozoic plant fossils in Japan have aroused little interest among Japanese paleontologists. Microfloral research in the Upper Paleozoic of Japan is even more limited as it was commonly believed that spores and pollen are only pre- served in terrestrial environments. However, there are many cases from around the world of Upper Paleozoic ter- restrial microflora preserved in marine sediments, where they are significant to both stratigraphy and phytogeography (Sullivan, 1965; Yang, 1999). Prior to this paper there have been no reports of late Paleozoic miospores from Japan, al- though Takahashi and Yao (1969) reported the occurrence of problematic Permian plant microfossils from a sandstone block of the Jurassic melange in the Harayama area, Mino Belt, southwest Japan. The Hikoroichi Formation is a Lower Carboniferous (Tournaisian and Viséan) formation, distributed in the Hikoroichi area, western part of the southern Kitakami Mountains (Figure 1). The Hikoroichi Formation overlies, with angular unconformity, the Middle Devonian Nakazato Formation (Okubo, 1951; Minato et al., 1979), and is in turn overlain conformably by the Lower Carboniferous (Upper Viséan) Onimaru Formation (Mori and Tazawa, 1980; Tazawa, 1981, 1984b; Kawamura, 1983). According to Tazawa (1984b), the Hikoroichi Formation consists mostly of sandstone, with a basal conglomerate and intercalations of shales, acidic to intermediate tuffs and limestones, 560 m in total thickness, and is subdivided into the following four members in ascending order: (1) HK1 Member, sandstone dominant, 164 m thick, (2) HK2 Member, shale dominant, 102 m thick, (3) HK3 Member, basic to intermediate tuff dominant, 114 m thick, (4) HK4 Member, sandstone domi- nant, 180 m thick (Figure 2). The miospores, described below, are from samples col- lected from the middle horizon of the HK2 Member at the Onimaru Quarry in the Hikoroichi area (Figures 1, 2). All the specimens are housed in the Department of Geology, Faculty of Science, Niigata University with the registered number (NU-P1-NU-P5). The other fossils, corals (Kato et al., 1989), bryozoans (Sakagami, 1989), brachiopods (Tazawa, 1984a, 1985, 1989), gastropods (Kase, 1988), cephalopods (Niko, 1990) and trilobites (Kaneko, 1989) were collected from almost the same horizon in the same quarry. However, the plants alone were collected from the lowermost part of the HK3 Member in the same locality (Asama et al., 1985, 1989). These fossils from the HK2 and HK3 Members of the Hikoroichi Formation in the Onimaru Quarry are summarized in Table 1. Miospore preservation and processing technique The extraction of palynomorphs from Japanese Paleozoic rocks is difficult. Lithologies suitable for the preservation of palynomorphs make up only about 10% of the Hikoroichi Formation (see Figure 2). Further, the miospores pre- served in the shales of the Hikoroichi Formation are rather dark and thermally mature and need strong oxidation after conventional palynological processing (Wood et al., 1996). Processing of samples from the Hikoroichi Formation in- volved crushing the samples to pea size or even finer and 58 Wei-Ping Yang and Jun-Ichi Tazawa = ESS HIKOR Figure 1. published by the Geographical Survey of Japan). PER TETAVEFLVET EN oro Hoyer Upper Part Lower Part Formation Hikoroichi limestone. shale sandstone conglomerate acidic tuff basic to intermediate tuff o1c Index map showing the fossil locality (using the topographical map of “Sakari” scale 1:25,000 then demineralisation in dilute 35% HCL and 40% HF. Standard oxidation reagents did not react at all with the car- bonized organic residues from the Hikoroichi Formation samples and so a very strong oxidation agent-fuming HN O; plus KCL (“fuming Schulze’s solution”) was used. The times required for oxidation using “fuming Schulze’s solution” vary from sample to sample (as in Western Yunnan, Yang, 1993). In general, suitable oxidation will be achieved after seconds of oxidation. However, oxidation times for the Hikoroichi samples varied from one to several minutes even when heating the oxidation tube in a beaker of boiling water. Using this technique brown or light-brown coloured miospores were produced. Permanent slides were made with the rapid mounting medium Entellan. Figure 2. Columnar section of the Hikoroichi Formation in the Hikoroichi area; arrow showing the stratigraphical horizon of the miospore fossils collected (adopted from Tazawa, 1984b). Early Carboniferous miospores from Japan 59 Table 1. The paleontological data from the HK2 and HK3 Members of the Hikoroichi Formation in the Onimaru Quarry, Hikoroichi area, southern Kitakami Mountains, northeast Japan Taxonomic group Literature source Species Lowermost part of the HK3 Member of the Hikoroichi Formation Plant Asama et al. (1989) Psedusporochnus n. sp., Rhodeopteridium sp. ?, Sublepidodendron? wusihense, Lepidodendron sp., Archaeocalamites scrobiculatus HK2 Member of the Hikoroichi Formation Amygdalophyllum sp., Bifossularia sp., Lophophyllidium sp., Multithecopora sp., Syringopora sp. Acanthocladia? sp. cf. A. pecularis, Hemitrypa? sp. Adnatoceras onimarensis, Dolorthoceras (?) sp., Mooreoceras kinnoi, Neocycloceras (?) sp., Sueroceras nishimurai. Coral Kato et al. (1989) Bryozoa Sakagami (1989) Cephalopoda Niko (1990) Trilobite Kaneko (1989) Gastropoda Kase (1988) Linquaphillipsia choanjiensis, L. subconica, Liobole (?) sp. Baylea yvanii, Kawanamia onimarensis, Littorinides sp., Pseudozygopleura (Stephanozyga) nishimurai, Straparollus (Euomphalus) asanoi, S. (E.) Sp. Brachiopoda Tazawa (1989) Buxtonia sp., Lamellosathyris lamellosa, Linoprotonia Sp., Marginatia sp., Unispirifer sp. Miospores This paper Auroraspora sp. cf. A. macra, Calamospora sp., Crassispora trychera, Cyclogranisporites sp., Densosporites sp., Grandispora sp. cf. G. echinata, Leiotriletes sp. cf. L. incomptus, Microreticulatisporites araneum, Punctatisporites irrasus, P. minus, P. planus, Spelaeotriletes sp. cf. S. pretiosus, S. crustatus, Schophites sp., Verrucosisporites Sp. Palynostratigraphy The miospore assemblages from the upper part of the lower Hikoroichi Formation (HK2 Member) in the Onimaru Quarry are relatively abundant compared with the Middle Permian ones from the Kanokura Formation in the Kamiyasse area, southern Kitakami Mountains, northeast Japan (Yang and Tazawa, 2000). Stratigraphically signifi- cant species include Auroraspora sp. cf. A. macra, Crassi- spora trychera, Schopfites sp., Spelaeotriletes crustatus and S. sp. cf. S. pretiosus. Common species are Auroraspora sp., Calamospora sp., Crassispora sp., Cyclogranisporites sp., Densosporites sp., Grandispora sp. cf. G. echinata, Leiotriletes sp. cf. L. incomptus, Microreticulatisporites ara- neum, Punctatisporites minus, P. irrasus, P. planus and Verrucosisporites sp. Auroraspora macra is a common species in Lower Carbo- niferous (mainly Tournaisian) assemblages around the world (Van der Zwan and Walton, 1981). This species ranges from the latest Devonian (Famennian) to the earliest Viséan in Western Europe (Clayton et al, 1977) and Australia (Playford, 1990). In Canada it ranges from the Tournaisian to early Viséan (Utting, 1987a, b). Spelaeotriletes pretiosus is mainly distributed from the Tournaisian to early Viséan in Poland (Turnau, 1978, 1979). Since it first appears in the late Tournaisian strata in Ireland, it was selected as an index fossil for the PC (Spelaeotriletes pretiosus-Raistrickia clavata) Biozone by Higgs et al. (1988). However, it has oc- casionally been reported from the latest Devonian in Morocco (Rahmanin-Antari, 1990) and Eastern Alaska (Scott and Doher, 1967). Spelaeotriletes crustatus is com- monly distributed from the late Famennian to late Tournaisian in SE Ireland (Higgs, 1975). Crassispora trychera is a characteristic species of the late Tournaisian to early Viséan in Western Europe (Clayton et al., 1977), Poland (Turnau, 1978) and Canada (Utting, 1980; Utting et al., 1989). It was once reported by Utting (1991) from the Lower Namurian in northern Yukon. Schopfites sp. is usu- ally one of the common elements of the late Tournaisian and possible the early Viséan strata (Higgs et al., 1988). The other species recorded include Grandispora sp. cf. G. echinata, Leiotriletes sp. cf. L. incomptus, Densosporites sp. and Verrucosisporites sp., which are also common members of the Early Carboniferous (mainly Tournaisian and Viséan) miospore assemblages from around the world. Early Carboniferous (Tournaisian) miospore assemblages from Gengma, West Yunnan, China are correlated with the Western European BP and PC Biozones based on the oc- currence of Auroraspora macra, Kraeuselisporites hiber- nicus, Rugospora polyptycha, Spelaeotriletes balteatus and S. pretiosus in the Longba Formation (Yang et al., 1997). All of the miospore taxa recorded from the Onimaru 60 Wei-Ping Yang and Jun-Ichi Tazawa Higgs er al. (1988 Pu: Lycospora pusilla Schopfites claviger CM: Auroraspora macra Mian PC: Spelaeotriletes pretiosus HD: Kraeuselisporites hibernicus VI: Vallatisporites verrucosus Retusotriletes incohatus LN: Retispora lepidophyta Verrucosisporites nitidus Pu: L. pusilla No palynomorphs PB: S.pretiosus Schopfites claviger ee lizonates ia BP Spelaeotriletes balteatus Tn2 Rugospora polyptycha Nova Scotia Utting et al. (1989 S. Kitakami, Japa This pape Schopfites sp. Crassispora trychera Auroraspora macra Spelaeotriletes Figure 3. Suggested correlation of miospore assemblages from the southern Kitakami Mountains with late Devonian to early Carboniferous miospore biozones of Western Europe, Lower Yangtze and Nova Scotia. Quarry are typical members of the latest Tournaisian (Tn3) in Western Europe (PB and CM Biozones), China (PC and CM equivalent Biozones), Nova Scotia and eastern Canada (Spelaeotriletes pretiosus var. pretiosus Biozone and Crassispora trychera-Colatisporites decorus Biozone). But most of them can extend to the early Viséan. A correlation chart of these biozones is provided in Figure 3. The brachiopods (Tazawa, 1984a, 1985, 1989), gastro- pods (Kase, 1988) and cephalopods (Niko, 1990) from the HK2 Member of the Hikoroichi Formation at the Onimaru Quarry indicate an early Viséan age (see Table 1). However, the palynomorph assemblages from that member have a strong late Tournaisian character and are without the typical Viséan genus Lycospora. Furthermore, some plant fossils (Archaeocalamites scrobiculatus, Knorria sp. and Sub- lepidodendron? wushiense) were described by Asama et al. (1985, 1989) from the lowermost part of the H3 Member of Kawamura (1983), which is supposed to be equal to the HK3 Member of Tazawa (1985) at the same locality (see Table 1). Archaeocalamites scrobiculatus is one of the dominant representatives of Viséan plant assemblages in both South China and North China (Wu, 1995), and has also been re- ported by Wu (1995) from the Tournaisian of South China to- gether with Eolepidodendron wusihense Sze or Sublepido- dendron? wusihense Sze. It seems likely that the plant- bearing bed of the lowermost part of the HK3 Member is early Visean. The Viséan Lycospora pusilla Biozone can be informally divided into a lower division containing rare Lycospora pusilla and an upper division with abundant rep- resentatives of that species (Higgs, 1996). This suggests that the miospore-containing strata of Onimaru Quarry can be dated as late Tournaisian to early Visean rather than solely early Viséan as suggested by the brachiopods, gas- tropods and cephalopods. Sullivan (1965, 1967) first defined the differences between the various Early Carboniferous microfloral assemblages around the world and demonstrated a clear relationship be- tween their distribution and their probable paleolatitude. He described five distinct assemblage suites in the Early Carboniferous, two (Vallatisporites Suite and Lophozono- triletes Suite) in the Tournaisian and three (Grandispora Suite, Monilospora Suite and Kazakhstan Suite) in the Upper Mississippian (late Viséan-early Namurian). In 1981, Van der Zwan supported Sullivan’s conclusion through his statistically based correlation of late Tournaisian and early Viséan assemblages from 14 selected areas using both Jaccard and Simpson correlation coefficients. Clayton (1985) made some progress on microflora provinces propos- ing seven microfloras instead of Sullivan’s five suites. In general, five microfloras can be distinguished in the Early Carboniferous (Clayton, 1985, figs. 2, 3) around the world: the Granulatisporites frustulentus Microflora in Australia, the Spelaeotriletes balteatus Microflora in North Africa, the Kazakhstan Microflora in Kazakhstan, and the Vallati- sporites Microflora (middle Tournaisian to early Viséan) and the Grandispora Microflora (middle-late Viséan), which ex- tended from the eastern United States and eastern Canada through Western Europe to China. The Lophozonotriletes Microflora (middle Tournaisian to early Viséan) and the Monilospora Microflora (middle-late Viséan) were mainly dis- tributed in Western Canada, Spitsbergen and the north- western part of Russia. Assemblages from Eastern Europe are more or less transitional in nature between the Vallatisporites Microflora and the Lophozonotriletes Micro- flora. The microflora in the southern Kitakami Mountains can be Early Carboniferous miospores from Japan 61 circumscribed within the Vallatisporites Microflora in the sense of Clayton’s division (Clayton, 1985) based on the presence of Auroraspora sp. cf. A. macra, Crassispora trychera, Spelaeotriletes crustatus, S. sp. cf. S. pretiosus and Schopfites sp. Systematic palynology The suprageneric classification used is mainly based upon the schemes by Potonie and Kremp (1954), Potonie (1956, 1975), Dettmann (1963) and Smith and Butterworth (1967). Anteturma Sporites H. Potonie, 1893 Turma Triletes Reinsch emend. Dettmann, 1963 Suprasubturma Acavatitriletes Dettmann, 1963 Subturma Azonotriletes Luber emend. Dettmann, 1963 Infraturma Laevigati (Bennie and Kidston) R. Potonié, 1956 Genus Leiotriletes (Naumova) Potonié and Kremp, 1954 Type species.—Leiotriletes sphaerotriangulus (Loose) Po- tonié and Kremp, 1954. Leiotriletes sp. cf. L. incomptus (Felix and Burbridge) Higgs, Clayton and Keegan, 1988 Figure 4.9 Compare.— Punctatisporites incomptus Felix and Burbridge, 1967, p. 357, pl. 53, fig. 12. Leiotriletes incomptus (Felix and Burbridge). Higgs et al., 1988, p. 50, pl. 1, fig. 9. Material.—Seven specimens logged from NU-P1 to NU- P4, Figure 4.9 from NU-P2. Description. — Trilete acamerate miospores. Amb rounded triangular, sides convex. Suturae simple and dis- tinct, extending approximately to the equator. Laesurae bordered by flexuous labra. Exine laevigate, approximately 1.5-2 um thick. Diameter.—38-45 um. Remarks.—The Kitakami specimens are similar to those recorded by Felix and Burbridge (1967) as Punctatisporites incomptus and Higgs et al. (1988) as Leiotriletes incomptus, but are significantly smaller than the type (60-90 um) and lack the prominent labra. Genus Punctatisporites Ibrahim emend. Potonié and Kremp, 1954 Type species. — Punctatisporites punctatus (Ibrahim) Ibrahim, 1933. Punctatisporites irrasus Hacquebard, 1957 Figure 4.7 Punctatisporites irrasus Hacquebard, 1957, p. 308, pl. 1, figs. 7, 8; Sullivan, 1964, p. 372, pl. 2, figs. 3.4; Higgs et al. 1988, p. 51, plate figeti7 Punctatisporites cf. irrasus Hacquebard. p. 365, pl. 1, fig. 1. Dolby and Neves, 1970, Material.—Six specimens logged from NU-P2 to NU-P5, Figure 4.7 from NU-P2. Description.—Acamerate trilete miospores. Amb subcir- cular. Suturae distinct to obscure with a narrow labra. Suturae extend 1/2 to 3/4 of the spore radius, usually dark- ening along its length. Exine 1-2 um thick, often laevigate or finely infragranulate accompanying large compression folds. Diameter.—45-54 um. Remarks.—The Kitakami specimens conform very closely to those described by Sullivan (1964), Dolby and Neves (1970), and Higgs et al. (1988), who reported size ranges of 59-98 um, 42-65 um and 50-92 um, respectively. Infraturma Apiculati Bennie and Kidston emend. R. Potonié, 1956 Genus Schopfites Kosanke, 1950 Type species.—Schopfites dimorphus Kosanke, 1950. Schopfites sp. Figure 4.12 Material.—One specimen logged from NU-P4, distal view. Description.—Miospore trilete, acamerate. Amb oval to circular. Suturae distinct to indistinct, straight, extend al- most to equator of miospores. Intexine thin, indistinct to distinct, approximately conformable with the amb, about 3/4 of the diameter. Distal surface and equator ornamented with pilae, rounded baculae, and rare verrucae. The size of the elements ranges from 0.5-3 um in height and 0.5- 2.5 um in width. Sculptural elements are normally discrete and closely spaced. Proximal surface laevigate. Diameter.—35 um. Remarks. — This specimen is attributed to the genus Schopfites on the basis of the type and distribution of the or- namentation, patchy distal ornament predominantly of verrucae, bacula or pila suggested by Higgs et al. (1988). Genus Verrucosisporites Ibrahim emend. Smith, 1971 Type species.— Verrucosisporites verrucosus (Ibrahim) Ibrahim, 1933. Verrucosisporites sp. Figure 4.8 Material.—One specimen from NU-P2. Description.—Trilete acamerate miospore. Amb rounded triangular. Suturae distinct, simple, length 2/3 to 3/4 the spore radius. Exine 2-3 um thick. Distal surface and equatorial region of proximal surface ornamented with verrucae. Verrucae 1.5-2.5 um in basal diameter, 1.5-2 um in height with predominantly rounded tops. Elements evenly spaced 3-5 um apart. Diameter.—40 um. Remarks. — This sole specimen from the southern Kitakami Mountains is unlike the previously described spe- cies of the genus Verrucosisporites. 62 Wei-Ping Yang and Jun-Ichi Tazawa Figure 4. Early Carboniferous (late Tournaisian to early Viséan) miospores from the HK2 Member of the Hikoroichi Formation in the Onimaru Quarry, southern Kitakami Mountains, northeast Japan. The miospores are illustrated at the magni- fication of x 700. 1. Microreticulatisporites araneum Higgs, Clayton and Keegan, proximal view, high focus, NU-P5. 2, 3. Auroraspora sp. cf. A. macra Sullivan. 2. Proximal view, median focus, NU-P4. 3. Proximal view, high focus, NU-P3. 4. Spelaeotriletes sp. cf. S. pretiosus (Playford) Neves and Belt, proximal view, median focus, NU-P4. 5, 6. Spelaeotriletes crustatus Higgs. 5. Proximal view, high focus, NU-P5. 6. Proximal view, median focus, NU-P3. 7. Punctatisporites irrasus Hacquebard, proximal view, high focus, NU-P2. 8. Verrucosisporites sp., distal view, median focus, NU-P2. 9. Leiotriletes sp. cf. L. incomptus (Felix and Burbridge) Higgs, Clayton and Keegan, proximal view, median focus, NU-P2. 10. Crassispora trychera Neves and loannides, proximal view, high focus, NU-P2. 11. Densosporites sp., distal view, median focus, NU-P2. 12. Schopfites sp., proximal view, median focus, NU-P4. Early Carboniferous miospores from Japan 63 Infraturma Murornati Potonié and Kremp, 1954 Genus Microreticulatisporites Knox emend. Potonié and Kremp, 1954 Type species. — Microreticulatisporites lacunosus (lbra- him) Knox, 1950. Microreticulatisporites araneum Higgs, Clayton and Keegan, 1988 Figure 4.1 Dictyotriletes sp. Keegan, 1977, p. 552, pl. 2, figs. 13-14. Dictyotriletes sp. B, Playford, 1978, p. 128, pl. 8, figs. 8-10. Microreticulatisporites araneum Higgs, Clayton and Keegan, 1988, p. 65, pl. 7, figs. 6, 9-10. Material.—Six specimens logged from NU-P2, NU-P3, NU-P5, Figure 4.1 from NU-P5. Description.—Trilete acamerate miospores. Amb sub- circular to convexly triangular. Suturae distinct to indistinct, straight to slightly sinuous and extending to the spore mar- gin. Exine 1.5-2um thick, ornamented with close reticulum of tiny muri. Muri 0.5-1um in thickness, enclosing lumina 2-3 um in width. Luminar usually polygonal to subcircular in shape. Reticulation normally comprehensive but occa- sionally less evident near equator and on the proximal sur- face. Diameter.—30-35 um. Remarks.—These specimens, recorded from the southern Kitakami Mountains, are definitely attributed into M. araneum because of their particular reticulation and the size range. Suprasubturma Laminatitriletes Smith and Butterworth, 1967 Subturma Zonolaminatitriletes Smith and Butterworth, 1967 Infraturma Crassiti Genus Crassispora Bharadwaj emend. Sullivan, 1964 Type species.—Crassispora kosankei Potonie and Kremp emend. Bharadwaj, 1957. Crassispora trychera Neves and loannides, 1974 Figure 4.10 Crassispora trychera Neves and loannides, 1974, p. 78, pl. 7, figs. 6-8; Higgs et al., 1988, p. 55, pl. 3, fig. 24. Material. — Four specimens logged from NU-P2 and NU-P3, Figure 4.10 from NU-P2. Description.—Miospores trilete, variably camerate. Amb subcircular to rounded triangular. Suturae straight, simple, extend almost to the margin of spores. The subparallel pe- ripheral folding is often seen around the equator surface. Distal surface ornamented by the combination of coni, pila and grana (up to 1-1.5 um in height). Diameter.—53-68 um. Remarks.—These specimens are attributed to C. trychera by the presence of variable camerate and distal ornament of coni, pila and grana. Suprasubturma Psedodsaccititriletes Richardson, 1965 Infraturma Monopseudosacciti Smith and Butterworth, 1967 Genus Auroraspora Hoffmeister, Staplin and Malloy emend. Richardson, 1960 Type species.—Auroraspora solisortus Hoffmeister, Stap- lin and Malloy, 1955. Auroraspora sp. cf. A. macra Sullivan, 1968 Figure 4.2, 4.3 Compare.— Auroraspora macra Sullivan, 1968, p. 124, pl. 27, figs. 6-10; Higgs et al., 1988, p. 69, pl. 9, figs. 17-19. Material.—Ten specimens logged from NU-P1 to NU-P4, Figure 4.2 from NU-P4 and Figure 4.3 from NU-P3. Diagnosis.—Size 48-68 um, mean 58 um (65 specimens); amb subcircular to irregular; exoexine laevigate, intexine laevigate to scabrate; trilete mark exceeds two-thirds radius of spore body Description. — Trilete camerate miospores. Amb fre- quently irregular due to folding. Trilete straight, simple. Suturae distinct with labra extend up to 2/3 or more of the spore radius. Exoexine thin, thickness not determinable, often finely folded in an irregular pattern, usually pitted and torn with fine grana. The equatorial darkened zone de- scribed by Higgs et al. (1988) is occasionally observed, Intexine 1.5 um thick. Diameter.—30-35 um. Remarks.—The specimens from the Hikoroichi Formation are similar to those described by Sullivan (1968) and Higgs et al. (1988) but are significantly smaller. Higgs et al. (1988) extend the size range of A. macra to 35-65 um. The present specimens fall beyond this range and so are not at- tributed to A. macra sensu Stricto. Genus Spelaeotriletes Neves and Owens, 1966 Type species. — Spelaeotriletes triangulus Neves and Owens, 1966. Spelaeotriletes crustatus Higgs, 1975 Figure 4.5, 4.6 Spelaeotriletes crustatus Higgs, 1975, pl. 6, figs. 7-9; non pl. 6, figs. 4-6. Spelaeotriletes exiguus Keegan, 1977, p. 556, pl. 4, figs. 7-10. Spelaeotriletes resolutus Higgs. Van der Zwan and Van Veen, 1978, pl. 2, fig. 1; Van der Zwan, 1980, pl. 18, fig. 5; Higgs et al., 1988, pl. 13, figs. 8-9. Material.—Seven specimens logged from NU-P3 to NU- P5, Figure 4.5 from NU-P5 and Figure 4.6 from NU-P3. Description.—Trilete camerate miospores. Amb convexly triangular with rounded apices. Suturae distinct, straight to slightly sinuous. Suturae extend up to 3/4 of the spore ra- dius, terminating in curvaturae perfectae. Exoexine 1-2 um in thickness, distal surface and equator densely ornamented with fine to coarse grana and less commonly coni and small 64 Wei-Ping Yang and Jun-Ichi Tazawa spinae. Sculptural elements 1-1.5 um in width, up to 1 um in height, discrete but often fused to give short irregular- shaped rugulae. Intexine distinct to obscure, laevigate, al- most conformable with amb, comprising 3/4 or more of the total spore diameter and attached to the exoexine on the proximal surface only. Diameter.—50-60 pm. Remarks.—These specimens recorded from the southern Kitakami Mountains are similar to S. crustatus with ornament mainly of fine to coarse grana instead of coni or small spinaes usually distributed on the distal surface and equator. Spelaeotriletes sp. cf. S. pretiosus (Playford) Neves and Belt, 1971 Figure 4.4 Compare.— Pustulatisporites pretiosus Playford, 1964, p. 19, pl. 4, figs. 9-7; pl. 5, fig. 1; text-fig.1a. Spelaeotriletes pretiosus (Playford). Neves and Belt, 1971, p. 1241; Higgs et al., 1988, pl. 13, figs. 16-18. Material. — Six specimens logged from NU-P2,NU -P4, Figure 4.4 from NU-P4. Description.—Trilete camerate miospores. Amb rounded to convexly triangular. Trilete distinct to indistinct, sinuous, suturae extend almost to the equator, terminating in curvaturae imperfectae. Exine infragranulate, 2 um thick at the equator. Exoexine ornamented with low, simple verrucae, mammillate verrucae and wide-based spinae. Ornament evenly to irregular distributed, usually concen- trated at the distal polar region and often discernible at the equator. Verrucae subcircular in basal outline, 2-3 um in width, 1-2 um in height, with rounded flattened or more com- monly mammillate tops. Bases of verrucae discrete, or fused to form very large irregular-shaped verrucae. Diameter.—35-38 um. Remarks. — The present specimens are assigned to Spelaeotriletes cf. pretiosus on the basis of the type of orna- ment. Playford (1964) indicated a size of 98 to 195 um for the type material of S. pretiosus. Higgs et al. (1988) re- corded specimens between 68 and 110 um. The present specimens are considerably smaller. Infraturma Cingulicamerati Neves and Owens, 1966 Genus Densosporites Berry emend. Butterworth, Jansonius, Smith and Staplin, 1964 Type species.—Densosporites convensis Berry in Butter- worth, Jansonius, Smith and Staplin, 1963. Densosporites sp. Figure 4.11 Densosporites sp. A, Higgs, Clayton and Keegan, 1988, p.79, pl. 15, figs 10, 11. Material.—Seven specimens logged from NU-P1 to NU- P4, Figure 4.11 from NU-P2. Description.—Trilete cinguli-camerate miospores. Amb convexly triangular to subtriangular. Suturae obscure, sim- ple, often gaping. Intexine often obscure. Exine 1-1.5 um thick. Equatorial margin and distal surface ornamented with wide-based spinae, 1.5-2.5 um in basal diameter and 1.5-3 um in height. Spinae discrete but more commonly fused at their bases to form low sinuous and irregular cristae. Diameter.—33-45 um. Remarks.—The Kitakami specimens are similar to those described by Higgs et al. (1988) in Ireland but just slightly smaller in size and with more dense ornament on the distal surface. Conclusion 1. These records represent the first authenticated occur- rence of Early Carboniferous miospores in Japan. 2. This significant miospore data might extend the geologi- cal age of the HK2 Member of the Hikoroichi Formation into late Tournaisian to early Viséan. 3. This miospore assemblage from the Hikoroichi area is more likely included in the Vallatisporites Microflora, which is to some degree similar to the Euramerican Realm in terms of megafloral phytogeography. Acknowledgments The first author (YWP) is indebted to JSPS for support in Japan. This research was financially assisted by Monbu- sho. We sincerely thank Professors Y. Hasegawa and A. Matsuoka of Niigata University for use of their laboratory and technical support. Appreciation also extended to Professor T. Kimura of the Institute of Natural History, Tokyo for infor- mation about the Late Paleozoic plants in Japan. Thanks must also go to three reviewers, Professor G. Playford, and Drs. J. Utting and D. Mclean for their careful comments and suggestions, from which this paper greatly benefited. References Asama, K., Asano, T., Sato, E. and Yamada, Y., 1985: Early Carboniferous plants from the Hikoroichi Formation, southern Kitakami Massif, northeast Japan (preliminary report). The Journal of the Geological Society of Japan, vol. 91, p. 425-426, pl. 1. 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Science Reports of Niigata University, Series E, no. 15, p. 35-47, pl. 1. 67 en nels ne a - ya AWE WU yee) Brae A ee eas Oo te aie whist XC fear a ii Paleontological Research, vol. 4, no. 1, pp. 69-74, April 28, 2000 © by the Palaeontological Society of Japan Pisulinella miocenica, a new genus and species of Miocene Neritiliidae (Gastropoda: Neritopsina) from Eniwetok Atoll, Marshall Islands YASUNORI KANO' and TOMOKI KASE’ ‘Department of Biological Sciences, Graduate School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan (Mailing address: Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo, 169-0073, Japan; kano@kahaku.go.jp) “Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo, 169-0073, Japan (kase @kahaku.go.jp) Received 18 September 1999; Revised manuscript accepted 7 January 2000 Abstract. Pisulinella is proposed as a new monotypic genus in the neritopsine family Neritiliidae, with the single species Pisulinella miocenica sp. nov. Miocene sediments from Eniwetok Atoll, Marshall Islands, western Pacific. This new taxon occurs in subsurface Nine specimens of P. miocenica were previously regarded as close to Nerita (Amphinerita) polita Linnaeus of the Neritidae. Reallocation of this species from Neritidae to Neritiliidae is based mainly on the shape of the protoconch, which is conspicuously tilted relative to the teleoconch whorls and has several spiral ridges. The discovery of this neritiliid species, previously allocated to the Neritidae, sug- gests that detailed examination of protoconchs is necessary for defining the systematic position of fossil neritopsines. Pisulinella miocenica sp. nov. may have lived in a cryptic habitat. Key words: Eniwetok, Neritiliidae, Pisulinella miocenica, protoconch, submarine cave Introduction The gastropod superorder Neritopsina has a fossil record from Silurian to Recent (Tracey et al., 1993). This group underwent major adaptive radiation in the geological past, which has resulted in fairly diverse shell morphology and soft-part anatomy. The early history of neritopsine evolu- tion is unknown, although some suprageneric phylogenies have been proposed for extant groups (e. g. Holthuis, 1995). Bandel (1992) documented the supposed earliest neritop- sine from the Ordovician, although it differs greatly in teleoconch morphology from modern relatives. Unconven- tional species of neritopsines occur even in Recent faunas, such as the bizarre gastropod Pluviostilla palauensis, possi- bly belonging to a new neritopsine group, from a submarine cave in Palau (Kase and Kano, 1999). Additional discover- ies such as these may eventually lead to a better under- standing of neritopsine evolution. Neritopsines are usually “neritiform” and tightly coiled, but may also have a limpet-like shape or, rarely, be shell-less (Cox and Knight, 1960; Ponder, 1998). Frequent conver- gence and parallelism, however, prevent reliable classifica- tion of the fossil forms and hinder an understanding of neritopsine evolution. Cox and Knight (1960) recognized 19 fossil genera of Neritidae and diagnosed most genera solely on the basis of general teleoconch shape. These fossil neritopsines must be reexamined to document their more conservative characters, such as shell microstructure, shell muscle scars, and protoconchs, in order to clarify their systematic positions. We describe a new genus and spe- cies in the family Neritiliidae from Miocene sediments at Eniwetok Atoll in the Marshall Islands, with special attention being given to protoconch morphology. This new species was once thought to be a modern species of the family Neritidae. Materials The nine specimens described here were recovered from three deep subsurface cores drilled by the U. S. Geological Survey in 1951-1952 on Eniwetok Atoll in the Marshall Islands. The drill holes penetrated Recent to upper Eocene sediments, and the cores and cuttings of the drill holes yielded gastropods of remarkably high diversity, which were described by Ladd (1966, 1972, 1977) in his series of mono- graphs on Cenozoic polyplacophorans and gastropods of tropical western Pacific islands. Specimens of the present new species were recovered from cores at depths ranging 70 Yasunori Kano and Tomoki Kase from 253 to 298 meters (830 to 978 feet) below the surface and dated as early to late Miocene. See Ladd and Schlanger (1960) and Schlanger (1963) for details of the drilling operations and stratigraphic information. All specimens used in this study are in the National Museum of Natural History, Washington, D. C. (USNM). SEM examinations were made in a low vacuum mode with- out a metal coating. Systematic paleontology Superorder Neritopsina Cox and Knight, 1960 Family Neritiliidae Schepman, 1908 Genus Pisulinella gen. nov. Type species.—Pisulinella miocenica sp. nov. Diagnosis.—Genus similar to Pisulina. Inner lip of aper- ture smooth, convex, bearing three or four inconspicuous teeth at margin; a shallow groove on inner lip callus extends along inner line. Outer lip thick, with a blunt, rounded mar- gin and with weak tubercles along the interior. Protoconch multispiral, inclined; larval shell sculptured with six or seven spiral ridges. Etymology.—Combination of the neritiliid genus Pisulina and ellus (Latin: diminutive), referring to the smaller shell similar to Pisulina. Discussion. —Neritiliidae Schepman, 1908 is a distinct family in Neritopsina, but until quite recently it had been thought to be a subfamilial taxon (Neritiliinae) of Neritidae (e. g. Cox and Knight, 1960; Ponder, 1998). Based upon her extensive anatomical study, Holthuis (1995) has clarified the paraphyly of Neritidae, and shown that Neritilia (the type genus of Neritiliidae) is the first offshoot in the clade “Neriti dae” + Phenacolepadidae. Recently, Kano and Kase (in press) have reallocated the submarine-cave genus Pisulina from Smaragdiinae in Neritidae to Neritiliidae, based on find- ing 11 synapomorphies of Pisulina and Neritilia in the ana- tomical and shell characters. Figure 1. Pisulinella miocenica gen. et sp. nov. (USNM 648333). Scale bar = 1 mm. 1-4. Front, apical, apertural and lateral views of the holotype New neritopsine genus 71 The most important shell character for defining the taxo- nomic position of Pisulinella is protoconch morphology. The protoconchs of neritopsine species with planktotrophic development are unique and quite uniform in shape (e. g. Bandel, 1982). The larval shell is oval to globular- naticiform, smooth except for fine growth lines, and coils al- most planispirally. Kano and Kase (in press) distinguish Neritiliidae from the other families in the superorder based on the fact that its coiling axis is remarkably tilted compared to that of the teleoconch, and because the protoconch sur- face bears several spiral ridges near the aperture. Pisulinella shares protoconch features with Pisulina and Neritilia, as described in the systematic part of this report. Although the soft anatomy of P. miocenica sp. nov. is not known, the new genus unequivocally belongs to Neritiliidae. The family Neritiliidae heretofore included the two modern genera Neritilia Martens and Pisulina Nevill and Nevill (Kano and Kase, in press). Pisulinella is related to Pisulina rather than to Neritilia. Neritilia rubida, the type species of the genus, has a thin calcareous layer that covers the embryonic shell (Kano and Kase, in press). Bandel and Riedel (1998, fig. 6A, B) showed another example in a species of the genus from Cebu, Philippines, but the calcareous layer ap- pears to be thinner than that of N. rubida. However, this layer is absent in Pisulina and Pisulinella (this condition in Pisulina is typically developed in P. adamsiana; see Herbert and Kilburn, 1991, fig. 3). Teleoconch morphology also in- dicates that Pisulinella is close to Pisulina rather than to Neritilia. In Pisulinella and Pisulina (particularly P. adamsiana), the inner line of the apertural inner lip callus has a reversed S-shape, and the basal lip bears a weak pro- tuberance (Figures 1, 2). On the other hand, Pisulinella possesses more numerous spiral ridges on the larval shell, and the exposed area of the embryonic shell is much smaller than in Pisulina adamsiana. The apertural morphology is also characteristic of P. miocenica. When the shell is fully grown, the outer lip is thickened along its interior with many obscure tubercles, and is blunt and rounded along its margin (Figure 2.1). Furthermore, the inner lip callus of Pisulinella has a shallow groove that extends along the inner line (Figure 2.2). None of the species of Pisulina and Neritilia have such features. We therefore conclude that Pisulinella is a distinct genus in Neritiliidae. Pisulinella miocenica sp. nov. Figures 1-3 Nerita (Amphinerita) aff. N. polita Linnaeus: Ladd, 1966, p. 56, pl. 10, figs. 17, 18. Diagnosis.—As for the genus. Description.—Shell small, up to 4.0 mm in diameter, 3.7 mm in height (Table 1), thick, solid, obliquely ovate with a low spire, brownish cream in color without color markings (Figure 1). Inner walls of whorls resorbed, producing a hol- low cavity inside. Protoconch multispiral, consisting of em- bryonic and larval shells, deeply immersed in first teleoconch whorl, separated from teleoconch by a clearly demarcated line; protoconch axis inclined significantly rela- tive to teleoconch (Figure 3.1). Embryonic shell largely cov- ered by larval shell and also sometimes by first teleoconch whorl, depending on protoconch inclination, and sculptured with faint, reticulate grooves (Figure 3.2); exposed portion of embryonic shell ca. 60 um in maximum dimension; larval Figure 2. bar = 1 mm. Drawings showing the detail of apertural characteristics in Pisulinella miocenica gen. et sp. nov. 1. Holotype with four teeth along the inner lip, a weak protuberance in the basal lip, and many obscure tu- bercles on the outer lip. 2. Paratype 6 (USNM), juvenile shell, with an unornamented outer lip that has a sharp margin. Arrow indicates a shallow groove in the inner lip callus along the inner line. Scale 12. Yasunori Kano and Tomoki Kase Figure 3. SEM micrographs of the protoconch of Pisulinella miocenica gen. et sp. nov. 1. Apical area of paratype 8 (USNM). Scale bar = 100 um. 2. Protoconch of the holotype, showing an exposed embryonic shell (arrow) and seven spiral ridges on the larval shell. Scale bar = 50 um. Table 1. shell surrounded by suture of first teleoconch whorl, and ex- posed drop-shaped area 295-375 um in maximum dimen- sions, sculptured with microscopic pits scattered all over surface, and also with six or seven, ca. 3-um-wide, up to 200-um-long spiral ridges near apertural lip. Teleoconch whorls less than 2.3 in number, increase rapidly in size, in- flated with a round periphery, slightly concave below su- tures; last whorl more or less descending abapically in final growth stage. Suture shallowly impressed. Shell surface smooth, polished, and ornamented with fine growth lines and microscopic, sparse spiral grooves. Aperture widely open and semicircular in outline. Outer lip prosocline, blunt at margin, angled 30° to 40° to shell axis, and thickened along interior with many weak tubercles (Figure 2.1). Inner lip covered with a white, smooth, thick and convex callus; adaxial margin bears 3 or 4 slightly protruding teeth, inner line of callus with a deep and distinct, reverse-S shaped groove surrounding columellar area and continuing to basal lip without sinuation; a shallow groove carved on inner lip callus extends along inner line (Figure 2.2). Basal lip usu- ally bears a weak protuberance. Operculum unknown. Etymology.—The species name is derived from the word Miocene, the age of the specimens. Types.—Holotype: USNM 648333, drill hole F-1 at depth of 930-940 feet (283-287 m), Elugelab Island, Eniwetok Atoll, Marshall Islands, lower Miocene (Tertiary f). Eight paratypes, USNM, from three drill holes F-1, K-1B, E-1 (on Elugelab Island, Engebi Island, and Parry Island, respec- tively), Eniwetok Atoll, at a depth of 830-978 feet (253-298 m), lower to upper Miocene (Tertiary fg). See Table 1 for details. Occurrence.—This species is known only from drill-holes on Eniwetok Atoll, early to late Miocene. Discussion.—Ladd (1966) assigned this species to Nerita (Amphinerita) in Neritidae and suggested an affinity to N. (A.) polita Linnaeus, a modern species widely inhabiting the tropical Indo-West Pacific, including the Marshall Islands. However, the present fossil species differs markedly from N. (A.) polita and also from other species of the subgenus in several important ways. The fully grown adult shell of P. miocenica is less than 4 mm in maximum diameter (Table Locality and shell measurements of Pisulinella miocenica gen. et sp. nov. Paratypes 6-8 are immature specimens and have a sharp margin along their outer lips. The outer lips of paratypes 4 and 5 are largely broken so that the diameters and heights (in parentheses) are not representive of the species. Number of ; Maximum Specimen na u gen teleocorch parsers Height ee = exposed (mm) Holotype USNM 648333 F-1 (930-940) 2.3 3.8 3:7: 375 Paratype 1 USNM F-1 (920-930) 2.3 4.0 3.4 325 Paratype 2 USNM F-1 or E-1 (940-950) 232 3.7, 3.3 335 Paratype 3 USNM F-1 (900-910) 2.2 3.6 3.3 360 Paratype 4 USNM E-1 (830-840) 2.2 (2.7) (2.9) 365 Paratype 5 USNM F-1 (900-910) 251 (2.7) (3.1) 295 Paratype 6 USNM K-1B (968-978) 2.0 3.0 2.7 385 Paratype 7 USNM K-1B (936-946) 1.8 2.8 2.5 340 Paratype 8 USNM E-1 (900-910) 1.6 2.0 1.9 365 New neritopsine genus 73 1), while the largest specimen of N. (A.) polita at hand, from Okinawa, Japan, is over 35 mm in maximum diameter. Even the smallest adult of Nerita (Amphinerita) species at hand is over 15 mm in maximum diameter. Moreover, the shells of P. miocenica are plain cream in color and lack the color pattern that is characteristic of Nerita (Amphinerita). Ladd (1966, p. 11) stated that the fossil shells in the drill-hole section from which this species was recovered apparently never were raised above sea level to be leached and recrystallized. The shells of this new species are almost in- tact, and many mollusk shells from the same section retain original color patterns (e. g. Smaragdia species; see Ladd, 1966, pl. 11, figs. 5-9). These facts strongly suggest that shells of P. miocenica were originally plain white, but were subsequently stained brownish cream during fossilization. The presence of a distinct inner line in the callused apertural inner lip, also noted by Ladd (1966), is another character separating P. miocenica from Nerita (Amphinerita) species. Schlanger (1963) stated that the reef-associated sedi- ments in the drill-hole section from which the shells of P. miocenica were recovered were deposited in lagoonal and shore-bank environments. The basis for this belief was the very high content of delicate branching corals and the abun- dance of large mollusks. Gastropod species associated with P. miocenica in the drill holes include a number of mi- croscopic and macroscopic species that also are suggestive of lagoonal and shore-bank environments within a coral reef. Interestingly, however, the plain creamy color of P. miocenica suggests a cryptic habitat for this species. Loss of shell color and reduction of shell size are adaptations to gloomy to totally dark cave habitats for mollusks (Kase and Hayami, 1992; Hayami and Kase, 1993, 1996). Four Pisulina species found in marine caves are plain white in color and lack color markings (Kano and Kase, in press). Seven species of undescribed neritiliid genera recently found in submarine caves of tropical Pacific islands, and a species of Neritilia recently found in anchialine caves (sub- terranean caves with haline water which have no surface connection to the sea; see Stock et al., 1986), are entirely white (unpublished data). We suggest that P. miocenica was a cryptic species that inhabited submarine caves and/or crevices in a coral reef, and that the shells were secondarily transported to an open reef-associated environment by water currents and/or by subsequent destruction of the reef bodies. Acknowledgements We thank J. W. M. Thompson (USNM) for the loan of ma- terial. This study was financially supported by grants from the Ministry of Education, Science and Culture, Japan (nos. 11833018 and 11691196) to T. K. References Bandel, K., 1982: Morphologie und Bildung der fruhontogene- tischen Gehause bei conchiferen Mollusken. Facies, vol. 7, p. 1-198. Bandel, K., 1992: Platyceratidae from the Triassic St. Cassian Formation and the evolutionary history of the Nerito- morpha (Gastropoda). Paläontologische Zeitschrift, vol. 66, p. 231-240. Bandel, K. and Riedel, F., 1998: Ecological zonation of gastro- pods in the Matutinao River (Cebu, Philippines), with focus on their life cycles. Annales de Limnologie, vol. 34, p. 171-191. Cox, L. R. and Knight, J. B., 1960: Suborder Neritopsina. In, Moore, R. C. ed., Treatise on Invertebrate Paleontology. Part I. Mollusca 1, p. 275-290. Geological Society of America and Kansas University Press, Lawrence. Hayami, I. and Kase, T., 1993: Submarine cave Bivalvia from the Ryukyu Islands: systematics and evolutionary signifi- cance. The University Museum, the University of Tokyo, Bulletin, no. 35, p. 1-133. Hayami, |. and Kase, T., 1996: Characteristics of submarine cave bivalves in the northwestern Pacific. American Malacological Bulletin, vol. 12, p. 59-65. Herbert, D. G. and Kilburn, R. N., 1991: The occurrence of Pisulina (Neritidae) and Neritopsis (Neritopsidae) in southern Africa (Mollusca: Gastropoda: Neritoidea). Annals of the Natal Museum, vol. 32, p. 319-323. Holthuis, B. V., 1995: Evolution between marine and fresh- water habitats: a case study of the gastropod Neritopsina. 286 p. Doctoral dissertation, University of Washington. Kano, Y. and Kase, T., in press: Taxonomic revision of Pisulina (Gastropoda: Neritopsina) from submarine caves in the tropical Indo-Pacific. Paleontological Research. Kase, T. and Hayami, |., 1992: Unique submarine cave mollusc fauna: composition, origin and adaptation. Journal of Molluscan Studies, vol. 58, p. 446-449. Kase, T. and Kano, Y., 1999: Bizarre gastropod Pluviostilla palauensis gen. et sp. nov. from a submarine cave in Palau (Micronesia), possibly with neritopsine affinity. Venus (The Japanese Journal of Malacology), vol. 58, p. 1-8. Ladd, H. S., 1966: Chitons and gastropods (Haliotidae through Adeorbidae) from the western Pacific islands. United States Geological Survey Professional Paper 531, p. 1- 98, pls. 1-16. Ladd, H. S., 1972: Cenozoic fossil mollusks from western Pacific islands; Gastropods (Turritellidae through Strombidae). United States Geological Survey Profes- sional Paper 532, p. 1-79, pls. 1-20. Ladd, H. S., 1977: Cenozoic fossil mollusks from western Pacific islands; Gastropods (Eratoidae through Harpidae). United States Geological Survey Professional Paper 533, p- 1-84, pls. 1-23. Ladd, H. S. and Schlanger, S. O., 1960: Drilling operations on Eniwetok Atoll. United States Geological Survey Profes- sional Paper 260-Y, p. 863-903. Ponder, F. W., 1998: Superorder Neritopsina. /n, Beesley, P. L., Ross, G. J. B. and Wells, A. eds., Mollusca: The Southern Synthesis. Fauna of Australia, vol. 5, p. 693- 703. CSIRO Publishing, Melbourne. Schepman, M. M., 1908: The Prosobranchia of the Siboga Expedition. Part 1. Rhipidoglossa and Docoglossa. Résultats des Explorations Zoologiques, Botaniques, Océanographiques et Géologiques entreprises aux Indes Orientales en 1899-1900, a bord du Siboga, sous le commandement de G. F. Tydeman, no. 39, p. 1-107, pls. 1-9. Schlanger, S. O., 1963: Subsurface geology of Eniwetok Atoll. United States Geological Survey Professional Paper 74 Yasunori Kano and Tomoki Kase 260-BB, p. 991-1066. Tracey, S., Todd, J. A. and Erwin, D. H., 1993: Mollusca: Stock, J. H., lliffe, T. M. and Williams, D., 1986: The concept Gastropoda. In, Benton, M. J. ed., The Fossil Record 2, of “anchialine” reconsidered. Stygologia, vol. 2, p. 90- p. 131-168. Chapman and Hole, London. 92. Paleontological Research, vol. 4, no. 1, pp. 75-80, April 28, 2000 © by the Palaeontological Society of Japan A new fossil bonito (Sardini, Teleostei) from the Eocene of England and the Caucasus, and evolution of tail region characters of its Recent relatives KENNETH A. MONSCH University of Bristol, Department of Earth Sciences, Queens Road, Bristol BS8 1RJ, England, UK (Kenny-Monsch @bristol.ac.uk) Received 23 July 1999; Revised manuscript accepted 20 January 2000 Abstract. A new species of a fossil bonito, Gymnosarda prisca (Scombridae, Perciformes) from the Early Tertiary shows an interesting combination of characters not seen in other, Recent, boni- tos. The new species is based on hypural bones from the caudal region. fossil hypural plates possess a caudal notch, a character not known in Recent bonitos. Although a bonito, the The dis- covery of this new taxon causes a redefinition of the synapomorphies of the caudal region that de- fine bonitos and their relatives, the tunas and Spanish mackerels. The fossil species has previously been described as part of Scomberomorus saevus. Key words: bonitos, evolution, fossil, new species, synapomorphies, tunas Introduction The discovery of a new fossil fish has changed concepts of the characters that define tunas, bonitos and the evolution of their characters. Tunas and bonitos (tribes Thunnini and Sardini, Scombridae) have been stably defined for sometime according to characteristics described in Collette and Chao (1975), Collette (1978) and Collette et al. (1984). A new fossil scombrid, described here, shows a remarkable combi- nation of characters which changes current concepts. This fossil species has been studied in the context of a phylogenetic study of the suborder Scombroidei. The main hypotheses (Collette et al., 1984; Johnson, 1986; Finnerty and Block, 1995) on phylogenetic relationships of scombroid fishes, based on data of Recent taxa, present highly conflict- ing results. In an attempt to solve this problem, | carry out a phylogenetic analysis, containing Recent as well as fossil taxa. Here | present part of my results. Scomberomorus saevus Bannikov was described from the Eocene of Turkmenistan and Kazakhstan (Bannikov, 1982, 1985). This paper concerns amongst others a specimen of a hypural plate, originally assigned to S. saevus. Hypural elements are bones that provide the principal support for the lepidotrichia of the tail in fishes, and are normally separate from one another. In the Scombridae the hypural elements are fused to such a degree that they form one single hypural plate. This plate articulates directly with the vertebral col- umn. Bannikov (1982) did not describe hypural plates in the original description of S. saevus, although the type mate- rial did include these plates (Bannikov pers. comm., 1998). They are described in a later account (Bannikov, 1985). These hypural elements are part of a series of paratypes. The holotype of S. saevus is a premaxilla. Bannikov’s (1982, 1985) material of S. saevus includes one specimen which | have identified as Sardini. One fossil specimen from England has been identified as identical to the afore- mentioned Sardini. Materials Except for RAN PIN 1878-8 (premaxilla), the fossil mate- rial consists of hypural plates. BMNH: the Natural History Museum, London: New species: P6485, Isle of Sheppey, England, Ypresian (London Clay Formation) . Gymnosarda unicolor (Rüppell): 1934.3.31, Red Sea (Recent). Scomberomorus niphonius (Cuvier): 1874.1.16.9, no data; 1890.2.26.90, inland sea, Japan (Recent). Sarda orientalis (Temminck and Schlegel): 1920.7.23.59, Durban, South Africa (Recent). RAN PIN: Russian Academy of Sciences, Paleontological Institute, Moscow: New species: 1878-2 Western extremities of Ustyurt, Kazakhstan, Upper Eocene (Shorym Svita); 1878-4, Turk- menistan, Upper Eocene (Shorym Svita); 1878-8 (holotype of S. saevus), Mangyshlak Peninsula, Karagiye basin, Kazakhstan, Upper Eocene (Shorym Svita). USNM: Natural History Museum, Smithsonian Institution, Washington DC: 76 Kenneth A. Monsch Scomberomorus plurilineatus (Fourmanoir): 64809 and 269760, Durban, South Africa (Recent). Sarda sarda (Bloch): USNM 26953, 26954, no data (Recent); 270730, New Jersey, U.S.A. (Recent); 270731, Ponte Delgada Fish Market, San Miguel, Azores (Recent). Systematic palaeontology Order Perciformes sensu Johnson and Patterson, 1993 Suborder Scombroidei sensu Carpenter et al., 1995 Family Scombridae Rafinesque, 1815 Genus Gymnosarda Gill, 1862 Gymnosarda prisca sp. nov. Figure 1A, B Scomberomorus saevus Bannikov, 1982, p. 135 (in part); Bannikov 1985, p. 37 (in part). Holotype.—BMNH P6485, (previously labelled “unidenti- Figure 1. Hypural plates, lateral view. Gymnosarda prisca sp. nov. A. Holotype, BMNH P6485 (left view). B. RAN PIN 1878-4 (right view). Arrow indicates perspective of Figure 2A. C. Gymnosarda unicolor (Rüppell) (left view), after Collette and Russo (1984) and BMNH 1934.3.31. D. Scomberomorus regalis (Bloch): USNM 270053, (right view). Abbreviations: hyp5: fifth hypural, n: caudal notch, p: parhypural, ps: parhypurapophysis, un: uroneural, us: urostyle, v: remnant of caudal notch. Scale bars indicate 10 mm. A fossil bonito and tail evolution 77 fied teleost”) (Figure 1A). Material. —Holotype, and RAN PIN 1878-4, (Figure 1B). Etymology.—Priscus is Latin for “old”, indicating it is an extinct ancient species of Gymnosarda. The only other species is the Recent Gymnosarda unicolor. Diagnosis. — Species of a Sardini: uroneural and fifth hypural fused to hypural plate and urostyle cross-section with long axis horizontal. Differs from other Sardini by hav- ing parhypural fused to hypural plate and possession of cau- dal notch. Recent bonitos lack a conspicuous notch, and of Recent bonitos only Gymnosarda unicolor has a fused parhypural (see Figure 1). Description. —Hypural plate, made up of fusion of urostyle, uroneural, hypurals 1-5 (hypural 5 not completely fused to plate) and parhypural. Plate diamond-shaped; sides equal in length. Height 75 mm (holotype, Figure 1A) or 79 mm (RAN PIN 1878-4, Figure 1B), which is twice the length with- out uroneural in both specimens (length: along axis of fish, height: along line perpendicular to axis). Posterior outline of diamond slightly swollen outwardly (more on dorsal side). Posteriorly, a clearly discernible notch. Markings made by fin rays crossing plate visible as shallow grooves, running parallel to rostral sides of diamond. Parhypurapophysis (damaged) making angle of about 41° with horizontal axis. Uroneural large, fused to urostyle [urostyle, according to definition of Potthoff (1975): fusion of preural centrum 1 and ural centrum]. Cross-section of urostyle round or slightly ovoid with the long axis vertical (as Thunnini, Figure 2). B 10mm Figure 2. Hypural plates viewed to show the diameters of urostyles. A. Gymnosarda prisca sp. nov., RAN PIN 1878-4. B. Scomberomorini indet., RAN PIN 1878-2. Remarks.—The hypural plate-based taxon G. prisca is ref- erable to the Sardini based on the diamond-shaped plate and the large anterior upturned end of the uroneural which is fused to the plate. With its proportions the hypural plate of G. prisca is almost identical to that of the Recent G. unicolor (Figure 1C). In Gymnosarda, the hypural plate is about twice as deep as long. In the other bonitos Sarda, Orcynopsis and Cybiosarda the hypural plate is less deep. Allothunnus was previously recognised as a bonito (Collette and Chao, 1975; Johnson, 1986). Collette et al. (1984) suggest that Allothunnus is better regarded as a primitive Thunnini, for which later convincing evidence has been found (Graham and Dickson, in press). | Gymnosarda unicolor is unique among Recent bonitos in having a fused parhypural, just like G. prisca, and has a small vestige where G. prisca has a caudal notch (BMNH 1934.3.31 and Collette and Chao, 1975, p. 578 and fig. 56). No bonito with a cau- dal notch is known (Collette and Chao, 1975). | have not seen such notches in specimens of Sarda (BMNH 1920.7.23.59; USNM 26953, 26954, 270730 and 270731). Still, the G. prisca hypural plate possesses all other charac- teristics of a Sardini. The specimen figured in Figure 2B (RAN PIN 1878-2) is an unknown scombrid, described and figured as S. saevus by Bannikov (1985, p. 37, figures 17 g, d) and is part of the S. saevus type series. The parhypural is fused to the plate and hence it is not a Scomberomorus (Table 1; see also Discussion), but no name as yet is assigned to that speci- men. The systematic position of the taxon this plate repre- sents is still under consideration. Discussion Previously, G. prisca was believed to belong to Scom- beromorus because of apparent similarities with the latter (Figure 1D). It now seems that it is not a Scomberomorus. The most conspicuous character to identify a Sardini from a Scomberomorini is the cross-section of their urostyles (see their descriptions and Figure 2). Gymnosarda prisca has a hypural plate in which the cross-section of the urostyle is ovoid with the long axis vertical (Figure 2A), whereas in Scomberomorini the long axis is horizontal (Figure 2B). In G. prisca the parhypural is fused with the hypural plate, whereas in Recent Scomberomorus it is not. Collette and Russo (1984) mention that Scomberomorus niphonius and Scomberomorus plurilineatus have parhypurals partially fused to the hypural plate. In specimens of S. plurilineatus (USNM 264809 and 269760) and Scomberomorus niphonius (BMNH 1874.1.16.9 and 1890.2.26.90) the parhypural is not fused to the hypural plate. Possibly there is a light degree of fusion in specimens that | have not seen. Bannikov (1982) noted that the parhypural of S. saevus is separated from the hypural plate by a fissure. Although the parhypural can be clearly identified in the hypural plate of G. prisca, the division between the plate and the parhypural is not sharp enough to represent an autogenous parhypural. The assignment of the name S. saevus to its whole type series is partially incorrect. Bannikov’s (1982, 1985) holo- type is RAN PIN 1878-8, which is a premaxilla that is identi- cal to one of Scomberomorus. A Scomberomorus premax- 78 Kenneth A. Monsch illa is recognised by a relatively long ascending process: 31-48% of the total premaxilla (Collette and Russo, 1984), and makes a sharp angle with the shank: 32°-61° (Collette and Russo, 1984). The holotype of S. saevus fits this de- scription well. Being recognised as a Scomberomorus and being the holotype of the epithet saevus, the name Scomberomorus saevus is retained for this specimen. Gymnosarda prisca shows a peculiar mix of characters. A noticeable caudal notch in the hypural plate is a primitive character, found in amongst others the Scomberomorini, where it can be large. | do not think that G. prisca can be anything but a Sardini and indeed, a Gymnosarda. Accord- ing to Collette and Chao (1975) and Collette et al. (1984) one of the synapomorphies of the scombrids above the Spanish mackerels (Scomberomorini) is the absence of the caudal notch (see Table 1). Gymnosarda prisca clearly possesses a large caudal notch. Gymnosarda unicolor is in fact not devoid of a caudal notch, it has a small, hard to spot vestigial one. It seems thus, that Sardini are not character- ised by the absence of a caudal notch, but rather by a ten- dency of this notch to close down, and ultimately disappear in their evolution. Thunnini are characterised by a complete absence of the notch. The caudal notch in G. prisca is evi- dence that it is not a sharp divider above species level: the Scomberomorini have a notch; so do primitive Sardini and in advanced ones this notch has disappeared. Therefore, be- Table 1. Overview of hypural plate characters of Scomberomorus and Sardini. Hypural Cross-section of Parhypural Caudal notch Uroneural fusion pattern urostyle Scomberomorus not fused ves not fused 1-4,5 long axis vertical Gymnosarda prisca sp. nov. fused yes fused 1-5 long axis horizontal Gymnosarda unicolor (Ruppell) fused remnant fused 1-5 long axis horizontal other Sardini not fused no fused 1-5 long axis horizontal | | | -— Scomberomorini | Grammatorcynus U U ne Re — Sardini —— Sardini and Thunnini — Thunnini 5 — Scomberomorus A U = B | Scomberomorini | — Thunnini — Sardini ree Scombrini Be Trichiuridae \ C Figure 3. After Johnson (1986). C. After Finnerty and Block (1995). Phylogenetic relationships of Sardini, Thunnini and their closest relatives. D. Proposed evolutionary sequence. Ê @\\ /other Sardini @\ / Gymnosarda unicolor Gymnosarda prisca @\\/ Scomberomorini Scombrini/Trichiuridae D A. After Collette et al. (1984). B. A fossil bonito and tail evolution 79 cause of the great similarities with G. unicolor, | describe this fossil taxon as a new species within this genus. The small vestigial notch of G. unicolor suggests that more primitive bonitos have once had a large caudal notch. This is confirmed by G. prisca. This notch is a primitive fea- ture, which thus suggests that the ancestor of the bonitos came from within the Scomberomorini (see Table 1). Collette et al. (1984) and Johnson (1986) published phylogenies of Scombroidei based on morphological data (Figs. 3A and B). Finnerty and Block (1995) published a phylogeny based on DNA analyses (Figure 3C). In Collette et al. (1984), Sardini and Thunnini are the most advanced scombroids, with Scomberomorini as the sistergroup. Ac- cording to Johnson (1986), Sardini+Thunnini are a special- ised offshoot of a paraphyletic Scomberomorini. Finnerty and Block (1995) present a phylogenetic relationship in which the Sardini+Thunnini clade is sister-group to a Scombrini (mackerels)+Trichiuridae (cutlassfishes) clade. The clade containing these four taxa is in turn the advanced sistergroup to Scomberomorini. Keeping in mind the pro- posed evolutionary sequence (Figure 3D), all three hypothe- ses of relationships in Fig. 3A-C seem to be possible. Finnerty and Block’s hypothesis is less parsimonious than the morphological ones, because it requires reversals. The caudal region of Scombrini and Trichiuridae is plesiomorphic compared to that of other Scombridae. Johnson’s (1986) Scomberomorini are paraphyletic, caused by the offshoot of Sardini and Thunnini, but his phylogenetic hypothesis re- mains possible. However, this hypothesis is less parsimo- nious than that of Collette et al. (1984). If you map tail- region morphology on Johnson’s (1986) phylogeny, there are character reversals (Figure 3B). Further research on the phylogeny of scombroids will hopefully contribute more to the solution of the controversy of these relationships. Although based on a hypural plate only, | do think that phylogenetic hypotheses can be made using G. prisca. Hypural plates provide strong characters, which are well indicative of genera (see Uyeno and Fujii, 1975). Conclusions While studying the type series of Scomberomorus saevus, a new species has been found: Gymnosarda prisca. Sardini are to be characterised by a tendency of the hypural notch to close and disappear in their evolution. Thunnini are characterised by a complete absence of the notch. Gymnosarda prisca fits in with every one of the different scombroid cladograms, with respect to Recent Sardini- Scomberomorini relationships. Finnerty and Block’s (1985) phylogeny seems to be less parsimonious than the morpho- logical phylogenies. In Johnson’s (1986) hypothesis, Scomberomorini are paraphyletic and the tail region evolu- tion requires reversals. Acknowledgements | thank P.L. Forey for access to the BMNH and for useful criticisms of my research and V.l. Young for arranging the loan of BMNH specimens. Investigations in the BMNH were in part funded by a Large Scale Facility Grant of the European Union. | also thank A.F. Bannikov for help and advice in RAN PIN, where my work in was partially subsidised by a grant of the Alumni Foundation (University of Bristol). My work at the USNM benefited greatly from as- sistance and advice of B.B. Collette and J.C. Tyler and was financed by a Smithsonian Institution Short Term Visitors grant. Lighting equipment for photographing USNM speci- mens was provided by R. Gibbons. M.J. Benton critically read a (very early version) of the manuscript. Bannikov’s (1985) publication in Russian has been translated for me by N. Bakhurina. This work forms part of my research for the PhD thesis “The Phylogeny of Scombroid Fishes”, which is financially supported by my parents and the Department of Earth Sciences, University of Bristol. References Bannikov, A. F., 1982: A new species of mackerel from the Upper Eocene of Mangyshlak. Paleontological Journal, vol. 16, no. 2, p.135-139. Bannikov, A. F. 1985: Iskopayemve skumbriyevye SSSR (Fossil scombrids of the USSR). Trudy Paleontolo- gischeskogo Instituta: Akademiya Nauk SSSR, vol. 210, p.1-111. Carpenter, K. E., Collette, B. B. and Russo, J. L., 1995: Unstable and stable classifications of scombroid fishes. Bulletin of Marine Science, vol. 56, no. 2, p. 379-405. Collette, B. B. and Chao, L. N., 1975: Systematics and mor- phology of the bonitos (Sarda) and their relatives (Scombridae, Sardini). Fishery Bulletin, vol. 73, no. 3, p.516-625. Collette, B. B., Potthoff, T., Richards, W. J., Ueyanagi, S., Russo, J. L. and Nishikawa, Y.,1984 : Scombroidei: de- velopment and relationships. In, Moser, H. G., et al. eds., Ontogeny and Systematics of Fishes, American Society of Ichthyologists and Herpetologists, Special Publication, no. 1, p. 591-620, Lawrence. Collette, B. B. and Russo, J. L. ,1984 (published 1985): Morphology, systematics, and biology of the Spanish mackerels (Scomberomorus, Scombridae). Fishery Bulletin, vol. 82, no. 4, p.545-692. Finnerty, J. R. and Block, B. A., 1995: Evolution of cytochrome bin Scombroidei (Teleostei): molecular insight into billfish (Istiophoridae and Xiphiidae) relationships. Fishery Bulletin, vol. 93, no. 1, p.78-96. Gill, T. N.,1862: On the limits and arrangements of the family of scombroids. Proceedings of the Academy of Natural Sciences of Philadelphia, vol. 14, p. 17-132. Graham, J. B. and Dickson, K. A., in press: The evolution of thunniform locomotion and heat conservation in scombrid fishes: New insights based on the morphology of Allothunnus fallai. Zoological Journal of the Linnean Society. Johnson, G. D., 1986: Scombroid phylogeny: an alternative hypothesis. Bulletin of Marine Science. vol. 39, no. 1, p.1-41. Johnson, G. D. and Patterson, C., 1993: Percomorph phy- logeny: a survey of acanthomorphs and a new proposal. In, Johnson, G. D. and Anderson, W. D. Jr. eds., Pro- ceedings of the Symposium on Phylogeny of Percomor- pha. Bulletin of Marine Science, vol. 52, no. 1, p. 554- 626. 80 Potthoff, T., 1975: Development and structure of the caudal complex, the vertebral column and the pterygiophores in the blackfin tuna (Thunnus atlanticus, Pisces, Scom- bridae).Bulletin of Marine Science, vol. 25, p. 205-231. Rafinesque-Schmaltz, C. S., 1815: Analyse de la Nature, ou Tableau de l'Univers et des Corps Organisés, 8+224 p., Kenneth A. Monsch Palermo. Uyeno T. and Fujii, S., 1975: A fish fossil of the family Scombridae from a Miocene bed in Toyoma Prefecture, Japan. 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(in Japanese with English abstract) mn fT EFF FF OF 149HlPI4(4, 200077 6 A24H (+) 25H (HB) KC [EBERVTEHRERMEI THERE TS. fA ABO LIAS HU EIt20007% 5 A 2H CK) CH. 6 H24H (4) VY REYIOALELT [15008 FRBORBOM-tOBVUKSLEMKS— EN RAINS - SAthal - MIBM—| SEES NES. AB, COYVYRVVIALBMARAVOLMBBbhPATTKHOET. &HU : Paleontological Research vol.3, no. 40{T# PE Cs, H149HPAOMKHA* [6 A23H (+) 25248 (H)] &l, M@ABBMOHRLUASHUA* [5 A 4H] ELTHXDELKD, BEAL ALY FEAR, EKHUAMACLKEOG, beOKDIATIERMLED. PLUMS OD EHATUr. OF150HIPMISit, 20017 1 A278 (+) £288 (A) lc (RRB AR) THESNEF. YY RY 7 ABO LAA) A (420007 4 AAA, AGE OO LIAS HU) H I420007F12A 1 H (4) TE. ©2001H4ES - BSS, 21H RIOFACITOT, [21H OH ÆME] ZH —-F-TeElL, Kt CYYRIYIAAMDELAEBAC, HRATHREBSH DOL > THEZLETFTZIEDRELTE DES, HEOSNIPERLOVTEANTRZAHRLEF. OF151EFI2 (2002 1 A FARE PE) ODER LASS, FDOETCAZHNERA. ©2002 FE F& - 8S (20024 6 A FHBAHE TE) LEEFRTENMEN DEA LuAdh D & LH. OHEMBE TIS, PARMCHHANSZI-FVYayvySPRPVYVa-—bIA-AEERLCTHVEF. FEDS SRASTEHENTNITZEDTLEFDOT, SHE BHEOAITHRE BEIN SR FAY, HABE. VV RIOD LRORLAASE fl BmBOR LAA SRRMBt BREAD FSW. emailP7 7 »7ATOMLIASI, HAE L TZUNITEUERA. 7240-0067 BAhktr AK BRATI-2 MEBILAFAA ARIE Ea BAB TEL 045-339-3349 (E18) FAX 045-339-3264 (FREE) E-mail majima@edhs.ynu.ac.jp FEW RE— (Th) HALBER, THRD PacOTSRBE CHA FEU. T 250-0031 / HE TH AA H499 #Z IATA TD EB + SHER ORE TEL 0465-21-1515 FAX 0465-23-8846 E-mail taru@pat-net.ne.jp B al (TERE) PLO LL LL LL LL LLL LOL LL LOLOL LL LL OL OL LL OL LL LL 000.00.0.0.000000.0.00000.0.0,000.00.0.,0.0.,0.00.,0,0,0.,0,0,0 0 OOO? ABORTICRTZBA, 2GEOSBVAL, HERFHTERH EN SOVUICRHASED SOS BATSNCWET, HEOBDAA IS TIONEN CT. es AVERY T ARASH | ARIA OR + HOEK | AL TL ERAS tt se AG Fr we tt RERVA¢ BAO MRE RIM; SE TE OXRAR FTA AMIE (ARR SEA) IK So Fa ae Ee Ae Ee eS 113-8622 HniX x AEA5-16-9 am Ee yy NA DRE NE th Ob AE RES ROM fi À À æm — hk * mM MK E ni LE OO M — et + EHE mM Fl ml À SWARÉSNRIMRR£H EH à 2,500] T176-0012 RRM EK SEIE201301 mea 0 3 — 319 9 1 = 3 7 5 4 2000 “44 A 21 H A fall 2000 Æ 4 A 28H FE fr ISSN 1342-8144 Paleontological Research BAB, #15 Ry Paleont ae ological Research . rs EN 4 April 28, 2000 © CONTENTS Hiroshi Kitazato, Masashi Tsuchiya and Kenji Takahara: Recognition of breeding populations in foraminifera: an example using the genus Glabratella *:::::::::::::............2. 1 Ritsuo Nomura and Yokichi Takayanagi: Foraminal structures of some Japanese species of the genera Ammonia and Pararotalia, family Rotaliidae (Foraminifera) :::::::-::-::::-:::.....2. 17 Tatsuro Matsumoto and Toshio Kijima: The turrilitid ammonoid Mariella from Hokkaido-Part 3 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXVII) +++: 33 Mike Pole: Dicotyledonous leaf macrofossils from the latest Albian-earliest Cenomanian of the Eromanga Basin, Queesland, Australia ::::-::-::::::............................... en 39 Shuji Niko and Tamio Nishida: A new pseudorthoceratid cephalopod from the Kazanian (middle Late Permian) of Japan --:----::::::.........................................00e 53 Wei-Ping Yang and Jun-ich Tazawa: Early Carboniferous miospores from the southern Kitakami Mountains, northeast Japan *+***++-+++Hreeeeeeseeessssnnnnnneeeeeessssennnnenennnesnnnnnnne 57 Yasunori Kano and Tomoki Kase: Pisulinella miocenica, a new genus and species of Miocene Neritiliidae (Gastropoda: Neritopsina) from Eniwetok Atoll, Marshall Islands ::::°::::::::::::::::: 69 Kenneth A. Monsch: A new fossil bonito (Sardini, Teleostei) from the Eocene of England and the Caucasus, and evolution of tail region characters of its Recent relatives ::::::::::::-:: seo 78 leontological Research ISSN 1342-8144 Formerly Transactions and Proceedings of the Palaeontological Society of Japan _ Vol. 4 No.2 June 2000 The Palaeontological Society of Japan Co-Editors Kazushige Tanabe and Tomoki Kase Language Editor Martin Janal (New York, USA) Associate Editors Jan Bergstrôm (Swedish Museum of Natural History, Stockholm, Sweden), Alan G. Beu (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Satoshi Chiba (Tohoku University, Sendai, Japan), Yoichi Ezaki (Osaka City University, Osaka, Japan), James C. Ingle, Jr. (Stanford University, Stanford, USA), Kunio Kaiho (Tohoku University, Sendai, Japan), Susan M. Kidwell (University of Chicago, Chicago, USA), Hiroshi Kitazato (Shizuoka University, Shizuoka, Japan), Naoki Kohno (National Science Museum, Tokyo, Japan), Neil H. Landman (Amemican Museum of Natural History, New York, USA), Haruyoshi Maeda (Kyoto University, Kyoto, Japan), Atsushi Matsuoka (Niigata University, Niigata, Japan), Rihito Morita (Natural History Museum and Institute, Chiba, Japan), Harufumi Nishida (Chuo University, Tokyo, Japan), Kenshiro Ogasawara (University of Tsukuba, Tsukuba, Japan), Tatsuo Oji (University of Tokyo, Tokyo, Japan), Andrew B. Smith (Natural History Museum, London, Great Britain), Roger D. K. Thomas (Franklin and Marshall College, Lancaster, USA), Katsumi Ueno (Fukuoka University, Fukuoka, Japan), Wang Hongzhen (China University of Geosciences, Beijing, China), Yang Seong Young (Kyungpook National University, Taegu, Korea) Officers for 1999-2000 President: Kei Mori Councillors: Kiyotaka Chinzei, Takashi Hamada, Yoshikazu Hasegawa, Itaru Hayami, Hiromichi Hirano, Noriyuki Ikeya, Junji Itoigawa, Tomoki Kase, Hiroshi Kitazato, Itaru Koizumi, Haruyoshi Maeda, Ryuichi Majima, Makoto Manabe, Hiroshi Noda, Ikuwo Obata, Kenshiro Ogasawara, Terufumi Ohno, Tatsuo Oji, Tomowo Ozawa, Yukimitsu Tomida, Tsunemasa Saito, Takeshi Setoguchi, Kazushige Tanabe, Akira Yao Members of Standing Committee: Hiroshi Kitazato (General Affairs), Tatsuo Oji (Laison Officer), Makoto Manabe (Finance), Kazushige Tanabe (Editor in Chief, PR), Tomoki Kase (Co-Editor, PR), Ryuichi Majima (Planning), Hiromichi Hirano (Membership), Kenshiro Ogasawara (Foreign Affairs), Haruyoshi Maeda (Publicity Officer), Noriyuki Ikeya (Editor, "Fossils"), Yukimitsu Tomida (Editor in Chief, Special Papers), Tamiko Ohana (Representative, Union of Natural History Societies). Secretaries: Masanori Shimamoto, Takao Ubukata (General Affairs), Hajime Taru (Planning), Tokuji Mitsugi (Membership), Shuko Adachi (Foreign Affairs), Kazuyoshi Endo, Yasunari Shigeta, Takenori Sasaki (Editors of PR), Akira Tsukagoshi (Editor of "Fossiles"), Naoki Kohno (Editor of Special Papers), Hidenori Tanaka (Publicity officer) Auditor: Nobuhiro Kotake Notice about photocopying: In order to photocopy any work from this publication, you or your organization must obtain permission from the following organization which has been delegated for copyright for clearance by the copyright owner of this publication. Except in the USA, Japan Academic Association for Copyright Clearance (JAACC), 41-6 Akasaka 9- chome, Minato-ku, Tokyo 107-0052, Japan. Phone: 81-3-3475-5618, Fax: 81-3-3475-5619, E-mail: kammori@msh.biglobe.ac.jp In the USA, Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. Phone: (978)750-8400, Fax: (978)750-4744, www.copyright.com Cover: Idealized sketch of Nipponites mirabilis Yabe, a Late Cretaceous (Turonian) nostoceratid ammonite. Various reconstructions of the mode of life of this species have been proposed, because of its curiously meandering shell form (after T. Okamoto, 1988). All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN c/o Business Center for Academic Societies, Honkomagome 5-16-9, Bunkyo-ku, Tokyo 113-8622, Japan Visit our society website at http://ammo.kueps.kyoto-u.ac.jp./palaeont/index.html Paleontological Research, vol. 4, no. 2, pp. 83-88, June 30, 2000 © by the Palaeontological Society of Japan Orthoconic cephalopods from the Lower Permian Atahoc Formation in East Timor SHUJI NIKO’, TAMIO NISHIDA’ and KEIJI NAKAZAWA’ ‘Department of Environmental Studies, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashihiroshima 739-8521, Japan (niko @hiroshima-u.ac.jp) “Department of Earth Science, Faculty of Education, Saga University, Saga 840-0027, Japan (nishidat @cc.saga-u.ac.jp) °28-2, Koyama Shimouchikawara-cho, Kitaku, Kyoto 603-8132, Japan Received 10 August 1999; Revised manuscript accepted 20 January 2000 Abstract. Three species of orthoconic cephalopods, Mooreoceras sp. and Atahococeras timorense gen. and sp. nov. of the Pseudorthoceratidae, and an indeterminate genus and species of the Bactritidae are described from the Lower Permian Atahoc Formation in the Cribas area, East Timor. Apparent changes in the surface ornamentation of Atahococeras are considered to be genus-level criteria that separate it from the most closely related genus, Bitaunioceras. This assemblage signi- fies a non-ammonoid cephalopod fauna in the northern margin of Gondwana near the Sakmari- an/Artinskian boundary. Key words: Atahococeras gen. nov., Bactritida, East Timor, Gondwana, Orthocerida, Sakma- rian/Artinskian boundary Introduction Timor is the largest (maximum ca. 365 km long and 100 km wide) island in the Banda Arc of the Indonesian Archipelago, where corresponds to a collision zone between the Indo-Australian and Asian Plates. Thus, the geology of this island is structurally complex. Carter et al. (1976) stated that the older rocks on Timor consist of the autochthonous Australian facies and overthrusting units de- rived from the Asian island arc. The purpose of this study is to document and describe an Early Permian orthocerid and bactritid cephalopod fauna of the Atahoc Formation, which is part of the autochthonous facies. The materials were collected by one of us (K. N.) from the right bank of the River Sumasse, west of Cribas under cooperation with H. Suzuki and T. Takahashi during field work of 1961 in East Timor (Figure 1). Other than "Orthocéres" that were re- ported by Gageonnet and Lemoine (1958), this is the first description of non-ammonoid cephalopods from the Atahoc Formation. The Lower Permian Atahoc Formation is made up of the oldest exposed sediments in East Timor, and forms the Cribas Anticline together with the Upper? Permian Cribas, the Triassic Aitutu and the Triassic to Jurassic Wai Luli Formations in the Cribas area (Audley-Charles, 1968; Figure 1). It consists of more than 600 m of sandstone and shale with thin intercalated beds of limestone and basaltic lava. The stratigraphic position of the present cephalopod-bearing reddish shale is considered to correspond to the ammonoid horizon of Audley-Charles (1968, p. 6, fig. 2, columnar sec- tion of the Cribas Anticline), about 150 m below the top of the Atahoc Formation. Since Grunau (1953, 1956) first as- signed this formation to the Sakmarian (Lower Permian) based on ammonoids, a number of subsequent workers have given support to this determination (e.g., Schouppé, 1957; Shimizu, 1966; Audley-Charles, 1968). More recent and detailed paleontological research by Nishida et al. (1997) revealed co-occurrence of ammonoids with the pre- sent orthocerids and bactritid, namely Somoholites beluenis (Haniel), Agathiceras cf. sundaicum Haniel, Metapronorites timorensis (Haniel) and Atsabites weberi Haniel. They con- cluded that the fossil horizon corresponds stratigraphically to the boundary between the Somohole and Bitauni Formations in West Timor, the age of which horizon is cor- relative with near the Sterlitamakian (latest Sakmarian)/ Aktastinskian (earliest Artinskian) boundary. Blendinger et al. (1992) stated, on the basis of ammonoids, that a conspecific middle Permian fauna flour- ished from Timor to the western Mediterranean along the northern margin of Gondwana. We shall not comment on the paleobiogeographic implications of the present result, because knowledge concerning Permian nautiloids and bactritoids in this province is still sparse. Besides a record of a Wordian (early Late Permian) fauna from Oman (Niko et al., 1996), the present paper represents the only other docu- mentation of non-ammonoid cephalopods with modern 84 Shuji Niko et al. Manatuto SA D | ——— 2! = „eo = aS DS — —s A Betano STUDY Aitutu Fm. Cribas Fm. Atahoc Fm. x 3 Figure 1. Map showing fossil locality (arrow), and geology of the Cribas area, East Timor (modified from Audley-Charles, 1968). taxonomic treatment in the northern margin of Gondwana, and therefore provides the base data for paleobiogeography of nautiloids and bactritoids. The specimens studied are deposited in the pale- ontological collections of the Department of Geology and Mineralogy, Faculty of Science, Kyoto University (KU). Systematic paleontology Subclass Nautiloidea Agassiz, 1847 Order Orthocerida Kuhn, 1940 Superfamily Pseudorthocerataceae Flower and Caster, 1935 Family Pseudorthoceratidae Flower and Caster, 1935 Subfamily Pseudorthoceratinae Flower and Caster, 1935 Genus Mooreoceras Miller, Dunbar and Condra, 1933 Type species.—Mooreoceras normale Miller, Dunbar and Condra, 1933. Mooreoceras sp. Figures 2.1-2.4; 3.9 Description.—Relatively large-sized orthocones with grad- ual shell expansion, and dorsoventrally depressed, oval cross section; apical end of a fragmentary specimen (KUTMP 20004; Figure 2.2-2.4) is 21.4 mm in dorsoventral diameter and 27.0 mm in lateral diameter, giving a form ratio of 1.26; shell surface lacks annulation, but details are not preserved. Sutures transverse, nearly straight in observ- able parts; camerae short, maximum _ dorsoventral diameter/length ratio approximately 3.4; septal curvature shallow. Siphuncle subcentral, shifted dorsally from center, consists of cyrtochoanitic septal necks, 0.70-0.99 mm in length, and inflated connecting rings that are subcylindrical to fusiform in shape; adnation area narrow. Cameral de- posits thin, episeptal-mural apically and mural adorally; endosiphuncular deposits weakly developed, form annuli that are unfused and restricted near septal foramina. Discussion.— Although the surface ornamentation of the examined specimens is not observable, their oval shell cross sections, short camerae, inflated connecting rings with the narrow adnation area and unfused annuli of the endosiphuncular deposits are the characteristics of Mooreoceras. This discovery is of particular interest as one of the rela- tively rare records of Permian Mooreoceras, which also oc- curs in Early Permian faunas of the Blaine and Dog Creek Formations in Texas (Mooreoceras "normale" and M. gigantea Clifton, 1942), the Callytharra Limestone in West Australia (Mooreoceras sp., Teichert, 1951; Teichert and Glenister, 1952), and the Barfield Formation in East Australia (Mooreoceras australis Waterhouse, 1987). Material. — KUTMP 20003, 40.2 mm in length, and KUTMP 20004, 47.2 mm in length; both are incomplete phragmocones. Subfamily Spyroceratinae Shimizu and Obata, 1935 Genus Atahococeras gen. nov. Type species.—Atahococeras timorense sp. nov. Diagnosis.—Like Bitaunioceras but differs by apparent Permian cephalopods from Timor 85 Figure 2. Mooreoceras sp. 1. KUTMP 20003, longitudinal polished section, showing details of siphuncle, X 7. 20004; 2. ventral view, X1.5; 3. Lateral view, venter on left, X 1.5; 4. Septal view of apical end, venter down, X 1.5. changes in surface ornamentation; i.e., only transverse lirae on juvenile shell, then strongly oblique ridges are added, and reticulated ridges with ribs on the most adoral shell; constric- tion absent. Etymology.—The generic name is derived from the Atahoc Formation, in which the type specimens were found. Atahococeras timorense sp. nov. Figure 3.1-3.8 Diagnosis.—As for the genus. Description.—Orthoconic shells with circular cross sec- tion, gradual shell expansion; angle of shell expansion ranges from 4.8° to 5.5°; largest specimen (holotype; Figure 3.2-3.4, 3.7, 3.8) of phragmocone reaches 17.5 mm in diameter. Surface ornamentation apparently changes with shell growth: 1) only transverse lirae of somewhat une- qual size in juvenile shell (up to 3.9 mm in shell diameter), 2) apically strongly oblique and adorally longitudinal ridges that are absent for approximately 5 mm in shell length, but immediately are succeeded by similar ridges, in addition transverse and relatively strong lirae, 3) longitudinal ridges, broad transverse ridges, in addition very weak lirae are also present in interspaces of transverse ridges (beyond 4.5 mm in shell diameter), then 4) longitudinal ridges, and transverse ornamentation consists of ridges and broad, annulation-like but subdued ribs; these ridges form a reticulate pattern (at least up to 11.5 mm in shell diameter); strong sinuation in transverse ornamentation not recognized; transverse con- strictions caused by shell thickening and surface constriction are absent. Sutures straight, directly transverse in apical shell; adoral sutures not observed, but weak obliquity of ap- proximately 5° to rectangular direction of shell axis recog- nized in longitudinal section; strongly concave septa form 2-4. KUTMP long camera, with maximum width/length ratio approximately 1.4 in most adoral camerae; mural part of septum relatively wide. Siphuncle central in position, narrow; septal necks suborthochoanitic, short, 0.9 mm in length in well-preserved septal necks of holotype; connecting ring not preserved; ratio of outside diameter of septal neck/corresponding shell diameter approximately 0.08. Cameral and endosiphun- cular deposits not detected. Discussion.—The surface ornamentation of the juvenile shell, the septal neck structure and the cameral form of Atahococeras gen. nov. are in common with Bitaunioceras (Shimizu and Obata, 1936), which is based on Orthoceras bitauniense Haniel (1915, pl. 56, figs. 5a-c) from the Bitauni Formation in West Timor. The diagnostic features of Atahococeras appear in the adoral shell, where the changes in surface ornamentation and the absence of the constric- tions separate the new genus from Bitaunioceras. Except for its possessing periodic surface constrictions and salients, Bitaunioceras elegantulum (Gemmellaro, 1890, pl. 11, figs. 12-17; Niko and Nishida, 1987) from the Lower Permian of Sicily is more similar to Atahococeras timorense sp. nov. in having the longitudinal ornamentation than the other Bitaunioceras species. Ontogenetic changes in the surface ornamentation of this Sicilian species are unknown. Haniel (1915, pl. 56, figs. 3a-c, 4) described "Orthoceras" welteri, which has the reticulate ornamentation, from the Bitauni Formation. Owing to the lack of detailed information about its internal structure and juvenile shell morphology, the generic assignment of this species is uncertain in mod- ern Classification. However, sinuation of its transverse sur- face ornamentation distinguishes "O." welteri from A. timorense sp. nov. at the species level. Reticulate ornamentation is recognized in some genera belonging to Pseudorthoceratidae, Orthoceratidae and Shuji Niko et al. 86 Permian cephalopods from Timor Geisonoceratidae. Among them, a Carboniferous pseudor- thoceratid Sueroceras (Riccardi and Sabattini, 1975; type species, S. irregulare Riccardi and Sabattini, 1975, pl. 22, figs. 1-12, from Argentina), which has a relatively similar pattern to Atahococeras. However, its internal structure, such as partly cyrtochoanitic septal necks, shorter camerae, and thick lining deposits in the siphuncle, suggests that Sueroceras has a close phylogenetic relationship with Dolorthoceras (Miller, 1931) rather than with Bitaunioceras and Atahococeras. Etymology.—The specific name refers to the island of Timor. Material.—The holotype, KUTMP 20001, is an incomplete phragmocone 68.9 mm in length. In addition, a single paratype 26.2 mm in length, KUTMP 20002, that represents a more apical phragmocone than the holotype. Subclass Bactritoidea Shimanskiy, 1951 Order Bactritida Shimanskiy, 1951 Family Bactritidae Hyatt, 1884 Genus and species indeterminate Figure 3.10 Discussion.— This species is represented by a single specimen of a longitudinal thin section. Its diagnostic fea- tures are as follows: initial camera (protoconch) subcircular in section, 0.51 mm in diameter, 0.48 mm in length, in con- junction with probably cylindrical second to third develop- mental stages of phragmocone; adoral diameter of second camera smaller than that of initial camera, 0.37 mm; first three septa recognized, but they and their septal necks are not well preserved. The general shape and size of the initial camera of the present species are characteristic to the family Bactritidae as shown by Clarke (1894), Erben (1964) and Mapes (1979). Haniel (1915) reported two orthoconic forms, "Orthoceras" sp. indet. Nr. 2 (fig. 38) and "O." sp. indet. Nr. 3, which have marginal siphuncular positions, from the Bitauni Formation. Although they may be assignable to the family Bactritidae in modern terms, the materials are too incom- plete to discuss relationships with this species. Material. KUTMP 20005, 1.0 mm in length, is an apical phragmocone with a complete initial camera. Acknowledgments The third author is indebted to Hiroyuki Suzuki and Toru Takahashi, former students of Kyoto University, for their as- sistance in the field. References Agassiz, L., 1846 - 1847: Nomenclatoris Zoologici Index Universalis, 393 p. Jent and Gassmann, Soloduri. Audley-Charles, M. G., 1968: The geology of Portuguese Timor. Memoirs of the Geological Society of London, no. 4, p. 1-76, pls. 1-13. Blendinger, W., Furnish, W. M. and Glenister, B. F., 1992: Permian cephalopod limestones, Oman Mountains: evi- dence for a Permian seaway along the northern margin of Gondwana. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 93, p. 13-20. Carter, D. J., Audley-Charles, M. G. and Barber, A. J., 1976: Stratigraphical analysis of island arc-continental margin collision in eastern Indonesia. Journal of the Geological Society of London, vol. 132, p. 179-198. Clarke, J. M., 1894: The early stages of Bactrites. American Geologist, vol. 14, p. 37-43, pl. 2. Clifton, R. L., 1942: Invertebrate faunas from the Blaine and the Dog Creek Formations of the Permian Leonard Series. Journal of Paleontology, vol.16, p. 685-699, pls. 101-104. Erben, H. K., 1964: Bactritoidea. /n, Moore, R. C. et al., eds., Treatise on Invertebrate Paleontology, Part K, Mollusca 3, p. K491-K505. Geological Society of America and University of Kansas Press, Lawrence, Kansas. Flower, R. H. and Caster, K. E., 1935: The stratigraphy and paleontology of northeastern Pennsylvania. Part Il: Paleontology. Section A: The cephalopod fauna of the Conewango Series of the Upper Devonian in New York and Pennsylvania. Bulletins of American Paleontology, vol. 22, p. 199-271. Gageonnet, R. and Lemoine, M., 1958: Contribution a la connaissance de la géologie de la province Portugaise de Timor. Estudos, Ensaios e Documentos, Junta de Inve stigaçôes Cientificas do Ultramar, vol. 48, p. 1-138. Gemmellaro, G. G., 1890: La fauna dei calcari con Fusulina della valle del fiume Sosio (nella provincia di Palermo). Giornale di Scienze Naturali ed Economiche, vol. 20, p. 37-138, pls. 11-19. Grunau, H. R., 1953: Geologie von Portugiesisch Osttimor. Eine kurze Ubersicht. Eclogae Geologicae Helvetiae, vol. 46, p. 29-37. Grunau, H. R:, 1956: Zur Geologie von Portugiesisch-Ost- Timor. Mitteilungen der Naturforschenden Gesellschaft Bern, Neue Folge, vol. 13, p. 11-18. Haniel, C. A., 1915: Die Cephalopoden der Dyas von Timor. Paläontologie von Timor, Lieferung 3, p.1-153, pls. 46- 56. Hyatt, A, 1883 - 1884: Genera of fossil cephalopods. Proceedings of the Boston Society of Natural History, vol. 22, p. 253-338. Kuhn, O., 1940: Paläozoologie in Tabellen, 50 p. Fischer, — Figure 3. 1-8. Atahococeras timorense gen. and sp. nov. 1, 5, 6. Paratype, KUTMP 20002; 1. Side view, silicone rubber cast, *3; 5. Details of apical surface ornamentation, silicone rubber cast, “10; 6. Details of adoral surface ornamentation, silicone rubber cast, “10. 2-4, 7, 8. Holotype, KUTMP 20001; 2. Longitudinal thin section, X2; 3. Transverse polished section at apical end, <2; 4. Details of surface ornamentation, silicone rubber cast, note reticulated ridges and subdued ribs, X 10; 7. Longitudinal thin section, showing details of siphuncle, X7; 8. Longitudinal polished section, showing details of septal neck, X 10; 9. Mooreoceras sp., KUTMP 20003, longitudinal polished section, X 2; x40. 10. Bactritidae, genus and species indeterminate, KUTMP 20005, longitudinal thin section, 87 88 Shuji Niko et al. Jena. Mapes, R. H., 1979: Carboniferous and Permian Bactritoidea (Cephalopoda) in North America. The University of Kansas Paleontological Contributions, Article 64, p. 1-75, pls. 1-41. Miller, A. K., 1931: Two new genera of Late Paleozoic cephalopods from Central Asia. American Journal of Science, Fifth Series, vol. 22, p. 417-425. Miller, A. K., Dunbar, C. O. and Condra, G. E., 1933: The nautiloid cephalopods of the Pennsylvanian System in the Mid-Continent region. Nebraska Geological Survey, Bulletin 9, Second Series, p. 1-240, pls. 1-24. Niko, S. and Nishida, T., 1987: Early Permian cephalopods from the Mizuyagadani Formation, Fukuji district, Central Japan. Transactions and Proceedings of the Palaeon- tological Society of Japan, New Series, no. 146, p. 35-41. Niko, S., Pillevuit, A. and Nishida, T., 1996: Early Late Permian (Wordian) non-ammonoid cephalopods from the Hamrat Duru Group, central Oman Mountains. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 183, p. 522-527. Nishida, T., Nakazawa, K. and Kato, M., 1997: Early Permian ammonoids of East Timor. Abstracts of the 1997 Annual Meeting of the Palaeontological Society of Japan, p. 73. (in Japanese) Riccardi, A. C. and Sabattini, N., 1975: Cephalopoda from the Carboniferous of Argentina. Palaeontology, vol. 18, p. 117-136. Schouppé, A. von., 1957: Beiträge zur Paläontologie des Ostindischen Archipels. XXII Zwei Pterocorallia aus dem Perm von Portugiesisch Timor. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, vol. 104, p. 359-381, pl. 23. Shimanskiy, V. N., 1951: K voprosu ob evolyutsii verkhnepaleozoiskikh pryamkh golovonogikh (On the evolution of the Upper Paleozoic straight cephalopods). Doklady Akademii Nauk SSSR, vol. 79, p. 867-870, pl. 1. (in Russian) Shimizu, D., 1966: Permian brachiopod fossils of Timor (Palaeontological study of Portuguese Timor, 3). Memoirs of the College of Science, University of Kyoto, Series B, Geology and Mineralogy, vol. 32, p. 401-427. Shimizu, S. and Obata, T., 1935: New genera of Gotlandian and Ordovician nautiloids. The Journal of the Shanghai Science Institute, Section 2, Geology, Palaeontology, Mineralogy and Petrology, vol. 2, p. 1-10. Shimizu, S. and Obata, T., 1936: Remarks on Hayasaka’s Protocycloceras cfr. cyclophorum and the Permian and Carboniferous orthoconic nautiloids of Asia. The Journal of the Geological Society of Japan, vol. 43, p. 11-29. (in Japanese with English abstract) Teichert, C., 1951: The marine Permian faunas of Western Australia. Paläontologische Zeitschrift, vol. 24, p. 76-90. Teichert, C. and Glenister, B. F., 1952: Fossil nautiloid faunas from Australia. Journal of Paleontology, vol. 26, p. 730- 752, pls. 104-108. Waterhouse, J. B., 1987: Late Palaeozoic Mollusca and correlations from the south-east Bowen Basin, East Australia. Palaeontographica, Abteilung A, vol. 198, p. 129-233, pls. 1-14. Paleontological Research, vol. 4, no. 2, pp. 89-94, June 30, 2000 © by the Palaeontological Society of Japan A new species of Ancistrolepis (Gastropoda: Buccinidae) from the Iwaki Formation (lower Oligocene) of the Joban coal field, northern Japan YUTAKA HONDA Department of Earth Sciences, Faculty of Education, Mie University, Tsu 514-8507, Japan (eoshonda @ edu.mie-u.ac.jp) Received 26 December 1998; Revised manuscript accepted 21 January 2000 Abstract. Ancistrolepis (Ancistrolepis) iwakiensis sp. nov. from the lower Oligocene of the Joban coal field, northern Japan closely resembles both Ancistrolepis (A.) matchgarensis (Makiyama) from the upper Eocene to Oligocene of Sakhalin and Ancistrolepis (A.) rategiensis Titova from the upper Eocene of northwestern Kamchatka. A. (s.s.) iwakiensis sp. nov. documents an early evolutional history of Ancistrolepis (s.s.) that appeared in the northwestern Pacific during late Eocene time. Key words: Ancistrolepis, early Oligocene, Gastropoda, northwestern Pacific Introduction The Ancistrolepidinae is one of the most common groups of the gastropod family Buccinidae: it occurs in shallow to deep waters in the boreal and arctic regions. Unlike some other buccinids, the fossil and living species of Ancistrolepidinae have a restricted distribution, being found only in the northern Pacific. The systematics of the subfam- ily is still not clearly understood (Amano et al., 1996). According to Egorov and Barsukov (1994), who studied the living species of Ancistrolepidinae, the subfamily con- tains six genera: Ancistrolepis (with three subgenera: Ancistrolepis (s.s.), Bathyancistrolepis, and Clinopegma), Pseudoliomesus, Neancistrolepis, Sulcosinus, Japelion, and Parancistrolepis. The species of Ancistrolepis (s.s.) live at present in lower sublittoral to bathyal waters (100 to 690 m) around Honshu, Hokkaido, Sakhalin, and Kamchatka (Higo and Goto, 1993). In addition, Ancistrolepis (A.) vietnam- ensis Sirenko and Goryachev has been recorded at depths from 400 to 700 m in the South China Sea (Egorov and Barsukov, 1994). Titova (1993) discussed the evolution of the fossil Ancistrolepidinae in the northern Pacific, and adopted the systematics of Ancistrolepidinae as follows: Ancistrolepis (with Ancistrolepis (s.s.), Bathyancistrolepis, and Clino- pegma), Neancistrolepis, and Pseudoliomesus. She sug- gested that Ancistrolepis (s.s.) appeared in the northwestern Pacific (northern Japan to Kamchatka) during the late Eocene. However, the Paleogene Ancistrolepidinae are rather scarce in the northern Pacific. Matsui (1958) de- scribed the earliest representatives of Ancistrolepidinae in Japan from the Urahoro and Ombetsu Groups (upper Eocene to lower Oligocene) of the Kushiro coal field, eastern Hokkaido, placing the species in Neptunea. These species are here referred as Ancistrolepis (A.) huruhatai (Matsui), A. (A.) subcarinatus (Matsui), and A. (Bathyancistrolepis) sitakaraensis (Matsui). Honda (1989) also originally de- scribed Ancistrolepis (A.) ogasawarai as a Neptunea from the Charo Formation (lower Oligocene) of the Ombetsu Group. In addition, Ancistrolepis (A.) modestoideus (Takeda) has been recorded from the Poronai Formation (upper Eocene to lowermost lower Oligocene) of the Ishikari coal field, central Hokkaido, and the Urahoro and Ombetsu Groups (Takeda, 1953; Matsui, 1958; Honda, 1989). The southernmost area yielding Paleogene Ancistrolepis (s.s.) is located in the Joban coal field, northeastern Honshu, northern Japan (Figure 1). Only two poorly preserved specimens of Ancistrolepis (s.s.) have been recorded from the lower Oligocene of the Joban coal field. They are Ancistrolepis sp. cf. A. (A.) subcarinatus (as Neptunea ezoana Takeda; Kamada, 1962, p. 166, pl. 20, fig. 19) from the Iwaki Formation and Ancistrolepis (A.) sp. (as A. yamanei Kanehara, 1937, p. 13, pl. 4, fig. 8, in part) from the Asagai Formation (Titova, 1993). Yanagisawa et al. (1989) studied the subsurface litho- and biostratigraphy of the Cenozoic strata in the Futaba area of the Joban coal field (Figure 1). Their drill core A-1 yielded numerous well-preserved molluscan fossils at seven hori- zons of the Iwaki (IW-1-3) and Asagai (AS-1-4) Formations (Figure 2). The mollusks include Acila (Truncacila) oyamadensis Hirayama, Cyclocardia laxata (Yokoyama), Clinocardium asagaiense (Makiyama), Papyridea (Profulvia) harrimani Dall, Mya sp., and Turritella sp. (Yanagisawa et al., 1989). In this paper, | describe a new species of Yutaka Honda JOBAN ° COAL FIELD IWAKI <= JOBAN COAL FIELD a-mac Tomiok AS NS Ties =~ 14058 9051, km Figure 1. A. Map of the northwestern Pacific showing the location of the Joban coal field and place names referred to in the text. B. Map of the Joban coal field showing the location of drill core A-1 (parts of 1:25,000 scale maps, "Iwaki-Tomioka" and "Yonomori" published by the Geographical Survey of Japan). New Oligocene Ancistrolepis 91 A-1 DEPTH TERRACE DEPOSITS = Om SENDAI GROUP pe TAGA GROUP YUNAGAYA GROUP Bi; 200 SHIRASAKA FORMATION 400 SHI RAMI ZU GROUP AS-4 ASAGAI AS- 3 FORMATION ne AS-1 = mudstone (UPPER | iw-3 d PART) | 5 san y mudstone IWAKI IW- 2 ES very fine- to fine- IW-1 grained sandstone F. rei medium- to very 800 coarse-grained ss. congl omer ate [_ I] alternating beds x EJ coal (lignite) =] granitic rocks 1000 Figure 2. Columnar section of drill core A-1 (compiled from Yanagisawa et al., 1989; Kubo et al., 1994). Ancistrolepis (s.s.) obtained from the horizon IW-3 of the Iwaki Formation in drill core A-1. Geological setting Drill core A-1 of Yanagisawa et al. (1989) is lithologically divided into six units, which are, in ascending order, the basement granitic rocks (pre-Tertiary), the Shiramizu (lower Oligocene), Yunagaya (lower Miocene) and Taga (middle to upper Miocene) Groups, the upper part of the Sendai Group (upper Pliocene), and terrace deposits (Pleistocene) (Yanagisawa et al., 1989, Kubo et al., 1994; Figure 2). The Shiramizu Group is further divided into the Iwaki, Asagai, and Shirasaka Formations, in ascending order (Figure 2). The lower part of the Iwaki Formation consists largely of mudstone with intercalating arkose, fine- to me- dium-grained sandstone, coal seams, and coaly mudstone. The upper part of the formation is composed of silty, very fine- to fine-grained sandstone with intercalated fine- to me- dium-grained sandstone and coal seams (Yanagisawa et al., IW-1-3, AS-1-4; fossil horizons. 1989). The Asagai Formation is made up of massive, very fine- to fine-grained sandstone with small carbonaceous fragments. The Shirasaka Formation consists of grey sandy mudstone (Yanagisawa et al., 1989). Tomida (1986) dated the Iwaki Formation as early Oligocene by the occurrence of the mammalian fossil Entelodon. Using fossil diatoms and silicoflagellates, Yanagisawa et al. (1989) also dated the Shirasaka Formation as early Oligocene. Consequently, the Shiramizu Group as a whole should be attributed to the lower Oligocene (Yanagisawa et al., 1989). Description of new species Family Buccinidae Rafinesque, 1815 Subfamily Ancistrolepidinae Habe and Sato, 1972 Genus Ancistrolepis Dall, 1895 Subgenus Ancistrolepis s.s. Type species.—Chrysodomus eucosmius Dall, 1891 92 Yutaka Honda Ancistrolepis (Ancistrolepis) iwakiensis sp. nov. Figure 3 Neptunea sp., indet. Yanagisawa et al., 1989, pl. 12, fig. 6. Type locality.—At a depth of 675.00 to 675.20 m in drill core A-1 (GSJ B326), along a tributary of the Tomioka-gawa, Honcho-nishi, Tomioka-machi, Futaba-gun, Fukushima Prefecture, Japan (Lat. 37°20’16’”N, Long. 140°59’20’E; Figure 1B). Holotype. — GSJF15135 (Figure 3) in the Geological Museum, Geological Survey of Japan, Tsukuba, Japan. Etymology.—The name is derived from the formation name "Iwaki." Material.—One specimen (holotype GSJF15135). Diagnosis.—Shell moderate in size and fusiform. Spire high, with five whorls. Surface sculptured with three (four on penultimate whorls) subrounded spiral cords. Each interspace occupied by one fine cord. Description.— Shell moderate in size, rather thin, and fusiform. Whorls five in number, and divided by moderately incised suture. Whorl profile moderately convex with rounded shoulder. Surface sculptured with spiral cords, which intersect feeble growth lines. Three spiral cords on upper whorls, four on fourth (penultimate) whorl, equally spaced, subrounded, and narrower than interspaces. Each interspace on third to forth whorls occupied by one fine cord. Four spiral cords on upper part of body whorl, subrounded, and narrower than interspaces. More than six spiral cords on lower part, very low, subrounded, and much broader than interspaces. Each interspace on upper part of body whorl occupied by one fine cord. Measurements. — Holotype, GSJF15135, height 56.5 mm+, diameter 34.7 mm, pleural angle 36°. Horizon.—IW-3, upper part of the Iwaki Formation (Figure 2). Lower Oligocene. Associated fauna.—The new species is associated with Clinocardium asagaiense (Yanagisawa et al., 1989). Remarks.—One rather well-preserved, nearly complete specimen, with pale brown shell material, was obtained from the greenish-grey, fine-grained sandstone of the upper part of the Iwaki Formation. The specimen largely lacks the siphonal area, because the core diameter is limited to ap- proximately 60 mm. The features of the siphonal area are therefore not observable. The new species resembles Ancistrolepis (A.) matchgarensis (Makiyama, 1934) from the Matchigar Formation (upper Eocene to Oligocene; Barinov and Gladenkov, 1998) of northern Sakhalin and the Arakai Formation (Oligocene) of southern Sakhalin (Titova, 1993). Ancistrolepis matchgarensis has only three primary cords, however, the new species has both three or four primary cords and one secondary cord. Titova (1993, p. 12, figs. 2A-D) described Ancistrolepis (A.) rategiensis from the Rategian Formation (upper Eocene) of northwestern Kamchatka. The present new species differs from A. rategiensis in having more broadly rounded spiral cords. Ancistrolepis iwakiensis sp. nov. also differs from A. (A.) sp. (=Ancistrolepis yamanei Kanehara, 1937, p. 13, pl. 4, fig. 8, in part; see Titova, 1993) from the Asagai Formation in having a less convex whorl profile and a fine cord between the spiral cords. Discussion The genus Ancistrolepis (s.s.) is the earliest representa- tive of the Ancistrolepidinae, which probably originated from a common ancestor with the Neptunea altispirata group (Titova, 1993). N. altispirata was originally described by Nagao (1928) from the Doshi Formation (upper Eocene to lowermost lower Oligocene Funazuan stage; Honda, 1994) of Kyushu, southern Japan. N. altispirata has also been re- corded from the upper Eocene of western Kamchatka (Gladenkov et al., 1991). The N. altispirata group includes N. onbetsuensis Matsui from the Omagari and Charo Formations (uppermost upper Eocene to lower Oligocene) of the Kushiro coal field, eastern Hokkaido, and Neptunea vinjukovi Krishtofovich from the Oligocene of northern Sakhalin (Titova, 1993). The new species is similar to spe- cies of the N. altispirata group in having a rather moderately elevated spire. Honda (1991, 1994) noted that several cold-water genera such as Neptunea, Clinocardium, and Mya appeared from tropical or subtropical ones of Japan and Sakhalin from late middle Eocene to early Oligocene time. Titova (1993) also noted that Ancistrolepis (s.s.) appeared in the region of northern Japan to Kamchatka during late Eocene time. These four genera originated in the northwestern Pacific, probably concurrent with the Eocene-Oligocene transition to a global cooling trend. Titova (1993) divided Ancistrolepis (s.s.) into the Ancistrolepis eucosmius and A. grammatus stocks. The A. eucosmius stock is characterized by having a smaller shell, less numerous and weaker radial cords than the A. grammatus stock. Accordingly, the new species belongs to the A. grammatus stock based on general features of the shell. Titova (1993) further subdivided the A. eucosmius stock from the late Eocene to early Miocene into three groups. These are: 1) the Ancistrolepis huruhatai-A. subcarinatus group from the upper Eocene and lower Oligocene of Hokkaido and northern Honshu; 2) the Ancistrolepis rategiensis-A. matchgarensis group from the upper Eocene and Oligocene of northern Honshu, Hokkaido, Sakhalin, and Kamchatka; and 3) the group of Ancistrolepis clarki Tegland and A. rearensis (Clark) from the Oligocene and lower Miocene of Northwest America, which probably evolved from A. rategiensis. The A. huruhatai-A. subcarinatus group is characterized by well-developed sec- ondary spiral cords (Titova, 1993). The new species has only one secondary cord, so it belongs to the A. rategiensis- A. matchgarensis group of Titova (1993). Acknowledgments | express my deep gratitude to Kenshiro Ogasawara (University of Tsukuba) for helpful suggestions and critical reading of the manuscript. | also express my deep gratitude to Ludmila V. Titova (Moscow State University), for helpful suggestions on the generic assignment of the present new species and for critical reading of the manuscript. Thanks New Oligocene Ancistrolepis Figure 3. Ancistrolepis (Ancistrolepis) iwakiensis sp. nov., Horizon IW-3, Holotype, GSJF15135. a. Apertural-backside view, «1.5. b. Backside view, X 1.5. c. Close-up of the third to fourth (penul- timate) whorls, X 3.1. GSJ; Geological Museum, Geological Survey of Japan, Tsukuba, Japan. are expressed to Yukio Yanagisawa (Geological Survey of Japan), for providing the opportunity to study the specimen. Thanks are also expressed to Louie Marincovich, Jr. (California Academy of Sciences), for critical review of the manuscript, and to Paul Callomon (Elle Scientific Publications), for proofreading an early draft of the manu- script. References Amano, K., Ukita, M.and Sato, S., 1996: Taxonomy and dis- tribution of the subfamily Ancistrolepidinae (Gastropoda: 93 94 Yutaka Honda Buccinidae) from the Plio-Pleistocene of Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 182, p. 467-477. Barinov, K. B. and Gladenkov, Yu. B., 1998: Subdivision of Oligocene and lower Miocene sediments of northern Sakhalin evidenced by mollusks. Stratigraphy and Geological Correlation, vol. 6, no. 3, p. 280-292. (Translated from Stratigrafiya i Geologicheskaya Korrelyatsiya, vol. 6, no. 3, 1998, p. 74-86) Dall, W. H., 1891: Scientific results of exploration by the U. S. Fish Commission steamer Albatross.XX. On some new or interesting West American shells obtained from the dredging of the U. S. Fish Commission steamer Albatross in 1888, and from some other sources. Proceedings of the United States National Museum, vol. 14, no. 849, p. 173-191, pls. 5-7. Dall, W. H., 1895: Scientific results of exploration by the U. S. Fish Commission steamer "Albatross." XXXIV. Report on Mollusca and Brachiopoda dredged in deep water, chiefly near the Hawaiian Islands with illustrations of hith- erto unfigured species from northwest America. Proceedings of the United States National Museum, vol. 17, no. 1032, p. 675-733, pls. 23-32. Egorov, R. V. and Barsukov, S. L., 1994: Recent Ancistrolepidinae (Buccinidae). 48p., "Tropa", Moscow. Gladenkov, Y. B., Sinelinikova, V. N., Shantser, A. E., Chelebaeva, A. |., Oleinik, A. E., Titova, L. V., Bratseva, G. M., Fregatova, N. A., Zyryanov, E. V. and Kazakov, K. G., 1991: The Eocene of Western Kamchatka. Academy of Sciences of the USSR, Order of the Red Banner of Labour Geological Institute, Transactions, vol. 467, 184 p., 48 pls. Izdatelistvo "Nauka", Moscow. (in Russian with English abstract) Habe, T. and Sato, J., 1972: A classification of the family Buccinidae from the North Pacific. Proceedings of the Japanese Society of Systematic Zoology, vol. 8, p. 1-8, pls. 1-2. (in Japanese with English summary) Higo, S. and Goto, Y., 1993: A Systematic List of Molluscan Shells from the Japanese Is. and the Adjacent Area. 879 p. Elle Scientific Publications, Yao, Osaka. (in Japanese) Honda, Y., 1989: Paleogene molluscan faunas from the Kushiro coal field, eastern Hokkaido. The Science Reports of the Tohoku University, Sendai, Japan, Second Series (Geology), vol. 60, no. 1, p. 1-137, pls. 1-10. Honda, Y., 1991: Paleogene molluscan biogeography of Japan. /n, Dickins, J. M., McKenzie, K. G., Mori, K., et al. eds., Proceedings of the International Symposium on Shallow Tethys 3, Sendai, Japan/20-23 September 1990, Saito Ho-on Kai. Special Publication, Saito Ho-on Kai, no. 3, p. 489-506. Honda, Y., 1994: History of the Paleogene molluscan fauna of Japan. Palaeogeography, Palaeoclimatology, Palaeoe- cology, vol. 108, nos. 3-4, p. 295-309. Kamada, Y., 1962: Tertiary marine Mollusca from the Joban coal-field, Japan. Palaeontological Society of Japan, Special Papers, no. 8, p. 1-187, pls. 1-21. Kanehara, K., 1937: Miocene shells from the Jöban coal field. Bulletin of the Imperial Geological Survey of Japan, vol. 27, no. 1, p. 1-21, pls. 1-5. Kubo, K., Yanagisawa, Y., Yoshioka, T. and Takahashi, Y., 1994: Geology of the Namie and Iwaki-Tomioka district. With Geological Sheet Map at 1:50,000. 104 p. Geological Survey of Japan. (in Japanese with English abstract) Makiyama, J., 1934: The Asagaian molluscs of Yotukura and Matchgar. The Memoirs of the College of Science, Kyoto Imperial University, Ser. B, vol. 10, no. 2, p. 121-167, pls. 3-7. Matsui, M., 1958: Species of the genus Neptunea from the Palaeogene formations in the Kushiro coal field, Hokkaido, Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 30, p. 201-210, pls. 29-30. Nagao, T., 1928: Palaeogene fossils of the island of Kyüshü, Japan. Part 2. The Science Reports of the Tohoku Imperial University, Sendai, Japan, Second Series (Geology), vol. 12, no. 1, p. 11-140, pls. 1-17. Rafinesque, C. S., 1815: Analyse de la Nature, ou Tableau de l'Univers et des Corps organisés. 224 p. Palermo, Italy. Takeda, H., 1953: The Poronai Formation (Oligocene Tertiary) of Hokkaido and South Sakhalin and its fossil fauna. Studies on Coal Geology, no. 3, p. i-iv, 1-45 (in Japanese); p. i-ill, 1-103 (in English); pls. 1-13; Geological Section, The Hokkaido Association of Coal Mining Technologists, Sapporo, Japan. Titova, L. V., 1993: The early history of the North Pacific Ancistrolepidinae (Gastropoda: Buccinidae). Ruthenica, vol. 3, no. 1, p. 1-16. Tomida, Y., 1986: Recognition of the genus Entelodon (Artiodactyla, Mammalia) from the Joban Coalfield, Japan, and the age of the Iwaki Formation. Bulletin of the National Science Museum, Tokyo, Ser. C (Geology & Paleontology), vol. 12, no. 4, p. 165-170. Yanagisawa, Y., Nakamura, K., Suzuki, Y., Sawamura, K., Yoshida, F., Tanaka, Y., Honda, Y. and Tanahashi, M., 1989: Tertiary biostratigraphy and subsurface geology of the Futaba district, Joban coalfield, northeast Japan. Bulletin of the Geological Survey of Japan, vol. 40, no. 8, p. 405-467. (in Japanese with English abstract) Paleontological Research, vol. 4, no. 2, pp. 95-106, June 30, 2000 © by the Palaeontological Society of Japan Carbon-isotope stratigraphy and its chronostratigraphic significance for the Cretaceous Yezo Group, Kotanbetsu area, Hokkaido, Japan TAKASHI HASEGAWA’ and TAKAYUKI HATSUGAF ‘Division of Global Environmental Sciences and Engineering, Graduate School of Natural Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan; Department of Earth Sciences, Faculty of Science, Kanazawa University, Kakuma, Kanazawa 920-1192 Japan (jh7ujr@kenroku.kanazawa-u.ac.jp) *Geoplanning, Ichinazaka, Izumi-ku, Sendai 981-3117 Japan Received 14 July 1999; Revised manuscript accepted 21 January 2000 Abstract. A positive carbon isotopic excursion across the Cenomanian/Turonian boundary in the Kotanbetsu area, Hokkaido, Japan provides accurate positioning of the boundary. A microscopic study based on organic petrology reveals that the organic matter included in mudstones of the Kotanbetsu River section is exclusively terrestrial. The results of stratigraphic time-series analy- sis of stable carbon isotopes from these mudstone samples can be translated as representing an average of a terrestrial plant community signal. records information on the global ocean-atmosphere system. events characterize the uppermost Cenomanian through middle Turonian. The isotopic fluctuation through this time interval Two internationally recognized On the basis of this study the Cenomanian/Turonian boundary can be recognized within a stratigraphic range of ~14 meters. inoceramids and planktonic foraminifers). This horizon of the boundary is concordant with that from biostratigraphy (ammonoids, Above the middle Turonian strata, the isotopic pattern supports the biochronology of planktonic foraminifers rather than that of inoceramids. Key words: biostratigraphy, carbon isotope, Cenomanian/Turonian boundary, Coniacian, correla- tion, Cretaceous, Kotanbetsu, terrestrial organic matter, Yezo Group Introduction International chronostratigraphic correlation of the Cretaceous Yezo Group, especially the Cenomanian through Turonian has been extensively discussed in this decade mainly with reference to the Oyubari area and by the use of megafossils (e.g. Nishida et a/., 1993a; Hirano, 1995) and planktonic foraminifers (Motoyama et al. 1991; Hasegawa, 1995, 1997; Takashima et al., 1997). On the other hand, carbon-isotope stratigraphy through the Cretaceous was first shown by Sholle and Arthur (1980) to be a potential correlational tool in the Tethyian region. After this pioneering study, many carbon-isotopic studies using marine carbonate and marine organic matter across the Cenomanian/Turonian (C/T) boundary were performed for detailed correlation at the same resolution as biostratigraphy (e.g. Pratt, 1985; Gale et al., 1993). In Japan, Hasegawa (1995, 1997) analyzed the stable carbon-isotope composi- tion of terrestrial organic carbon from the Oyubari section and discussed its isotope stratigraphy against the control of the planktonic foraminiferal biostratigraphy. Hasegawa (1995) identified the well-known positive isotopic event caused by an Oceanic Anoxic Event (Schlanger and Jenkyns, 1976) at the C/T boundary and supported the idea that it was a global signal (e.g. Gale et al., 1993; Jenkyns et al., 1994). This was subsequently compared with the carbon-isotope curve derived from marine carbonate carbon established in southern England (Jenkyns et al., 1994) and Italy (Corfield, 1995; Jenkyns et al., 1994). This led to the identification of three isotopic events as global markers for correlation (Hasegawa, 1997). Even though carbon-isotope stratigraphy can be a powerful tool for international correla- tion (Hasegawa, 1997, Beerling and Jolley, 1998; Gröcke et al, 1999), it has not been employed for detailed stratigraphic positioning of the C/T boundary in other areas of Hokkaido Island except for a study in the Tappu area by Hasegawa and Saito (1993). Nishida et al. (1992, 1993b) performed detailed biostratigraphy of megafossils and foraminifers along the Kotanbetsu River in the Kotanbetsu area, Hokkaido focusing on the positioning of the C/T bound- ary. Hatsugai et al. (1999) also discussed detailed planktonic foraminiferal biostratigraphy using internationally 96 Takashi Hasegawa and Takayuki Hatsugai N | ae @ Kotanbetsu area (Fig. 2) _) HOKKAIDO | = aaa Sapporo q CA oe N NE | Figure 1. Index locality of the Kotanbetsu area. map showing the recognized species along the same section. The purpose of this study is to show how carbon-isotope stratigraphy is a powerful and important tool for correlation. The Kotanbetsu River section was selected as the best sec- tion to demonstrate the applicability of carbon-isotope stratigraphy not only for intra-regional but also for inter- regional correlation of the Yezo Group. Geological setting The Yezo Group exposed along the Kotanbetsu River in the Kotanbetsu area, Hokkaido, Japan (Figure 1) is inter- preted as a forearc basin (Okada, 1979, 1983). The se- quence of the Cenomanian through Turonian is represented, in ascending order, by six lithologic units, namely Mf-h, Mi, 119 425 116 118] 120a 124 117 ala) à Fig. 8 y Oku- 134 135 Futamata Tributary 123122 121 Figure 2. Mj-o, Ua-b, Uc-e and Uf-g which were originally defined by Igi et al. (1958). These lithologic units strike meridionally and dip westward at an angle of ~60°. They are nearly con- tinuously exposed and are composed dominantly of dark gray mudstone with either occasional intercalations of sand- stone layers of less than 30 cm in thickness or alternating layers of turbiditic sandstone and siltstone. Frequency of intercalating sandstone layers increases in the Units Mi and Ua-b. The averaged rate of sedimentation for this succession is inferred as approximately 200 m/m.y. based on planktonic foraminiferal biostratigraphy (Hatsugai et a/., 1999) using the first occurrence of Helvetoglobotruncana helvetica and the first occurrence of the genus Archaeoglobigerina and time scale of Gradstein et al. (1995). This is more than ten times as fast as the English Chalk section (Jenkyns et al., 1994). Based on four K-Ar ages from four different bentonite lay- ers encompassing the Unit Mi (Shibata and Miyata, 1978; Shibata et al., 1997), Shibata et al. (1997) concluded that the K-Ar age of C/T boundary in the Tappu area was 93.1 +1.2(10). Hirano et al. (1997) also obtained similar K-Ar ages from the Tappu and Oyubari sections. Materials and methodology Samples were collected along the Kotanbetsu River in the Kotanbetsu area (Figures 1, 2). All samples subjected to isotopic analysis were obtained from the pelagic mudstone unit, whereas turbidite units were ignored. The stratigraphic intervals for samples are between 20-100 m along the sec- tion (Figure 2). Powdered mudstones were treated with a 5N solution of HCI for 12 hours to remove carbonate miner- als. Each acid-processed sample was then baked in an oven at 850°C for 8 hours in a tube under vacuum together with CuO to convert organic carbon into CO: gas. After pu- rification of CO; gas on a cryogenic vacuum line, carbon- isotope analyses were performed with a Finnigan MAT Map showing sampling localities in the Kotanbetsu area. Carbon-isotope stratigraphy of the Yezo Group 97 Figure 3. Kerogen observed under microscope with reflected light. Note that most struc- tured particles are identified as semifusinite and vitrinite, which are terrestrial in origin (see text for details). Semifusinites which have obvious lignitic cellular structure in selected samples docu- ment vascular plants as their origin. Examples of indeterminable vitrodetrinites and inertodetrinites are also indicated by arrows. a. Vitrinite (v) with smaller particles of semifusinite (s) from KOT-148. b. Semifusinites (s) with obvious cellular structure from KOT-130. c. Semifusinites (s) with obvious cellular structure from KOT-129. d. Semifusinites (s) with obvious cellular structure from KOT-101. delta-E mass spectrometer at Indiana University. The re- sults reported herein are obtained using reference CO; as a working standard calibrated by NBS standards. Carbon- isotope results are expressed in the standard delta notation with respect to the PDB standard, where 6"°C = {(°C/'?C) campicl ('°C/"*C) stancara-1} X 1000, with a reproducibility of analyses of + 0.1%. The isotopic values were checked by an isotopically known laboratory standard (triphenylamine). Total organic carbon (TOC) content of whole rock was esti- mated by CO: gas volume with a Baratron pressure trans- ducer. For visual observation of kerogen, crushed mudstone was made into polished blocks following the standard preparation procedure (Bustin et al., 1983). Polished pellets were ex- amined using a MPV-2 microscope to identify organic parti- cles. Results Visual observation of kerogen Kerogen was analyzed on selected samples optically under reflected light and in fluorescent mode. Microscopic observation was carried out on seven selected samples (KOT-101, 113, 126, 129, 130, 148 and 152) as representa- tive horizons of stratigraphically-important isotopic events (see below) through the Kotanbetsu River section. Kerogen from all selected samples is dominated by semifusinite and vitrinite with a minor amount of particulate vitrodetrinite and inertodetrinite (Figure 3a-d) derived exclusively from cellular lignins of terrestrial vascular plants. Preservation of cell structure in semifusinite indicates its origin as woody plant matter. Organic matter of other than terrestrial woody plant origin (alginite and liptinite) was rarely (1%) detected dur- ing microscopic examination. Sporinites, resinites and bitu- men were the only fluorescent organic matters in the samples. This fluorescent property can be explained by the absence of marine organic matter. Some nonoxidized vitrinite might have incorporated marine organic molecules through the process of condensation during early stage of diagenesis. But in such a case, marine alginite and/or liptinite should have been more conspicuous components under microscope. The result from visual observation of kerogens strongly suggests no significant incorporation of marine organic materials in the kerogens. Carbon isotopes and total organic carbon (TOC) A stratigraphic profile with carbon isotope ratios (6 °C) for terrestrial organic matter from the Kotanbetsu area is shown 98 Lithology ample horizon Lithological Unit TOC (%) 0.6 -[0.2 1.0 S zB [e) pa — ı Ua-b| Uc-e S =) © _ © O N © > Takashi Hasegawa and Takayuki Hatsugai Kotanbetsu Section (Kotanbestu River) 13 Ô Garren %o (PDB) 2290,21 COM 22 Legend Mudstone V Bentonite bed (<30cm) Laminated mudstone Sandstone (<3cm) Sandstone (<30cm) Alternating beds of sandstone and siltstone Sandy siltstone Figure 4. Carbon iSotope profile of terrestrial organic matter in the Kotanbetsu River section, Hokkaido, Japan. Labels KC-1 to KC-6 indicate different events on the 6 ‘°C curve discussed in the text. KC-3 is composed of three subevents namely KC-3a, KC-3b and KC-3c. Note a sharp peak of 6 °C values (KC-3c) at the middle of the section and a stepwise negative shift through KC-3c~KC-6. in Figure 4. The profile is divided into six "events" by char- acteristics in the isotopic fluctuation and are expressed by a KC-numerical notation (designating Kotanbetsu carbon iso- topic event): KC-1: Characterized by a positive isotopic event (-23.3 %o) observed in the lower part of Unit Mf-h. Above the peak at KOT-152, à °C shows a gradual negative shift toward -24.7% at KOT-145. KC-2: Segment of relatively negative values fluctuating between -24.2 and -24.9% through the upper Unit Mf-h. KC-3: Characterized by two positive excursions. At the top of Unit Mf-h, 6 °C reaches -23.1% at the horizon KOT -133 (KC-3a: designated as "a" in Figure 4). However, the value rebounds down to -25.0% at KOT-132 just above KOT-133 (KC-3b: designated as "b"). The most prominent feature is a sharp positive excursion of -2.5-3% which oc- curs in the middle Unit Mi at the horizon KOT-130 and 129 (KC-3c: designated as "c"). Carbon-isotope stratigraphy of the Yezo Group 99 Table 1. Carbon isotopic ratio and TOC along the Kotanbetsu section. The Cenomanian/Turonian boundary is expected just above KOT-129 (see text for details). 68°C org. terr. %o Sample (PDB) TOC (%) KOT-101 -24.1 0.74 KOT-103 -24.2 0.68 KOT-105 -24.4 0.59 KOT-107 -24.4 0.58 KOT-109 -24.6 0.63 KOT-111 -24.5 0.42 KOT-113 -24.3 0.30 KOT-115 -24.2 0.77 KOT-117 -24.8 0.64 KOT-119 -23.7 0.44 KOT-120a -23.1 0.53 KOT-121 -24.0 0.60 KOT-122 -24.1 0.78 KOT-123 -24.1 0.63 KOT-124 -24.4 0.55 KOT-125 -24.2 0.80 KOT-126 -23.9 0.95 KOT-127 -24.2 0.65 KOT-128 -23.5 0.66 KOT-129 -21.8 0.84 KOT-130 -22.6 0.64 KOT-132 -25.0 0.56 KOT-133 -23.1 0.40 KOT-134 -24.6 0.54 KOT-135 -24.4 0.52 KOT-137 -24.9 0.60 KOT-139 -24.2 0.60 KOT-140 -24.9 0.86 KOT-142 -24.2 0.68 KOT-143 -24.4 0.66 KOT-144 -24.4 0.69 KOT-145 -24.7 0.68 KOT-146 -24.3 0.64 KOT-148 -23.9 1.10 KOT-150 -23.5 0.89 KOT-151 -23.7 0.86 KOT-152 -23.3 0.68 KOT-153 -24.4 0.60 KOT-154 -24.0 0.82 KOT-156 -24.1 0.69 KOT-157 -24.2 0.76 KC-4: Relatively stable isotopic ratios above KC-3c ex- cursion. 6 °C drops rapidly above KOT-129 and stabilizes around -24.0 Unit MI-o. KC-5: Characterized by a minor positive excursion of 0/ /00 between the middle Unit Mi and the middle —1% at KOT-120 followed by a negative shift back to KC-6. KC-6: Characterized by stable isotopic ratio between -24.8 and -24.1%. The most negative value is recorded in the lowest part of this interval (-24.8%o). Values of total organic carbon content (TOC) range be- tween 0.2 and 1.0% with no notable fluctuation in the Kotanbetsu River section. Discussion No organic-rich layer across the C/T boundary In spite of fine parallel laminations in the Mi Unit indicating limited benthic activity and dysaerobia, no TOC spike (ex- traordinary accumulation of organic matter) at the C/T boundary (=peak horizon of 6 °C; see following discussion) was observed (Figure 4) contrary to the case of many car- bonate sections around the world (e.g. Schlanger et al. 1987). This is caused by the depositional environment of the Kotanbetsu section, which was far different from that of those sections with an accumulation of organic matter at the boundary. The sedimentation rate of the Kotanbetsu sec- tion is about 200 m/m.y. and substantially all materials in- cluding organic matter are terrestrial in origin. Most of the organic matter in the mudstone samples are very residual lignitic material. Therefore, the concentration of organic matter across the section was controlled predominantly by the content of organic matter in terrigenous debris and never affected by oceanographic events. Factors controlling carbon-isotope fluctuations Kerogen from two samples representing the KC-3 event were optically examined and the results were compared with those from KC-4, KC-6 and KC-1. All visually checked samples are dominated by semifusinite and vitrinite. This means organic matter in the samples is derived from nothing but lignins of terrestrial woody Cs plants which are exclu- sively resistant to oxidation. Rare occurrences of small amounts of alginite, sporinite, resinite, and bitumen should not affect the following discussion dealing with differences larger than 0.1% of carbon isotopic fluctuation. Since these samples were selected from the intervals of major isotopic events of stratigraphic importance, the isotopic fluctuation of terrestrial organic carbon obtained in this study cannot be ascribed to the composition of kerogens. That the lithological evidence shows no significant change of depositional environment also suggests that the composition of kerogens is a feature of the sedimentary rock through the Kotanbetsu River section. In Figure 5, 6 °C values are plotted against TOC with no systematic relation revealed between them. This indicates that the 6 °C values are independent of mechanisms of sup- ply and deposition of organic matter; organic matter derived from lignins of terrestrial woody C; plants has not been car- bon-isotopically biased by these mechanisms and has es- sentially kept its original isotopic signature. As mentioned above, the isotopic fluctuation of organic carbon in the Kotanbetsu River section can be interpreted as representing the average biomass of woody plants in the provenance area. The isotopic fluctuation of global atmospheric CO: is 100 Takashi Hasegawa and Takayuki Hatsugai 1.2 = 1.0 = s 2 = —~0.8 = " S Ce = = iP os? u.“ S ag | ee = a . a H Ir u LE = 0.4 G 5 a 0 0.2 + TT —T- T r TR Te = -25 -24 -23 -22 -21 5 i Corg.terr. %o (PD B) Figure 5. Carbon-isotope ratios of terrestrial organic car- bon (6 “Corg.terr.) against total organic carbon content (TOC; dry weight %) along the Kotanbetsu River section. interpreted to be a primary factor responsible for 6 °C fluc- tuation of the terrestrial biomass as discussed in Hasegawa (1997), Beerling and Jolley (1998) and Gröcke et al. (1999). If this assumption is accepted and other environmental and/- or ecological factors are negligible, 6 °C fluctuation of ter- restrial organic matter is essentially parallel to that of carbonates. Arthur et al. (1988) ascribed a discrepancy of amplitude observed between marine carbonate and marine organic carbon across the C/T boundary to a marked de- crease of partial pressure of CO: in the ocean-atmosphere system. Gröcke et al. (1999) discussed the possibility that the partial pressure of atmospheric CO: may have also af- fected carbon-isotopic fluctuation of fossil woods as a sec- ondary factor in conjunction with the isotopic composition of CO:. If ö'C of atmospheric CO; during the deposition of the studied sequence exclusively reflects proportion of fluxes of organic and inorganic carbons into/out of the ocean-atmospheric reservoir, changes of partial pressure of atmospheric CO; should lead to exaggeration of the 6 °C events in terrestrial and marine organic matter against ma- rine carbonates (see also discussion of Popp, et al., 1989; Gröcke et al., 1999). Therefore, even if the 6 °C curve ob- tained in this study was affected by the partial pressure of at- mospheric CO;, it is still plausible to correlate it with 6 °C curves derived from marine carbonates as well as those from terrestrial organic matter of other Hokkaido sections. Kuypers et al. (1999) discussed a turnover from a C; plant community to a C;-dominated community, which had been derived from a decrease of partial pressure of CO:, as a fac- tor in an exaggerated 6 *C excursion of n-alkanes. This factor could only exaggerate a positive excursion of 6 °C. The kerogens examined under the microscope show pre- dominance of lignitic macerals in both samples from the C/T boundary excursion (KOT-129 and 130) and other horizons. This indicates no turnover of C:/C; plant communities was in- volved with the 6 °C excursion at the C/T boundary shown in the present study. Shift of atmospheric humidity and taxonomic turnover in the provenance of organic matter may have affected carbon isotopic fractionation during photosyn- thesis of the biomass (O’Leary, 1993). These factors could result in some local, regional or sometimes global isotopic disturbance and should be considered during carbon-iso- tope correlation. Nguyen Tu et al. (1999) proposed that en- vironmental stress derived from salinity had affected significantly the carbon isotopic composition of fossil terrestrial plants from Cenomanian strata. However, the or- ganic matter treated in this study is interpreted to have been transported from wide and distant provenance. It should be highly mixed enough to eliminate such a local salt stress dis- cussed in Nguyen Tu et al. (1999). Significance of carbon isotope stratigraphy as a tool for correlation The Kotanbetsu River section has been subdivided into stages by biostratigraphic studies of megafossils (Nishida et al., 1992, 1993b) and planktonic foraminifera (Nishida et al., 1992; Hatsugai et al., 1999) (Figure 6). No bio- chronological study of megafossils is available above the middle Turonian along the Kotanbetsu River section. However, Sekine et al. (1985) studied the Tappu area next to the Kotanbetsu area and that study was adopted to draw boundaries above the middle Turonian. Planktonic foraminiferal biostratigraphy (Hatsugai et al., 1999) indicates no appreciable diachroneity in lithologies between the Tappu and Kotanbetsu areas. As Hatsugai et al. (1999) noted, stages defined by both megafossils and planktonic foraminifers correspond well with each other below the upper part of Unit Mj-o (Figure 6). There are two conspicuous isotope events (KC-3 and KC-4) in the Kotanbetsu River section which can be correlated in- ternationally (Figure 7). KC-1 is regionally correlated to H1 of the Oyubari section (Figure 7) by its shape and amplitude of isotopic fluctuations as Well as by biostratigraphic position (within planktonic foraminiferal Rotalipora cushmani Zone). Though this event could be globally correlated, however, it is not conclusive because of low chronological resolution across this event in Japan. KC-2 is the common event of three Hokkaido sections (Oyubari, Tappu and Kotanbetsu; Figure 7) and equivalent to H2 in the Oyubari area (Hasegawa, 1997). This negative isotopic feature of KC- 2/H2 cannot be observed in European sequences (Jenkyns et al., 1994). Shift of atmospheric humidity and/or taxo- nomic turnover in the provenance of organic matter may ex- plain this event, which is specific to terrestrial organic carbon (see O’Leary, 1993). KC-3 is the most prominent feature of the Kotanbetsu River section and is regarded to be the best worldwide stratigraphic marker across the C/T boundary in relation to the Oceanic Anoxic Event II (Schlanger and Jenkyns, 1976; Arthur et a/., 1988). KC-3 is composed of a double peak and a trough between (Figure 4). These subevents in KC-3, namely KC-3a, b and c ("a", "b" and "c" in Figure 4) can be correlated with isotopic subevents a, b and c, respectively at the C/T boundary of the Oyubari (Hasegawa, 1995) and Tappu areas (Hasegawa, 1994), al- 101 Carbon-isotope stratigraphy of the Yezo Group ‘pusBe] 104 € auiBl4 89S “UOI}OaS eu} Jo do} eu] Je payNUap! 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(en == EN Ba Osu 65 02s4 — 2 7 |2 | 4 = RÉ RS 4 = — Een =|" & an LS a N QE =. = : = 25 33 = 3 ce 35 QE. sg = GP” 38 5 N Bee 93 Fe € é x 8 (gad)°% 49 0 R = ° el ©) & [e] = 5 "u ve Ge SS See ÿ € a So (add) °% ‘2160 9 0 (add)°% mo, Si ns Q ueder ‘ueqnho Aye ‘oiqqno Puejßug uieumnos >|? Carbon-isotope stratigraphy of the Yezo Group 103 (shear zone) | 55 siltstone K siltstone KOT-125 Or KOT-126 Futamata Tributary in laminated sittstone TA alternating beds if fine sandstone and laminated siltstone 1-2 cm sandstone layers KOT-128 „ small tributary sandy siltsone | siltstonewith sandy siltstone 5 KOT-129 = DA Cenomanian/ Turonian boundary Within this range KOT-132 "77 --" (logging road) KOT-133 sandy siltstone fine sandstone (shear zone) Figure 8. Plan map along the Kotanbetsu River showing detailed position of the Cenomanian/Turonian boundary expected from carbon isotope stratigraphy. The possible boundary is limited stratigraphically within ~14 m between KOT-129 and KOT-128. though inconclusively, due to sparse sampling encompass- ing KC-3 and difference of amplitude of the subevent KC- 3b. Hence it is still open to question whether the entire KC-3 or only KC-3c corresponds to the globally oberved carbon isotope excursion at the C/T boundary (see Schlanger et al, 1987). As discussed in detail by Hasegawa (1995), the C/T boundary can be drawn just above the positive 6 °C excursion; the C/T boundary in the Kotanbetsu River section is drawn just above the horizon of KOT-129 (Figures 6, 8). The horizon of the C/T boundary is stratigraphically limited to ~14 m between KOT-129 and KOT-128. Nishida et al. (1993b) reported occurrences of Inoceramus nodai just below KOT-129. In the Oyubari area, /. nodai was reported from 10 m below the carbon-isotopic excur- sion identifying the C/T boundary (Hasegawa, 1995; Nishida et al., 1993a; Hirano, 1995) suggesting I. nodai is an important boundary marker in Hokkaido. According to Hatsugai et al. (1999), KC-3 is stratigraphically included in a "zone of rare occurrence" of planktonic foraminifera. A similar planktonic foraminiferal event encompassing the car- bon isotopic excursion at the C/T boundary is also reported from the Oyubari area (Hasegawa, 1999) and the Tappu area (Hasegawa, 1994) suggesting an environmental dete- rioration across the boundary. Controlling factors other than 6 °C fluctuation in the global CO. reservoir may have disturbed the stratigraphic position of KC-3 and might have spoilt the discussion above the C/T boundary. In such a case, additional "noise" should be superimposed on the global signal derived from isotopic change of the CO; reser- voir. Even though such a possibility cannot completely be rejected, KC-3 event showing similar magnitude of 6 *C ex- cursion to that of carbonate (e. g. Jenkyns et al., 1994; Pratt et al., 1985) and terrestrial organic matter (Hasegawa and Saito, 1993; Hasegawa, 1997) should contain the least "noise" for correlation of the C/T boundary. Ulicny et al. (1997) interpreted isotopic fluctuation of organic carbon en- compassing parasequence boundary near the C/T boundary based on a steady isotopic ratio of terrestrial organic carbon through the sequence in Bohemia. The present study and Hasegawa (1997) clearly shows that this interpretation cannot be accepted because the major positive "spike" of terrestrial organic carbon exists across the C/T boundary. Based on 200 m/m.y. for sedimentation rate; duration of KC-3 (from KOT-133 to KOT-129) is estimated as 0.73 m.y. Another international event is KC-4 just above the C/T boundary and is represented by a stable "plateau" of the iso- topic curve (Figure 7). Both megafossil and planktonic foraminiferal chronology indicate KC-4 falls in the lower- middle Turonian (Figure 6). Both in the Oyubari and Tappu areas, a similar isotopic event is also recognized. On the isotopic curve of the Kotanbetsu River section, there is a minor positive event (KC-5) above KC-4. A similar feature also exists on the curve from the Tappu section but is dimin- ished in magnitude on the curves from Oyubari (Figure 7). KC-5 could be correlated to E5 of southern England (Figure 7); however, this is not definite because of the insufficient age control and different magnitude of the positive excursion between these areas. Therefore, KC-5 can be either a global signal or a local/regional isotopic perturbation super- imposed on the global KC-4 event caused by influx of less mixed (isotopically not averaged) plant debris derived from a narrower provenance. Contrary to the chronostratigraphic concordance of megafossil and planktonic foraminifera below the middle Turonian, there are considerable discrepancies above it (Hatsugai et al., 1999). Motoyama et al. (1991) also dis- cussed a chronostratigraphic discrepancy on the 104 Takashi Hasegawa and Takayuki Hatsugai Turonian/Coniacian boundaries at the Oyubari area between megafossils and microfossils. Even though internationally it is recognized that the total range of Helvetoglobotruncana helvetica is limited to the middle Turonian (Robaszynski and Caron, 1979; Caron, 1985; Sliter, 1989), the stratigraphic distribution of Inoceramus teshioensis spans the Upper Turonian and /noceramus uwajimensis the Coniacian (Toshimitsu et al., 1995) which all overlap the range of H. helvetica. The first occurrence of Inoceramus amakusensis is positioned far below the first occurrence of Margino- truncana sinuosa (indicating the top of the Turonian; Caron, 1985) and genus Archaeoglobigerina (indicating the basal Coniacian; Caron, 1985). They show clear discrepancies with the stratigraphic relationship compiled by Toshimitsu et al. (1995) (Figure 6; see also Table 1 of Toshimitsu et al., 1995). As a result, the stages identified by megafossils tend to give a younger age than that identified by planktonic foraminifers. These chronological inconsistencies occur above the top of the stratigraphic range of /. hobetsensis. This fact means that stratigraphic distributions of either/both inoceramids (/. teshioensis, |. uwajimensis and |. amaku- sensis) and/or planktonic foraminifers (H. helvetica, M. sinuosa and genus Archaeoglobigerina) show diachroneity. Above isotopic profile KC-5, the carbon-isotope ratio reaches a minimum at KOT-117. This horizon can be cor- related to the oldest part of the negative isotope event (H5 of the Oyubari section and E6 of the South England section: see Fig. 6 and 8 of Hasegawa, 1997). The steady isotopic ratios between -24.6 and -24.1% above horizon KOT-115 suggest that this section does not extend to the upper part of the Santonian. Hasegawa et al. (1997) reported a positive carbon-isotope event in the middle Santonian from an equivalent of the Yezo Group in Sakhalin. This Santonian event can be correlated to southern England (Jenkyns et al. 1994) and Italy (Corfield, 1995; Jenkyns et al., 1994). If the Kotanbetsu River section in this study reached the Santonian, the positive excursion should be observed near the top of the stratigraphic column in Figure 6. Comparing general carbon isotopic patterns from southern England and Italy (Corfield, 1995; Jenkyns et al., 1994; Figure 7), the up- permost part of the Kotanbetsu River section studied herein can be interpreted to be the lower part of the Coniacian. This chronological assumption is close to the age assign- ment by planktonic foraminifera rather than that based on inoceramids. Conclusion In order to demonstrate the applicability of carbon-isotope stratigraphy of the Yezo Group for correlation, a stratigraphic time-series isotopic analysis of terrestrial organic carbon was studied from the Cenomanian to Coniacian along the Kotanbetsu River in Hokkaido, Japan. The carbon-isotope curve generated was compared with similar profiles of terrestrial organic carbon from Oyubari and Tappu in Hokkaido (Hasegawa, 1995, 1997) and marine carbonate from southern England and Italy (Jenkyns et a/., 1994). The salient conclusions are as follows: 1. The origin of organic carbon is interpreted to be exclu- sively terrestrial woody plants. Petrographic study on or- ganic matter in mudstone samples reveals practically no marine organic matter in the seven examined samples. The carbon-isotope ratios of organic matter from the Kotanbetsu River section can be interpreted as that of an average lignitic material from woody plants. Global carbon-isotope events can be recognized in the isotopic curve from Kotanbetsu. 2. Event KC-3 records the isotopic event of the Cenomanian/Turonian boundary. It is still unclear which carbon-isotope event, namely all of KC-3 or only KC-3c, represents the C/T boundary. Notwithstanding this, the Cenomanian/Turonian boundary is drawn just above sample KOT-129, which has the most positive 6 *C ratio. 3. Event KC-4 is correlated to the event H4/E4 of both the Oyubari and southern England sections. 4. Anegative event above KC-5 is correlated to the ear- liest part of event H5/E6 of Oyubari and southern England. 5. The most plausible chronologic interpretation for the younger part of KC-6 is middle Turonian to Coniacian and supports planktonic foraminiferal evidence rather than that derived from inoceramids. In spite of occurrences of Inoceramus amakusensis, the studied succession does not reach the Santonian because the general isotopic pattern differs from that of the Santonian from southern England (Jenkyns et al., 1994) and Sakhalin (Hasegawa et al., 1997). Acknowledgments The authors express their deep appreciation to K. Konishi of Kanazawa Univ. for his critical readings of the manuscript and helpful discussions, and to L. M. Pratt of Indiana Univ. for providing T. Hasegawa an opportunity to use instruments at Indiana Univ. The authors wish to ex- tend their appreciation to S. Studley and J. Fong of Indiana Univ. for their helpful support during analyses. Acknowl- edgments are also due to T. Matsumoto of Kyushu Univ. for his identification of megafossils and M. Mastalerz of the Indiana Geological Survey for her advice and helpful discus- sions during work on organic petrology. Financial support for this study was provided by a Grant-in-Aid for Encouragement of Young Scientists from the Ministry of Education, Science and Culture of the Government of Japan, no. 09740387 and by a Grant for Encouragement of Young Scientists from the Nissan Science Foundation (both given to T. Hasegawa). References Arthur, M.A., Dean, W. E. and Pratt, L. M., 1988: Geochemical and climatic effects of increased marine organic carbon burial at the Cenomanian / Turonian boundary. Nature, vol. 335, p. 714-717. Beerling, D. 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Palaeogeography Palaeoclimatology Palaeoecology , vol. 132, p. 265-285. Paleontological Research, vol. 4, no. 2, pp. 107-129, June 30, 2000 © by the Palaeontological Society of Japan Taxonomic revision of Pisulina (Gastropoda: Neritopsina) from submarine caves in the tropical Indo-Pacific YASUNORI KANO' and TOMOKI KASE? "Department of Biological Sciences, Graduate School of Science, the University of Tokyo, 3-23-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan (Mailing address: Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan: kano@kahaku.go.jp) * Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan (kase @kahaku.go.jp) Received 1 December 1999; Revised manuscript accepted 14 February 2000 Abstract. Species of the tropical Indo-Pacific gastropod Pisulina (superorder Neritopsina), previ- ously known only from empty shells and regarded as a genus of Smaragdiinae (Neritidae), are re- vised on conchological criteria. Pisulina dwells in gloomy to totally dark, tropical and subtropical, shallow-water submarine caves, where their empty shells are ubiquitous. Study of the previously described modern and fossil species and examination of newly collected material from more than 50 submarine caves on Pacific islands show that there are six species in the genus: P. adamsiana Nevill and Nevill, 1869 (Holocene), P. subpacifica Ladd, 1966 (late Miocene), P. biplicata Thiele, 1925 (Recent), P. maxima new species (Recent), P. tenuis new species (Recent), and Pisulina sp. (Pleistocene). An analysis of previously unstudied shell characters (shell form, shell microstruc- ture, protoconch morphology, and opercular features) of Pisulina and other modern, representative genera of Neritopsina places the genus close to the freshwater and brackish-water genus Neritilia, based on three unique characters (inclined protoconch, spiral ridges on the protoconch surface, and perpendicularly arranged prisms in the outer shell layer), and both genera are herein included in the family Neritiliidae. This study shows that the protoconch and shell microstructure analysis is important for re-evaluating fossil species previously placed in Neritidae. Key words: Neritiliidae, Pisulina, protoconch, shell microstructure, submarine cave Introduction Pisulina Nevill and Nevill, 1869 has been a gastropod genus of systematically uncertain placement. Aside from the type species, Pisulina adamsiana Nevill and Nevill, 1869, the genus has included one modern species, Pisulina biplicata Thiele, 1925, and one fossil species, Pisulina subpacifica Ladd, 1966. The species previously have been known only from empty shells, so knowledge of their anat- omy, operculum, radula and habitat have been entirely lack- ing. Empty shells occasionally have been found in beach drift from the tropical western Pacific (Habe, 1963; Hinoide and Habe, 1991; Fukuda, 1993; Loch, 1994; Sasaki, 1998) and have been dredged from 70 m off southern Africa (Herbert and Kilburn, 1991). Nevill and Nevill (1869) thought the genus was close to Teinostoma (currently classified in Vitrinellidae of Caeno- gastropoda; e.g., Ponder and de Keyzer, 1998) and Calceolina [junior synonym of Teinostoma (Calceolata); Thiele, 1929] based on overall similarity in shell morpholo- gies. Thiele (1925) was the first author to place Pisulina in Neritidae, and this familial allocation was followed in his monograph (Thiele, 1929). Wenz (1938) included Pisulina in the subfamily Smaragdiinae Baker, 1923, of Neritidae, and was subsequently followed by Knight et a/. (1960) and Komatsu (1986). However, Herbert and Kilburn (1991) found that Pisulina differs in protoconch morphology not only from Teinostoma but also from Smaragdia, the type genus of Smaragdiinae. They observed that the change of coiling axis occurs between the larval shell and teleoconch whorls in P. adamsiana, although they followed Robertson’s (1971) view that this change occurs between the embryonic and 108 Yasunori Kano and Tomoki Kase Figure 1. post-embryonic shells in Smaragdia. However, they did not elaborate on the systematic position of this enigmatic genus from their observations, and the systematic position of Pisulina has remained speculative. Since 1989, the junior author and his co-workers have been conducting biological sampling in shallow-water sub- marine caves on tropical and subtropical Pacific islands with the help of skilled SCUBA divers. During the course of the sampling, they have found a molluscan community that is distinctive in species composition and reproductive biology (Kase and Hayami, 1992; Hayami and Kase, 1993, 1996). They also found that a huge number of empty shells of Pisulina species had accumulated in the bottom sediments in many caves, and that living animals were abundant on the walls and ceilings of several caves in Hawaii, Saipan, Palau, the Philippines and Malaysia. The purpose of this paper is (1) to describe the conchological characteristics of Pisulina in detail, (2) to de- fine the genus and discuss its systematic position based on conchological characteristics, (3) to review all previously known species of Pisulina, and (4) to describe new species. Materials and methods We examined more than 5000 empty shells of Pisulina species obtained from the bottom sediments of more than 50 submarine caves, tunnels, grottos or caverns (at depths Pisulina adamsiana Nevill and Nevill, 1869 from Sipadan Island, Sabah, Malaysia (NSMT-Mo71619). Scale bar = 2 mm. ranging from 1.3 to 55 m), on tropical and subtropical Pacific islands. We also examined shells in beach drift and dredged samples, and fossil shells from Henderson Island (the Pitcairn Group) and Niue Island (Cook Islands). In the descriptions given below, the "Material examined" headings refer to empty shells, unless otherwise stated. Living ani- mals were obtained from walls inside caves and tunnels by hand, or by brushing the undersurface of coral rubble on the bottom sediments. Empty shells were obtained from the sediments (mainly calcareous mud) of the cave floors by hand sorting. For comparison, we examined embryonic shells of Neritilia rubida (Pease, 1865) from Tahiti. In addition, live speci- mens of another Neritilia species [collected in a stream in Tabaru Valley, Yonaguni Island, Okinawa Prefecture, Japan; identified by Kubo and Koike (1992) as N. rubida] were kept in a freshwater aquarium, and embryonic shells were ob- tained after spontaneous oviposition and following develop- ment. In the aquarium, egg capsules which each retained only one embryo were laid in small pits on the undersurface of limestone cobbles taken from the original habitat. The veligers were hatched as embryonic shells after two weeks of oviposition. We prepared specimens for SEM observation using stan- dard techniques: shells were cleaned with an ultrasonic cleaner, dried, mounted on stages, coated with gold, and ex- amined under a scanning electron microscope (JOEL T330A), or were examined in a low-vacuum mode without a Taxonomic revision of Pisulina Figure 2. SEM micrographs of the subsutural surface of the last teleoconch whorls in four modern Pisulina species; all are oblique apical views. Scale bars = 50 um. A. Pisulina adamsiana Nevill and Nevill from Sipadan Island, Malaysia. from Shimoji Island, Okinawa, Japan. Island, Okinawa. metal coating in another SEM (JEOL 5200LV). Polished and etched sections were prepared for microstructural analysis of the shell wall in the following manner: blocks of shells were embedded in synthetic resin, polished, cleaned ultrasonically to remove polishing grit, etched in 0.3% acetic acid for 60 seconds, and cleaned again. The terminology and usage of shell ultrastructure follow Carter and Clark (1985). Museum abbreviations. — AMS: Australian Museum, Sydney; MNHB: Museum fur Naturkunde der Humboldt- Universitat, Berlin; MNHN: Muséum National d'Histoire Naturelle, Paris; NSMT: National Science Museum, Tokyo; UMZC: University Museum of Zoology, Cambridge, England; USNM: National Museum of Natural History, Washington. B. Pisulina biplicata Thiele C. Pisulina maxima sp. nov. from Sipadan Island. D. Pisulina tenuis sp. nov. from Yonaguni Systematic description Superorder Neritopsina Cox and Knight, 1960 Family Neritilidae Schepman, 1908 Genus Pisulina Nevill and Nevill, 1869 Pisulina Nevill and Nevill, 1869, p. 160. Type species.— Pisulina adamsiana Nevill and Nevill, 1869, by monotypy. Distribution and age.—Tropical and subtropical Indo- Pacific. Late Miocene to Recent. Diagnosis. — Shell small to medium in size, globose neritiform, white, smooth, solid. Inner lip of aperture smooth, convex, covered with a thick and widespread callus, with a robust projection or 3 to 7 teeth on margin. Outer lip with a weak inner ridge inside and a sharp margin. Protoconch either multispiral or paucispiral; multispiral 109 110 Yasunori Kano and Tomoki Kase protoconch with a larval shell inclined approximately 30° to teleoconch axis, sculptured with several spiral ridges, and embryonic shell partially covered by larval shell whorls and also by first teleoconch whorl due to protoconch inclination. Outer layer of shell wall very thin, simple prismatic structure; each prism almost perpendicularly arranged to the outer shell surface. Operculum semicircular, paucispiral, thin, concave externally; external surface smooth, corneous, red- dish straw in color; inner surface calcified except for mar- ginal area, with an apophysis near base of inner margin. General conchological features Teleoconch.—The shell is small to medium in size, globose to subglobose or sometimes hemispherical, solid, white, and translucent when it is fresh (Figure 1). The teleoconch coils number less than four, increase rapidly in size, and have a less convex upper whorl surface. The su- ture is shallowly impressed. The last whorl is well inflated and has a round periphery. The exterior surface bears mi- croscopic spiral ridges and very fine growth lines (Figure 2A-D). The aperture is small to large and crescent-shaped to semicircular in outline. The outer lip is prosocline, angled 30° to 50° from the shell axis, sharp along its margin, and is thickened interiorly into an indistinct inner ridge. The inner lip is covered with a smooth, thick and convex callus that spreads widely onto the base of the previous whorl. The adaxial margin of the inner lip bears a robust projection in P. adamsiana and P. subpacifica, and three to seven teeth in all other species. The inner line of the callus surrounds the columellar area, then merges gradually with the basal lip. The inner walls of the whorls are resorbed, producing a hol- low cavity inside (Figure 3), except for the last 1/3 whorl, where the cavity forms a relatively long, narrow, tube-like inner space and continues to the apertural opening. Inside the whorls is a funnel-like cavity which is separated from the main cavity by a steep wall and positioned just beneath the inner lip callus. This cavity, visible from the outside through the translucent inner lip callus, encases the distal end of an adapically projected digestive gland. Two muscle attach- ment scars are carved as shallow depressions; one corre- sponds to the left shell muscle of the animal, is spirally elongate and located beneath the convex part of the inner line of the aperture, while the other corresponds to the right shell muscle, is subcircular in shape and located close to the apex. Protoconch.—The protoconch is deeply immersed in the first teleoconch whorl, separated from the teleoconch by a clear line of demarcation, and is either multispiral or paucispiral (Figures 4A-F; 5A-E). A multispiral protoconch, Figure 3. Shell adamsiana Nevill and Nevill from South Kona, Hawai'i Island, showing the hollow internal space and the vertical cavity (v), the latter encasing the digestive gland of the animal; oblique apical view. Arrow indicates the elongate left muscle scar. Scale bar = 500 um. (apical whorls removed) of Pisulina seen in P. adamsiana and P. subpacifica, consists of an em- bryonic shell (protoconch-l) and larval shell (protoconch-Il). The embryonic shell is generally smooth and largely in- volved with the larval shell that bears four or five spiral ridges and many minute pits. The axis of the multispiral protoconch is sharply inclined (approximately 30°) compared to the teleoconch whorls, so the embryonic shell is partly covered by the initial teleoconch whorl (Figure 4A, E, F). The inner walls of the protoconch are resorbed into the teleoconch. A paucispiral protoconch, seen in some spe- cies, consists only of a large and smooth embryonic shell. In this case, the coiling axis of the protoconch appears to be the same as that of the teleoconch. Shell microstructure.—The shell consists of three layers, excluding the myostracum, and Figure 7 shows their occur- rence in the shell. The outermost layer (OL) is very thin (less than 20 um thick in P. adamsiana), and is composed of simple, irregular prisms (Figure 6A, B). Each prism is less than 2 um long, 0.3 um thick, and oriented with its long axis less than 10° to the outer shell surface. The middle layer (ML) is of very thick, simple crossed-lamellar structure (Figure 6A-D). The inner shell layer (IL) consists of alter- Figure 4. SEM micrographs of the multispiral protoconch in Pisulina adamsiana Nevill and Nevill. All specimens came from off South Kona, Hawai'i Island. A-D. Juvenile specimen with 0.6 of a teleoconch whorl. B. Apertural view. Scale bar = 100 um. C. Detail of the apical area of the opisthocline larval shell aperture. Scale bar = 100 um. A. Abapertural view showing the biconvex and protoconch, oblique lateral view. Embryonic shell partly exposed. Arrow indicates spiral ridges on the shoulder of the larval shell. Scale bar = 50 um. D. Close-up of the larval shell surface near the aperture, showing the presence of granules within pits. Scale bar = 5 pm. E. Oblique apical view of a juvenile specimen with 0.9 of a teleoconch whorl, showing faint spiral ridges on the larval shell surface. Scale bar =100 um. F. Oblique apical view of an immature shell with 1.7 teleoconch whorls, showing wavy ridges on the embryonic shell sur- face that are visible due to a lesser degree of overlapping by the teleoconch whorl. Scale bar = 100 pm. nu & I ® Qo = © (‘= S A > oO 2 Q E O O x œ F 112 Yasunori Kano and Tomoki Kase Figure 5. SEM micrographs of paucispiral protoconchs in Pisulina species. A, B. Pisulina biplicata Thiele, juvenile specimen with 0.5 of a whorl from off Kohama Island, Okinawa. Scale bar = 100 um. A. Abapertural view. B. Slightly oblique apical view. C. Pisulina maxima sp. nov., oblique apical view of an immature specimen from off Aulong Island, Rock Islands, Palau. Arrow indicates longitudinal folds on the protoconch near the suture with the first teleoconch whorl. Scale bar = 50 um. D,E. Pisulina tenuis sp. nov., juvenile speci- mens with 0.5 and 0.6 of a teleoconch whorl, respectively, from Yonaguni Island, Okinawa. Scale bar = 100 um. D. Abapertural view showing transverse growth ridges near the protoconch aperture. E. Slightly oblique apical view. Figure 6. SEM micrographs showing microstructures of the shell and operculum in Pisulina adamsiana Nevill and Nevill. A. Fractured shell surface of the outer lip of the aperture, cut perpendicular to the apertural margin, showing very thin outer prismatic layer and thick simple crossed-lamellar middle layer. The shell margin is to the right and the shell surface toward the top. Scale bar =100 um. B. Close-up of the fractured shell surface near the outer shell surface in A, showing details of the outer prismatic layer (PR) and the mid- dle crossed-lamellar layer (CL). Scale bar = 10 um. C-E. Etched surfaces of the section shown in Figure 7. C. The etched surface of an abapertural shell area, showing simple crossed-lamellar middle layer (CL) and inner layer. The inner shell surface faces toward the bottom. The inner layer consists of two irregular prismatic sublayers (PR) and an intervening complex crossed-lamellar layer (CCL). Scale bar = 10 um. D. An etched shell surface near the back of the inner line of the inner lip shows the simple crossed-lamellar middle layer (CL) and the inner layer. The inner layer consists of alternating irregular prismatic sublayers (PR) and complex crossed-lamellar sublayers (CCL). Scale bar = 20 um. E. Complex crossed-lamellar structure of the reconstructed inner shell wall. Scale bar = 10 pm. F. Fractured surface of an operculum, showing spherulitic prismatic structure. Scale bar = 10 pm. 113 Taxonomic revision of Pisulina 114 Yasunori Kano and Tomoki Kase Figure 7. Arrangement of shell layers in Pisulina adamsiana Nevill and Nevill. The section is roughly perpendicu- lar to the shell axis. Abbreviations: OL: very thin outer layer with prismatic structure; ML (light gray): thick middle layer with simple crossed-lamellar structure; IL (dark gray): inner layer made up of alternating sublayer(s) of complex crossed-lamellar and simple prismatic structures; CCL (dark gray): complex crossed-lamellar structure; ap: apertural projection; ar: apertural ridge; ci: callused inner lip of aperture; vc: vertical cavity. nating sublayer(s) of complex crossed-lamellar and simple prismatic structure (Figure 6C, D). The prismatic sublayers consist of irregular prisms that are arranged vertically. The first-order lamellae of the complex crossed-lamellar struc- ture are indistinct, variable in shape, and composed of a small number of thin, lath-like second-order lamellae (Figure 6E). The same shell structure is present in the robust inner lip area and in a small area just posterior to the inner ridge of the aperture, which are areas constructed secondarily after absorption of the original layers (CCL in Figure 7). Operculum.—The operculum is semicircular in shape, with a minimum length/maximum length ratio of ca. 0.7, paucispiral, rather thin, and has a concave exterior surface (Figures 8A, B; 9A-C). The exterior surface fits well into the convex surface of the shell’s inner lip when the animal fully extends its head-foot mass. The number of volutions may be up to 1.7, apart from the nucleus. The operculum con- sists of an outer corneous layer (up to 5 um thick) and inner calcareous layers. The surface of the outer corneous layer is smooth (except for faint growth lines), reddish straw in color, and the color gradually becomes paler from the mar- gin to nucleus. The nucleus appears only on the outer sur- face, is semicircular, located more or less abaxially and adapically from the center, paucispiral in P. adamsiana (Figure 8B) and concentric in the other modern species (Figure 9C). The inner surface of the operculum is calcified, except for the marginal area. The calcified area is covered with fine growth lines and bears a long apophysis near the base of the inner margin. The apophysis appears first as a weak ridge along the opercular suture, then becomes a curved calcified rod, and finally projects beyond the margin while remaining attached along its whole length to the basal margin of the operculum by a thin septum-like base. The muscle attachment scar can be divided into three areas: two are shallow, elongate depressions that are positioned at the Figure 8. Operculum of Pisulina adamsiana Nevill and Nevill from Sipadan Island, Malaysia. A. Internal, lateral and external views (arranged from top to bottom). Scale bar = 500 um. B. Oblique lateral view of the paucispiral nucleus on the external surface, showing 0.3 of a volution. Scale bar = 100 um. Taxonomic revision of Pisulina 115 Figure 9. Operculum of Pisulina maxima sp. nov. from Sipadan Island, Malaysia. A. Internal (top) and external (bottom) views. Scale bar = 500 um. B. Detail of apophysis and muscle attachments on the internal surface. Scale bar = 200 um. C. Oblique view of the concentrically growing nucleus on the external surface of operculum. Scale bar = 100 um. inner and basal margins, and the other is between the apophysis and nucleus and is thicker than the other calcified areas due to having additional calcitic layers (Figure 9B). The calcareous part of the operculum is composed of spherulitic prisms (Figure 6F). Systematic position of Pisulina The protoconch morphology and shell microstructure of Pisulina are unique and almost identical to those of the freshwater genus of Neritopsina, Neritilia Martens, 1879; these are the only conchological characters useful for sys- tematic placement. Apart from species with non-planktotrophic development (see below), protoconchs of extant aquatic members of Neritopsina are quite uniform in shape and differ from those of all other gastropods (Bandel, 1982; Sasaki, 1998). The protoconchs of the following genera have been figured previ- ously as SEM images: Nerita (Bandel, 1982; Sasaki, 1998), Smaragdia (Robertson, 1971; Bandel, 1982; Herbert and Kilburn, 1991), Clithon, Neritina, Septaria (Bandel and Riedel, 1998) [Neritidae]; Phenacolepas (Bandel, 1982; Sasaki, 1998), Shinkailepas, Olgasolaris (Beck, 1992) [Phenacolepadidae] and Neritopsis (Bandel and Fryda, 1999) [Neritopsidae]. These genera all share the same protoconch features: the embryonic shell is globular in shape, and the larval shell is oval to globular naticiform and has less than 3.5 volutions. As Bandel (1982) has noted, the larval shell is smooth except for fine growth lines, coils almost planispirally, and the suture line abuts the surface more adapical to the previous suture, so that the number of coils cannot be counted from the outside. Moreover, the inner walls of the larval shell are absorbed internally (Neritopsis is a possible exception; Bandel, 1992). The protoconch of Pisulina adamsiana is fundamentally the same as in the Neritopsina mentioned above. However, 116 Yasunori Kano and Tomoki Kase Figure 10. Multispiral protoconch and embryonic shell of Neritilia. A. Apical view of a juvenile shell with 1.2 teleoconch whorls. The surface is mostly intact. Arrow indicates the apex of the larval shell. Scale bar = 100 um. B. Oblique close-up of the larval shell surface in A, showing the presence of spiral and axial ridges and minute pits entirely covering the protoconch surface. Scale bar = 20 um. C. Oblique apertural view of juvenile shell with 1.2 teleoconch whorls. Outermost layer of the protoconch is partially eroded, so that the suture and growth lines of the larval shell are visible. Arrow indicates suture line. Scale bar = 100 um. D. Apical view showing an embryonic shell of Neritilia sp. that was extracted from an egg capsule shortly before hatching. Part of the operculum protrudes from the aperture. Scale bar = 20 pm. as already pointed out by Herbert and Kilburn (1991), the larval shell of P. adamsiana is distinctly tilted with respect to the teleoconch (Figure 4A-F). This tilting resulted from the change in direction of the growth lines from the larval shell (opisthocline) and the teleoconch whorls (prosocline). In addition, P. adamsiana has characteristic ridges (Figure 4A, C, E) and microscopic pits (Figure 4C, D) on the larval shell surface near the aperture (see description of P..adamsiana, below), which are sculptural features unknown in the other aquatic groups of Neritopsina. A-C. Immature shells of Neritilia rubida (Pease) from Tahiti. We have found that members of the freshwater and brack- ish-water genus Neritilia have a protoconch almost identical to that of P. adamsiana, suggesting a close affinity between the two genera. Bandel and Riedel (1998) have already noted the unique protoconch morphology of Neritilia within the superfamily Neritoidea. The protoconch surface of the type species, Neritilia rubida, is smooth and has no suture line, so it appears to be a simple globular protoconch (Figure 10A, B). However, this is due to the subsequent laying down of a very thin calcareous layer over the surface of a Taxonomic revision of Pisulina 117 Oblique lateral view of a paucispiral nucleus Figure 11. with 0.3 of a volution on the operculum of Neritilia sp. from Yonaguni Island, Okinawa. Scale bar = 50 pm. multispiral protoconch. In specimens whose protoconch surfaces are slightly eroded, the suture line and distinct growth lines are visible (Figure 10C), the once-hidden em- bryonic shell emerges close to the suture of the teleoconch, and a discontinuity in coiling is noticeable between the larval shell and teleoconch. The number of larval shell coils can- not be precisely counted, but appears to be about one, as seen in P. adamsiana (the paucispiral nucleus of the operculum, which is formed during the larval phase, is also similar to that of P. adamsiana in number of volutions; Figure 11). The calcareous layer over the protoconch appears to have been secreted after the last whorl of the larval shell was formed. In addition to the presence of this calcareous layer, N. rubida shows additional minor differences in its protoconch: the inclination of the coiling axis appears to be somewhat smaller, the larval shell has more numerous spiral ridges (five or six; Figure 10B) than P. adamsiana, and the microscopic pits are scattered all over the surface of both embryonic and larval shells without an evident pattern (Figure 10B, D). Bandel and Riedel (1998, fig. 6A, B) fig- ured the protoconch of Neritilia sp. cf. N. rubida, from the Matutinao River, Cebu, the Philippines. The spirally ar- ranged pits on the larval shell of this species differ from those described here for N. rubida. The spiral rows of pits in the Philippine Neritilia species evidently are a homologous character shared with P. adamsiana. Shell microstructure is a second clue to the close relation- ship between Pisulina and Neritilia. Previous descriptions of shell microstructure of Neritopsina have been mostly re- stricted to Neritidae (e.g., Baggild, 1930; Gainey and Wise, 1980; Bandel, 1990). The presence of a calcitic outer layer (with a homogeneous or prismatic structure) and aragonitic middle and inner layers (crossed-lamellar structure) are fea- tures shared among Neritopsina (e.g., Ponder and Lindberg, 1997:103). Pisulina has shell microstructure features that are basically the same as seen in Neritidae (Figures 6A-E; \ «à Am mn / \ NN / RR Figure 12. Radula of Pisulina maxima sp. nov. from Sipadan Island, Malaysia. The radula is characterized by a large, strongly oblique outer lateral tooth and the absence of a central tooth, the features almost identical to that of Neritilia (see Baker, 1923). Scale bar = 50 um. 7). However, Pisulina differs markedly from Neritidae in the inclination of prisms in the outer layer. The prisms are ar- ranged almost perpendicularly in Pisulina (Figure 6B), while they are almost horizontal or very oblique relative to the ex- terior shell surface in neritids (Boggild, 1930; Knight et al. 1960:123; Bandel, 1990; personal observation). Although the outer prismatic layer is brown in color and much thicker than in Pisulina, Neritilia rubida shares characteristic fea- tures regarding the inclination and size of prisms with Pisulina. The monogeneric family Neritiliidae was erected for the genus Neritilia by Schepman (1908) based upon its unique radular morphology. However, the genus has been as- signed to the subfamily Neritiliinae of Neritidae (e.g., Baker, 1923; Thiele, 1929; Wenz, 1938; Knight et al., 1960). Holthuis (1995) has recently shown the paraphyly of "Neritidae" and concluded that Neritilia is the sister group of Neritidae and Phenacolepadidae. Thus, Neritilia should be classified as an independent family of the superorder Neritopsina, namely Neritilidae Schepman, 1908, rather than being placed in Neritidae. Although the detailed systematic position of Pisulina must ultimately be determined by phylogenetic analysis based on conchological, anatomical, and molecular criteria, it is rea- sonable to conclude at present that Pisulina is not a member of Neritidae, but should be allocated along with Neritilia to Neritiliidae. The close relationship between the two genera is also confirmed by radular and anatomical characters (Figure 12; Kano and Kase, in preparation). We believe that the protoconch with the whorl inclination and spiral ridges, and the almost perpendicular prisms in the outer shell layer, are synapomorphies of Pisulina and Neritilia. These synapomorphies are important criteria for re- 118 Yasunori Kano and Tomoki Kase Figure 13. Paucispiral protoconch of Neritopsis radula (Linnaeus), juvenile specimen with 0.2 of a teleoconch whorl, from Yonaguni Island, Okinawa, in apical view. Bandel and Fryda (1999) illustrated a multispiral protoconch of N. radula from Mauritius. Further research is needed to resolve whether N. radula from the western Indian Ocean and Pacific are different species or an example of poecilogony (different early ontogenies within a single species; Bandel and Riedel, 1998), unknown among the Gastropoda. Scale bar = 100 um. evaluating fossil species previously placed in Neritidae, which ranges in age from Triassic to Recent. Knight et al. (1960) recognized 19 fossil genera (4 are still living) in the family and diagnosed most genera solely on the basis of teleoconch characters. The apical whorls of fossil neritids tend to be lost by abrasion and/or dissolution, but in rare in- stances they are preserved intact in sediments deposited in low-energy, soft-bottom environments. By examining fossil species, we have found that two species, Pisulinella miocenica Kano and Kase, 2000, and "Neritilia" tracyi Ladd, 1965, both from the Miocene of the Marshall Islands, are un- doubtedly members of Neritilidae. As in Neritilia and Pisulina, these two species possess an inclined protoconch bearing spiral ridges, but differ from Neritilia and Pisulina in important ways (Kano and Kase, 2000; unpublished data). Implications of paucispiral protoconch Pisulina species have either a paucispiral or multispiral protoconch. Nevertheless, the species are undoubtedly closely related to one another, because of the many close similarities in other shell characters. We suggest that the paucispiral protoconch originated from the multispiral protoconch of an ancestral Pisulina species, as described below. Most aquatic species of Neritopsina have a long planktotrophic duration after hatching from their egg cap- sule, and feeding veligers secrete a multispiral larval shell. However, species of some freshwater genera (e.g., Theodoxus) have a very large (ca. 0.9 mm) paucispiral protoconch and their development is quite different from that of other members of Neritopsina. They undergo benthic de- velopment, and metamorphosis occurs within the egg cap- sule by means of nurse-egg feeding (Bandel, 1982). The juveniles crawl out from the capsule with their foot. According to Holthuis (1995), free-swimming veligers (an- cestral for the group) were lost at least four times in the evo- lutionary history of Neritidae, and in Nerita and Vitta the loss occurred within the genus (or subgenus). The non- planktotrophic (benthic or lecithotrophic) development of Pisulina seems to have originated from a planktotrophic an- cestor, after the origin of the genus, by exploiting an adap- tive modification different from freshwater neritids. Benthic development is much more prevalent in freshwater inverte- brates than in their marine relatives, because the down- stream loss of freshwater larvae in moving water is the primary determinant for benthic development (Holthuis, 1995). Meanwhile, the non-planktotrophic development of Pisulina may be an adaptation to the unique cryptic environ- ments in marine caves. Kase and Hayami (1992) and Hayami and Kase (1996) have shown that the predomi- nance of non-planktotrophic development and the domi- nance of brooding species among submarine cave bivalves primarily resulted from an adaptation to food-limited condi- tions. Although no examples of this have been found in gastropods so far, it may be that Pisulina underwent non- planktotrophic development and acquired a paucispiral protoconch by adapting to a cryptic habitat. Neritopsis radula (Linnaeus, 1758), another cave-dwelling species of Neritopsina, developed a similar paucispiral protoconch (Figure 13). It is worth noting that paucispiral and concentric opercular nuclei are connected with multispiral and paucispiral protoconchs. The paucispiral nucleus (the operculum of a veliger) grows during the planktotrophic period, while the concentric nucleus is formed in the egg capsule, providing an additional criterion for inferring the mode of development in gastropods. Pisulina adamsiana Nevill and Nevill, 1869 Figures 1; 2A; 3-4; 6-8 Pisulina adamsiana Nevill and Nevill, 1869, p. 160, pl. 17, fig. 4; Thiele, 1925, p. 32, pl. 3, fig. 16; Thiele, 1929, p. 111, fig. 54; Wenz, 1938, p. 431, fig. 1060; Knight et a/., 1960, p. 285, fig. 185-3; Habe, 1963, p. 231, 232, fig. 1; Ladd, 1977, p. 14, 15, pl. 1, figs 1, 2; Herbert and Kilburn, 1991, p. 320-322, figs. 1-3; Hinoide and Habe, 1991, p. 49 (in part), fig. 1. Material examined.— INDIA: "Calcutta"; 1 specimen, coll. Paetel, MNHB.—"Ganges River delta" (21°40’N, 88°00’E); pre 1913, 3 specimens, AMS C-034497.—MALDIVES: Ari Atoll; 25 m depth; January 1996; 1 specimen, coll. S. Gori.— JAPAN: "Shodokutsu (= small cave)", le Island, Okinawa (26°42.9’N, 127°50.1’E); 20 m depth, totally dark submarine cave; 1988; 12 specimens.—"Umagai" diving site, north of Hatenohama, east of Kume Island (26°21.1’N, 126°53.1’E); 24-28 m depth, submarine caves, totally dark inside; July 1996, 2 specimens.—"Witch’s House (= Majono-yakata)" diving site, northwest of Shimoji Island, Miyako Islands, Okinawa (24°49.3’N, 125°08.3’E); 35 m depth, submarine Taxonomic revision of Pisulina 119 Figure 14. The geographic distribution of Recent Pisulina species. Pisulina adamsiana Nevill and Nevill (solid circles), Pisulina biplicata Thiele (open circles), Pisulina maxima sp. nov. (solid triangles) and Pisulina tenuis sp. nov. (open triangle). The type locality of P. biplicata is not plotted, because it was designated only as "Indian Ocean." cave, totally dark inside; 54 specimens (10 specimens NSMT-Mo71618). — "Toriike" diving site, northwest of Shimoji Island (24°49.1’N, 125°08.3’E); 12-40 m depth, sev- eral caves branching from a huge tunnel, gloomy to totally dark inside; 1992-1996, 2 specimens.—"Black Hole" diving site, northwest of Shimoji Island (24°49.1’N, 125°08.3’E); 35 m depth, submarine cave, totally dark inside; 1 specimen.— "Sabachi Cave", southeast of Yonaguni Island, Yaeyama Islands, Okinawa (24°26.1’N, 122°57.5’E); 25-30 m depth, submarine cave, totally dark inside; September 1994, 2 specimens.—MALAYSIA: "Turtle Cavern", Sipadan Island, west Celebes Sea, Sabah (5°04.8'N, 118°36.5’E); 9-17 m depth, totally dark inside; May 1997, 10 specimens (includ- ing 9 live individuals; 1 empty shell NSMT-Mo71619).— PHILIPPINES: "Marigondon Cave" diving site, Mactan Island, Cebu (10°15.8’N, 123°59.2’E); 27 m depth, large submarine cave, totally dark inside; May 1994, more than 1000 specimens; November 1998, 3 live specimens. — Balicasag Island, Panglao, Bohol (9°32.7’N, 123°40.7’E); 14-40 m depth; submarine caverns, gloomy inside; May 1994, 162 specimens (10 specimens NSMT-Mo71620).— "Mapatin Cave" diving site, southwest of Maricaban Island, Batangas, Luzon (13°40.0’N, 120°49.0’E); 46 m depth, lava tube, totally dark inside; November 1998, 1 live specimen.— PALAU: "Virgin Hole", west of Ngemelis Island, Rock Islands (7°07.3/N, 134°14.1’E); 17 m depth, submarine cave, totally dark inside; April 1995, 4 specimens.—"Siaes Tunnel" diving site, southwest of Siaes drop off, ca. 6 km west-northwest of Aulong Island, Rock Islands (7°18.7’N, 134° 13.6’E); 24- 53.5 m depth, huge submarine tunnel; April 1995, 141 speci- mens; December 1997, 19 specimens. — NORTHERN MARIANAS: near "Grotto" diving site, north of Saipan Island (15°15.3’N, 145°49.5’N); 12-30 m depth, huge cave, gloomy to totally dark inside; November 1997, 31 specimens (includ- ing 3 live individuals).— near "Tinian Grotto" diving site, west of Tinian Island; 50-51 m depth, huge cave, gloomy to totally dark; November 1997, 6 specimens.— POHNPEI: "Plang Point" diving site, west of Pohnpei Island (6°51.4’N, 158° 06.6’E); 55m depth, cavern, gloomy inside; November 1999, 2 specimens.— HAWAI'I: "Worm Cave", off Ahihi-Kinau, Makena, Maui Island (20°35.3’N, 156°25.8’W); 26-31 m depth, submarine cave, gloomy to totally dark inside; October 1997, 54 specimens (including 5 live individuals).— "Lost Crater Caves" diving site, off Ahihi-Kinau (20°35.3’N, 156°25.7’W); 25 m depth, submarine lava cave, gloomy in- side; October 1997, 1 live individual.—"Long Lava Tube", off Pali Kaholo, South Kona, Hawai'i Island (19°21.8’N, 155° 56.8’W); 11 m depth, long lava tunnel, gloomy; November 1997, 16 specimens.—"Gustav Cave", off Ka’u Loa Point, South Kona (19°19.1’N, 155°53.2’W); 6-8 m depth, subma- rine cave, gloomy to totally dark inside; November 1997, 19 live individuals. PAPUA NEW GUINEA: between Magulata and Kabuluna Points, Kiriwina Island, Trobriand Group (8°27’S, 150°59’E); 73 m depth, coral sand bottom, outside outer reef; June 1970, 1 specimen, coll. W. F. Ponder and P.H. Colman, AMS C-345150.—NAURU: Aiwo (0°32.6’S, 166°54.5’E); 15-25.5 m depth, cavern, open to gloomy in- side; November 1999, 43 specimens. — AUSTRALIA: "Hangover Cave" diving site, west of Direction Island, Cocos (Keeling) Islands (12°06.3’S, 96°52.5’E); 51-52.3 m depth, cavern, gloomy inside; December 1999, 4 specimens. — "Boat Cave" diving site, Christmas Island; 2.4 m depth; to- tally dark inside; November 1999, 1 specimen.—"Thunder Dome" diving site, Christmas Island; 7.7-10.2 m depth, long cave, totally dark inside; December 1999, 12 specimens.— NEW CALEDONIA: east of Nuu Poa islet, Iles des Pins, New Caledonia (22°31.6’S, 169°25.8’E); 17-19.5 m depth, meandering submarine cave, gloomy inside; October 1996, 3 specimens, MNHN.—FIJI: north of Ono Island, Great Astrolabe reef (18°51.8’S, 178°27.0’W); 7-16 m depth; sub- marine tunnel, gloomy inside; December 1996, 2 specimens. —northwest of Dravuni Island, Great Astrolabe reef (18° 45.3’S, 178°28.0’W); 23-24 m depth; December 1996, 18 specimens.— TONGA: north of Haano Island, Ha’apai Group (19°38.2’S, 174°18.0’W); 44 m depth, cavern; December 1996, 6 specimens.—west of Mo’ung’one Island, Ha’apai 120 Yasunori Kano and Tomoki Kase Table 1. Comparison of shell characters in five species of Pisulina. Some of the character states in Pisulina subpacifica Ladd (those shown in parentheses) may not represent general features of the species, owing to the immature condition of the holotype. Shell diameter Shell Width of ridges Apertural Number of Species of largest à on teleoconch ? inner lip à thickness width specimen surface teeth Pisulina adamsiana 6.7 mm thick ca. 7um small 1 Pisulina subpacifica (1.2 mm) thick ? small 1 Pisulina biplicata 4.8 mm thick ca. Ium small 3-5 Pisulina maxima sp. nov. 13.7 mm very thick ca. 4um very large 3-7 Pisulina tenuis sp. nov. 4.0 mm thin ca. 4um large 4-5 Sinuation of Tubercle Max. dimension of à À : Protoconch Species inner line on ein protoconch exposed near base basal lip 9 adove teleconch Pisulina adamsiana absent present multispiral 155-215um Pisulina subpacifica absent (absent) multispiral 275um Pisulina biplicata present absent paucispiral 155-220um Pisulina maxima sp. nov. present absent paucispiral 180-275um Pisulina tenuis sp. nov. present absent paucispiral 210-300um Group (19°23.2’S, 174°28.6’W); 20.5-37.5 m depth, subma- rine cave, totally dark inside; December 1996, 1 specimen.— "Sea Fans Cave" diving site, east of Taungiskika Island, Vava'u Group (18°39.7’S, 174°04.2’W); 7 m depth, subma- rine cave, gloomy inside; December 1996, 9 specimens.— SOCIETY ISLANDS: Tetuatiare Passage, north of Raiatea (16°49.5’S, 151°29.6’W); 10 m depth; submarine caves, gloomy inside; December 1996, 1 specimen, MNHN. — "Cave Arue" diving site, west of Tahiti Island (17°30.9’S, 149°32.1’W); 22-30 m depth; submarine caves, gloomy in- side; December 1996, 12 specimens, MNHN.—'"Banc des Daulphins" diving site, west of Tahiti Island (17°29.9’S, 149°38.3’W); 20 m depth; submarine cavern, gloomy inside; December 1996, 103 specimens (50 specimens registered; MNHN). Distribution and age. — Tropical and subtropical Indo- Pacific (Figure 14). Holocene. Diagnosis.— Medium-sized Pisulina characterized by a thick, globose to obliquely ovate shell, a robust projection on inner lip, and ca. 7 um-wide wavy spiral ridges over teleoconch surface; protoconch multispiral, with exposed portion drop-shaped and 155 to 215 um in maximum dimen- sion; larval shell with 3 or 4 spiral ridges and many micro- scopic pits; inner line of inner lip callus continuous with basal lip without a sinus; basal lip with a weak tubercle. Description.—Shell small, up to 6.7 mm wide and 7.0 mm high, thick, globose to obliquely ovate, with a low spire and a blunt apex (Figure 1). Protoconch multispiral. Em- bryonic shell covered by larval shell whorls and by first teleoconch whorl to varying degrees based on protoconch inclination, smooth, sometimes with faint wavy ridges near teleoconch suture (Figure 4F); exposed portion of embryonic shell 70 to 90 um in maximum dimension. Larval shell coils about 1 volution, surrounded largely by first teleoconch whorl, obliquely ovate, about 360 um wide and 250 um high, inclined about 30° to teleoconch (Figure 4A, B, E, F); ex- posed drop-shaped area 155-215 um in maximum dimen- sion, almost smooth except for unevenly spaced growth lines; surface near apertural lip sculptured with 3 or 4 indis- tinct, ca. 3 um-wide, 80 to 140 um-long spiral ridges (Figure 4C), and also with many pits more or less irregularly ar- ranged in a spiral direction and sometimes giving rise to short grooves (bearing granules up to 0.5 um in diameter) by being connected with one another (Figure 4D). Apertural lip of larval shell biconvex, opisthocline and very discordant with first teleoconch whorl (Figure 4A). Teleoconch coils less than 3.3 in number, smooth to somewhat polished, first whorl coils almost planispirally; teleoconch surface with dense, ca. 7 um-wide spiral ridges, subdivided by growth lines (Figure 2A). Aperture narrow and semilunar; outer lip prosocline, angled 35° to 40° to shell axis, beveled and not reflected; inner lip thickened by callus, with a broad, strong, quadrangular projection at its middle and a weak tubercle on the base; inner line of inner lip callus is an inverse-S shape, without sinuation at base. Operculum (Figure 8A) with a paucispiral nucleus 215 to 230 um in maximum dimension (Figure 8B); apophysis moderately long and weakly curved spirally. Remarks.—According to Herbert and Kilburn (1991), the holotype from Southern Province of Sri Lanka (Ceylon) is thought to be in the Indian Museum, Calcutta. We have not examined the type specimen, but there is little possibility of mistaking the shells at hand with any but this remarkable species. Pisulina adamsiana is a quite distinctive species because it has a single robust quadrangular projection on the inner lip, whereas other modern species have multiple teeth. Moreover, this is the only modern species with a multispiral protoconch (Figure 4) and a paucispiral opercular nucleus (Figure 8B), which strongly suggest a relatively long Taxonomic revision of Pisulina 121 Figure 15. Pisulina subpacifica Ladd, (USNM 648341). Scale bar =1 mm. 1966. Holotype planktotrophic period for this species (see below). Furthermore, P. adamsiana differs from other Pisulina spe- cies by the inner line of its inner lip callus being inversely S- shaped, by the lack of a sinuation between the basal lip and the inner line of the inner lip callus, and by the presence of a weak tubercle on its basal lip (see Table 1). Intraspecific variation of shell characters is small in this species, perhaps because of genetic homogeneity related to its well-developed dispersion ability. Scheltema (1971) es- timated the duration of pelagic stage less than 55 days for Smaragdia viridis (Linnaeus, 1758). Taking the smaller size and fewer number of the larval shell whorls into considera- tion, the planktotrophic period of P. adamsiana is assumed to be shorter than that of S. viridis. Koike (1985) described the spermatozoon ultrastructure of "P. adamsiana (?)" and stated that the spermatozoon is simi- lar to that in Clithon retropictus (Martens, 1879), Neritina plumbea Sowerby, 1855, Neritina variegata Lesson, 1830, and Septaria porcellana (Linnaeus, 1758). However, the sperm of P. adamsiana from Sipadan Island is similar to the sperm of Waldemaria in Helicinidae rather than to the sperm of neritids (J. Healy, personal communication). It is likely that Koike’s (1985) identification of P. adamsiana is incor- rect. Pisulina subpacifica Ladd, 1966 Figure 15 Pisulina subpacifica Ladd, 1966, p. 59, pl. 11, fig. 10. Material examined.— Holotype from Bikini Island, Bikini Atoll, Marshall Islands; horizon in drill hole, at a depth of 789-799 feet (240-244m), late Miocene, USNM 648341. Distribution.—Marshall Islands, known only from the type locality. Late Miocene. Diagnosis.— Small Pisulina characterized by a globose and thick shell, a semilunar aperture and a strong quadran- gular projection on inner lip; exposed portion of protoconch drop-shaped, ca. 275 um in maximum dimension. Description.—Shell minute, 1.2 mm wide, 1.4 mm high, globose, thick, eroded, creamy in color, opaque, with a very low spire (Figure 15). Protoconch surrounded by first teleoconch whorl, drop-shaped in apical view, and visible portion is ca. 275 um in maximum dimension. Teleoconch of 1.5 whorls, with first whorl coiled almost planispirally; ex- terior surface lacking visible sculpture. Aperture small and semilunar in shape; outer lip prosocline, angled 35° to shell axis; inner lip thick and blunt at margin due to erosion, bear- ing a large, robust, adaxially convex quadrangular projection ca. 310 um wide and ca. 120 um high at its midpoint; inner line of inner lip callus inversely S-shaped, strongly concave in parietal area, and continues to basal lip without sinuation. Remarks.—This Miocene species is known only from the holotype. Pisulina subpacifica is very similar to P. adam- siana in having a large, broad and quadrangular projection on its inner lip. Moreover, the present species seems to pos- sess a multispiral protoconch as seen in P. adamsiana, judg- ing from the drop-shaped protoconch that is exposed above the first teleoconch. Ladd (1966) separated this species from P. adamsiana based on its smaller shell size and lower spire, but the holotype of Pisulina subpacifica is unequivo- cally an immature specimen so these differences cannot be used to separate the two species. Fortunately, there are two characteristics that convincingly separate these two species. In P. subpacifica, the maximum dimension of the exposed portion of the protoconch is much larger (Table 1), and the inner lip projection is much stronger and twice as large as in P. adamsiana. Pisulina biplicata Thiele, 1925 Figures 2B; 5A, B; 16; 17A Pisulina biplicata Thiele, 1925, p. 32, pl. 3, fig. 15. Pisulina adamsiana Nevill and Nevill. Komatsu, 1986, p. 42, 43, pl. 8, fig. 9; Hinoide and Habe, 1991, p. 49 (in part), fig. 2; Fukuda, 1993, p. 31, fig. 120; Sasaki, 1998, p. 117, figs. 78g, h. Material examined.—Holotype from Indian Ocean ("East India?"), coll. von Finsch, MNHB.—JAPAN: Tsuchihama, Amami-Ohshima Island, Kagoshima (28°24.4’N, 129° 21.1’E); beach drift; July 1991, 14 specimens.—March 1993, 18 specimens.—Sankakubama, Naze-shi, Amami-Ohshima Island (28°23.1’N, 129°30.3’E); beach drift; July 1991, 36 specimens. — Ankyaba, Kakeroma Island, Amami Islands 122 Yasunori Kano and Tomoki Kase Figure 16. Pisulina biplicata Thiele, 1925. from Shimoji Island, Okinawa (NSMT-Mo71621). bar = 2 mm for B and C. (28°06.2’N, 129°21.1’E); beach drift; August 1993, 18 speci- mens. — Kunigami, Okinoerabu Island, Amami Islands (27°25.9'N, 128°42.8’E); beach drift; August 1992, 3 speci- mens. — "Devils Palace (= Mao-no-kyuden)" diving site, Shimoji Island, Miyako Islands, Okinawa (24°49.7’N, 125° 08.2’E); 25 m depth, submarine tunnels, gloomy inside; 1992, 93 specimens (10 specimens NSMT-Mo71621).— "Cross Hole" diving site, northwest of Irabu Island, Miyako Islands (24°51.6’N, 125°09.5’E); 15 m depth, submarine cave gloomy inside; 4 specimens, coll. M. Taniguchi.—north of Kohama Island, Yaeyama Islands (24°21.5’N, 12388.9’E); 15-20 m depth, crevices; March 1996, more than 1000 A. Holotype (MNHB), juvenile shell. Scale bar = 1 mm. B. Mature shell (four views) C. Mature shell (lower left specimen only) from Yap Island (NSMT-Mo71623). Scale specimens (20 specimens NSMT-Mo71622).—off Nishino- hama, Kuroshima Island, Yaeyama Islands (24°14.6’N, 123° 59.0’E); 10 m depth, sandy bottom; March 1996, 1 speci- men.— PHILIPPINES: Balicasag Island, Panglao, Bohol (9° 32.7'N, 123°40.7’E); 14-40 m depth; submarine caverns, gloomy inside; May 1994, 56 specimens.—PALAU: "Siaes Tunnel" diving site, southwest of Siaes dropoff, ca. 6 km west-northwest of Aulong Island, Rock Islands (7°18.7’N, 134°13.6’E); 24-53.5 m depth, huge submarine tunnel; April 1995, 3 specimens.—YAP: "Spanish Wall" diving site, west of Gilman, Yap Island (9°27.2’N, 138° 02.5’E); 20-24 m depth, caverns and a small tunnel; November 1997, 18 Taxonomic revision of Pisulina 123 specimens (6 specimens NSMT-Mo71623).— "Big Bend" diving site, west of Kanifay, Yap Island (9°28.1’N, 138° 02.8’E); 8 m depth, a small cave, gloomy inside; November 1997, 4 specimens.—AUSTRALIA: Michaelmas Cay, Great Barrier Reef, Queensland (16°36’S, 145°59’E); May to June 1926, 1 specimen, coll. T. Iredale and G. P. Whitley (G. B. R. Boring Expedition), AMS C-345143.—Green Island, Great Barrier Reef (16°46’S, 145°58’E); May 1926, 1 specimen, coll. T. Iredale (G. B. R. Expedition), AMS C-345144.—East Face, Lizard Island, Great Barrier Reef (14°40’S, 145°29’E); 20 m depth; December 1974, 1 specimen, coll. W. F. Ponder, P. H. Colman and I. Loch, AMS C-345145.—NEW CALEDONIA: east of Nuu Powa islet, lles des Pins, New Caledonia (22°31.6’S, 169°25.8’E); 17-19.5 m depth, mean- dering submarine cave, totally gloomy inside; October 1996, 2 specimens, MNHN.—Noumea (22°16’S, 166°27’E); pre- 1950, 1 specimen, coll. T. Iredale, AMS C-345147. — VANUATU: White Sands, ca. 40 km from Port Vila, south- east of Efate Island (17°47’S, 168°33’E); March 1975, 2 specimens, coll. P. H. Colman, AMS C-345148.—west of Efate Island (17°39.1’S, 168°11.3’E); cavern; October 1996, 1 specimen.—"Taj Mahal" diving site, west of Efate Island (17°38.4’S, 168°08.7’E); 18 m depth, submarine cave, gloomy to totally dark inside; October 1996, 7 specimens.— FlJI: Nadi Bay (Tomba Ko Nandi), Viti Levu Island (17°44’S, 177°25’E); 9-35 m depth; 1962, 2 specimens, coll. J. Laseron, AMS C-345149.—northwest of Dravuni Island, Great Astrolabe reef (18°42.5’S, 178°29.8’W); 8 m depth, submarine cave, totally dark inside; December 1996, 1 specimen.—northwest of Dravuni Island, Great Astrolabe reef (18°45.3’S, 178°28.0’W); 23-24 m depth, cavern, gloomy to totally dark inside; December 1996, 5 specimens. —north of Ono Island, Great Astrolabe reef (18°51.8’S, 178° 27.0'W); depth 7-16 m, submarine tunnel, gloomy in- side; December 1996, 13 specimens.—TONGA: east of Fao Island, Ha’apai Group (19°46.5’S, 174°22.6’W); 6-7.5 m depth, submarine tunnel, gloomy inside; December 1996, 2 specimens. — southwest of Mo’ung’one Island, Ha’apai Group (19°38.3’S, 174°29.6’W); 11-28 m depth, cavern; December 1996, 3 specimens.—PITCAIRN GROUP: North Beach, Henderson Island; middle or late Pleistocene sedi- ments in an uplifted cave; 1 specimen, coll. R. C. Preece (Pitcairn Islands Scientific Expedition 1991-2), UMZC. Distribution and age.—Tropical and subtropical areas of the Indo-Pacific (Figure 14). Middle or late Pleistocene to Recent. Diagnosis. — Medium-size Pisulina characterized by a glossy, thick, globose to pear-shaped shell, a high conical spire, a paucispiral protoconch, a semilunar aperture, and 3 to 5 blunt, somewhat squarish teeth along inner lip; teleoconch surface with microscopic spiral rows of granules. Description.—Shell small, up to 4.8 mm wide and 5.5 mm high (1.7 mm wide and 1.6 mm high in holotype; Figure 16A), thick, globose to pear-shaped, with a moderately low to rather high conical spire (Figure 16B, C). Protoconch paucispiral, coiling almost planispirally with a slightly angulate periphery, ca. 310 um wide and ca. 250 um high, not inclined with respect to teleoconch (Figure 5A, B); outer lip of protoconch with faint and fine growth lines, remainder of protoconch smooth except for 15 to 25 indistinct longitudi- Figure 17. Ontogenetic changes in the apertural teeth of individuals of three Pisulina species from different geographic regions, seen in oblique apertural view. A. Pisulina biplicata Thiele, a-h: from Okinawa, i: Indian Ocean (Holotype), j: the Philippines, k: Palau, I-o: Yap, p-q: Fiji. B. Pisulina maxima sp. nov., a: Saipan Island (Holotype), b: the Philippines, c-j: Palau. C. Pisulina tenuis sp. nov., a-f: Okinawa. nal folds; protoconch aperture longitudinally straight and clearly demarcated from teleoconch; visible portion of protoconch 155 to 220 um in maximum dimension (ca. 170 um in holotype). Teleoconch of up to 3.3 whorls (2.2 in holotype); last whorl inflated and with a small, somewhat concave area below suture; exterior surface smooth and glossy, but weakly sculptured with faint growth lines and mi- croscopic spiral ridges (ca. 1 um wide; Figure 2B), consisting of rows of minute granules. Aperture semilunar, small; outer lip prosocline, angled 40° to 50° to shell axis and beveled; inner lip heavily callused with 3 to 5 rather blunt and somewhat squarish teeth at margin (Figure 17A); inner line of inner lip callus convex on columellar area, and contin- ues toward the basal lip with a shallow sinus. Remarks.—The shell of P. biplicata is frequently found as beach drift in southern Japan, but live specimens have not been found. Several opercula most probably from P. biplicata have been found together with more than 1000 124 Yasunori Kano and Tomoki Kase Figure 18. Pisulina maxima sp. nov. A. Holotype (NSMT-Mo71624) from Saipan. B. Paratype (NSMT-Mo71625) from Balicasag Island, Philippine Islands. Scale bars = 2 mm. empty shells of this species in sediments from crevices north of Kohama Island in Okinawa Prefecture. The operculum of P. biplicata is almost identical to that of P. adamsiana. Variation in shell characters is primarily manifested by the number and shape of teeth along the inner lip (Figure 17A). Specimens from Japan and the Philippines generally bear three squarish teeth, while those from Micronesian and southern Pacific islands commonly have more than three round teeth. Japanese authors have long overlooked P. biplicata and misidentified it as P. adamsiana (Komatsu, 1986; Hinoide and Habe, 1991; Fukuda, 1993; Sasaki, 1998). Thiele (1925) established P. biplicata based on a single specimen and distinguished it from P. adamsiana by its supposed lower spire and the presence of two teeth on its inner lip. Unfortunately, these characters cannot be used to separate the two species, because the holotype of P. biplicata clearly is an immature specimen. The degree of spire elevation is highly dependent on growth stage, and mature P. biplicata possess the highest spire in this genus. Also, the presence of only two teeth along the inner lip (Figures 16A; 17A-i) is attributed to the immature state of the holotype. Examination of thousands of specimens from a number of localities clearly reveals that this species can easily be dis- tinguished from P. adamsiana by the presence of a paucispiral protoconch, multiple teeth along the inner lip and a sinus in the inner line of the inner lip callus (Table 1). In addition, the shell surface of P. biplicata is covered with rows of microscopic granules, while that of P. adamsiana is cov- ered with dense microscopic ridges (Figure 2A, B). Pisulina maxima sp. nov. Figures 2C; 5C; 9; 17B; 18 Holotype. — NSMT-Mo71624, A huge cave near the "Grotto" diving site, on the northern side of Saipan Island, northern Mariana Islands (15°15.3’N, 145°49.5’N); 20-23.6 m depth. Taxonomic revision of Pisulina 125 x P.maxima | o P.tenuis 4 P.biplicata | ee | X (mm) Figure 19. Relationship between the shape of the last whorl and the aperture in three Pisulina species: Pisulina maxima sp. nov. (Y=1.668X°*", R°=0.995, n=100), Pisulina tenuis sp. nov. (Y=1.650X°**, R°=0.985, n=100) and Pisulina biplicata Thiele (Y=2.417X°’*, R°=0.989, n=100). Specimens were measured in the following way under a microscope with a drawing attachment: X = apertural length from the abapertural margin of whorl to apertural teeth along the axis of the maximum dimension; Y = apertural height along an axis that is perpendicu- lar to X and in contact with the apertural teeth. Shells used for measurements were selected arbitrarily to include all the ontogenetic stages greater than Y = 1 mm. Probabilities that the observed differences in the slopes of the growth lines arose by chance were calculated using a formula shown in Imbrie (1956). This figure shows that P. biplicata and P. tenuis are significantly different in having distinct slopes (P < 0.01); P. maxima and P. tenuis are meaningfully different (0.01 < P < 0.05). Nineteen specimens of P. maxima greater than 4 mm in the Y dimension are not plotted in this graph (the largest such specimen attains Y = 7.53 mm). Paratypes.—JAPAN: Serakaki, Onna, Okinawa Island; 25 m depth, submarine cave; August 1998, 3 specimens, coll. H. Kinjo.— MALAYSIA: "Turtle Cavern", Sipadan Island, west Celebes Sea, Sabah (5°04.8’N, 118°36.5’E); 9-17 m depth, totally dark inside; May‘ 1997, 17 live individuals. — PHILIPPINES: "Marigondon Cave" diving site, Mactan Island, Cebu (10°15.8’N, 123°59.2’E); 27 m depth, large submarine cave, totally dark inside; May 1994, 1 specimen. —Balicasag Island, Panglao, Bohol (9°32.7’N, 123°40.7’E); 14-40 m depth, submarine caverns, gloomy inside; May 1994, 2 specimens (NSMT-Mo71625).— PALAU: "Siaes Tunnel" diving site, southwest of Siaes dropoff, ca. 6 km west-northwest of Aulong Island, Rock Islands (7°18.7'N, 134° 13.6’E); 24-53.5 m depth, huge submarine tunnel; April 1995, 65 specimens; December 1997, 148 specimens (30 specimens NSMT-Mo71626). — "Blue Hole" diving site, northwest of Ngemelis Island, Rock Islands (7°08.3’N, 134° 13.3’E); 36-38 m depth, submarine cave, totally dark inside; December 1997, 2 live individuals. — NORTHERN MARIANAS: (the type locality); 12-30 m depth, huge cave, gloomy to totally dark inside; November 1997, 24 specimens (10 specimens NSMT-Mo71627); October 1999, 11 speci- mens.—near "Tinian Grotto" diving site, west of Tinian Island; 50-51 m depth, huge cave, gloomy to totally dark; November 1997, 3 specimens.—AUSTRALIA: "Thundercliff Cave" diving site, Christmas Island (10°28.4’S, 105°36.4’E); 1.3-6 m depth, totally dark inside; November 1999, 4 speci- mens. Distribution and age. — Southeast Asia (Figure 14). Recent. Diagnosis. — Large Pisulina characterized by a sub- globose to hemispherical and very thick shell, a paucispiral protoconch with an almost smooth surface, a large semicir- cular aperture and 3 to 7 teeth along inner lip; microscopic spiral ridges on shell surface are ca. 4 um wide. Description.—Shell medium in size, up to 13.7 mm wide and 12.1mm high (10.9mm wide and 9.8mm high in holotype), very thick, somewhat swollen hemispherical in shape (Figure 18); spire very low and apex pointed. Protoconch paucispiral, a simple low dome-shape in apical view, glossy, smooth, without inclination to teleoconch; visi- ble portion surrounded by teleoconch 180 to 275 um in maxi- mum dimension, ornamented by 15 to 25 indistinct longitudinal folds, with faint growth lines on outer lip (Figure 5C); protoconch aperture clearly demarcated from teleoconch by a sharp line. Teleoconch whorls less than 4 in number (3.8 in holotype), striated by microscopic growth lines and spiral ridges ca. 4 um wide (Figure 2C), the last whorl coiling nearly planispirally. Aperture semicircular, largely open, prosocline with an angle of 30° to 35° to shell axis; outer lip thick, widely beveled and slightly dilated out- ward; inner lip covered with a moderately thick callus, con- vex adaxially at middle, with 3 to 7 dull teeth (Figure 17B); inner line of inner lip callus convex at columellar area and continues to basal lip with shallow concavity. Operculum with a concentric nucleus ca. 220 um in maximum dimension (Figure 9C), and bears a long and spirally curved apophysis (Figure 9A, B). Remarks.—This new species is similar in protoconch mor- phology to P. biplicata, but is primarily distinguished from the latter by its much larger shell size and less glossy teleoconch surface. In addition, the whorls of P. maxima expand more rapidly than in P. biplicata, so that the former species has a lower spire and a larger aperture than the lat- ter species (Figure 19). This species further differs from P. biplicata in the number and shape of the inner lip teeth: P. maxima has up to seven rounded teeth, with the largest one located centrally, whereas P. biplicata has less than five squarish teeth, with the largest tooth located adapically. In addition, the third tooth ontogenetically appears above the first and second ones in the new species, while it appears below them in P. biplicata (Figure 17). Pisulina tenuis sp. nov. Figures 2D; 5D, E; 17C; 20 Holotype.—NSMT-Mo71628, "Sabachi Cave," southeast of Yonaguni Island, Yaeyama Islands, Okinawa, Japan (24° 26.1’N, 122°57.5’E); 25-30 m depth, submarine cave, 126 Yasunori Kano and Tomoki Kase Figure 20. Pisulina tenuis sp. nov. Holotype (NSMT-Mo71628) from Yonaguni Island, Okinawa. Scale bar = 2 mm. totally dark inside. Paratypes.—More than 1000 specimens from the type lo- cality; September 1994 (100 specimens registered; NSMT- Mo71629). Distribution and age. Japan (Figure 14). Recent. Diagnosis.—Small Pisulina characterized by a thin shell, subglobose to swollen hemispherical shape, a moderately large semicircular aperture, and 4 or 5 teeth along inner lip. Protoconch paucispiral, ovate and smooth. Teleoconch surface with spiral ridges ca. 4 um wide. Description.—Shell small, 4.0 mm wide and 3.6 mm high in largest specimen (3.9 mm wide and 3.5 mm high in holotype), obliquely ovate to hemispherical in shape, and thin but solid. Spire low, with a pointed apex (Figure 20). Protoconch paucispiral, smooth except for 15 to 25 indistinct longitudinal folds near suture, glossy, ca. 330 um wide and ca. 270 um high, coils almost planispirally, and not inclined to teleoconch (Figure 5D, E); visible portion surrounded by teleoconch 210 to 300 um in maximum dimension (ca. 210 um in holotype); outer lip sculptured with indistinct growth lines and ridges (Figure 5D); protoconch aperture demar- cated clearly from teleoconch and weakly sinuous in its mid- dle part. Teleoconch coils up to 2.9 in number (2.8 in holotype), slightly concave below suture; exterior surface smooth except for faint growth lines and microscopic spiral ridges ca. 4 um wide (Figure 2D). Aperture semicircular in shape and widely open; outer lip prosocline, angled 35° to 40° from shell axis, weakly beveled and somewhat thick- ened on interior; inner lip moderately thick, bearing a convex Known only from Yonaguni Island, adaxial margin and 4 or 5 dull teeth of almost equal strength (Figure 17C); inner line of inner lip callus convex in columellar area and continues to basal lip with a shallow sinus. Remarks.— Pisulina tenuis sp. nov. most closely resem- bles P. maxima, since both species share the same protoconch morphology, shell form and surface micro- sculpture. The two species are also similar in the number and shape of the inner lip teeth. However, P. tenuis clearly differs from P. maxima by its thinner shell and smaller shell size (see Table 1). A morphometric analysis shows that P. tenuis differs from P. maxima in having a smaller Y/X ratio (Figure 19). Pisulina tenuis has not yet been found alive. Opercula thought to belong to this species were found among a vast number of empty shells at the type locality. The opercular features of P. tenuis are the same as seen in P. adamsiana and P. maxima. Pisulina sp. Figure 21 Material examined.— North Beach, Henderson Island, Pitcairn Group; middle or late Pleistocene sediments in an uplifted cave; 2 specimens, coll. R. C. Preece (Pitcairn Islands Scientific Expedition 1991-2), UMZC. Distribution and age.— Known only from Henderson Island. Middle or late Pleistocene. Description.—Shell small, thick, up to 4.2 mm wide and 3.8 mm high, hemispherical in outline (Figure 21A). Spire Taxonomic revision of Pisulina 127 Figure 21. Pisulina sp. from Henderson Island, Pitcairn Group (UMZC). A. Scale bar = 2 mm. details of apertural teeth. Scale bar = 500 um. relatively high, with a protruding apex. Protoconch poorly preserved, smooth, a simple dome-shape, 205 to 240 um in maximum dimension and _ sunken into teleoconch. Teleoconch of up to 3.1 volutions, concave below suture; ex- terior surface eroded to some extent, but seemingly smooth except for indistinct growth lines. Aperture semicircular and large; outer lip prosocline, angled about 35° to shell axis, beveled and slightly expanded outward; inner lip covered with a moderately thick callus, roundly convex with 4 dull teeth at margin (Figure 21B); inner line of inner lip callus merges into basal lip with a shallow sinus. Remarks.—This unnamed Pleistocene species is similar to P. tenuis in shell size, the shape of its teleoconch whorls, and the number and shape of the teeth on the inner lip (Figure 21B). Moreover, both species have almost the same dimensions for the portion of the protoconch exposed above the teleoconch whorls. This fossil species seems to be distinct from P. tenuis by its thicker shell and higher spire, but it is left unnamed until better preserved material is avail- able. Several fossil specimens similar to this unnamed fossil species have been collected from early to middle Pleistocene sediments on Niue, Cook Islands, by G. Paulay. They differ slightly from Pisulina sp. by having a lower spire and fewer teeth on the inner lip, and by the absence of a concavity below the suture of the teleoconch whorls. However, the specimens from Niue cannot be compared in detail, owing to their poor state of preservation. B. Oblique apertural view showing Acknowledgments The materials in this paper were collected during the sub- marine cave expeditions in the tropical Pacific islands for the last 10 years directed by the second author. Special thanks are due to S. Ohashi and S. Kinjo who joined all the expedi- tions as members and dove many deep caves. Without doubt, our expeditions would have failed had it been without their self-sacrificing cooperation. Other members of the ex- pedition include |. Hayami (Kanagawa University) and G. Paulay (University of Guam), to whom we are acknowl- edged. We thank the following persons who helped us in various ways: M. Cathrein (Christmas), K. Ekawa (Kago- shima), A. Fielding (Hawai’i), R. Gibson (Vanuatu), S. Gori (Italy), B. Holthuis (Guam), H. Kinjo (Okinawa), H. Kubo (Okinawa), C. Meyer (Guam), K. Mochizuki (Palau), K. Ogura (Okinawa), H. Saito (NSMT), M. Severns (Hawai'i), J. Starmer (Palau), M. Taniguchi (Okinawa) and Y. Yamazaki (Palau). ORSTOM (Noumea) and the University of the South Pacific gave facilities and logistic support for our expeditions in New Caledonia and Fiji, respectively. We also thank the following for the loan of materials: M. Glaubrecht (MNHB), I. Loch (AMS) and J. Thompson (USNM). This study was sup- ported by grants to T. K. from the Ministry of Education, Science and Culture, Japan (nos. 06454003, 08041162, 11691196 and 11833018), the Fujiwara Natural History Foundation, and the Research Institute of Marine Inverte- brates. 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(cl vd so : 4 AVIIÉ CLR ‘ ee Be & eT ea her der Paleontological Research, vol. 4, no. 2, pp. 131-137, June 30, 2000 © by the Palaeontological Society of Japan A new potamolepid freshwater sponge (Demospongiae) from the Miocene Nakamura Formation, central Japan KEIJI MATSUOKA' and YOSHIKI MASUDA’ ‘Toyohashi Museum of Natural History, 1-238, Oiwa-cho, Toyohashi, Aichi 441-3147, Japan (matsuoka @amitaj.or.jp) *Department of Biology, Kawasaki Medical School, 577, Matsushima, Kurashiki, Okayama 701-0192, Japan Received 22 November 1998; Revised manuscript accepted 8 March 2000 Abstract. The freshwater sponge Oncosclera kaniensis sp. nov. of the demospongian family Potamolepidae is described from the Early Miocene Nakamura Formation (Mizunami Group) in Gifu Prefecture, central Japan. This is the first fossil record of the Potamolepidae in the world and also is the first documentation of fossil sponges from the Nakamura Formation. Oncosclera kaniensis sp. nov. is briefly discussed. Paleoecology of Key words: freshwater sponge, Potamolepidae, Oncosclera, Early Miocene, Nakamura Formation Introduction A number of well preserved sponges assignable to a new species of the genus Oncosclera Volkmer-Ribeiro, 1970 of the family Potamolepidae (Demospongiae) were recovered from the Early Miocene Nakamura Formation, Mizunami Group in Gifu Prefecture, central Japan. This is the first fos- sil record of the genus Oncosclera as well as of the family Potamolepidae. The discovery dramatically extends the fossil record of the family Potamolepidae back to the Early Miocene. Recent species of potamolepid sponges are dis- tributed in South America, Africa, and Asia, and have been considered as Gondwanian elements (Volkmer-Ribeiro and De Rosa-Barbosa, 1978). The discovery of a fossil potamo- lepid sponge from Japan is very important for future paleogeography and phylogenetic analysis. The purpose of this paper is to describe a new species and discuss its paleoecology. Geologic setting The fossil sponges were collected from tuffaceous sand- stone exposed on a riverbed of the Kiso River, Dota area of the Minokamo basin, Kani City, Gifu Prefecture, central Japan (Figure 1). Distributed in this riverbed is the Mizunami Group, a stratotype of the Lower to Middle Miocene in Japan, that is composed of nonmarine sedi- ments, while the group is composed of marine sediments in the neighboring Mizunami and Iwamura basins. A recent detailed lithostratigraphical study of the Mizunami Group along the Kiso River in the Minokamo basin by Shikano (1995) has shown that the group can be divided into three formations in ascending orders: the Hachiya Formation, Nakamura Formation, and Hiramaki Formation. The Nakamura Formation, from which the fossil sponges were recovered, is 130 m thick, of fluvial and lacustrine ori- gin, and subdivided into the Lower Member, Middle Member, and Upper Member. The potamolepid sponges described here were recovered from a sandstone layer of the Upper Member, about 2 m below the contact with the Hiramaki Formation (Figure 2). The Upper Member is estimated to be 30 m thick and consists of tuffaceous mudstone, sandstone, conglomerate, and lignite. The basal layer of the Upper Member consists of massive tuff, and was dated as 21.7+ 1.5 Ma by the fission track method (Shikano, 1995). The sponge-bearing sandstone layer is ill-sorted and con- tains much granular material and organic debris. Other fos- sils associated in this sandstone layer are diatoms, macroplants, molluscs, fishes, and mammals. The fossil molluscs in this sandstone include an undescribed viviparid gastropod, Bellamya sp. and undetermined unionid bivalves such as Anodonta sp. and "Unio" sp. The fossil fishes were identified as Cypris sp., Cyprininae gen. et sp. indet., and Cultrinae gen. et sp. indet. (Yasuno, 1982; 1983). The fos- sil molluscs and cyprinids are all permanent freshwater dwellers. The fossil mammals from the sandstone layer are Plesiosorex sp., Amphilagus sp., Youngofiber sinensis, Anchitheriomys sp., Pseudotheridomys sp., and Apeomys (?) sp. (Tomida and Setoguchi, 1994; Tomida and Goda, 1995; Tomida et al., 1995). Systematic description Class Demospongiae Sollas, 1885 Order Hadromerida Topsent, 1894 Family Potamolepidae Brien, 1967 Genus Oncosclera Volkmer-Ribeiro, 1970 132 Keiji Matsuoka and Yoshiki Masuda 36°N x Pacific Ocean = St. RARE =. Jane on DS Imawatari Kani City 136°E 137°E Figure 1. Fu E 8 | x = Mudstone <@ Fossil potamolepid sponge Nakamura Formation 50cm Figure 2. Columnar section showing the sponge-bearing horizon in the Nakamura Formation. Type species: Spongilla jewelli Volkmer, by original desig- nation. Diagnosis.—Megascleres slightly curved, stout, occasion- ally microspined, amphioxea to amphistrongyla. Micro- scleres absent. Gemmoscleres short, stout, feebly curved, extremely variable, amphistrongyla or amphioxea, swollen at central portion, usually spined; spines more numerous at both ends. Map showing the sponge locality of the Nakamura Formation, Dota, Kani City. Discussion. — Brien (1967) proposed the new family Potamolepidae for the Ethiopian genera Potamolepis and Potamophloios. The family consists of six genera: Oncosclera, Uruguaya, Sterrastrolepis, Potamolepis, Pota- mophloios, and Stratospongilla, and the family is considered to have been derived from a certain marine group of the order Hadromerida (Volkmer-Ribeiro and De Rosa-Barbosa, 1978). Of the six genera above, Oncosclera, Uruguaya and Sterrastrolepis from South America have been thought in part to be relicts of the Gondwanian fauna (Volkmer-Ribeiro, 1981). Oncosclera was originally introduced as a genus of the family Spongillidae by Volkmer-Ribeiro (1970), which in- cluded two living species in Brazil, ©. jewelli (Volkmer, 1963) and O. navicella (Carter, 1881). This genus is very close to the genus Stratospongilla, but differs from the latter in the absence of microscleres. The genus Oncosclera from South America consists of ten species: Oncosclera petricola (Bonetto and Ezcurra, 1967), ©. stolonifera (Bonetto and Ezcurra, 1967), ©. schubarti (Bonetto and Ezcurra, 1967), O. ponsi (Bonetto and Ezcurra, 1968), O. tonollii (Bonetto and Ezcurra, 1968), O. atrata (Bonetto and Ezcurra, 1970), O. spinifera (Bonetto and Ezcurra, 1973), and O. intermedia (Bonetto and Ezcurra, 1973) by Volkmer- Ribeiro (1981), who suggested that the number will be re- duced by synonymies in future studies. Spongilla (Stratospongilla) diahoti Rützler, 1968 from northern New Caledonia was transferred to the genus Oncosclera by Volkmer-Ribeiro and Rützler (1997). According to Volkmer- Ribeiro (1970, 1981), Spongilla rousseletti Kirkpatrick, 1906 and S.(Stratospongilla) shulbotzi Weltner, 1913 from central Africa, S. (Stratospongilla) gilsoni Topsent, 1912 from the Fiji Islands, and S. clementis Annandale, 1909 from the Philippines belong to the genus Oncosclera. Miocene potamolepid sponge from Japan 133 6 Figure 3. Oncosclera kaniensis sp. nov. 1. Sponge bodies encrust the postero-ventral area of the left valve of Anodonta sp., TMNH-02882 (paratype), “1. 2. Enlargement of the sponge bodies of TMNH-02882, X2.1. 3. Sponge bodies encrust the surface of Anodonta sp., vertical section, TMNH-02889a (paratype), * 1.2. 4. Sponge bodies encrust the surface of a cortex fragment (black color), TMNH-02881j (holotype), “1.2. 5. Attached surface of sponge bodies, TMNH-02886 (paratype), showing the outline of the gemmules represented by ring spots, X2.0. 6. Sponge bodies encrust the surface of a wood fragment, TMNH-02887, X 1.2. Oncosclera kaniensis sp. nov. nicipality of the type locality. Material studied. — Twenty-two specimens. Holotype: TMNH-02881 a-m, on 13 isolated blocks. Paratypes: Type locality.—Riverbed on the Kiso River, Dota, Kani TMNH-02885, 2883a, b, 02882, 02884 a, b, 02886. All de- City, Gifu Prefecture, Japan (Figure 1). posited in the Toyohashi Museum of Natural History. Etymology.—The species name is after Kani City, the mu- Diagnosis.—A species of Oncosclera characterized by Figures 3-5 134 Keiji Matsuoka and Yoshiki Masuda 50 um Figure 4. Spicular components of Oncosclera kaniensis sp. nov. 1. Amphistrongylous megasclere. 2. Amphioxeous megasclere. 3-5. Three forms of gemmoscleres. Scale bar= 50um. domination of amphistrongylous megascleres, small amount of amphioxeous megascleres, amphistrongylous gemmo- scleres, and dense covering of spines at both ends. Description. —Sponge encrusting shell surfaces of bivalve and wood fragments. Sponge surface even and generally less than 1 mm in thickness. Skeletal components consist- ing of megascleres and gemmoscleres. Gemmules with round spots, firmly adhering to basal part of sponge body, about 500 um in diameter, but compressed subspherically. Megascleres moderately small, almost straight, solid, amphistrongyla to amphioxea, covered with distinct spines at both ends, 100 to 179 pm in length and 7 to 15 um in thickness. Majority of megascleres stout and cylindrical amphistrongyla (Figure 4.1), occasionally with a few inter- mixed true amphioxea (Figure 4.2). Microscleres absent. Gemmoscleres stout, variably curved, inflated at middle (Figure 4.3-4.5); amphistrongyla densely covered with dis- tinct spines that are numerous at both ends; some of spines polyfurcate, and inner curved area smooth, 23 to 100 um in length, 4 to 7 um in thickness. Comparison.—The present new species is assigned to the genus Oncosclera in its shape and surface ornamentation of megasclere and gemmosclere. The new species is similar to the following Recent species from Argentina: Oncosclera ponsi (Bonetto and Ezcurra, 1968), Oncosclera atrata (Bonetto and Ezcurra, 1970), and Oncosclera tonollii (Bonetto and Ezcurra, 1968). Of the three species O. kaniensis sp. nov. is most similar to Oncosclera ponsi in spicular components, but it differs in having spinose amphioxeous megascleres. The present new species differs from Oncosclera atrata from the Parana River, Argentina in having amphistrongyla densely covered with distinct spines at both ends of the gemmoscleres. It also differs from Oncosclera tonollii from the Uruguay River, Argentina (Bonetto and Ezcurra, 1967) in having a less spinose sur- face of gemmoscleres and megascleres. This new species has gemmoscleres similar to the Recent species Oncosclera jewelli (Volkmer, 1963) known only from the Tainhas River of Brazil (Volkmer-Ribeiro, 1970) and O. schubarti (Bonetto and Ezcurra, 1967) from the Uruguay River, Argentina, but differs distinctly from the latter species in its spinose amphistrongylous and amphioxeous megascleres. Paleoecology. — Potamolepids commonly have highly silicified skeletons and lack spongin fibers. Many species of the genus Oncosclera encrust stable bottom surfaces in streams. Oncosclera atrata inhabits a curved bank of a tribu- tary of the Parana River in the Misiones Province, Argentina, where it encrusts surfaces of partly submerged rocks (Bonetto and Ezcurra, 1970). Oncosclera ponsi and O. tonollii encrust rocky bottoms in rapid and turbulent waters in the Uruguay River (Bonetto and Ezcurra, 1968). Both spe- cies grow in the upper and lower surfaces of the rocks, and the sponges encrusting the lower surfaces are disposed to grow exuberantly. Oncosclera jewelli in the Tainhas River of Brazil also encrusts exclusively stable bottom surfaces in fast streams close to rapids and/or falls. | Oncosclera navicella in the Amazon River of Brazil and Iguazu Fall of Argentina, on the other hand, encrusts ligaments and valves of the living freshwater bivalve Anodontites trapesialis forbesianus and Paxyodon syrmatophorus (Volkmer- Ribeiro, 1970; Tavares and Volkmer-Ribeiro, 1997). Oncosclera kaniensis sp. nov. is represented entirely by fossilized sponge bodies and encrusts two types of sub- strates: shell surface of the unionid bivalve Anodonta sp.(Figure 3.1-3.3) and surface of wood fragments (Figure 3.4-3.6). The sponge bodies on the unionid bivalve encrust the ventral and posterior parts of almost horizontally embed- ded articulated valves that are preserved as composite moulds (Figure 6.1). They also encrust the outer surfaces of isolated valves that are diagenetically compacted and em- bedded with the convex side up (Figure 6.2). The sponge bodies also encrust strongly compacted woods almost en- tirely (Figure 6.3) and encrust partly the wood fragments that remain in possession of annual rings (Figure 6.4). The shells and wood fragments may have provided hard sub- strates for colonization of the fossil sponges in the soft bot- tom environment. The gemmules of O. kaniensis sp. nov. can be seen by naked eye as ring spots. The gemmules of the fossils are located at the basal portion of the sponge as in O. jewelli and O. navicella (Figure 3.5). These facts strongly suggest that O. kaniensis sp. nov. dwelled in a river like the Recent Oncosclera species and had a habitat prefer- ence to the upper and lower surfaces of hard substrates (Figure 6.5 - 6.8). The unusual preservation of the megascleres and gemmoscleres of O. kaniensis sp. nov. may have resulted from its comparatively stout skeleton, strong attachment to the substrates and rapid burial after death. Acknowledgments We thank C. Volkmer-Ribeiro of Museu Rio-Grandense de Ciencias Natures, Porto Allegre, Brazil and Junji Itoigawa of Sugiyama Jogakuen University, Nagoya for reading the manuscript and offering valuable suggestions. Appreciation is also expressed to T. Goda, Aichi Prefecture, Japan for supplying specimens of the fossil sponges for this study. Miocene potamolepid sponge from Japan 135 7 Figure 5. SEM micrographs of Oncosclera kaniensis sp. nov. 1. Gemmule, vertical section, scale bar=100 um. 2. Amphi- strongylous megascleres, scale bar=50 um. 3. End parts of amphistrongylous megascleres, scale bar=10 um. 4. End parts of amphioxeous megascleres, scale bar=5 um. 5.Gemmoscleres, scale bar=10 um. 6.Gemmoscleres, scale bar=10 um. 7. End parts of gemmostcleres. scale bar=5 um. 136 Keiji Matsuoka and Yoshiki Masuda Figure 6. Mode of occurrences of Oncosclera kaniensis sp. nov. 1-4. Four types of encrustation. 1. Sponge bodies encrust an articulated valve of the unionid bivalve Anodonta sp. The bivalve is embedded with its comissure plane almost horizontal and is preserved as a composite mould. 2. Sponge bodies encrust the outer surface of an isolated valve of the unionid bivalve Anodonta sp. The valve is compacted diagenetically. 3. Sponge bodies encrust a strongly compacted wood fragment almost entirely. 4. Sponge bodies encrust a wood fragment that retains its annual rings. 5-8. Reconstruction of the four types of encrustation for 1 to 4, respectively. References Annandale, N., 1909: Freshwater sponges in the collection of the United States National Museum. —Part 1. Specimens from the Philippines and Australia. Proceedings of the United States National Museum, vol. 36, p. 627-623. Bonetto, A. A. and Ezcurra, |. D., 1967: Esponjas del Noreste Argentino. Acta Zoologica Lilloana, vol. 23, p. 331-347. Bonetto, A. A. and Ezcurra, |. D., 1968: El genero Spongilla Lamarck en el Rio Uruguay (Porifera, Spongillidae). Physis, vol. 27, no. 75, p. 429-436. Bonetto, A. A. and Ezcurra, |. D., 1970: Esponjas de los afluentes del alto Parana en la provincia de Misiones. Acta Zoologica Lilloana, vol. 27, p. 37-61. Bonetto, A. A. and Ezcurra, |. D., 1973: Aportes al conocimiento de las esponjas del Orinoco. Physis, vol. 32, no. 84, p. 13-18. Brien, P., 1967: Formation des statoblastes dans le genre Potamolepis: P. symoensi (Marshall), P. pechuelli (Marshall), P. schoutedeni (Burton). Bulletin de la Classe des Sciences, Académie royale de Belgique, vol. 53, p. 573-590. Carter, H. J., 1881: History and classification of the known species of Spongilla. The Annals and Magazine of Natural History, 5th Series, vol. 7, p. 77-107, pls. 5 6. Kirkpatrick, R., 1906: Report on the Porifera, with notes on species from the Nile and Zambesi. Zoological results of the third Tanganyika Expedition. Proceedings of the Miocene potamolepid sponge from Japan 137 Zoological Society of London, vol. 2, no. 1, p. 218-227. Rützler, K., 1968: Freshwater sponges from New Caledonia. Cahiers O. R. S. T. O. M. (Office de la Recherche Scientifique et Technique Outre-Mer, Serie Hydro- biologie, vol. 2, no. 1, p. 57-66. Shikano, K., 1995: Stratigraphy of the Nakamura Formation. In, Paleontology and stratigraphy of the Nakamura Formation in Minokamo Basin. Board of Education of Minokamo City, p. 2-18. (in Japanese) Tavares, Maria da Conceiçäo Marques and Volkmer-Ribeiro, C., 1997: Redescrigao das esponjas de agua doce Oncosclera navicella (Carter, 1881) (Potamolepidae) e Spongilla spoliata Volkmer-Ribeiro & Maciel, 1983 (Spongillidae). Biociéncias, Porto Alegre, vol. 5, no. 1, p. 97-111. Tomida, Y. and Goda, T., 1995: Dota local fauna: the first small mammal fauna from the Japanese Tertiary. Journal of Vertebrate Paleontology, vol. 15, no. 3 suppl., 57A. Tomida, Y., Kawai, K., Setoguchi, T. and Ozawa, T., 1995: A new record of Youngofiber (Castoridae: Mammalia) from the Early Miocene of Kani City, Central Japan. Bulletin of the National Science Museum, Ser. C, vol. 21, nos. 3, 4, p.103-109. Tomida, Y. and Setoguchi, T., 1994: Tertiary rodents from Japan. National Science Museum Monographs, no. 8, p. 185-195. Topsent, E., 1912: Description de Spongilla (Stratospongilla) gilsoni n. sp. Annales de Biologie Lacustre, vol. 5, p. 187-190. Volkmer, C., 1963: Spongilla jewelli n. sp. from fresh-water sponge at Brazil. Anais Academia Brasileira de Ciencia, vol. 35, no. 2, p. 271-273. Volkmer-Ribeiro, C., 1970: Oncosclera—a new genus of freshwater sponges (Porifera-Spongillidae) with rede- scription of two species. Amazoniana, vol. 2, no. 4, p. 435-442. Volkmer-Ribeiro, C., 1981: Porifera. In, Huribert, S. H., Rodriguez, G., and Santos, N. D. eds., Aquatic Biota of Tropical South America, Part 2: Anarthropoda. San Diego State University, San Diego, California. 298 pp. Volkmer-Ribeiro, C. and De Rosa-Barbosa, R., 1978: Neotropical freshwater sponges of the family Potamo- lepidae Brien, 1967, p. 503-511. In, Levi, C. and Boury- Esnault, N. eds., Biologie des Spongiaires, Colloques Internationaux Centre National de la Recherche Scientifique (Paris), no. 291. Volkmer-Ribeiro, C. and Rützler, K., 1997: Pachyrotula, a new genus of freshwater sponges from New Caledonia (Porifera: Spongillidae). Proceedings of the Biological Society of Washington, vol. 110, no. 4, p. 489-501. Weltner, W., 1913: Süsswasserschwämme (Spongillidae) der Deutschen Zentralafrika-Expedition 1907 - 1908. In, Wissenschaftliche Ergebnisse der: Deutschen Zentral- Afrika-Expedition, 1907-1908, vol. 4, (Zoology) 12, p. 475-485. Yasuno, T., 1983: Fossil pharyngeal teeth of sub-family Cultrinae collected from the Miocene Kani Group and Plio-Pleistocene Kobiwako Group in Japan. Journal of Fossil Research, vol. 16, p. 41-46. (in Japanese with English abstract) etm et i su | a ù a Ber ae, Eee! TP STEEL DR | a a ra | | nie Pang cassis Pee us] joss 2 | | a vk. a ee OR R Ca | Hwee | | DRE no x Re | Paleontological Research, vol. 4, no. 2, pp. 139-145, June 30, 2000 © by the Palaeontological Society of Japan Additions to Cretaceous decapod crustaceans from Hokkaido, Japan—Part 1. Nephropidae, Micheleidae and Galatheidae HIROAKI KARASAWA' and HIROSHI HAYAKAWA?’ ‘Mizunami Fossil Museum, Yamanouchi, Akeyo, Mizunami, Gifu 509-6132, Japan (e-mail: GHA06103 @nifty.ne.jp) *Mikasa City Museum, Mikasa 068-2111, Japan (e-mail: HQH03526 @ nifty.ne.jp) Received 17 January 2000; Revised manuscript accepted16 March 2000 Abstract. Four new species of decapod crustaceans are described from the Upper Cretaceous Upper Yezo Group in Hokkaido, Japan. The monotypic genus Paki (Thalassinidea, Micheleidae) is erected with P. rurkonsimpu sp. nov. Hoploparia kamuy sp. nov. (Astacidea, Nephropidae) repre- sents the first record of the genus Hoploparia from the Turonian-Santonian of Japan. Luisogalathea gen. nov. (Anomala, Galatheidae), erected with the type species L. tomitai sp. nov., contains two North American Cretaceous species, Galathea cretacea Stenzeland Eomunidopsis cobbani Bishop. Eomunidopsis kojimai sp. nov. (Anomala, Galatheidae) represents the first record of the genus from the North Pacific realm. Key words: Crustacea, Decapoda, Hokkaido, Japan, Upper Cretaceous, Upper Yezo Group Introduction The Upper Cretaceous decapod Crustacea from Hokkaido comprises nine species, Linuparus japonicus Nagao, 1931 (Palinura, Palinuridae), Callianassa ezoensis Nagao, 1941 (Thalassinidea, Callianassidae), and seven brachyurans (Collins, Kanie and Karasawa, 1993). In the present paper we describe four additional new species, one astacidean, one thalassinidean and two anomalans, from the Upper Yezo Group of Hokkaido. The described specimens are deposited in the Mikasa City Museum (MCM) and the Mizunami Fossil Museum (MFM). Systematic paleontology Infraorder Astacidea Latreille, 1802 Superfamily Nephropoidea Dana, 1852 Family Nephropidae Dana, 1852 Subfamily Homarinae Huxley, 1879 Genus Hoploparia McCoy, 1849 Type species.—Astacus longimanus Sowerby, 1826 by subsequent designation by Rathbun, 1926. Hoploparia kamuy sp. nov. Figure 1.1, 1.2, 1.5, 1.6 Diagnosis.—Moderate-sized Hoploparia. Carapace with well developed grooves on anterior half. Antennal region bearing antennal ridge and one postantennal spine. Abdominal somites simple without tubercles and spines. Description.— Hoploparia with moderate-sized body. Carapace laterally compressed.. Rostrum and posterior part of carapace lacking. Surface finely granulated. Orbit small, rounded, bordered by narrow, rounded ridge. Postcervical groove well defined, deep, broad, obliquely extending ven- trally, becoming shallower at junction with hepatic groove. Branchiocardiac groove weak. Intercervical groove shallow, extending anteroventrally to, but not joining cervical groove. Second intercervical groove broad, shallow, extending to cervical groove. Hepatic groove shallow, curving to join antennal and cervical grooves. Cervical groove well de- fined, deep, slightly arcuate, parallel to postcervical groove, extending ventrally to join antennal groove. Antennal groove weakly arcuate, well defined over prominence omega. Prominence omega well defined, triangular. Gastro-orbital groove shallow, extending to near upper part of cervical groove. Antennal region with antennal ridge and with small, forwardly directed postantennal spine. Metorbital spine pre- sent, small. Supraorbital and postorbital spines wanting. Terga of abdominal somites 1-5 smooth, but tergum of somite 6 finely pitted; tergum of somite 1 short; somite 2 largest of all terga. All pleura of somites finely punctuate. Pleuron of somite 1 reduced. Pleuron of somite 2 subrectangular; margins gently convex; anteroventral and posteroventral corners smoothly rounded; surface with mar- ginal furrows joining transverse furrow on anterior part of tergum. Pleura of somites 3-5 triangular, transversely con- vex with sharp, posteroventral corners with shallow, broad marginal furrow along posterior margin. Pleuron of somite 6 reduced. Telson broken, but dorsal surface finely pitted. 140 Hiroaki Karasawa and Hiroshi Hayakawa Cretaceous decapod crustaceans from Hokkaido 141 Exp Enp Figure 2. Paki rurkonsimpu gen. et sp. nov., MCM.A539 (holotype). Cg vrsp x] vrsp Ic . Pi : g = Mxp3 P2 Pi 1 jee Saas] 1. Carapace, abdominal somites, telson, uropod and pereiopods, right lateral view. 2. Abdominal somite 6, dorsal view. 3. Carapace and pereiopod 1, left lateral view. Abbreviations: C, carapace; cg, cervical groove; Enp, uropodal endopod; Exp, uropodal exopod; Ic, lateral carina; mrsp, marginal row of setal pits; Mxp3, maxilliped 3; P1, pereiopod 1; P2, pereiopod 2; P3, pereiopod 3; P4, pereiopod 4; PS5, pereiopod 5; r, rostrum; T, telson; vrsp, vertical row of setal pits; II, abdominal somite 2; abdominal somite 6. Uropodal exopod triangular in outline, finely pitted dorsally, with weakly convex lateral margin and with diaeresis. Chelae of pereiopod 1 unknown. Some pereiopods pre- served, slender. Discussion.—The species differs from Hoploparia miya- motoi Karasawa, 1998, the only known Japanese species from the Maastrichtian Izumi Group, by having the carapace with an antennal ridge and with well developed cervical and postcervical grooves. H. kamuy sp. nov. lacks well devel- oped ridges between terga and pleura of abdominal somites, and marginal spines of pleura of abdominal somites 3-5. Hoploparia kamuy sp. nov. is most similar to Hoploparia pusilla Secretan, 1964, from the Campanian of Madagascar, but differs in that the carapace bears a weak hepatic groove, a straight gastro-orbital groove, and a well defined promi- nence omega. H. kamuy sp. nov. resembles Hoploparia arbei Aguirre-Urreta, 1989 from the Puesto EI Almo Formation (Turonian-Coniacian) of Argentina, but differs by absence of two tubercles on pleura of abdominal somites and of a granulated ridge on the branchial region. Hoploparia kamuy represents the first record of the genus from the Turonian-Santonian of Japan. Etymology.—The specific name is formed from ‘kamuy, the name of a god in the Ainu language of Hokkaido. Material examined.—MCM.A609 (holotype), Loc. YEZ-16, Oyubari, Yubari City; Upper Yezo Group (Lower Santonian; Ill, abdominal somite 3; IV, abdominal somite 4; V, abdominal somite 5; VI, Inoceramus amakusensis Zone by Ando and Kodama (1998)); collected by N. Nikkawa. MCM.A536 (paratype), Loc. YEZ-17, Ponbetsuzawa, Mikasa City; the basal part of the Upper Yezo Group (Upper Turonian; Inoceramus teshioensis Zone by Ando and Kodama (1998)); collected by S. Matsuda. Infraorder Thalassinidea Latreille, 1831 Superfamily Axioidea Huxley, 1879 Family Micheleidae Sakai, 1992 Genus Paki gen. nov. Type species.—Paki rurkonsimpu sp. nov. by monotypy. Diagnosis.—Large-sized micheleid. Rostrum of carapace with rounded tip; lateral carina well developed; cervical groove distinct; linea thalassinica absent; anterolateral re- gion with two vertical rows of setal pits anterior to cervical groove. Terga and pleura of abdominal somites 2-5 bounded by weak ridge; pleuron of somite 2 with two vertical rows of setal pits posteriorly and with marginal row of setal pits anteriorly; pleura of somites 3-6 with single vertical row of setal pits anteriorly; pleuron of somite 6 with two vertical rows of setal pits anteriorly and single vertical row of setal pits posteriorly. Telson rectangular with two longitudinal carinae. Uropodal exopod and endopod with median dorsal ridge and with convex margins. Figure 1. 1,2, 5, 6. Hoploparia kamuy sp. nov. 1. MCM.A536 (paratype), carapace, abdominal somites, telson and uropod, X 2.0, right lateral view. 2. MCM.A609 (holotype), carapace and abdominal somites, X 2.0, left lateral view. 5. MCM.A536 (paratype), ab- dominal somites and uropod, X 2.0, left lateral view. 6. MCM.A609 (holotype), abdominal somites, X 2.0, right lateral view. 3, 4, 7. Paki rurkonsimpu gen. et sp. nov. 3. MCM.A539 (holotype), carapace and eye stalks, X 3.0, dorsal view. 4. MCM.A539 (holotype), carapace and left pereiopod 1, “3.0, left lateral view. 7. MCM.A539 (holotype), carapace, abdominal somites, telson, uropod and pereiopods, X 3.0, right lateral view. 142 Hiroaki Karasawa and Hiroshi Hayakawa Messe aan TS. Discussion.— The present new genus and species is as- signed to the family Micheleidae Sakai, 1992 in the superfamily Axioidea Huxley, 1879 by lacking linea thalassinica on the carapace and by having rows of setal pits on the carapace and pleura of abdominal somites. According to Poore (1997) Micheleidae contains four Recent genera, Michelea Kensley and Heard, 1991, Tethisa Poore, 1994, Meticonaxius De Man, 1905 and Marcusiaxius Rodrigues and de Carvalho, 1972. The pattern of rows of setal pits on the anterior part of the carapace and the char- acters of propodi of pereiopods 1-5 are not observed, but in the character of the remaining carapace and abdominal somites, the genus is most similar to Meticonaxius and Marcusiaxius. Two rows of pits anterior to the cervical groove on the carapace, two vertical rows of pits on the pleuron of abdominal somite 2, and rounded margins of the uropodal exopod and endopod readily distinguish the new genus from Meticonaxius and Marcusiaxius. Paki differs from Tethisa by having rows of setal pits on abdominal somites 3-5 and having an ovate uropodal exopod. The new genus also differs from Michelea in that the carapace bears a lateral carina and rows of pits in front of the cervical groove. In the pattern of rows of setal pits on the abdominal somites Upogebia rhacheochir Stenzel, 1945 from the Turonian Britton Formation of Texas belongs to the family Micheleidae and may be assigned to Meticonaxius or Marcusiaxius. However, a well preserved carapace of Stentzel's species is needed to more precisely define the systematic position. Poore (1997: 364) described Marcu- siaxius sp. from the Albian of Gault, Folkestone of England. Therefore, these occurrences extend the geologic range for the family Micheleidae back to the Cretaceous. Etymology.—The generic name is derived from the word, ‘paki’, meaning shrimp in the Ainu language of Hokkaido; masculine gender. Paki rurkonsimpu sp. nov. Figures 1.3, 1.4, 1.7; 2.1-2.3; 3 Reconstruction of Paki rurkonsimpu gen. et sp. nov. Description.—Large micheleid. Carapace laterally com- pressed. Anterior half of carapace poorly preserved. Rostrum extended anteriorly into rounded tip; dorsal surface missing. Eye stalks visible in dorsal view. Lateral carina well developed. Cervical groove distinct. Linea thalassinica absent. Anterolateral region with two vertical rows of setal pits anterior to cervical groove. Abdominal somites 2-6 preserved. Somite 2 about 1.5 times as long as 3. Terga and pleura of somites 2-5 bounded by weak ridges. Pleuron of somite 2 with two verti- cal rows of setal pits posteriorly and with marginal row of setal pits anteriorly; pleura of somites 3-6 with single vertical row of setal pits anteriorly; pleuron of somite 6 reduced with two vertical rows of setal pits anteriorly and single vertical row of setal pits posteriorly. Surfaces of pleura of somites 2-5 finely punctuate. Telson rectangular, slightly wider than long, about 1/3 times as long as somite 6; lateral margin di- vergent posteriorly; dorsal surface with two longitudinal carinae and with two pits anteriorly. Uropodal exopod, lack- ing posterior half, with median dorsal ridge, convex anterolateral margin and finely serrated lateral margin. Uropodal endopod lacking anterior half, bearing median dorsal ridge and convex posterior margin. Merus of pereiopod 1 bearing convex lateral margin with longitudinal ridge and with two spines on ventral margin. Carpus and merus of pereiopod 2 flattened. Propodus of pereiopod 3 flattened; merus about 1.5 times as long as carpus. Merus of pereiopod 4 ovate in cross section. Pereiopod 5 short; merus about 1.5 times as long as carpus. Merus and carpus of maxilliped 3, slender, flattened later- ally. Discussion. — The species is similar to Upogebia rhacheochir, but differs by possessing two vertical and one marginal rows of setal pits on the pleuron of the abdominal somite 2. Etymology.—The specific name is derived from the word ‘rurkonsimpu’, meaning a fairy living in seas in the Ainu lan- guage of Hokkaido. Material examined.—MCM.A5339 (holotype), Loc. YEZ-18, Kotanbetsu, Tomamae-cho, Tomamae-gun; Upper Yezo Group (Lower Campanian; Sphenoceramus orientalis Zone); Cretaceous decapod crustaceans from Hokkaido 143 Figure 4. type), carapace, MFM247.011 (holotype), carapace, * 3.0, dorsal view. x 3.0, dorsal view. collected by H. Hayakawa. Infraorder Anomala Boas, 1880 Superfamily Galatheoidea Samouelle, 1819 Family Galatheidae Samouelle, 1819 Genus Luisogalathea gen. nov. Type species.—Luisogalathea tomitai sp. nov. Diagnosis.—Moderate-sized galatheid. Carapace exclud- ing rostrum, longer than wide, dorsally longitudinally gently convex. Rostrum triangular, simple, lacking lateral spines, concave dorsally; lateral margins smooth but bearing a small lateral projection on distal fifth. Lateral margin gently convex with small spines. Dorsal surface rugose without spines. Cervical and postcervical grooves well defined. Discussion.—There may be, in the general outline of the carapace, similarity between Luisogalathea and the Tithonian-Maastrichtian genus, Eomunidopsis Via Boada, 1981, but absence of a median dorsal ridge on the rostrum and presence of spines on the lateral margin of the carapace readily distinguish Luisogalathea from Eomunidopsis. In Eomunidopsis supplementary dorsal furrows of the cara- pace are more or less developed. Stenzel (1945) described two new galatheids, Galathea cretacea and Galathea? limonitica from the Pawpaw Shale (Albian-Cenomanian) of Texas. Bishop (1985) described Eomunidopsis cobbani Bishop, 1985 from the Campanian Larimer Sandstone of Colorado and assigned both of Stenzel’s species to Eomunidopsis. Fraaye and Collins (1996: 323) suggested that these American species, G. cretacea and E. cobbani, having the rostrum without a me- dian ridge, possibly belonged to Paragalathea Patrulius, 1959. G. cretacea differs from members of Galathea Fabricius, 1793 by having a triangular rostrum with smooth lateral margins. Paragalathea is characterised by having a large, broadly triangular rostrum and by having the dorsal surface of the carapace more or less tuberculate and with smooth lateral margins that diverge anteriorly. Both G. 1. Luisogalathea tomitai gen. et sp. nov., MFM247.010 (holo- 2. Eomunidopsis kojimai sp. nov., cretacea and E. cobbani are transferred from Eomunidopsis to the present genus in that their carapaces have the genus characteristics of an acutely triangular rostrum with smooth lateral margins and without a median rostral ridge, a rugose dorsal surface, and gently convex lateral margins bearing spines. Only Galathea? limonitica belongs to the genus Eomunidopsis by exhibiting well defined carapace furrows. Etymology.—The generic name is dedicated to the late Spanish paleocarcinologist, Dr. Luis Via Boada; feminine gender. Species included. — Luisogalathea tomitai sp. nov., Luisogalathea cobbani (Bishop, 1985) comb. nov. from the Campanian-Maastrichtian of U.S.A., Luisogalathea cretacea (Stenzel, 1985) comb. nov. from the Cenomanian of U.S.A. Luisogalathea tomitai sp. nov. Figure 4.1 Diagnosis.—Carapace excluding rostrum, subquadrate, dorsally longitudinally gently convex, width about 3/4 the length. Rostrum triangular, smooth dorsally with median de- pression; lateral margins bearing a small lateral projection on distal fifth. Orbital margin concave. Outer orbital angle weakly produced. Anterolateral angle with small spine. Lateral margin with 6 small spines. Orbitofrontal region de- pressed. Gastric, cardiac and branchial regions with trans- verse ridges and without spines. Cervical and epibranchial grooves well defined. Description.—Carapace excluding rostrum, subquadrate in outline, dorsally longitudinally gently convex, width about 3/4 the length, greatest width about midlength. Rostrum tri- angular, gently downturned, about 1/4 as long as carapace width at the base, about 1/4 times as long as carapace length; dorsal surface smooth, with median depression; lat- eral margins smooth but bearing a small lateral projection on distal fifth. Orbital margin concave. Outer orbital angle weakly produced. Anterolateral angle with small spine. Lateral margin gently convex, bearing 6 small, forwardly di- 144 Hiroaki Karasawa and Hiroshi Hayakawa rected spines; 2 between cervical and epibranchial notches, and 4 posterior to epibranchial notch. Orbitofrontal region depressed. Gastric region inflated; gently arched, raised edge between orbitofrontal and gastric regions; epigastric region ornamented with interrupted, transverse ridges, lacking spines, with shallow, median de- pression; proto- and mesogastric regions with 6 broadly rounded V-shaped ridges. Hepatic regions flattened. Cervical groove well defined, broad, deep. Cardiac region weakly marked, gently convex with 8 transverse ridges. Epibranchial regions inflated, separated from mesobranchial regions by deep postcervical grooves, ornamented with weak, transverse ridges. Other branchial regions densely decorated with interrupted transverse ridges. Discussion.—Luisogalathea tomitai sp. nov. resembles L. cretacea (Stenzel) from the Pawpaw Shale (upper Albian) of Texas, but differs in having the rostrum with a smooth dorsal surface, the outer orbital angle with a weak projection, and the gastric, cardiac and branchial regions with fine ridges. Etymology.— From A. Tomita who collected the type specimen. Material examined.—MFM247.010 (holotype), Loc. YEZ- 19, Nakafutamatagawa, Haboro-cho, Tomamae-gun; Upper Yezo Group (Santonian; Inoceramus amakusensis Zone by Ueda et al. (1961)). Genus Eomunidopsis Via Boada, 1981 Type species.— Galathea navarrensis Van Straelen, 1940 by original designation. Diagnosis. — Céphalothrax allongé, portant des crêtes transversales saillantes. Régions délimitées par des sillons bien visibles. Rostre caractérisé par sa pointe tridentée, dépourvu de dentelure sur ses bords latéraux et orné d’une carène médiane (from Via Boada, 1982). Eomunidopsis kojimai sp. nov. Figure 4.2 Diagnosis.— Carapace excluding rostrum, subquadrate, slightly longer than wide, dorsal surface moderately convex longitudinally. Orbital margin slightly concave. Outer orbital angle not produced. Anterolateral angle with small spine. lat- eral margin gently convex with 8 small spines. Gastric, car- diac, hepatic and branchial regions ornamented with transverse and/or oblique ridges. Cervical and postcervical grooves well defined. Description.—Carapace excluding rostrum, subquadrate in outline, about 4/5 times as wide as long. Rostrum not pre- served about 1/4 as long as carapace width at the base. Orbital margin slightly concave. Outer orbital angle not pro- duced. Anterolateral angle with very small spine. Lateral margin gently convex, armed with 8 small, forwardly directed spines; 1 anterior to cervical notch, 4 between cervical and epibranchial notches, 3 behind epibranchial notch. Dorsal surface moderately convex longitudinally. Orbital regions flattened. Gastric region inflated; epigastric region vaulted, broadly triangular with oblique anterior ridge, inter- rupted, transverse ridge and median ridge behind it; proto- and mesogastric regions with 2 transverse ridges, anterior one extending to hepatic region, gently curved ridge behind anterior one; mesogastric region with 3 gently curved ridges behind posterior transverse ridge, anterior and posterior ones shorter than middle; protogastric region with a pair of oblique ridges behind anterior transverse ridge. Hepatic re- gions ornamented with short, oblique ridges anteriorly. Cervical groove deep, broad. Cardiac region poorly defined with 3 transverse ridges diminishing in length posteriorly. Epibranchial region with 5 irregular, oblique ridges. Postcervical groove distinct. Other branchial regions with in- terrupted transverse ridges. Discussion.—Eomunidopsis kojimai sp. nov. has close af- finity with Eomunidopsis navarrensis (Van Straelen, 1940) from the Cenomanian of Spain, but differs by the presence of spines on the lateral margins of the carapace, and by absence of granules and tubercles on ridges of the dorsal regions. Ridges of the dorsal regions in E. kojimai are coarser than those in E. navarrensis. The new species re- sembles Eomunidopsis meerssensis Collins, Fraaye and Jagt, 1995 from the Maastrichtian Maastricht Formation of the Netherlands. In E. kojimai ridges are transversely and obliquely arranged on the dorsal surface while in E. meerssensis transverse ridges cover the dorsal surface. Eomunidopsis, earliest known from the Oxfordian (Fraaye and Collins, 1996), is recorded from the Tithonian of Austria and Bulgaria (Via Boada, 1982), from the Cenomanian of Spain (Via Boada, 1982), from the Albian-Cenomanian of U.S.A. (Bishop, 1985) and the Maastrichtian of the Netherlands (Collins, Fraaye and Jagt, 1995). The occur- rence of E. kojimai indicates that the genus reached Japan by the Santonian. Etymology.—From Mr. T. Kojima who collected the type specimen. Material examined.— MFM247.011(holotype), Loc. YEZ- 20, Wakkauenbetsugawa, Nakagawa-cho, Teshio-gun; Nigorikawa Formation (Santonian), Upper Yezo Group (Osanai et al., 1960). Acknowledgements We thank J. S. H. Collins (London) for reading our manu- script, T. Kojima (Hikone, Shiga), N. Nikkawa (Yokohama, Kanagawa), S. Matsuda (Mikasa, Hokkaido), and A. Tomita (Sapporo, Hokkaido) for offering us fossil specimens, and H. Hayano (Kasugai, Aichi) and T. Kaede (Inazawa, Aichi) for useful information of fossil localities. The senior authors field work was supported by a Grant-in-Aid for Scientific Research from Ministry of Education, Science, Sports and Culture (no. 0816024). References Ando, H. and Kodama, T., 1998: Shallow-marine bivalvian faunal change during Cenomanian to Turonian, Late Cretaceous - Ponbetsu River section in the Mikasa Formation, Middle Yezo Group, Hokkaido, Japan. Bulletin of the Mikasa City Museum, Natural Science, no. 2, p. 1-15. Aguirre-Urreta, M. B., 1989: The Cretaceous decapod Crustacea of Argentina and the Antarctic Peninsula. Cretaceous decapod crustaceans from Hokkaido Palaeontology, vol. 32, p. 499-552. Bell, T., 1857: A Monograph of the Fossil Malacostracous Crustacea of Great Britain. Part 1, Crustacea of London Clay. Palaeontographical Society Monograph, 44 p. London. Bishop, G. A., 1985: A new crab, Eomunidopsis cobbani from the Pierre Shale of Colorado. Journal of Paleontology, vol. 59, 601-604. Boas, J. E. V., 1880: Studier over Decapodernes Slaegtska- bsforhold. 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Dufart, Paris. Latreille, P. A., 1831: Cours d’Entomologie, ou de l'histoire naturelle des Crustacés, des Arachnides, des Myriapodes et des Insectes, etc. Annales |. Atlas, 26 p. Roret, Paris. McCoy, F., 1849: On the classification of some British fossil Crustacea with notices of new forms in the University Collection at Cambridge. Annals and Magazine of Natural History, Series 2, vol. 4, p. 161-179, 330-335. Nagao, T., 1931: Two new decapod species from the Upper Cretaceous deposits of Hokkaido, Japan. Journal of the Faculty of Science, Hokkaido Imperial University, series 4, vol. 1, p. 207-214. Nagao, T., 1941: On some fossil Crustacea from Japan. Journal of the Faculty of Science, Hokkaido Imperial University, Series 4, vol. 6, p. 86-100. Osanai, H., Mikami, K. and Takahashi, K., 1960: Kyowa. 1/50,000. Explanatory of the Geological Map of Japan. 59 p. Geological Survey of Hokkaido. (in Japanese with English resume) Patrulius, D., 1959: Contributions a la systématique des Decapodes neojurassiques. Revue de Geologie et de Géographie, vol. 3, p. 249-257. Poore, G. C. B., 1994: A phylogeny of the families of Thalassinidea (Crustacea: Decapoda) with keys to fami- lies and genera. Memoirs of the Museum of Victoria, vol. 54, p. 79-120. Poore, G. C. B., 1997: A review of the thalassinidean families Callianideidae Kossmann, Micheleidae Sakai, and Thomassiniidae de Saint Laurent (Crustacea, Decapoda) with descriptions of fifteen new species. Zoosystema, vol. 19, nos. 2-3, p. 345-420. Rathbun, M. J., 1926: The fossil stalk-eyed Crustacea of the Pacific slope of North America. U. S. National Museum, Bulletin, vol. 138, 155 p. Rodrigues, S. de A. and Carvalho, H. A. de, 1972: Marcusiaxius lemoscastroi, 9. n., sp. n., premeira occurréncia da familia Axiidae (Crustacea, Decapoda, Thalassinidea) no Brazil. Ciincia e Cultura, Suplementa, vol. 24, p. 357. Sakai, K., 1992: The families Callianideidae and Thalas- sinidae, with the description of two new subfamilies, one new genus and two new species (Decapoda: Thalas- sinidea). Naturalists, no. 4, p. 1-33. Samouelle, G., 1819: The Entomologist's Useful Compen- dium, or an Introduction to the Knowledge of British Insects. 486 p. London. Secretan, S., 1964: Les Crustacés décapodes du Jurassique supérieur et du Crétacé de Madagascar. Mémoires du Museum National d'Histoire Naturelle, Nouvelle serie, Série C, Sciences de la Terre, vol. 14, 226 p., 20 pls. Sowerby, J., 1826: Description of a new species of Astacus, found in a fossil state at Lyme Regis. Zoological Journal, vol. 2, p. 493-494. Stenzel, H. B., 1945: Decapod crustaceans from the Cretaceous of Texas. University of Texas Publications, vol. 4401, p. 401-476. Ueda, Y., Matsumoto, T. and Akatsu, K., 1961: The Cretaceous deposits in the Chikubetsu area, Hokkaido. Science Reports of the Faculty of Science, Kyushu University, Geology, vol. 6, no. 3, p. 15-32. Via Boada, L., 1981: Les Crustacés décapodes du Cenoman- ien de Navarre (Espagne): premiers resultats de l'étude des Galatheidae. Géobios, vol. 14, p. 247-251. Via Boada, L., 1982: Les Galatheidae du Cénomanien de Navarra (Espagne). Annales de Paléontologie, vol. 68, fasc. 2, p. 107-131. Van Straelen, V., 1940: Crustacés décapodes nouveaux du crétacique de la Navarre. Bulletin du Musée royal d'Histoire naturelle de Belgique, vol. 16, no. 4, p. 1-5. 145 hy bao Ty | ee 4 An wg Paleontological Research, vol. 4, no. 2, pp. 147-162, June 30, 2000 © by the Palaeontological Society of Japan Early Silurian (Llandoverian) radiolarians from the Ise area of the Hida "Gaien" Belt, ceniral Japan TOSHIYUKI KURIHARA' and KATSUO SASHIDA’ ‘Doctoral Program in Geoscience, University of Tsukuba, Ibaraki 305-8571, Japan (tosiyuki@arsia.geo.tsukuba.ac.jp) *Institute of Geoscience, University of Tsukuba, Ibaraki 305-8571, Japan Received 14 September 1999; Revised manuscript accepted 4 April 2000 Abstract. A moderately well-preserved Llandoverian (early Early Silurian) radiolarian fauna has been discovered from the Ise area of the Hida "Gaien" Belt, in Izumi Village, Fukui Prefecture, cen- tral Japan. This is the oldest known radiolarian fauna in Japan, and was recovered from calcare- ous nodules in the siliceous shale portion of a sedimentary sequence consisting of siliceous shale, alternating tuffaceous sandstone and shale, and tuffaceous sandstone. The fauna contains Haplotaeniatum tegimentum, Syntagentactinia afflicta, S. excelsa, Oriundogutta sp., Inanihella sp., Auliela sp., Palaeoephippium? sp., and Orbiculopylorum sp. This fauna is characterized by an abundance of species in the genera Haplotaeniatum, Syntagentactinia and Oriundogutta, and is comparable with the early to middle Llandoverian Haplotaeniatum tegimentum Assemblage and its equivalents in the southern Urals, Germany, and Nevada. Seventeen species of radiolarians belong- ing to 12 genera were systematically investigated. Key words: Hida "Gaien" Belt, Ise area, Llandoverian, Radiolaria, Silurian Introduction An understanding of the biostratigraphy and taxonomy of Silurian and Devonian radiolarians has progressed remarka- bly in the past decade (e.g., Nazarov and Ormiston, 1993; Noble and Aitchison, 1995). Numerous late Early Silurian to Middle Devonian radiolarian studies have been published for Japan (e.g., Wakamatsu et al., 1990; Furutani, 1990; Aitchison et al., 1996; Umeda, 1998), Australia (e.g., Stratford and Aitchison, 1997; Aitchison et al., 1999), the United States (Noble, 1994), the southern Urals (Amon et al., 1995), westernmost China (Li, 1994), and Germany (Kiessling and Tragelehn, 1994). Based on these radiolar- ian biostratigraphic studies, we can estimate the age of ra- diolarian-bearing rocks of this interval. Ordovician to early Early Silurian radiolarian biostrati- graphy has been outlined by Nazarov and Popov (1980), Nazarov (1988), and Nazarov and Ormiston (1993). In ad- dition to these studies, conducted in Kazakhstan and the southern Urals by Nazarov and his collaborators, a large number of Ordovician radiolarians have been reported from Spitsbergen (Fortey and Holdsworth, 1971), Newfoundland (Bergstrom, 1979; Renz, 1990a), the United States (Dunham and Murphy, 1976; Renz, 1990a, b; Kozur et al., 1996), Australia (Webby and Blom, 1986; Goto et al., 1992; Umeda et al., 1992; Iwata et al., 1995), Estonia (Nazarov and Nylvak, 1983), the Baltic region (erratic boulders) (Eisenack, 1971; Gorka, 1994), China (Wang, 1993; Li, 1995), and Scotland (Aitchison,1998; Danelian and Clarkson, 1998). In contrast, besides Nazarov’s works (Nazarov, 1998; Nazarov and Ormiston, 1993), only a few papers describing early Early Silurian (Llandoverian) radio- larians were published before the mid-1990s (Rust, 1892; Stürmer, 1951, 1952, 1966; Goodbody, 1986). More re- cently, Llandoverian faunas have been described from the Cherry Spring Chert in Nevada (Noble et al., 1997; Noble et al., 1998), Dalarna, Sweden (Maletz and Reich, 1997), Cornwallis Island, Arctic Canada (MacDonald, 1998), and Germany (Noble et a/., 1998). These studies demonstrate that Llandoverian radiolarians have a high biostratigraphic potential. Early Silurian radiolarians, however, are still in- sufficiently known. Additional collecting is needed to estab- lish a biostratigraphy and provide information on the faunal composition for this time period. We are now studying the lithostratigraphy and radiolarian biostratigraphy of the Hida "Gaien" (=marginal) Belt in order to understand its tectonic and paleobiogeographic history (Kurihara and Sashida, 1998). We fortuitously discovered Llandoverian radiolarians in calcareous nodules from the si- liceous shale part of the clastic and volcaniclastic sequence exposed in the Ise area of the westernmost part of the Hida "Gaien" Belt, in Izumi Village, Ohno County, Fukui Prefecture. This early Early Silurian radiolarian fauna is the oldest one known in Japan. In this paper, we discuss the age assignment of the radiolarian fauna and systematically describe 17 species which belong to 12 genera including 148 Toshiyuki Kurihara and Katsuo Sashida IT f \toshiro R. Fukui P.» LA ‘ 7 \ Figure 1. four undetermined genera. Geologic setting The Hida "Gaien" Belt, one of the most structurally com- plex areas in the Japanese geologic framework, occurs in a narrow area between the Hida and Mino Terranes. This belt is composed of weakly metamorphosed or unmetamor- phosed Paleozoic and Mesozoic strata, including Ordovician to Devonian sediments, crystalline schists, and basic to ultrabasic rocks. Outcrops of these rocks can be found in the Omi-Renge, Fukuji, Moribu (Arakigawa), Naradani and Ise areas (e.g., Komatsu, 1990; Igo, 1990). The latter four of these five areas are covered by Middle Paleozoic strata and have been investigated by many workers (e.g., Tazawa et al., 1997). Recent micropaleontological investigations of Ordovician strata show them to be fairly widely distributed in the Hitoegane district of the Fukuji area (Tsukada and Koike, 1996; Tsukada, 1997). The Ise area, which extends from Izumi Village to Ohno City, Fukui Prefecture, is situated in the westernmost part of the Hida "Gaien" Belt. Its constituent rocks are exposed around Kuzuryu Lake and in the upper reaches of the Ise River to the Sasou-Mana River (Figure 1). The geology of this area has been studied by Kawai (1956), Kawai et al. (1957), Yamada (1967), and the Metal Agency of Japan (1980). Miyakawa and Yamada (1988) summarized the stratigraphy of the sedimentary rocks cropping out around Kuzuryu Lake, based on the studies of Yamada (1967) and Ohno et al. (1977). They subdivided these rocks into the following eight lithostratigraphic units, in ascending order: an unnamed Silurian unit, the Lower to Middle Devonian Kamianama Group, Middle Carboniferous Nagano For- mation, Lower Permian Oboradani Formation, Middle Permian Nojiri Group and Magatoji Formation, post- Permian? Ohtani and Motodo Formations, and the Ashidani Group of unknown age. Among these litho- Index map showing the study area. stratigraphic units, the Nojiri Group, which is subdivided into the Oguradani Formation and overlying Konogidani Formation, crops out widely around Kuzuryu Lake. The other units, especially the Silurian and Devonian strata, complexly occur in narrow zones on the north side of Kuzuryu Lake and along the upper reaches of the Ise River. Strata in this area contain rich Carboniferous and Permian fossils, including fusulinacians and corals in the Oboradani and Ohtani Formations, and brachiopods in the Oguradani Formation (e.g., Niko and Watanabe, 1987; Niko et al., 1997; Tazawa and Matsumoto, 1998). The Devonian lime- stone of the Kamianama Group yields various kind of fossils (e.g., Hamada, 1959; Okazaki et al., 1974; Kamiya and Niko, 1997) but no detailed paleontological study of them has been published. Recently, micropaleontological investiga- tion by the present authors revealed the occurrence of Late Silurian to Middle Devonian radiolarians in the Kamianama Group (Kurihara and Sashida, 1998). Lithology of the radiolarian-bearing rocks The Early Silurian radiolarian-bearing calcareous nodules were collected from the siliceous shale portion of a se- quence that consists of thin alternations of tuffaceous sand- stone and shale, tuffaceous sandstone, and siliceous shale. The sequence crops out along a stream near the Kagero Tunnel, west of Nojiri, Izumi Village (Figure 2). Similar rocks are exposed in a roadcut east of the Anama Temple. These strata were previously assigned to the Konogidani Schalstein Formation (Ozaki et al., 1954), the Tomedoro Schalstein "Member" [=Formation] (Kawai, 1956; Kawai et al., 1957; Metal Agency of Japan, 1980), and the Permian Konogidani Formation (Yamada, 1967; Miyakawa and Yamada, 1988). Revision of the litho- and biostratigraphy in this area is needed (Kurihara, 1999). In this stratigraphic section, the beds generally strike N25° to 35°W and dip 70° to 80°S (and sometimes almost verti- Silurian (Llandoverian) radiolarians 149 Figure 2. Locality map showing the location of the study section. Base map is after 1:25,000-scale topographic map of Japan, Quadrangle "Echizen-Asahi", Geographical Survey Institute of Japan. Legend | tuffaceous sandstone alternation of tuffaceous \| sandstone and shale siliceous shale \ calcareous nodule dip and strike 5m I Figure 3. Route map along the study section. Legend — —— tuffaceous sandstone 7 alternation of | tuffaceous sandstone and shale = siliceous shale calcareous nodule R radiolarian horizon 5m Om Figure 4. Column along the study section. cally) (Figure 3). Although the stratigraphically highest structures were inaccessible in this section, we tentatively regard these rocks as a north-upward sequence, because sedimentary structures such as graded beddings indicating a north-upward orientation are observable at an outcrop east of the Anama Temple. The rock sequence of this section is as follows, in ascending order: tuffaceous sandstone (about 5.5 m); alternating tuffaceous sandstone and shale (about 4.5 m); siliceous shale (2 m); alternating tuffaceous sand- stone and shale (4.5 m); and tuffaceous sandstone (5 m) (Figure 4). The tuffaceous sandstone is medium- to coarse- grained, massive and dark green to dark gray in color. The alternating tuffaceous sandstone and shale is thinly bedded and dark gray, gray, dark green, and black in color. Microscopic observation reveals that the sandstone layers are composed mainly of angular quartz fragments with a small amount of plagioclase and opaque minerals. The shale layers are partly similar to chert and contain very fine quartz grains in a muddy matrix with frequent thin lamina- 150 Toshiyuki Kurihara and Katsuo Sashida 1. Photograph showing the occurrence of radio- larian-bearing calcareous nodules (white arrows) in the study Figure 5. section (see Figure 3 for locality). 2. Photomicrograph of radio- larian-bearing calcareous nodule. Scale bar=1 mm. tions of coarse quartz grains. The siliceous shale is dark gray and pale green in color and the thickness of each bed is 2 to 5cm. In this exposure, the shale contains two cal- careous nodules which are lenticular in shape and measure 15 cm and 6 cm in the major and minor axes, respectively (Figure 5.1). These nodules are hard, compact, dark gray in color and contain many radiolarian spheres. Radiolarian skeletons are scattered in a calcareous and muddy matrix, most are altered to calcite, and only their outlines formed of fine-grained quartz are preserved (Figure 5.2). Method of extracting radiolarians We collected calcareous nodules, siliceous shale, and the shaly part of the alternating tuffaceous sandstone and shale for radiolarian analysis. In order to extract radiolarians from the calcareous nodules, we soaked crushed rocks, each several centimeters in diameter, in a dilute acetic acid solu- tion (5%) for 10 to 12 hours. For the siliceous rock sam- ples, crushed rocks were soaked in a dilute hydrofluoric acid Table 1. ous nodule. HAPLENTACTINIIDAE Haplotaeniatum tegimentum Nazarov & Ormiston Haplotaeniatum sp. A Syntagentactinia afflicta Nazarov & Ormiston Syntagentactinia excelsa Nazarov & Ormiston Syntagentactinia ? sp. List of Llandoverian radiolarians from the calcare- INANIGUTTIDAE Oriundogutta sp. Oriundogutta ? sp. Inanihella sp. Inanihella ? sp. Inaniguttidae gen. et sp. indet. sp. A ANAKRUSIDAE Auliela sp. PALAEOSCENIDIIDAE Palaeoephippium ? sp. SPONGURIDAE Sponguridae gen. et sp. indet. sp. A PYLENTONEMIDAE Cessipylorum ? sp. INCERTAE SEDIS Orbiculopylorum sp. Spumellaria gen. et sp. indet. sp. A Spumellaria gen. et sp. indet. sp. B Spumellaria gen. et sp. indet. (HF) solution (5 to 10%) for about 24 hours. The samples were washed and sieved through 270# nylon mesh. Radiolarians picked from the dried residues were coated with gold in a vacuum evaporator and observed with a scan- ning electron microscope. Other specimens were sealed on a slide glass and observed with a transmitted light micro- scope. Radiolarian fauna and age Radiolarians were recovered only from the calcareous nodules, and were absent in the siliceous shale and the shaly part of the alternating tuffaceous sandstone and shale. The identified radiolarians consist of 18 species belonging to 13 genera (Table 1). Radiolarians extracted from the cal- careous nodules are generally poorly preserved, and uni- dentified spumellarian fragments are also numerous. This fauna is characterized by abundant species of the families Haplentactiniidae and Inaniguttidae, in association with Anakrusidae, Palaeoscenidiidae, Sponguridae, and Pylen- tonemidae. Haplotaeniatum and Syntagentactinia, in the family Haplentactiniidae, are common and are characterized by large, spherical, spongy, or concentric-layered shells. The following Haplentactiniidae species are present: Silurian (Llandoverian) radiolarians 151 Haplotaeniatum tegimentum Nazarov and Ormiston, Haplo- taeniatum sp. A, Syntagentactinia afflicta Nazarov and Ormiston, Syntagentactinia excelsa Nazarov and Ormiston, and Syntagentactinia? sp. Radiolarians of the family Inaniguttidae comprise the next most-dominant faunal com- ponent, including the following species: Oriundogutta sp., Inanihella sp., Inanihella? sp., and Inaniguttidae gen. et sp. indet. sp. A. Species in the families Palaeoscenidiidae and Sponguridae are less common, although Palaeoephippium? sp. and Sponguridae gen. et sp. indet. sp. A are present. The following species were allocated to the families Anakrusidae, Pylentonemidae, and to incertae sedis; Auliela sp., Cessipylorum? sp., and Orbiculopylorum sp. Silurian radiolarian biostratigraphy was first rationalized by Nazarov (1988) and Nazarov and Ormiston (1993), who pro- posed two radiolarian assemblages: the Early Silurian Haplotaeniatum tegimentum Assemblage and the Late Silurian /nanihella tarangulica-Secuicollacta cassa Assem- blage. The H. tegimentum Assemblage, described from a middle Llandoverian to Wenlockian siliceous rock sequence in the Sakmarsky Suite of the southern Urals, is character- ized by Haplotaeniatum labyrintheum Nazarov and Ormiston, H. cathenatum Nazarov and Ormiston, H. tegi- mentum Nazarov and Ormiston, Haplentactinia silurica Nazarov and Ormiston, Syntagentactinia excelsa Nazarov and Ormiston, and S. afflicta Nazarov and Ormiston. As noted above, the present radiolarian fauna is characterized by species of Haplotaeniatum and Syntagentactinia, and therefore is referable to the H. tegimentum Assemblage of Nazarov (1988) and Nazarov and Ormiston (1993). Noble et al. (1997) made a preliminary study of an early Llandoverian radiolarian fauna in the Cherry Spring Chert of Nevada. They extracted from sulfide nodules a well- preserved radiolarian fauna consisting of abundant, large pylomate sphaerellarians identified as Cessipylorum (?) sp. A and Cessipylorum (?) sp. B, some rotasphaerids such as Rotasphaera sp. and Secuicollacta spp., and Oriundogutta sp. In addition, Noble et al. (1998) noted that the Nevada fauna described by Noble et al. (1997) contains abundant species of Haplotaeniatum. From the Frankenwald and Thuringia, Germany, Noble et al. (1998) also reported Secuicollacta spp. from black, organic-rich chert, the age of which is constrained by co-occurring graptolites as early Rhuddanian to early Telychian (early to late Llandoverian). In the Main Valley, Germany, black chert gravel in Pleistocene river deposits contains well-preserved radiolari- ans, and was probably derived from the Frankenwald (Stürmer, 1951, 1952, 1966). Richter (1951) cited the age of this gravel as middle Rhuddanian to Aeronian (early to middle Llandoverian), and Noble et al. (1998) identified the following species in it: Syntagentactinia? sp., Orbicu- lopylorum adobensis Noble, Braun and McClellan, Orbicu- lopylorum sp., and Haplotaeniatum sp. Noble et al. (1997) pointed out the following characters of the Nevada fauna: (1) the species belonging to the family Inaniguttidae of the Wenlockian to Ludlowian, which have long and robust spines, are different from inaniguttids of the Nevada fauna. (2) Wenlockian to Ludlowian rotasphaerids commonly have six rods per spine unit and highly diversified spines such as grooved or bladed ones. In contrast, rotasphaerid species in the Nevada fauna have five rods per spine unit and rod-shaped spines. (3) The Nevada fauna does not contain species in the families Palaeoscenidiidae and Ceratoikiscidae, which are notable taxa in Wenlockian faunas (Goodbody, 1986; Renz, 1988). Rotasphaerids have never been found in the present fauna, although their absence may be due in part to preservational bias, as these taxa are small and delicate. The morphological characters of the inaniguttids and the absence of ceratoikiscids are con- sistent with the work of Noble et al. (1997). The Nevada fauna also contains species of Syntagentactinia and Haplotaeniatum. In addition, large spherical radiolarians with the concentric and loosely spongy layers of the German fauna (Stürmer, 1951, 1952, 1966; Noble et al., 1998) are very similar to the species of Syntagentactinia and Haplotaeniatum in the present fauna. Although Orbi- culopylorum is rare, the present fauna is similar in its taxo- nomic composition to those in Nevada and Germany. Nazarov and Ormiston (1993) inferred the age of the H. tegimentum Assemblage to be middle Llandoverian to Wenlockian by showing that this assemblage occurs in a si- liceous shale sequence that contains Monograptus triangu- latus to M. testis zone graptolites. Noble et al. (1998) noted that the age of the H. tegimentum Assemblage is Rhudda- nian (early Llandoverian) to early Homerian (late Wenlo- ckian) and that the lower range of this assemblage is consistent with the age of the Nevada and German faunas. However, they questioned the upper range of this assem- blage, because the early to middle Llandoverian radiolarian fauna is markedly different from the late Llandoverian fauna. The late Llandoverian faunas reported by Maletz and Reich (1997) and MacDonald (1998) lack large spongy spu- mellarians such as Haplotaeniatum and are characterized by the abundance of various taxa of rotasphaerids and entactiniids. According to Noble et al. (1998), the fauna from the middle Telychian (upper Llandoverian) of Dalarna, Sweden contains Haplotaeniatum species but otherwise dif- fers from the Nevada fauna in faunal composition. Therefore, as pointed out by Noble et al. (1998), the upper range of the H. tegimentum Assemblage does not extend above the Telychian, and possibly not above the Rhuddanian to Aeronian (early to middle Llandoverian). We cannot determine the precise age of the present fauna, but we assign it to the early to middle Llandoverian, based on its similarity to the H. tegimentum Assemblage and to the Nevada and German faunas, as mentioned above. Systematic paleontology All specimens described in this paper are deposited in the Institute of Geoscience, University of Tsukuba (IGUT). Order Polycystina Ehrenberg, 1838, emend. Riedel, 1967b Suborder Spumellaria Ehrenberg, 1875 Family Haplentactiniidae Nazarov in Nazarov and Popov, 1980 Subfamily Haplentactiniinae Nazarov in Nazarov and Popov, 1980 Genus Haplotaeniatum Nazarov and Ormiston, 1993 152 Toshiyuki Kurihara and Katsuo Sashida a radial beam outermost shell É Haplotaeniatum tegimentum internal cavity ee cortical ”} shells medullary shell radial beam Syntagentactinia excelsa Figure 6. Schematic diagrams of skeletal structures and light transmission microphotographs of Haplotaeniatum tegi- mentum Nazarov and Ormiston (a, b) and Syntagentactinia excelsa Nazarov and Ormiston (c, d). Scale bars=100 pm. Type species.— Haplotaeniatum labyrintheum Nazarov and Ormiston, 1993. Remarks.— Nazarov and Ormiston (1993) stated that the internal shells of this genus are interpreted as having formed by apophyses developed on the main spines. They also il- lustrated the schematic internal structure of this genus (Nazarov and Ormiston, 1993, text-figure 8b) and empha- sized an important role of the main spines on skeletal struc- ture as the characteristic of the family Haplentactiniidae. However, no specimen has the entactiniid-like internal struc- ture formed by the main spines and extremely eccentrically positioned innermost shell among the photos presented by Nazarov and Ormiston (1993, pl. 3, figs. 9-16). Therefore, the generic diagnosis concerning the main spine by Nazarov and Ormiston (1993) is unconvincing, and the suprageneric classification of the genus Haplotaeniatum is problematic. We are not able to make an emendation for this genus owing to our poorly preserved material. However, the generic di- agnosis and suprageneric classification of this genus will need to be revised on the basis of well-preserved material. In this paper, we follow the diagnosis presented by Nazarov and Ormiston (1993). Haplotaeniatum tegimentum Nazarov and Ormiston, 1993 Figure 7.1-7.13 Haplotaeniatum tegimentum Nazarov, 1988, p. 188, pl. 11, fig. 7 (nomen nudum); Nazarov and Ormiston, 1993, p.42, pl.3, figs. 14-16. Description.— The external appearance of the shell is spherical, irregular spherical, or slightly elliptical. The out- ermost shell has many oval to irregularly rounded pores. In some specimens, a pylome-like oversized pore is present on the outermost shell surface (Figure 7.9-7.13). The inside of the outermost shell has an irregular spongy meshwork. The internal shells are spherical to subspherical, three to four in number, and concentrically arranged (Figure 6a, b). The in- nermost shell is often eccentrically positioned. Pores of the internal shells are circular to oval and differ in size. A small number of short, conical spines arise from the surface of the outermost shell. Under a transmitted light microscope, a ra- dial beam (probably the main spine) penetrating the concen- tric internal shells and extending to the outermost shell is present (Figure 6a, b), but its detailed morphology is unclear owing to poor preservation. Short radial beams randomly arise from the outer surface of the internal shell. These beams connect the internal and outermost shells. Measurements.— Based on 13 specimens, in um. Di- ameter of the outermost shell, 230-270, average, 250. Remarks.—More than twenty specimens of this species were examined. According to the generic diagnosis of Nazarov and Ormiston (1993), this genus is characterized by having several concentric or spiral forms for the internal shelis. A distinct spiral form was not observed in the pre- sent specimens, because the complex connections of the ra- dial beams prevented us from appraising the inner structure of the shell. As shown in Figure 6a and 6b, several concen- tric internal shells are present. This species is distinguished from Haplotaeniatum labyrintheum Nazarov and Ormiston by having short, conical spines. Haplotaeniatum cathenatum Nazarov and Ormiston, which is characterized by having a large pylome, is similar to this species, especially to the above-described pylomate form. However, it is difficult to compare this species with H. cathenatum, because only one broken specimen of the latter species was illustrated by Nazarov (1988) and Nazarov and Ormiston (1993). Haplo- taeniatum? aperturatum Noble, Braun and McClellan differs from the present species by having an irregular, spongy ball- like external shape and lacking a distinct internal shell. Range and occurrence.— Middle to late Llandoverian, southern Urals, southern Bashkiria and Northwestern Mu- godzhar; Silurian, Cabriere, France; Llandoverian, Ise area in the Hida "Gaien" Belt. Haplotaeniatum sp. A Figure 7.14-7.16 Description.—The shell is subspherical or slightly ellipti- cal. The outermost shell has more than ten large circular to oval pores per hemisphere. The outermost shell bears no spines, but has small conical protuberances at the junction of intervening bars. The internal shell consisting of a loose lattice is subspherical, with large oval pores on its surface. Radial beams arise from the surface of the internal shell and connect the internal and cortical shells. These beams are Silurian (Llandoverian) radiolarians 153 usually unbranched, but rarely bifurcate. Measurements. — Based on three specimens, in pm. Diameter of the outermost shell, 230-270, average, 260. Remarks.—This form is easily distinguished from other species of Haplotaeniatum by having large circular to oval pores and the loose lattice to its internal shell. This species is similar to specimens of Haplotaeniatum primordialis? (Rist, 1892) described by Nazarov and Ormiston (1993). According to Nazarov and Ormiston (1993), the latter spe- cies is characterized by its smaller dimensions (194 to 208 um) and a smaller number of internal shells. The pre- sent species differs from H. primordialis? (Rust, 1892) by having a large diameter to the outermost shell. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Genus Syntagentactinia Nazarov in Nazarov and Popov, 1980 Type species.— Syntagentactinia biocculosa Nazarov in Nazarov and Popov, 1980. Syntagentactinia afflicta Nazarov and Ormiston, 1993 Figure 7.17, 7.18 Syntagentactinia afflicta Nazarov, 1988, pl. 11 fig. 6 (nomen nudum); Nazarov and Ormiston, 1993, p. 40, pl. 5, figs. 12, 13; Noble, Braun and McClellan, 1998, p. 723, fig. 5-2. Description.—The shell of this species is composed of concentric cortical shells and a small medullary shell situ- ated in the internal cavity. The cortical shells are spherical and two or three in number with long, robust, rod-shaped main spines. The main spines are commonly four in num- ber and continuous into the medullary shell. In the interior of the medullary shell, however, the structure and emanation of the main spines are unclear. The diameter of the inner cortical shell is about two-thirds that of the outermost cortical shell. The surfaces of the outermost and inner cortical shells are irregularly perforated with oval to subangular pores. Many thin, radial beams connecting the outermost and inner cortical shells arise from the surface of the inner cortical shells. Due to being connected by many radial beams, the outermost and inner cortical shells form very complex sponge-like layers. Since only the broken medu- llary shell is preserved in our specimens, the detailed struc- ture of the medullary shell is unclear. Based on observation with a transmitted light microscope, the diameter of the medullary shell is about one-third to one-fifth that of the out- ermost cortical shell. Measurements. — Based on two specimens, in um. Diameter of the outermost cortical shell, 280-300, average, 290; diameter of the inner cortical shell, 160-200, average, 180. Remarks. —This species is easily distinguished from Syntagentactinia excelsa Nazarov and Ormiston by having long, robust main spines. Nazarov in Nazarov and Popov (1980) described Syntagentactinia biocculosa Nazarov and Syntagentactinia pauca Nazarov from the Middle Ordovician strata of eastern Kazakhstan. Nazarov’s figures in Nazarov and Popov (1980) of these Ordovician species are transmit- ted light photomicrographs, so it is difficult to compare Silurian species with Ordovician species in detail. Nazarov and Ormiston (1993), however, mentioned that S. afflicta is distinguished from Ordovician species by the clearly ex- pressed internal half-closed shells and the development in the majority of specimens of two to four rather than six main spines. Range and occurrence. — Early Llandoverian, northern Adobe Range, Nevada; middle to late Llandoverian, south- ern Urals, southern Bashkiria and Northern Mugodzhar; Llandoverian, Ise area in the Hida "Gaien" Belt. Syntagentactinia excelsa Nazarov and Ormiston, 1993 Figures 7.19, 7.20; 8.1-8.7 Syntagentactinia excelsa Nazarov and Ormiston, 1993, p. 40, pl. 6, figs. 13, 14. Description.—The external appearance of the cortical shell is spherical, subspherical, or elliptical, with thin rod-like main spines. The main spines are directly continuous into the internal portion of the shell (Figure 6c, d). The cortical shell is composed of two or three layers with irregular, three- dimensional meshwork. The surface of the cortical shell is irregularly porous and has small spines. The medullary shell, consisting of a spherical to irregularly shaped loose lattice, is placed in the internal cavity and has a diameter about 30% that of the cortical shell diameter. The medullary and cortical shells are connected by short radial beams arising randomly from the surface of the medullary shell. Measurements. — Based on five specimens, in pm. Diameter of the cortical shell, 200-270, average, 250; diameter of the medullary shell, 40-90, average, 70. Remarks.—This species is distinguished from other spe- cies of this genus by having thin, weakly developed main spines. Some specimens of this species have a smaller cortical shell than that of Syntagentactinia afflicta described above. Although Nazarov and Ormiston (1993) suggested that this species has a peculiar eccentric position of the medullary shell, this characteristic is not clearly shown in their illustrated specimen (Nazarov and Ormiston, 1993, pl. 4, fig. 13). The shell constitution of this species is similar to that of Syntagentactinia? sp. illustrated by Noble et al. (1998) from chert gravel of the Main Valley, Germany. However, Syntagentactinia? sp. of Nobel et al. (1998) has a large diameter of the cortical shell, up to 700 um. Syntagentactinia sp. A of Noble et al. (1998) is similar to the present species, but differs from S. excelsa by having a dis- tinctly latticed medullary shell. Range and occurrence.— Middle to late Llandoverian, southern Urals, southern Bashkiria and Northwestern Mugodzhar; Llandoverian, Ise area in the Hida "Gaien" Belt. Syntagentactinia? sp. Figure 8.8 Remarks.—Only one poorly preserved specimen was ob- tained. The shell of this species is composed of an irregu- “ee PE CA © D c a © Cp) o > an 2 © Va ne) = © © nn o = m =) x x > > <= ao © F Silurian (Llandoverian) radiolarians 155 larly fine spongy layer having three thick main spines. This spongy layer may be a product of the state of preservation. This species is similar to Syntagentactinia? sp. of Noble et al. (1998), except that it has a rather small shell diameter. Although its detailed shell structure has not yet been exam- ined, we tentatively include this form in Syntagentactinia. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Family Inaniguttidae Nazarov and Ormiston, 1984, emend. Noble, 1994 Genus Oriundogutta Nazarov, 1988 Type species.—Astroentactinia ramificans Nazarov, 1975. Oriundogutta sp. Figure 8.9-8.15 ?Oriundogutta sp. Noble, Ketner and McClellan, 1997, pl. 1, figs. 7, 8. Description.— The thick, spherical cortical shell is single and latticed with 10 to 15 external spines per hemisphere. The external spines are short, conical to rod-like and taper distally. Five to six main spines arising from the surface of the medullary shell in each hemisphere are long and have one or two short by-spines. The pores of the latticed shell are circular, and oval to irregularly circular in shape. Thick and broad pore frames are pentagonal or hexagonal in shape. The medullary shell is small, latticed and polyhedral to spherical in shape. The pores of the medullary shell are circular to oval and larger than those of the cortical shell. The pore frames of the medullary shell are thinner than those of the cortical shell. SEM and transmitted light micro- scopic observations show the absence of an internal spicule in the interior of the medullary shell. Measurements. — Based on five specimens, in pm. Diameter of the cortical shell, 150-300, average, 210; diameter of the medullary shell, 60-110, average, 90. Remarks.—More than twenty specimens of this species were examined and they bear diagnostic characters of the Oriundogutta: one porous, thick cortical shell, a polyhedral to spherical medullary shell, and more than eight external spines. It is distinguished from other species of this genus by having short, conical to rod-like external spines and a smaller number of these spines. ?Oriundogutta sp., re- ported by Noble et al. (1997) from the lower Llandoverian of Nevada, is exceedingly similar to this species in external shape. Range and occurrence.—Early Llandoverian, northern Adobe Range, Nevada; Llandoverian, Ise area in the Hida "Gaien" Belt. Oriundogutta? sp. Figure 8.16-8.20 Remarks.—The cortical shell of this species is spherical and has three to four sturdy, rod-like main spines per hemi- sphere. Some of the examined specimens have several thin, needle-like spines. The external shell features of Oriundogutta? sp. are similar to those of Oriundogutta ramificans (Nazarov), except that the former’s main spines are smaller in number. This species is distinguished from Oriundogutta sp. by having a finely perforated cortical shell and thin pore frames. The internal shell structure cannot be observed, so the generic position of this species is tentative. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Genus Inanihella Nazarov and Ormiston, 1984, emend. Noble, 1994 Type species. — Helioentactinia bakanasensis Nazarov, 1975. Inanihella sp. Figure 9.1-9.4 Description.—The shell of this species is composed of two latticed cortical shells with more than four main spines per hemisphere. The inner cortical shell is spherical and has circular to oval pores with pentagonal to hexagonal pore frames. The outer cortical shell is delicate and irregularly perforated. Several short, needle-like spines arise from the surface of the outer cortical shell. The inner and outer cor- tical shells are connected by many thin radial beams. Based on observations with a transmitted light microscope, the internal shell is single, and probably latticed, but its de- tailed structure has not been observed. The main spines are thin, rod-like and taper gently toward the distal end. Measurements. — Based on four specimens, in um. Diameter of inner cortical shell, 190-220, average, 200; di- ameter of outer cortical shell, 260-300, average, 280; maxi- mum length of spine, 70. Remarks.—This species is characterized by the presence of two cortical shells, yet no specimens were found that per- fectly preserve the delicate outer cortical shell. The present form has a spine morphology similar to /nanihella baka- nasensis (Nazarov) reported from the Middle Ordovician of Kazakhstan by Nazarov (1975). Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Figure 7. 1-13. Haplotaeniatum tegimentum Nazarov and Ormiston, 1: IGUT-TK 863, 2: IGUT-TK 816, 3: IGUT-TK 874, 4: IGUT- TK 894, 5: IGUT-TK 782, 6: IGUT-TK 858, 7: IGUT-TK 875, 8: IGUT-TK 958, 9: IGUT-TK 860, 10: IGUT-TK 783, 11: IGUT-TK 794, 12: IGUT-TK 884, 13: IGUT-TK 776. White arrows of 9 to 13 indicate a pylome-like oversized pore. 14-16. Haplotaeniatum sp. A, 14: IGUT- TK 866, 15: IGUT-TK 873, 16: IGUT-TK 801. 17, 18. Syntagentactinia afflicta Nazarov and Ormiston, 17: IGUT-TK 897, 18: IGUT-TK 824. 19, 20. Syntagentactinia excelsa Nazarov and Ormiston, 19: IGUT-TK 817, 20: IGUT-TK 747. Scale bars A and B each equal 100um; A applies to 15, 17, 18, B to 1-14, 16, 19, 20. © 42 I= D © [02] ° = D 2 © x D = © © © a fe — 3 x x =) >> [= a © + Silurian (Llandoverian) radiolarians 157 Inanihella? sp. Figure 9.5-9.7 Remarks.—The basic skeleton of this species is com- posed of a porous inner cortical shell with traces of delicate outer cortical shell. The internal shell structure has not yet been observed. Three or four rod-like main spines are pre- sent on the inner cortical shell per hemisphere. Many short conical spines arise from the junction of the pore frame of the inner cortical shell. The inner cortical shell and main spines of this species are very similar to those of the Inanihella sp. described above. Although only traces of the delicate outer cortical shell are present, we tentatively in- clude this form in /nanihella. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Inaniguttidae gen. et sp. indet. sp. A Figure 9.8, 9.9 Remarks.—Several poorly preserved specimens were ex- amined. This species is characterized by a large, spherical cortical shell with an oversized pore. This pylome-like pore is circular in shape and has no lip on its surrounding pore frame. The external shell morphology is somewhat similar to the Oriundogutta sp. herein. We tentatively include this species in the family Inaniguttidae. A larger sample of this species is needed in order to determine its generic position. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Family Anakrusidae Nazarov, 1977 Genus Auliela Nazarov, 1977 Type species.—Auliela aspersa Nazarov, 1977. Auliela sp. Figure 9.10 Description.—The shell is spherical, with more than one hundred spines arising from the hemisphere. The spines are straight, cylindrical and taper gently toward the distal end. Most of these spines are short or broken, owing to poor preservation, but some attain 60 um in length. There are no pores on the shell surface. The internal structure is unknown. Measurements.—Based on one specimen, in um. Di- ameter of shell, 300; maximum length of spine, 60. Remarks.—Only one specimen of this species was exam- ined. Our specimen has a spherical shell with numerous cylindrical spines. This character and the external shape in- dicate assignment to the genus Auliela. Auliela aspersa Nazarov, the type species of this genus, described from the Middle Ordovician of eastern Kazakhstan by Nazarov (1977), is similar to the present species. The spines of A. aspersa Nazarov are described as being hollow, but the pre- sent specimen has mostly solid spines. This difference may be attributed to the development of secondary deposits of silica and poor preservation. This species, however, differs from A. aspersa Nazarov in having a rather smaller shell and shorter spines. Auliela taplowensis Webby and Blom, described from the Upper Ordovician of eastern Australia by Webby and Blom (1986), differs from this species by having longer spines and a smaller shell diameter. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Family Palaeoscenidiidae Riedel, 1967a, emend. Holdsworth, 1977; Goodbody, 1982; Furutani, 1983; Goodbody, 1986 Genus Palaeoephippium Goodbody, 1986 Type species. — Palaeoephippium bifurcum Goodbody, 1986. Palaeoephippium? sp. Figure 9.11-9.13 Remarks.—Completely preserved specimens of this spe- cies have not yet been obtained. The basic skeleton of this species probably consists of a six-rayed form. The spines arising from each ends of a short medium bar are rod-like, gently tapered toward the distal end. Among these spines, three (probably four) spines have two or three rather thin secondary spines at the midpoint of their length, and the other spines lack the branched spines. Palaeoephippium tricorne Goodbody, described from the Cape Phillips Formation of the Canadian Arctic Archipelago by Goodbody (1986), has indistinguishable apical and basal spines and is similar to this species. Furthermore, this species has a re- semblance to Haplentactinia arrhinia Foreman, 1963 in hav- ing a six-rayed basic spicule. However, the former species differs from the latter by having branches arising at one level along some spines and lacking an irregularly latticed shell. In this paper, we tentatively assign this species to the genus Palaeoephippium, considering its similarity to P. tricorne. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Family Sponguridae Haeckel, 1887, emend. Pessagno, 1973 Sponguridae gen. et sp. indet. sp. A Figure 9.14, 9.15 Description. —The shell is elliptical, with two polar main Figure 8. 1-7. Syntagentactinia excelsa Nazarov and Ormiston, 1: IGUT-TK 723, 2: IGUT-TK 836, 3: IGUT-TK 961, 4: IGUT-TK 864, 5: IGUT-TK 724, 6: IGUT-TK 822, 7: IGUT-TK 766. 8. Syntagentactinia? sp., IGUT-TK 899. 9-15. Oriundogutta sp., 9: IGUT-TK 859, 10: IGUT-TK 895, 11: IGUT-TK 819, 12: IGUT-TK 879, 13: IGUT-TK 901, 14: IGUT-TK 761, 15: IGUT-TK 850. 16-20. Oriundogutta ? sp., 16: IGUT-TK 892, 17: IGUT-TK 931, 18: IGUT-TK 845, 19: IGUT-TK 865, 20: IGUT-TK 919. Scale bars A, B and C each equal 100um; A applies to 1, 8, 16, 17, B to 2-7, 9-11, 13-15, 18-20, C to 12. © Lo) i= ao © (9) o =) no 2 © x D (= © © © fo) fs = =) Va zZ > > dE ao © + Silurian (Llandoverian) radiolarians 159 These spines are rod-like, strongly tapered, and identical in length and thickness. The proximal portions of the spines are weakly bladed. The surface of the outer shell has many circular to polygonal pores of irregular size. The interior of the shell consists of a loose, irregular spongy meshwork. The distinctly layered internal structure was not observed. Measurements.—Based on one specimen, inum. Length of major axis of shell, 190; length of minor axis of shell, 150; length of spines, 100. Remarks.— Several poorly preserved specimens of this species were examined. Although the internal structure of the multiple concentric spongy layers is unknown, this form is characterized by an elliptical spongy shell and polar main spines, and is included in the family Sponguridae. Noble (1994) has recognized Late Silurian genera (Pseudospon- goprunum Wakamatsu, Sugiyama and Furutani, 1990, and Devoniglansus Wakamatsu, Sugiyama and Furutani, 1990) of the family Sponguridae. The species assigned to Pseudospongoprunum by Noble (1994) are especially char- acterized by a subspherical to elliptical spongy shell with polar main spines, and they are similar to the present spe- cies. This unidentified species, however, differs from all species of Pseudospongoprunum by having a loose spongy meshwork and equal lengths to the polar main spines. The exact identification of this species is postponed until suffi- cient specimens have been examined. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. spines. Family Pylentonemidae? Deflandre, 1963 Genus Cessipylorum Nazarov in Afanas’eva, 1986 Type species. — Pylentonema insueta Nazarov in Na- zarov, Popov and Apollonov, 1975. Remarks. — Nazarov and Ormiston (1993) tentatively placed the genera Cessipylorum and Aciferopylorum Nazarov and Ormiston, 1993 in the family Pylentonemidae Deflandre. We tentatively follow that placement. Cessipylorum? sp. Figure 9.16 Remarks.—Only one specimen was examined. The cor- tical shell is subspherical and irregularly porous, and bears a large circular aperture. The pore frame around the aper- ture is slightly turned up and has small conical spines. The presence of a medullary shell and an inner structure is un- clear. The other species in Cessipylorum, such as Cessi- pylorum apertum (Nazarov), have long, robust main spines, but this species has only a few thin and short spines. The generic placement of this species is tentative. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Family Incertae sedis Genus Orbiculopylorum Noble, Braun and McClellan, 1998 Type species. — Orbiculopylorum marginatum Noble, Braun and McClellan, 1998. Orbiculopylorum sp. Figure 9.17 Remarks.—The illustrated specimen is distinguished by a prominent pylome on the cortical shell. The cortical shell is thick and probably perforated. However, the detailed struc- ture of the cortical shell cannot be observed, owing to poor preservation. The pylome is circular and flanged. The medullary shell consists of a loose lattice and is irregularly spherical and centrally located. This species is similar to Orbiculopylorum adobensis Noble, Braun and McClellan, described from the Cherry Spring Chert of Nevada by Noble et al. (1998). However, the former species differs from the latter by having a less compact medullary shell. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. Spumellaria gen. et sp. indet. sp. A Figure 9.19, 9.20 Labyrinthine spumellarian Noble, Ketner and McClellan, 1997, pl. 1, fig. 14. Description.— The shell consists of a spongy, three- dimensional meshwork and is irregularly spherical. The spongy meshwork is loose, delicate and has no regular structure or layering. The exterior meshwork seems to be looser than that in the interior. The pores framed by the looped, loose, spongy meshwork are circular to elliptical and vary in size. On the external surface of the shell, short subconical to cylindrical spines arise from the pore frame and usually bifurcate, or rarely trifurcate, at their distal end. Measurements. — Based on two specimens, in um. Diameter of shell, 120-170, average, 145. Remarks.—This species is characterized by an irregular spongy shell without layering. A form referable to this spe- cies has been reported by Noble et al. (1997) as Labyrinthine spumellarian. Haplotaeniatum fenestratum Goto, Umeda and Ishiga, described from the Upper Figure 9. 1-4. Inanihella sp., 1: IGUT-TK 973, 2: IGUT-TK 976, 3: IGUT-TK 986, 4: IGUT-TK 893. 5-7. Inanihella? sp., 5: IGUT- TK 975, 6: IGUT-TK 855, 7: IGUT-TK 937. 8, 9. Inaniguttidae gen. et sp. indet. sp. A, 8: IGUT-TK 956, 9: IGUT-TK 808. White arrows of 8 and 9 indicate an oversized pore. 10. Auliela sp., IGUT-TK 732. 11-13. Palaeoephippium? sp., 11: IGUT-TK 843, 12: IGUT-TK 737, 13: IGUT-TK 842. 14, 15. Sponguridae gen. et sp. indet. sp. A, 14: IGUT-TK 940, 15: IGUT-TK 827. 16. Cessipylorum? sp., IGUT- TK 922. 17. Orbiculopylorum sp., IGUT-TK 743. White arrow of 17 indicates a pylome. 18. Spumellaria gen. et sp. indet., IGUT-TK 972. 19, 20. Spumellaria gen. et sp. indet. sp. A, 19: IGUT-TK 725, 20: IGUT-TK 851. 21. Spumellaria gen. et sp. indet. sp. B, IGUT-TK 868. Scale bars A, Band C each equal 100um; A applies to 1, 2, 8, 10, 14, 18, B to 3-7, 9, 11-13, 15-17, 19, 21, C to 20. 160 Toshiyuki Kurihara and Katsuo Sashida Ordovician of eastern Australia by Goto et al. (1992), is simi- lar to this species in the basic construction of its spongy shell. However, H. fenestratum lacks certain diagnostic characteristics of Haplotaeniatum, such as concentric layers or a Spiral form. The taxonomic placement of this species will depend on finding additional specimens. Range and occurrence. — Early Llandoverian, northern Adobe Range, Nevada; Llandoverian, Ise area in the Hida "Gaien" Belt. Spumellaria gen. et sp. indet. sp. B Figure 9.21 Remarks. — Several broken specimens were obtained. The illustrated specimen has a spherical shell consisting of a spongy, three-dimensional meshwork. The spongy mesh- work structure of this species is similar to that of Spumellaria gen. et sp. indet. sp. A, described above, but differs from the latter by having an internal cavity. Range and occurrence.—Llandoverian, Ise area in the Hida "Gaien" Belt. 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L. eds., Radiolaria of Giant and Subgiant Fields in Asia. Nazarov Memorial Volume. Micropaleontology Special Publication, vol. 6, p. 98-114. Webby, B. D. and Blom, W. M., 1986: The first well-preserved radiolarians from the Ordovician of Australia. Journal of Paleontology, vol. 60, no. 1, p. 145-157. Yamada, K., 1967: Stratigraphy and geologic structure of the Paleozoic formations in the Upper Kuzuryu River district, Fukui Prefecture, Central Japan. The Science Reports of Kanazawa University, Series 2, vol. 12, no. 1, p. 185-207. 163 The Palaeontological Society of Japan has revitalized its journal. Now entitled Paleontological Research, and published in English, its scope and aims have entirely been redefined. The journal now ac- cepts and publishes any international manuscript meeting the Society’s scientific and editorial standards. 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However, figures will be returned upon request by the authors after the paper has been pub- lished. Ager, D. V., 1963: Principles of Paleoecology, 371p. McGraw- Hill Co., New York. Barron, J. A., 1983: Latest Oligocene through early Middle Miocene diatom biostratigraphy of the eastern tropical Pacific. Marine Micropaleontology, vol. 7, p. 487-515. Barron, J. A., 1989: Lower Miocene to Quatemary diatom biostratigraphy of Leg 57, off northeastern Japan, Deep Sea Drilling Project. In, Scientific Party, Initial Reports of the Deep Sea Drilling Project, vols, 56 and 57, p. 641-685. U. S. Govt. Printing Office, Washington, D. C. Burckle, L. H., 1978: Marine diatoms. In, Hag, B. U. and Boersma, A. eds., Introduction to Marine Micropaleon- tology, p. 245-266. Elsevier, New York. Fenner, J. and Mikkelsen, N., 1990: Eccene-Oligocene diatoms in the westem Indian Ocean: Taxonomy, stratigraphy, and paleoecology. In, Duncan, R. A., Backman, J., Peterson, L. C., et al., Proceedings of the Ocean Drilling Program, Scientific Results, vol. 115, p. 433-463. College Station, TX (Ocean Drilling Program). Kuramoto, S., 1996: Geophysical investigation for methane hy- drates and the significance of BSR. The Journal of the Geological Soclety of Japan, vol. 11, p. 951-958. (in Japanese with English abstract) Zakharov, Yu. D., 1974: Novaya nakhodka chelyustnogo apparata ammonoidey (A new find of an ammonoid jaw ap- paratus). Paleontologicheskii Zhurnal 1974, p. 127-129. (in Russian) Ts ÿ Æ Os 15021 Flitz, 200177 1 A278 (+) £288 (A) ic (RKB ARE) THÉSNET. vy RY 7 ABO LA AU) 420007 4 AAA, ARO LIAS HU) A 4200047125 1A (&) T3. ©O20014F4ES - Bald QHCRVOFATIOT, [21H00 EME] ZH-7F-VEL, Kt CYYRYIASMDELKEAC, PRAHHBSAMS HOEK > CHE PIS 2 C LHRELTE DES. FÉDOENVÉREDUTIE [LA] 675, 83-8482 CHR SU. O#151IPIZ (2002 1 A FAHETE OEM LIASIL, ZSOLIABU EHER. ©20024FS + BS (20024 6 A FAIRE PE) 1 UMR HET NÉ MIRE SBE LiAADHOELK. OwEMBATIS, PAMCHHANSZI-DPVayvyTRPYa-—hI-REERBLTHV EF, FEDS SRESCEMATEICEMCAETOTC, SAL EHSOAITHRE CHM AY FAY. BABÉ + YY RYU LROR LASS ABHOR LUA PRR tBHSEKO RSW. e-mail? 7 7 » 7 ATOHLIASAI, IRB EL TZUNGTBOEHA, T240-0067 MATAR Tr FICHE 79-2 BREVAFARAREFEN EA TEL 045-339-3349 (i838) FAX 045-339-3264 (RE) E-mail majima@edhs.ynu.ac.jp NÉE (TER) BMUOAHS, THAD FLOTFREE CHA FAW. 7250-0031 / HE AA H499 HAR) RATA an D EB + SDK BE TEL 0465-21-1515 FAX 0465-23-8846 E-mail taru@pat-net.ne.jp Bll (FATF) POPE LL LL PL LL LL LL LL SLO LOLOL LL DL OL PL OL OLE LOLOL OL OL OLOLOCL OL OL OC OLO LO LOLOL CLE? ABORTICET4ZBAl, GROSRVUAK, MRAP SHARDS 5 UICRDARD 56OLE BYATSNTWESD, HEDOBMSE lt FOUT AVEAYT AIRIS ARIE © B+ ken = AE LIN 2 BA SS ee AMARA BRRASHt FH AmKA At KEARVNAEHBROHMEE $a-YTAN-7RMEARG OE (7 4 % x IE) OPERA HI HAM RABAEHERD ICES tT | BH A fF ££ BP = SZ 2000 6H 23H Fl &l F 113-8622 KRESCHRAHNAS-16-9 2000 Æ 6 A 30 H FE fT Ele Beer BE 03-5814-5801 BEE We — kh - 1 M X € HERE EME. RK A AE Al fl 4 Fanta EH OR 2,500F] T176-012 HHMAREXÉEI201301 SE 03-3991-3754 ISSN 1342-8144 Paleontological Research BAB, B25 eco Paleontological Research Vol. 4, No. 2 June 30, 2000 CONTENTS Shuji Niko, Tamio Nishida and Keiji Nakazawa: Orthoconic cephalopods from the Lower Permian Atahoc Formation in East Timor === === + = toe eee se els on ET Yutaka Honda: A new species of Ancistrolepis (Gastropoda: Buccinidae) from the Iwaki Formation (lower Oligocene) of the Joban coal field, northern Japan ---------::---:-::::::...... Takeshi Hasegawa and Takayuki Hatsugai: Carbon-isotope stratigraphy and its chronostratigraphic significance for the Cretaceous Yezo Group, Kotanbetsu area, Hokkaido, Japan ::--:------------. Yasunori Kano and Tomoki Kase: Taxonomic revision of Pisulina (Gastropoda: Neritopsina) from submarine caves in the tropical Indo-Pacific ::::-::::::::--.-........................ Be Keiji Matsuoka and Yoshiki Masuda: A new potamolepid freshwater sponge (Demospongiae) from the Miocene Nakamura Formation, central Japan «+--+ secretes Hiroaki Karasawa and Hiroshi Hayakawa: Additions to Cretaceous decapod crustaceans from Hokkaido, Japan—Part 1. Nephropidae, Micheleidae and Galatheidae :::-----:-:-:::::::::...... Toshiyuki Kurihara and Katsuo Sashida: Early Silurian (Llandoverian) radiolarians from the Ise area of the Hida “Gaien” Belt, central Japan ele eife 0. 00 010 ene) 01 oe slot ele line la 0.00.0000 0 7 00 0 00.000000:000000 FaE 7e | Paleontological Research | ISSN 1342-8144 Formerly Transactions and Proceedings of the Palaeontological Society of Japan Vol. 4 No3 | September 2000 — u The Palaeontological Society of Japan Co-Editors Kazushige Tanabe and Tomoki Kase Language Editor Martin Janal (New York, USA) Associate Editors Jan Bergström (Swedish Museum of Natural History, Stockholm, Sweden), Alan G. Beu (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Satoshi Chiba (Tohoku University, Sendai, Japan), Yoichi Ezaki (Osaka City University, Osaka, Japan), James C. Ingle, Jr. (Stanford University, Stanford, USA), Kunio Kaiho (Tohoku University, Sendai, Japan), Susan M. Kidwell (University of Chicago, Chicago, USA), Hiroshi Kitazato (Shizuoka University, Shizuoka, Japan), Naoki Kohno (National Science Museum, Tokyo, Japan), Neil H. Landman (Amemican Museum of Natural History, New York, USA), Haruyoshi Maeda (Kyoto University, Kyoto, Japan), Atsushi Matsuoka (Niigata University, Niigata, Japan), Rihito Morita (Natural History Museum and Institute, Chiba, Japan), Harufumi Nishida (Chuo University, Tokyo, Japan), Kenshiro Ogasawara (University of Tsukuba, Tsukuba, Japan), Tatsuo Oji (University of Tokyo, Tokyo, Japan), Andrew B. Smith (Natural History Museum, London, Great Britain), Roger D. K. Thomas (Franklin and Marshall College, Lancaster, USA), Katsumi Ueno (Fukuoka University, Fukuoka, Japan), Wang Hongzhen (China University of Geosciences, Beijing, China), Yang Seong Young (Kyungpook National University, Taegu, Korea) Officers for 1999-2000 President: Kei Mori Councillors: Kiyotaka Chinzei, Takashi Hamada, Yoshikazu Hasegawa, Itaru Hayami, Hiromichi Hirano, Noriyuki Ikeya, Junji Itoigawa, Tomoki Kase, Hiroshi Kitazato, Itaru Koizumi, Haruyoshi Maeda, Ryuichi Majima, Makoto Manabe, Hiroshi Noda, Ikuwo Obata, Kenshiro Ogasawara, Terufumi Ohno, Tatsuo Oji, Tomowo Ozawa, Yukimitsu Tomida, Tsunemasa Saito, Takeshi Setoguchi, Kazushige Tanabe, Akira Yao Members of Standing Committee: Hiroshi Kitazato (General Affairs), Tatsuo Oji (Liaison Officer), Makoto Manabe (Finance), Kazushige Tanabe (Editor in Chief, PR), Tomoki Kase (Co-Editor, PR), Ryuichi Majima (Planning), Hiromichi Hirano (Membership), Kenshiro Ogasawara (Foreign Affairs), Haruyoshi Maeda (Publicity Officer), Noriyuki Ikeya (Editor, "Fossils"), Yukimitsu Tomida (Editor in Chief, Special Papers), Tamiko Ohana (Representative, Union of Natural History Societies). 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Phone: (978)750-8400, Fax: (978)750-4744, www.copyright.com Cover: Idealized sketch of Nipponites mirabilis Yabe, a Late Cretaceous (Turonian) nostoceratid ammonite. Various reconstructions of the mode of life of this species have been proposed, because of its curiously meandering shell form (after T. Okamoto, 1988). All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN c/o Business Center for Academic Societies, Honkomagome 5-16-9, Bunkyo-ku, Tokyo 113-8622, Japan Visit our society website at http:/ammo.kueps.kyoto-u.ac.jp./palaeont/index.html Paleontological Research, vol. 4, no. 3, pp. 165-170, September 29, 2000 © by the Palaeontological Society of Japan The presence of an azhdarchid pterosaur in the Cretaceous of Japan NAOKI IKEGAMI', ALEXANDER W. A. KELLNER? and YUKIMITSU TOMIDA’ "Mifune Dinosaur Museum, 995-3 Mifune Mifune Town, Kamimashiki-gun, Kumamoto Prefecture 861-3207, Japan (e-mail: naokii @ fa2.so-net.ne.jp) ®Museu Nacional, Rio de Janeiro, Quinta da Boa Vista, RJ 20.940-040, Brazil “National Science Museum, 3-23-1 Hyakunincho, Shinjyuku, Tokyo 169-0073, Japan Received 24 September 1999; Revised manuscript accepted 14 April 2000 Abstract. An incomplete pterosaur cervical vertebra from the “Upper” Formation (Late Ceno- manian-Early Turonian) of the Mifune Group, Kumamoto Prefecture, Japan, is described. Although not complete, this vertebra is very elongated and has a reduced neural spine, allowing its assign- ment to the Azhdarchidae. morphology of the postzygapophyses. It differs from other azhdarchids by being less constricted and by the This Japanese occurrence extends the distribution of the Azhdarchidae during the Cretaceous to the easternmost part of Asia. Key words: Azhdarchidae, Late Cretaceous, Mifune Group, Pterosauria, Southwest Japan Introduction The occurrence of pterosaur remains in Japan is very lim- ited. The first record of these volant archosaurs in Japan was the distal part of a femur and other associated bones that were found in Cretaceous sediments of Hokkaido (Obata et al., 1972). Since then, a limited number of frag- mentary material has been recovered from a few localities. These include an incomplete wing phalanx (Okazaki and Kitamura, 1996) and the proximal articulation of a left wing metacarpal (Ikegami and Tamura, 1996) both found in the “Upper” Formation of the Mifune Group, in Kumamoto Prefecture, an incomplete wing phalanx (Unwin et al., 1996), and an incomplete cervical vertebra (Chitoku, 1996). To these we add the description of an incomplete cervical verte- bra that can be referred to the Azhdarchidae, a long-necked pterodactyloid. The occurrence of this specimen was previ- ously reported (Ikegami, 1997), and a full description and comparison of this material are presented here. Geological setting The pterosaur fossil described here was recovered from an outcrop near Amagimi dam, Mifune Town, Kamimashiki- gun, Kumamoto Prefecture, Japan (Figure 1), which is lo- cated approximately 20 km southeast of central Kumamoto City. The Mifune Group, broadly distributed in this area, was named by Matsumoto (1939), and was subdivided into three formations, namely the “Basal”, “Lower’, and “Upper” Formations (Figure 2). Although the terms basal, lower, and upper should not be used for formation names, those names were given as official names by Matsumoto (1939) and have not been revised since then. Therefore, these terms are used here until a full revision is published. Tamura and Sawamura (1964), Tamura and Tashiro (1966), and Tamura (1970, 1976, 1977, 1979) further investigated and expanded the distribution of the group, and studied the pelecypod fauna from those strata. The stratigraphy of the group, however, has not markedly changed from the original study of Matsumoto (1939). The “Upper” Formation is characterized by red mudstone, blue-green sandstone, and more than dozen tuff beds (Matsumoto, 1939). It reaches 800 to 1000 m in thickness, and vertebrate fossils have been found in several horizons (Tamura et al., 1991). The azhdarchid specimen described here was found in a coarse sandstone bed, about 30 cm thick and with muddy patches, which belongs to the middle part of the “Upper” Formation (Figure 2). This coarse sandstone is more or less lens-shaped, and appears at a distinct level between two tuff beds. The locality of the azhdarchid, as well as other sites from the same horizon, also yielded many frag- mentary bones of various taxa, including dinosaurs, croco- diles, turtles, fishes, and mammals (Tamura et al., 1991; Hirayama, 1998; Setoguchi et al., 1999). The “Upper” Formation is considered terrestrial based on the rock facies and fossil taxa. Although those fossils do not include taxa that are useful for identifying the age of the 166 Naoko Ikegami et al. = > ° Ds Matsubase | Figure 1. azhdarchid pterosaur. formation, Eucalycoceras sp. cf. E. spathi is known from the middle part of the “Lower’ Formation, suggesting a middle Cenomanian age for this unit (Tamura and Matsumura, 1974). However, the Gankaizan Formation that overlies the “Upper” Formation, south of Kumamoto City, yielded Inoceramus amakusensis, which indicates the early Santonian (Tamura and Tashiro, 1966). These specimens suggest that the age of the “Upper” Formation lies between middle Cenomanian and early Santonian. However, the lower part of the Ohnogawa Group, which outcrops east- northeast of the Mifune Group, includes red beds and tuff beds that resemble the “Upper’ Formation of the Mifune Group. The upper marine facies of the Ohnogawa Group has yielded /noceramus hobetsuensis, indicating middle Turonian age (Noda, 1969). Therefore, the age of the “Upper” Formation of the Mifune Group can be estimated as late Cenomanian to early Turonian (Matsumoto et al., 1982). Hirayama (1998) also suggested as the age of the “Upper” Formation late Cenomanian to early Turonian, based on the similarity between chelonian assemblages from this forma- tion and those of Central Asia. N Gankaizan F. MM ++ Fossil locality LSS ST ES 4 “Upper” Formation Mifune Group “Lower” Formation “Basal” Formation Serpentine Higo ___ Mizukoshi F. Metamorphic Rocks Kiyama Metamorphic Rocks Geological map of the area southeast of Kumamoto City (after Tamura, 1979), showing the locality of the Systematic description Family Azhdarchidae Nessov, 1984 Azhdarchidae gen. et sp. indet. Figure 3 Material.—MDM (Mifune Dinosaur Museum) 349, a cervi- cal vertebra from the Mifune Group; a cast in Museu Nacional, Rio de Janeiro (MN 5022-V). Description.—The specimen consists of an incomplete procoelous cervical vertebra, with the cranial part including the prezygapophyses missing (Fig. 3). The vertebra is compressed dorsoventrally, which causes distortion towards the left lateral side. Although this compression changed the natural shape of this bone, it is not completely flattened like many pterosaur specimens from the Niobrara Chalk of North America, but maintains some of its original three- dimensionality. Several breaks, cutting the vertebral body and some filled with matrix, are present, particularly on the dorsal surface (Figure 3 A, B). On the ventral side, the cor- tical bone is crushed, forming several bony plates in a “broken eggshell”-like pattern. Azhdarchid Pterosaur from Japan 167 Santonian GG | Conlaclan Turonian = pi] > à LP Cenomanian 3 (of ey III 4 | Te: my 7 u ( Mifune Group c. g. sandstone ~conglomerate f.sandstone © Eucalycoceras sp.cf.E. spathi ==] green shale E Inoceramus amakusensis EEE red shale ©) gastropods Fa _ tuff = fragmentaly bones & 5x azhdarchid = charophytes Figure 2. Stratigraphy of the Upper Cretaceous sedi- ments in the area southeast of Kumamoto City (after Tamura and Matsumura, 1973; Tamura and Tashiro, 1966; Matsumoto et al., 1982) on the left, and columnar section of the “Upper” Formation of the Mifune Group at the fossil locality on the right. Near the caudal articulation, the neural spine is broken, but the preserved parts suggest that it was very low. Slightly away from the articulation, this structure almost dis- appears, being reduced to a very thin ridge that extends for most of the preserved vertebral length. On the right side, another ridge runs parallel to the neural spine, about 5 mm away from the midline. Evidence of a similar ridge is also observed about 6 mm from the midline on the left side, most of which was lost during the compaction of the specimen. This ridge is interpreted as the transverse process that, in this specimen, is very reduced and does not reach the postzygapophysis. The postzygapophyses are set well apart from the verte- bral body, with the left one better preserved. They are not parallel to each other, and each of them forms an estimated angle with the midline of the centrum of about 33° (based on the right side) in dorsal view. Also in distal view, the postzygapophyses are set apart from the vertebral body, although the angle relative to the ventral surface is very difficult to estimate (Figure 3 G,H). The articular surface of the postzygapophysis is suboval; the dorsal part is constricted, and the ventral part is rounded. Above the dorsal margin, a small process is present. The posterior condyle is not very well preserved in this specimen. Apparently, it had a suboval outline, with the major axis directed lateromedially. The dorsal margin is rounded, and the ventral margin is flattened. On each side of the condyle, the postexapophyses are observed, of which the left side is better preserved. It forms a small process that is directed laterocaudally. Two pneumatic openings are observed lateral to the neu- ral canal; the right one is better preserved. Both pneumatic openings are slightly smaller than the neural canal and oc- cupy a relatively high position in the posterior surface of the vertebra. There is no evidence of a third pneumatic foramen above the neural canal. The reconstruction of the middle part for this cervical ver- tebra indicates that the transverse section was oval and slightly wider than high (see Table 1). Based on the pre- served part, this vertebra was very elongate, with a minimum length/width ratio of 4.3, but likely over 5. The exact length, however, is unknown. Comparisons and discussion. — Comparisons of this specimen with other pterosaur cervical vertebrae show that it shares one feature with the Azhdarchidae: its relative length. Elongated mid-cervical vertebra with a low neural spine is one of the synapomorphies of azhdarchids (Howse, 1986), indicating that this specimen represents a member of this pterosaur clade. Padian (1984, 1986) refined the diag- nosis of Nessov (1984), showing among other things that the vertebra centrum enclosed the neural canal, a situation nearly unique in vertebrates. As far as comparisons are possible, this cervical vertebra shows some differences from other azhdarchids. In dorsal view, the postzygapophyses are thinner and set apart at a greater angle relative to the vertebra’s midline, as compared to Quetzalcoatlus sp. (Howse, 1986) and to Azhdarcho (Nessov, 1984; cast MN 4692-V). The position of the pneu- matic foramina lateral to the neural canal is similar to the condition in Quetzalcoatlus (TMM 42422-24, cast MN 4699-V), and also of Azhdarcho. In the cranial articulation of some cervical vertebrae attributed to the latter, there is an extra pneumatic opening above the neural canal (Nessov, 1984). Whether a similar opening was present in the Japanese specimen is unknown. This specimen further differs from all known azhdarchids by having a well developed ridge parallel to the neural spine, by being less constricted with comparatively straighter lat- eral margins, and by having the process above the postzygapophyses smaller but comparatively more pointed. So far, only two azhdarchids with a complete or nearly complete neck are known: Quetzalcoatlus sp. from the USA and Zhejiangopterus linhaiensis from China. The former, unfortunately, is still undescribed. The latter was originally regarded as a nyctosaurid (Cai and Wei, 1994), but Unwin and Lü (1997) reclassified this taxon in the Azhdarchidae, based on the low position of the orbit relative to the nasoantorbital fenestra, which is an azhdarchid 168 Naoko Ikegami et al. oex rid P poz Figure 3. Azhdarchidae gen. et sp. indet. (MDM 349), cervical vertebra from the Mifune Group. A, B: dorsal; C, D: right lat- eral; E, F: ventral; G, H: posterior views. Natural size. Abbreviations: nc, neural canal; ns, neural spine; pf, lateral pneumatic foramen; poex, postexapophysis; poz, postzygapophysis; rid, lateral ridge. Table 1. Measurements of Azhdarchidae gen. et sp. indet. (MDM 349), cervical vertebra from the Mifune Group (in mm). preserved length 65 width of postzygapophyses 25.5 width of the centrum (preserved) 15:5 width of the centrum (reconstructed) = 13 height of middle part (preserved) 7 height of middle part (reconstructed) ah synapomorphy (Kellner and Langston, 1996). Because the cervical vertebrae of Z. linhaiensis were not sufficiently de- scribed and illustrated without any detail (Cai and Wei, 1994), a detailed comparison with Japanese specimen can- not be made. Therefore, some of the variations described above could be related to the position of the cervical verte- brae in the neck (e.g. lateral margins, directions of the postzygapophyses). The Azhdarchidae have been known to occur from the Cenomanian deposits of Morocco (Kellner and Mader, 1996); Turonian-Coniacian strata of Uzbekistan (Nessov, 1984); the Campanian Judith River Formation of Alberta, Canada (Currie and Russell, 1982); Campanian Two Medicine Formation of Montana, USA (Padian, 1984; Padian and Smith, 1992; Padian et al, 1995); Campanian- Maastrichtian deposits of Senegal (Monteillet et al., 1982); the Maastrichtian Javelina Formation of Texas, USA (Lawson, 1975; Kellner and Langston, 1996); Maastrichtian deposits in Jordan (Arambourg, 1959); and in late Maastrichtian deposits of Merigon, France (Buffetaut et al., 1997). Along with the Chinese specimens mentioned above (Z. linhaiensis, late Cretaceous), the occurrence of Azhdarchidae in Japan extends the distribution of those pterosaurs during the Cretaceous to the easternmost part of Asia. Azhdarchid Pterosaur from Japan Acknowledgments The specimen described here was collected by an exca- vation managed by the Mifune Board of Education with the cooperation of a number of people in 1996. That excava- tion was financially supported by the Mifune Board of Education and the Kumamoto Prefectural Board of Education. We would like to thank Minoru Tamura for many helpful comments during the field research. Also, we thank Yasuko Okamoto for the illustrations of figures 3 B, D, F, and H. References Arambourg, C. 1959: Titanopteryx philadelphiae nov. gen., nov. sp., ptérosaurien géant. Notes et Mémoires du Moyen Orient, 7, p. 229-234. Buffetaut, E., Laurent, Y., Le Loeuff, J. and Bilotte, M. 1997: A terminal Cretaceous giant pterosaur from the French Pyrenees. Geological Magazine, vol. 134, no. 4, p. 553- 556. Cai, Z. and Wei, F., 1994: On a new pterosaur (Zhejiangopterus linhaiensis gen. et sp. nov.) from Upper Cretaceous in Linhai, Zhjiang, China. Vartebrata Palasiatica, vol. 32, p. 181-194, pls. I-II. (in Chinese with English summary) Chitoku, T. 1996: Pterosaur bone from the Upper Cretaceous of Enbetsu, Hokkaido. Bulletin of the Hobetsu Museum, No. 12, p. 17-24. (in Japanese with English abstract) Currie, P. J. and Russell, D. A., 1982: A giant pterosaur (Reptilia: Archosauria) from the Judith River (Oldman) Formation of Alberta. Canadian Journal of Earth Sciences, vol. 19, no. 4, p. 894-897. Hirayama, R. 1998: Fossil turtles from the Mifune Group (Late Cretaceous) of Kumamoto Prefecture, Western Japan. In, Report of the research on the distribution of important fossils in Kumamoto Prefecture, “Dinosaurs from the Mufune Group, Kumamoto Prefecture, Japan”, p. 85-99. (in Japanese with English abstract) Howse, S. C. 1986: On the cervical vertebrae of the Pterodactyloidea (Reptilia: Archosauria). Zoological Journal of the Linnean Society, vol. 88, p. 307-328. Ikegami, N. 1997: An azhdarchid pterosaur from the Mifune Group, Kumamoto Prefecture, Japan. Abstracts of the 104th Annual Meeting of the Geological Society of Japan, p. 350. (in Japanese) Ikegami, N. and Tamura, M., 1996: New dinosaurs and a pterosaur from the Mifune Group. Proceedings of the Nishinihon branch Geological Society of Japan, No. 108, p. 9-10. Kellner, A. W. A. and Langston, W., Jr. 1996: Cranial remains of Quetzalcoatlus (Pterosauria, Azhdarchidae) from the Late Cretaceous sediments of Big Bend National Park, Texas. Journal of Vertebrate Paleontology, vol. 16, no. 2, p. 222-231. Kellner, A. W. A. and Mader, B. J. 1996: First report of Pterosauria (Pterodactyloidea, Azhdarchidae) from Creta- ceous rocks of Morocco. Journal of Vertebrate Paleon- tology, vol. 16, suppl. to no. 3, p. 45A. Lawson, D. A. 1975: Pterosaur from the Latest Cretaceous of West Texas. Discovery of the largest flying creature. Science, vol. 187, p. 947-948. Matsumoto, T., 1939: Geology of Mifune district, Kumamoto Prefecture, Kyusyu (with special reference to the Cretaceous system). The Journal of the Geological Society of Japan, vol. 46, no. 544, p. 1-12, pl. 1. (in Japanese with English résumé) Matsumoto, T., Obata, |., Tashiro, M., Ohta, Y., Tamura, M, Matsukawa, M., and Tanaka, H., 1982: Correlation of ma- rine and non-marine formations in the Cretaceous of Japan. Fossils (Kaseki), no. 31, p. 1-26. (in Japanese with English abstract) Monteillet, J., Lappartient, J. R., and Taquet, P. 1982: Un pte- rosaurien géant dans le Crétacé supérieur de Pake (Sénégal). Comptes rendues de l'Académie des Sciences, de Paris, 295, p. 409-414. Nessov, L. A. 1984: Pterosaurs and Birds from the Upper Cretaceous of Middle Asia. Paleontological Journal, vol. 1, p. 47-57. Noda, H., 1969: Biostratigraphic study of the Onogawa Group, Kyushu. Science Reports, Department of Geology, Kyushu University, Vol. 10, No. 1, p. 1-10. pls. 1-3. (in Japanese with English Abstract) Obata, I., Hasegawa, Y., and Otsuka, H., 1972: Preliminary re- port on the Cretaceous reptile fossils from Hokkaido. Memoirs of National Science Museum, vol. 5, p. 213-222. (in Japanese with English abstract) Okazaki, Y. and Kitamura, N., 1996: The first discovery of a pterosaur from the Cretaceous Mifune Group, Kyushu, Japan. Bulletin of the Kitakyushu Museum of Natural History, No. 15, p. 133-136. Padian, K., 1984: Large pterodactyloid pterosaur from the Two Medicine formation (Campanian) of Montana. Journal of Vertebrate Paleontology, vol. 4, no. 4, p. 516-524. Padian, K., 1986: A taxonomic note on two pterodactyloid families. Journal of Vertebrate Paleontology, vol. 6 no. 3, p. 289. Padian, K. and Smith M., 1992: New light on late Cretaceous pterosaur material from Montana. Journal of Vertebrate Paleontology, vol. 12, no. 1, p. 87-92. Padian, K., de Ricqlés A. J. and Horner, J. R., 1995: Bone his- tology determines identification of new fossil taxon of pterosaur (Reptilia: Archosauria). Comptes rendus de l'A cadémie des Sciences de Paris, Séries Il, no. 320, p. 77-84. Setoguchi, T., Tsubamoto, T., Hanamura, H., and Hachiya, K., 1999: An early Late Cretaceous mammal from Japan, with reconsideration of the evolution of tribosphenic mo- lars. Paleontological Research, vol. 3, no. 1, p. 18-28. Tamura, M., 1970: The hinge structure of Trigonioides, with description of Trigonioides mifunensis, sp. nov. from Upper Cretaceous Mifune Group, Kumamoto Pref., Japan. Memoirs of the Faculty of Education, Kumamoto University, no. 18, Natural Science, p. 38-53 Tamura, M., 1976: Cenomanian bivalves from the Mifune Group, Japan Part 1. Memoirs of the Faculty of Education, Kumamoto University, no. 25, Natural Science, p. 45-59. pls. I-lll. Tamura, M., 1977: Cenomanian bivalves from the Mifune Group, Japan Part 2. Memoirs of the Faculty of Education, Kumamoto University, no. 26, Natural Science, p. 107-144. pls. I-XIll. Tamura, M., 1979: Cenomanian bivalves from the Mifune Group, Japan Part 3. Memoirs of the Faculty of Education, Kumamoto University, no. 28, Natural Science, p. 59-74. pls. I-Ill. 169 170 Tamura, M. and Matsumura, M., 1974: On the Age of the Mifune Group, Central Kyushu, Japan. Memoirs of the Faculty of Education, Kumamoto University, no. 23, Natural Science, p. 47-56, pl. |. Tamura, M., Okazaki, Y., and Ikegami, N., 1991: Occurrence of carnosaurian and herbivorous dinosaurs from Upper Formation of Mifune Group, Japan. Memoirs of the Faculty of Education, Kumamoto University, no. 40, Natural Science, p. 31-45. (in Japanese with English ab- stract) Tamura, M. and Sawamura, M., 1964: Upper Cretaceous Mitake-yama Formations in central Kyushu. Memoirs of the Faculty of Education, Kumamoto University, no. 12, Natural Science, p. 15-22. (in Japanese with English ab- Naoko Ikegami et al. Stract) Tamura, M. and Tashiro, M., 1966: Upper Cretaceous system south of Kumamoto. Memoirs of the Faculty of Education, Kumamoto University. no. 14, Natural Science, p. 24-35. (in Japanese with English abstract) Unwin, D. M. and LU J., 1997: On Zhejiangopterus and the re- lationships of pterodactyloid pterosaurs. Historical Bio- logy, vol. 12, p. 199-210. Unwin, D. M., Manabe, M., Shimizu, K., and Hasegawa, Y., 1996: First record of pterosaurs from the Early Cretaceous Tetori Group: a wing-phalange from the Amagodani Formation in Shokawa, Gifu Prefecture, Japan. Bulletin of National Science Museum, Tokyo, Ser. C, vol. 22, nos. 1-2, p. 37-46. Paleontological Research, vol. 4, no. 3, pp. 171-181, September 29, 2000 © by the Palaeontological Society of Japan The suprageneric classification of the foraminiferal genus Murrayinella and a new species from Japan RITSUO NOMURA’ and YOKICHI TAKAYANAGF ‘Foraminiferal Laboratory, Faculty of Education, Shimane University, Matsue, 690-8504, Japan (e-mail: nomura @edu.shimane-u.ac.jp) *c/o Institute of Geology and Paleontology, Faculty of Science, Tohoku University, Sendai, 980-8578, Japan Received 29 November 1999; Revised manuscript accepted 24 April 2000 Abstract. Japanese species of the foraminiferal genus Murrayinella have a rotaliid aperture that is defined by a foraminal plate and umbilical coverplate. must be transferred from the family Glabratellidae to the family Rotaliidae. Our observations suggest that this genus Its morphological simi- larity to the genus Schackoinella, as shown by the presence of a peripheral spine on each chamber, must be a result of homeomorphic convergence. Murrayinella never possesses apertural grooves like those of glabratellids. We give a detailed description of the apertural structure of the Japanese species of Murrayinella and formally describe a new species, M. bellula. Key words: benthic foraminifera, Murrayinella, Rotaliidae, suprageneric taxonomy. Introduction Species of the foraminiferal genus Murrayinella are com- mon in shallow-water sediments of both the Sea of Japan and the Pacific Ocean. The following are well known spe- cies: Murrayinella minuta (Takayanagi, 1955), Murrayinella globosa (Millett, 1903), and Murrayinella takayanagii (Matoba, 1967), all of which have been reported from the late Pleistocene to Recent. Among them, Murrayinella minuta is the most common species in Japan. A Murrayinella species has also been reported from the early middle Miocene of Southwest Honshu, Japan (Nomura, 1990). The earliest appearance of the genus is thus not from the Pliocene (Loeblich and Tappan, 1987), but from the middle Miocene. Despite its common occurrence, the systematic position of this genus is still confused. Heron-Allen and Earland (1915) originally described Murrayinella murrayi as a Rotalia spe- cies, while the allied form M. globosa was described as a Discorbina species by Millett (1903). Subsequently, other species now allocated to Murrayinella were placed in the genus Pararotalia, except for some other generic allocations such as “Eponides” (Ujiie, 1963) and Praeglobotruncana (McCulloch, 1977). Thus, many workers regarded Murrayi- nella as closely related to the Rotaliidae. However, Loeblich and Tappan (1987) placed Murrayinella in the Glabratellidae, referring to their earlier systematic review (Loeblich and Tappan, 1964), on the basis of Heron-Allen and Earland’s observation that suggested a different mode of reproduction from the Rotaliidae, and an apparent similarity to the genus Schackoinella from the late Miocene of Austria (Weinhandl, 1958). Indeed, Haman and Christensen (1971) regarded Murrayinella as a synonym of Schackoinella. Previous investigations lacked detailed comparative ob- servations on the foraminal structure of these small taxa that were beyond the resolution power of binocular microscopes. We carried out detailed anatomical observations of the inner test by scanning electron microscope, using a method of Nomura (1983). As a result, all the species of this genus are shown to be devoid of radiating apertural grooves as in the glabratellids, instead their apertures have the foraminal plate and umbilical coverplate typical of the rotaliids. We now describe the Japanese species, including a new spe- cies, in detail and discuss the suprageneric position of the genus Murrayinella. Foraminal structures of Murrayinella In general, the apertural structures of the genus Murrayinella resemble those of Ammonia or Pararotalia spe- cies which have a foraminal plate and umbilical coverplate. These basic features of the rotaliid aperture are well shown in several species from Eocene sediments of the Paris Basin (Hottinger et al., 1991) and from the Red Sea (Hottinger et al, 1993; Revets, 1993) and Japan (Nomura and Takayanagi, 2000). The final aperture of Murrayinella is an umbilical to extraumbilical slit usually covered with numer- ous small spines. The penultimate and antepenultimate fo- ramina are a high arch or rounded openings with the 172 Ritsuo Nomura and Yokichi Takayanagi foraminal plate on the proximal side and with the umbilical coverplate closing up the umbilical side of the slit-shaped aperture. The foraminal structure of Murrayinella species funda- mentally resembles the Pararotalia-type rather than the Ammonia-type (Nomura and Takayanagi, 2000). Murrayi- nella minuta and M. bellula deviate little from the Pararotalia -type foramen. However, the foraminal plate of M. globosa is variable, ranging from the Pararotalia-type foramen to a form which is close to the Ammonia type. A quite different type is found in M. takayanagi. The Ammonia- or Pararotalia-type foramen can be distinguished by the posi- tion of the foraminal plate. The base of the foraminal plate in the Ammonia-type foramen is formed on the umbilical side of the previous whorl and thus the foramen is arch-shaped, while that of the Pararotalia-type foramen bends towards the inner side of the apertural opening, forming a lip-like struc- ture in its lower side (or proximal side). Thus, the foraminal plate of the Pararotalia-type foramen is called a lower lip in order to distinguish from a toothplate of Hottinger et al. (1991). This difference of foraminal structure is significant for the discrimination of larger forms of rotaliid taxa when discussing their phylogenetic relationships. However, we regard this difference in Murrayinella as a less significant cri- terion for the suprageneric classification of this genus, be- cause of the situation in M. takayanagii. The foramen of M. takayanagii is exceptional for rotaliid taxa, because the foraminal plate and chamber flap are poorly developed in contrast to the well developed umbilical coverplate observed from the outside of the test. We consider that this aperture has no systematic significance for the phylogenetic recon- struction of the rotaliid taxa. We would retain all these kinds of foramina in the genus Murrayinella. Discussion The most recent suprageneric classification of the genus Murrayinella places it within the family Glabratellidae, superfamily Discorbacea, although knowledge of both its ex- ternal and internal structures is imperfect (Loeblich and Tappan, 1987). Farias (1977) proposed that Murrayinella should include M. murrayi and M. globosa (=Rotalia erinacea Heron-Allen and Earland), but the latter species has been regarded by some authors to be better placed in Schackoinella (Quilty, 1975). According to our observa- tions, Murrayinella never shows the umbilical features, such as radial grooves, that aid attachment during plastogamy, the type of reproduction found in the Glabratellidae. The aperture of the Glabratellidae is a low interiomarginal slit on the umbilicus without additional internal structures. The ob- servation reported by Heron-Allen and Earland (1915) for M. murrayi showing “double (budded) specimens” must be questioned. The aperture of M. murrayi and M. globosa is an umbilical to extraumbilical slit, which must make plastogamic reproduction impossible. We believe that Heron-Allen and Earland’s budded specimens do not belong to Murrayinella. The external morphology of Schackoinella is similar to Murrayinella, but its aperture is mostly umbilical and has radial striations, typical of the Glabratellidae. These features clearly show that Murrayinella and Schackoinella have a different phylogenetic origin. The most obvious way to distinguish Murrayinella and Schackoinella is provided by the internal structure of the ap- erture. The foraminal plate and the umbilical coverplate in Murrayinella are never found in Schackoinella. Through our examination, we have found that the struc- ture of the aperture in Murrayinella resembles that found in the Rotaliidae and the foraminal structure is similar to the Pararotalia-type foramen. Exceptionally, there is the inter- mediate form between the Ammonia type and the Pararotalia type and one more type of foramen that does not belong to either of them. In view of these varied foramina, it was difficult to decide whether this genus should be placed in the subfamily Pararotaliinae or subfamily Ammoniinae in the scheme of Loeblich and Tappan’s (1987) suprageneric classification. Loeblich and Tappan (1987) defined the fo- ramen of the subfamily Pararotaliinae as having a “single interiomarginal slitlike aperture, converted into areal intercameral foramen” that is the typical Pararotalia-type fo- ramen. They did not refer to the foraminal structure in the subfamily Ammoniinae, but instead to structures associated with the aperture such as radial canals, fissures, and umbili- cal cavities. However, these structures are not restricted to the Ammoniinae. Members of the Pararotaliinae also have these structures (Hottinger et al., 1991, 1993; Nomura and Takayanagi, 2000). A strict usage of these structures would not help to discriminate between the Ammoniinae and the Pararotaliinae. Instead, the distinction between the Pararotalia-type and the Ammonia-type foramen provides the best character for deciding on the subfamily placement (Nomura and Takayanagi, 2000). A supplementary struc- ture, the labial aperture, is sometimes found in the Ammonia -type foramen but is never associated with the Pararotalia one. The foraminal structures of Murrayinella are rather simple and lack labial apertures. We are of the opinion that the difference between the Ammoniinae and the Pararotaliinae can be found in the foraminal structure and that this feature is most helpful for the subfamily-level classi- fication. Therefore, we suggest that the placement of this genus in the subfamily Pararotaliinae and in the family Rotaliidae is valid. Systematic descriptions Order Rotaliida Lankester, 1885 Superfamily Rotaliacea Ehrenberg, 1839 Family Rotaliidae Ehrenberg, 1839 Subfamily Pararotaliinae Reiss, 1963 Genus Murrayinella Farias, 1977 Type species.—Rotalia murrayi Heron-Allen and Earland, 1915. Emended description.—Test small, low trochospiral to high trochospiral with depressed or opened umbilicus; inflated to globular chambers usually rough with numerous small spines, four to six in the final whorl; sutures depressed to deeply depressed; periphery rounded to angled, usually lobulate; aperture a low interiomarginal slit located extraumbilically; apertures in preceding chambers rounded; walls hyaline, rough and translucent. Classification of foramineral genus Murrayinella 173 Remarks. — Loeblich and Tappan (1987) placed this genus in the family Glabratellidae Loeblich and Tappan (1964), based on their interpretation of Heron-Allen and Earland’s claim to have observed double (or budded) speci- mens in the type species. Rotalia erinacea Heron-Allen and Earland and Discorbina imperatoria var. globosa Millett were placed in the genus Schackoinella Weinhandl by Quilty (1975), which also belongs to the family Glabratellidae. Figure 1. um. 1a-c. Mature specimen. ture. 4. Peripheral view of specimen without the final chamber showing the arched opening of the penultimate foramen. 2a-c. Immature specimen. 5. Oblique view of specimen without the final chamber showing the foraminal plate. tepenultimate foraminal plates (fp) and the penultimate umbilical coverplate (uc). fo = foramen. bers removed showing the foraminal plate (fp) protruded from each foramen (fo). Murrayinella globosa (Millett) from Holocene bay-floor muds of Tateyama, Chiba Prefecture. 3. Obliquely viewed specimen showing the marginal slit of the aper- These observations strongly influenced Loeblich and Tappan’s (1987) decision to place this genus in the glabratellids. However, Whittaker and Hodgkinson (1979) once considered Murrayinella to be conspecific with Schackoinella, but they immediately changed their opinion after examining Quilty’s description of the type species Schackoinella sarmatica Weinhandl. In the postscript of their monographic paper, they suggested that the difference Scale bar: 100 6. Oblique view of the penultimate and an- 7. Specimen with dorsal cham- 8. Specimen with ventral chambers removed showing the foraminal plate (fp) from the penultimate foramen (fo) and the umbilical coverplate (uc). 174 Ritsuo Nomura and Yokichi Takayanagi in the aperture and the ventral feature formed a basis for dis- criminating between Murrayinella and Schackoinella. As observed herein, the basic structure of the Murrayinella ap- erture is the same as that of the rotaliids. Both are charac- terized by the foraminal plate and umbilical coverplate. The final aperture of Murrayinella is always an umbilical to extraumbilical slit, but the previous foramina are rounded to oval openings as a result of the umbilical side-slit being partly closed up by the umbilical coverplate. This apertural structure can only be explained by the rotaliid aperture and foraminal model (Hansen and Reiss, 1971; Nomura and Takayanagi, 2000). Murrayinella globosa (Millett) Figure 1.1-1.8 Discorbina imperatoria (d’Orbigny) var. globosa Millett, 1903, p. 701, pl. 7, figs. 6a-c. Rotalia erinacea Heron-Allen and Earland, 1915, p. 720, pl. 53, figs. 23-26. “Eponides” globosa (Millett). Ujiie, 1963, p. 233, pl. 1, figs. 27a-29 (part). Pararotalia cf. imperatoria globosa (Millett). Chiji and Lopez, 1968, pl. 12, figs. 5a-c. Pararotalia murrayi (Heron-Allen and Earland). Chiji and Lopez, 1968, pl. 12, figs. 6a, b. Pararotalia minuta (Takayanagi). Matoba, 1967, p. 256, pl. 27, figs. 5a, b. Pararotalia? globosa (Millett). Matoba, 1970, p. 57, pl. 6, figs. 8a-c. Schackoinella sarmatica Weinhandl. Haman and Christensen, 1971, p. 44, text-figs. 1-3. Schackoinella globosa (Millett). Quilty, 1975, p. 331; Loeblich and Tappan, 1994, p. 142, pl. 294, figs. 1-10. Murrayinella erinacea (Heron-Allen and Earland). Farias, 1977, pl. 1, figs. 7-10. Schackoinella (?) dissensa McCulloch, 1977, p. 317, pl. 169, figs. 5, 10a-c, 11a, b, 12a-c. Ammonia globosa (Millett). Zheng et al., 1978, p. 49, pl. 5, figs. 7a-11c. “Schackoinella” globosa (Millett). Whittaker and Hodgkinson, 1979, p. 63, pl. 5, figs. 11, 12a, b, pl. 10, fig. 6 (transferred to the genus Murrayinella in postscript). Pararotalia aff. globosa (Millett). Oki, 1989, p. 133, pl. 15, figs. 9a-d. Murrayinella globosa (Millett). Matoba and Fukasawa, 1992, fig. 9, nos. 16a-c. Examined specimens.—Specimens from Holocene bay- floor muds (7400-4100BP) of Tateyama, southern part of the Boso Peninsula. Sample locality is given by Fujiwara et al. (1997) as in the cliff of the Heguri-gawa River, approxi- mately 139°52’55’E and 35°0’27’N. Description.—Test rather small, planoconvex with a con- vex ventral side and flat to slightly inflated dorsal side; pe- riphery lobulate and with a short transparent spine on each chamber; sutures distinct, radiate, deeply depressed on ven- tral side, and curved on dorsal side; chambers four to five on ventral side, inflated; aperture indistinct with a covering of small spines, but apparently an umbilical to extraumbilical slit; wall rough and hispid, usually transparent; pores pre- sent, but usually indistinct with small spines on walls, opti- cally indistinctly radial. Apertural structure.—The final aperture is an umbilical to extraumbilical slit and is covered with small spines (Figure 1.1-1.3). The foramen is arch-shaped (Figure 1.4, 1.5), with an umbilically extended foraminal plate and umbilical coverplate (Figure 1.6-1.8). The foraminal plate obliquely protrudes from the apertural face and its proximal part con- tinues to the umbilical coverplate. The umbilical flap is dis- tinct and adheres to the preceding ones. It has a narrow slit, but does not connect with the labial aperture. Geographic occurrences.— Mostly limited to the Indo- Pacific region. In Japan, this species is widely distributed in the coastal areas of both the Sea of Japan and the Pacific. Stratigraphic occurrences.—Known from the late Miocene (Whittaker and Hodgkinson, 1979) to the Recent. Size and measurements.—Maximum test width is 250 um, maximum test length is 171 um; minimum test width is 99 um, minimum test length is 63 um; averaged test width is 166 um, averaged test length is 114 um. Remarks.—Heron-Allen and Earland (1915) placed this species in Rotalia, and erroneously renamed it Rotalia erinacea, since they believed that the original name was pre- occupied by Rotalia globosa (Hantken) (see Whittaker and Hodgkinson, 1979 for further discussion). However, later workers suggested the placement in Rotalia was invalid, be- cause of its rather different test morphology. This species is characterized by a small test and rough test surface totally covered with small spines, which obscure the details of the apertural structure. Ujiié (1963) considered it to belong to the genus Eponides, but he also questioned this generic placement, because of the different nature of the undevel- oped inframarginal sulcus around the aperture, the wall lamellarity, and other subordinate external differences of test. Based on our detailed observation, however, the aper- ture of this species is an extraumbilical slit similar to the rotalid one. The foraminal plate and the umbilical coverplate, which are basic components in the rotaliid aper- ture, are present but the foraminal plate is very variable. In general, these structures resemble the Pararotalia-type fora- men. However, some specimens have the Ammonia-type foramen proposed by Nomura and Takayanagi (2000). Nevertheless, the base of the foraminal plate is not well de- veloped in comparison with typical form of the Ammonia- type foramen that shows a hook-like structure. As far as the apertural structure is concerned, this species conforms to the Pararotalia-type foramen. Otherwise, it is usually char- acterized by a depressed umbilicus, where the chamber flaps are closely imbricated and fused to make a more rough umbilicus surface. Such features, and the covering of small spines, are enough to separate this species from both Ammonia and Pararotalia and to warrant a separate genus Murrayinella. Murrayinella globosa has been confused with M. murrayi (Heron-Allen and Earland, 1915) by some workers. Hatta and Ujiié (1992) considered these two species to be conspecific, based on the opinion that there are gradational changes between the peripheral spines of M. globosa and the acute papillae of M. murrayi. However, M. murrayi has six chambers in the final whorl and a more convex umbilical side of the test (Heron-Allen and Earland, 1915) and surface Classification of foramineral genus Murrayinella 175 Figure 2. 100 um. 3. Penultimate foramen with final chamber wall removed showing the basal part of the foraminal plate (fp) extended from the in- side of the penultimate foramen (fo). cw = chamber wall. 4. Obliquely sectioned specimen showing the preceding foramen with the foraminal plate (fp) and the umbilical coverplate (uc). fo = foramen. rugosity (Whittaker and Hodgkinson, 1979), while M. globosa has four to five chambers in the final whorl and a depressed umbilical center without a distinct protrusion. Murrayinella minuta (Takayanagi) Figure 2.1-2.5 Rotalia? minuta Takayanagi, 1955, p. 45, 52, text-figs. 29a-c. Pararotalia murrayi (Heron-Allen and Earland). Ujiie, 1963, p. 239, pl. 3, figs. 3a-9. Pararotalia ? minuta (Takayanagi). Matoba, 1970, p. 58, pl. 6, figs. 5a-c, 6a-c, 7a-c. Praeglobotruncana (7) wordeni McCulloch, 1977, p. 424, pl. 178, figs. 7, 10, pl. 179, figs. 7, 8. Murrayinella minuta (Takayanagi) from Holocene bay-floor muds of Tateyama, Chiba Prefecture. 1a, b. Mature specimen 2. Obliquely viewed specimen showing the penultimate foramen with broken foraminal plate. Scale bar: 5a, b. Immature specimen. Pararotalia minuta (Takayanagi). Huang, 1980, p. 55, pl. 1, figs. 1-6, pl. 2, figs. 1-6, pl. 3, figs. 1-6, pl. 4, figs. 1-6. Pararotalia globosa (Millett). Hatta and Ujiié, 1992, p. 198, pl. 43, figs. 5a-c. Murrayinella minuta (Takayanagi). Matoba and Fukasawa, 1992, fig. 9, nos. 17a-c; Kamemaru, 1996, pl. 20, figs. 3, 4. Examined specimens.— Specimens from Holocene bay- floor muds (7400-4100BP) of Tateyama, southern part of the Boso Peninsula. Sample locality is given by Fujiwara et al. (1997) as in the cliff of the Heguri-gawa River, approxi- mately 139°52’55’E and 35°0’27’N. Emended description.—Test small, planoconvex with a strongly convex ventral side and nearly flat dorsal side; su- 176 Ritsuo Nomura and Yokichi Takayanagi tures distinct, nearly straight, radiate, slightly depressed in mature specimens and depressed in immature specimens on ventral side, and oblique and curved on dorsal side; chambers five to six on ventral side, slightly inflated, but more inflated on ventral side in immature stage; umbilicus nearly closed and with protruded plug in mature, but slightly open in immature specimens; aperture indistinct with small covering spines, but appears to be an umbilical to extraumbilical slit; wall rough and hispid, usually translucent; pores present, but indistinct with small spines on the walls, optically indistinctly radial. Apertural structure.—The final aperture is an umbilical to extraumbilical slit with a poorly developed umbilical flap (Figure 2.1-2.3, 2.5). The foramen is oval and oblique to the base of the apertural face, with an umbilically extended foraminal plate (Figure 2.4). The protruded foraminal plate is close to the umbilicus and much inclined to the apertural face. The base of the foraminal plate extends onto the dis- tal side of the foramen, forming a lip-like structure (Figure 2.2). The umbilical coverplate is formed, but it does not cover the labial aperture in the preceding foramen. Geographic occurrences.—This species is widely distrib- uted in the coastal areas of both the Sea of Japan and the Pacific. Huang (1980) reported it from the Taiwan Strait at depths ranging from 5.5 to 100 m. Stratigraphic occurrences. — Known Quaternary to the Recent. Size and measurements.—Maximum test width is 218 um, maximum test length is 193 um; minimum test width is 133 um, minimum test length is 81 um; averaged test width is 177 um, averaged test length is 124 pm. Remarks.— Murrayinella minuta (Takayanagi) was origi- nally tentatively placed in the genus Rotalia because it had a closed umbilicus different from that of Rotalia as well as hispid walls. Later Ujiié (1963) considered this species to be synonymous with Rotalia murrayi and placed it in Pararotalia on account of the apertural and foraminal struc- tures. However, Matoba (1970) separated it from murrayi, stating that minuta has a strongly convex ventral side and flat dorsal side, while murrayi has a subglobular test with convex dorsal side and rounded periphery. We support his suggestion that minuta is different from murrayi. The variable form of this species is similar to M. globosa in having a more lobulate periphery and the incipient spines in earlier chambers of the last whorl. McCulloch (1977) re- garded one such variant as a new species that she tenta- tively assigned to the genus Praeglobotruncana. However, these characters fall within the range of minuta’s variation. Ujiié (1963) was the first to discuss the apertural structure of this species and mentioned that it has a toothplate (= the foraminal plate and umbilical coverplate) connected with the preceding foramen. His observation follows the result of Loeblich and Tappan (1957) who studied the type species of the genus Pararotalia [i.e., P. inermis (Terquem)]. Thus, he put this species in the genus Pararotalia. On the basis of observations of the internal structure of P. inermis given by Reiss and Merling (1958), he further mentioned that the an- terior side of the foraminal plate of M. minuta is abruptly cut off at a distance of half a chamber length. Ujiié’s observa- tions are important for understanding the true nature of this from the Late apertural structure. The foraminal plate of the Pararotalia- type foramen looks like a lip in the lower side of the foramen, resulting from the inward extension of the basal part of the foraminal plate to the distal side of the aperture (Nomura and Takayanagi, 2000). We agree that the aperture and fo- ramen of minuta are therefore the same as in Pararotalia. The foraminal structure seen by us was also noted by Huang (1980) who showed the foraminal plate (his lip) associated with the one side of the foramen (e.g., Huang, 1980, pl. 2, figs. 2-4). This feature suggests the close phylogenetic re- lation of minuta to Pararotalia species. Except for the apertural similarity, however, the small test and the rough test surface are diagnostic enough to separate minuta from Pararotalia and keep it in Murrayinella. Murrayinella takayanagii (Matoba) Figure 3.1-3.3 Pararotalia minuta (Takayanagi) var.. Matoba, 1967, p. 256, pl. 27, figs. 6a, b. Pararotalia ? takayanagii Matoba, 1970, p. 63, pl. 6, figs. 9a-c, 10 a-c. Murrayinella takayanagii (Matoba). Takayanagi and Hasegawa, 1986, pl. 2, figs. 3a-c. Examined specimens. — Four specimens from the Pleistocene of Well Kashimaoki SK-1, donated by Prof. S. Hasegawa, Hokkaido University; three specimens from the Recent sediment of Matsushima Bay (paratypes), donated by Prof. Y. Matoba, Akita University. Emended description.—Test very small, low trochospiral, planoconvex to concave-convex; spiral side of test gently concave due to the inflation of chambers of the last whorl; periphery subrounded and strongly lobulate becoming stellate; umbilical side deeply concave, usually open without a plug; chambers five to five and one half in final whorl, in- flated on periphery; sutures depressed on both umbilical and spiral sides; wall calcareous, thin, very finely perforate, cov- ered with small pustules, peripheral area in each last whorl chamber with blunt spines; aperture arch-shaped and large for test, opened to umbilicus with narrow overturned lip. Apertural structure.—The foraminal plate is poorly devel- oped, but each umbilical coverplate is clearly shown around the umbilicus (Figure 3.1-3.3). The umbilical coverplate is inflated toward the umbilicus, thus it looks like a part of the chamber wall. Geographic occurrences.—This species is known in the northern Pacific coast of Honshu Island, Japan. Stratigraphic occurrences.—Known from the Pleistocene to the Recent. Size and measurements.—Maximum test width is 135 um, maximum test length is 69 um; minimum test width is 119 um, minimum test length is 53 um; averaged test width is 127 um, averaged test length is 59 um. Remarks.—The well developed final aperture, and the widely opened and depressed umbilicus are characteristics of this species. Matoba (1970) placed it in the genus Pararotalia, based on the similarity of the aperture to that of Pararotalia minuta. However, the systematic position of this species has been questioned, because it lacks the umbilical Classification of foramineral genus Murrayinella 177 Figure 3. Murrayinella takayanagii (Matoba) from the Pleistocene of Well Kashimaoki SK-1. Scale bar: 100 um. 2. Enlargement of aperture (ap) showing the small foraminal plate (fp) and a completely covered umbilical coverplate (uc). Scale bar: 20 um. 3. Umbilical section of no. 2 specimen showing the internal rim of the penultimate foramen (fo). ap = aperture. Scale bar: 30 um. plug that is a characteristic feature of Pararotalia. After ex- amining these systematic problems, we are of the opinion that the aperture of takayanagii is fundamentally comparable to the foraminal plate and umbilical coverplate concept of the rotaliids, but these features at the same time are somewhat different from their expression in Pararotalia. The aperture of takayanagii is usually rounded, without special develop- ments such as the umbilical flap, while that of Pararotalia is an extraumbilical slit with a development of both the foraminal plate (=lower lip of Nomura and Takayanagi, 2000) and an umbilical coverplate. Because the chamber flap is poorly developed in takayanagii, the umbilical coverplate that partly conceals the umbilical side of the foramen is clearly shown in the umbilical view. The foraminal plate it- self is less developed and is not clearly differentiated from the chamber wall. These apertural characters, and the ab- 1a-c. Mature specimen. sence of the umbilical plug, both strongly suggest that the placement of this species in Pararotalia is inappropriate. On the basis of the basically trochospiral nature of the test, and taking the hispid nature of the test surface and the basic apertural structure of this species into consideration, we have put takayanagii in the genus Murrayinella. Murrayinella bellula sp. nov. Figures 4.1-4.2; 5.1-5.6; 6 “Eponides” globosa (Millett). Ujiie, 1963, p. 233, pl. 1, fig. 26 (part). Diagnoses.—Highly trochospiral test with inflated globular chambers; walls hispid; one spine usually in the earliest por- tion of the test; aperture an umbilical slit; foramen associated with a lip-like foraminal plate and an umbilical coverplate. 178 Ritsuo Nomura and Yokichi Takayanagi Figure 4. bay-floor muds of Tateyama, Chiba Prefecture. bellula sp. nov. Scale bar: 100 um. Holotype and paratypes.—Holotype (registered number, NFL 9901), Figure 4. 1a-c, Holocene bay-floor muds (7400-4100BP) in Tateyama, Chiba Prefecture; paratypes (registered number, NFL 9902), Figure 4. 2a-c, from the same deposits. Sample locality is given as number 7 by Fujiwara et al. (1997) in the cliff of the Heguri-gawa River, approximately 139°52’55’E and 35°0’27’N. Depository.—Holotype, paratypes and figured specimens are deposited in Nomura Foraminiferal Laboratory, Shimane University (NFL). Description.— Test small, cone-shaped, with a strongly convexed ventral side and nearly flat dorsal side; sutures distinct, radiate, and depressed on ventral side; chambers four to five on ventral side, inflated; periphery lobulate in final whorl; aperture indistinct and covered with small spines, but an umbilical slit; wall rough and covered with very small pus- tules; pores present, but indistinct due to rough surface, op- tically indistinctly radial. Apertural structures.—The final aperture is an umbilical slit and is covered with small spines (Figure 5.3). The foramen is elongate, oval and obliquely arranged to the plane of the whorl (Figure 5.2). The foraminal plate is formed at the base of the foramen and protruding from it (Figure 5.1, 5.4-5.6). The umbilical coverplate is continued from the foraminal plate and conceals the umbilical side of the foramen (Figure 5.4, 5.5). Geographic occurrence.—This species is common in the Holocene bay-floor muds (tsunami deposits) in Tateyama, southern part of the Boso Peninsula. Ujiie (1963) recorded 1a-c. Holotype (NFL 9901) of Murrayinella bellula sp. nov. from Holocene 2a-c. Paratype (NFL 9902) of Murrayinella this species from Tokyo. Thus, the known geographic dis- tribution is limited to the Kuwanto area. Stratigraphic occurrences. — Known only from the Holocene. Size and measurements.—Maximum test width is 215 um and maximum test length is 196 um; minimum test width is 97 um and minimum test length is 80 um; averaged test width is 139 um and averaged test length is 129 um. Remarks.— This new species is characterized by its high trochospiral coil and rough test surface. The foraminal structure is of the rotaliid type consisting of foraminal plate and umbilical coverplate. The foraminal plate is much in- clined to the previous whorl and forms a prominent plate in the lower side of the foramen, whose structure is the same as the Pararotalia-type foramen described by Nomura and Takayanagi (2000). The umbilical view of this species is similar to that of M. globosa in having four to five globular chambers in the final whorl and suggests a close phylogenetic relationship with the latter. Ujiié (1963) regarded this form as a variant of M. globosa. However, the size distribution (test length and maximum width) indicates the isolated position of this new species from M. globosa, particularly for mature individuals (Figure 6). A discriminant analysis also indicates statisti- cally significant differences between the two species. Moreover, this species possesses a short spine in the initial chamber, but is usually devoid of spines in subsequent chambers. This spine is one of the characteristics of the new Species. Classification of foramineral genus Murrayinella 179 Figure 5. Details of Murrayinella bellula sp. nov. Scale bar: 100 um. 1. Sectioned specimen with ventral chambers re- moved. uc = umbilical coverplate. 2. Oblique view of specimen showing the small spines and foraminal plate (fp) with oval opening of penultimate foramen. 3. Mature specimen showing the slit aperture with hispid crystals. 4. Closeup of no. 1 showing the protruded foraminal plates formed in the lower side of the foramen. fo = foramen, fp = foraminal plate, uc = umbilical coverplate. 5. Another view of no. 4. fp = foraminal plate, uc = umbilical coverplate. 6. Oblique view of penultimate foramen (fo) with foraminal plate (fp) and the remains of final chamber wall (cw). © Murrayinella globosa Murrayinella bellula occurs in sand and sandy gravel beds * Murrayinella bellula sp nov. in association with abundant Ammonia _ japonica, Pseudononion japonicum and miliolids, an assemblage ap- parently indicative of shallow marine conditions with some influence of brackish water. The assemblage containing this new species also includes planktic and some offshore species such as Uvigerina proboscidea, Planocassidulina helenae, Bulimina marginata, and Brizalina striata. These offshore-cum-brackish assemblages may derive from the Pleistocene Kazusa Group, which contains a well preserved offshore and shallow-water foraminiferal assemblage. However, Fujiwara et al. (1997) proposed that such a mixed occurrence of bay to offshore foraminiferal assemblages in the bay-floor muds could be explained by a tsunami event based on the analyses of the sedimentary facies and se- quence. This species possibly came from the shallower 150 Test length (lim) © Figure 6. Size distribution of Murrayinella. globosa (Millett) and M. bellula sp. nov. plotted against axes of maximum 2 109 150 200 250 >” diameter and test length. Ellipsoids indicating a 95% confi- Maximum diameter (um) dence region for each species. 50 180 Ritsuo Nomura and Yokichi Takayanagi coastal environment. Etymology.—The specific name is derived from Latin bellulus, pretty, referring to its small and delicate test. Conclusions We described four Japanese species of Murrayinella, in- cluding one new species, from the Late Quaternary tsunami deposits in Tateyama, in the southern part of the Boso Peninsula. Detailed observations of the Murrayinella aper- ture indicate that the grooves radiating from the aperture that are so diagnostic of the glabratellids are never developed. Instead, Murrayinella has a foramen associated with a foraminal plate and umbilical coverplate, which is typical of rotaliids. We therefore suggest that the suprageneric place- ment of Murrayinella is not in the family Glabratellidae, but the Rotaliidae. Acknowiedgements We express our appreciation to Y. Matoba (Akita University) and S. Hasegawa (Hokkaido University) for shar- ing Murrayinella takayanagii specimens. We are deeply in- debted to John E. Whittaker of the Natural History Museum, London, for the improvement of the manuscript and Stefan A. Revets of the University of Western Australia, for his criti- cal review. References Chiji, M., and Lopez, S. M., 1968: Regional foraminiferal as- semblages in Tanabe Bay, Kii Peninsula, central Japan. 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Nomura, R., 1990: Late middle Miocene foraminifera from the Matsue Formation, Shimane Prefecture. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 158, p. 459-484. Classification of foramineral genus Murrayinella Nomura, R. and Takayanagi, Y., 2000: Foraminal structures of some Japanese species of the genera Ammonia and Pararotalia, family Rotaliidae (Foraminifera). Paleonto- logical Research, vol. 4, no. 1.p. 16-30. Oki, K., 1989: Ecological analysis of benthonic foraminifera in Kagoshima Bay, south Kyushu, Japan. South Pacific Study (Kagoshima University Research Center for the South Pacific), vol. 10, no. 1, p. 1-191, pls. 1-22. Quilty, P. G., 1975: A new species of Schackoinella from the Eocene of Western Australia with comments on the Glabratellidae. Journal of Foraminiferal Research, vol. 5, p. 326-333. Reiss, Z., 1963: Reclassification of perforate foraminifera. Bulletin of the Geological Survey of Israel, vol. 35, p. 1- 111, pls. 1-8. Reiss, Z. and Merling, P., 1958: Structure of some Rotaliidae. Bulletin of the Israel Geological Survey, no. 21, 1-19, pls. 1-5. Revets, S. A., 1993: The foraminiferal toothplate, a review. Journal of Micropalaeontology, vol. 12, no. 2, p. 155-169, pls. 1-3. Takayanagi, Y., 1955: Recent foraminifera from Matsukawa- ura and its vicinity. Contribution from the Institute of Geology and Paleontology, Tohoku University, no. 45, p. 18-52, pls. 1-2. Takayanagi, Y. and Hasegawa, S., 1986: Pleistocene benthic foraminifera in Well Kashimaoki SK-1. /n, Matoba, Y. and Kato, M. eds., Studies on Cenozoic benthic foraminifera in Japan. Akita University, Akita, p. 95-104, 2 pls. Ujiié, H., 1963: Foraminifera from the Yurakucho Formation (Holocene), Tokyo City. Science Reports of the Tokyo Kyoiku Daigaku, Section C, vol. 8, no. 79, p. 229-243. Weinhandl, R., 1958: Schackoinella, eine neue Foramini- ferengattung. Verhandlungen der Geologischen Bunde- sanstalt, Wien, 1958, p. 141-142. Whittaker, J. E. and Hodgkinson, R. L., 1979: Foraminifera of the Togopi Formation, eastern Sabah, Malaysia. Bulletin of the British Museum (Natural History), Geology Series, vol. 31, no. 1, p. 1-120. Zheng, S., Cheng, T., Wang, X. and Fu, Z., 1978: The Quaternary foraminifera of the Dayuzhang irrigation area, Shandong Province, and a preliminary attempt at an inter- pretation of its depositional environment. Studia Marina Sinica, no. 13, p. 16-78, pls. 1-10. 181 Mt V duel | CH FR st Dat Es IN er | AAC May anal ar oped ne HRS Vo Ce 9 Be PS LE Ei ru ” y . ; Paleontological Research, vol. 4, no. 3, pp. 183-189, September 29, 2000 © by the Palaeontological Society of Japan Upper premolar dentitions of Deperetella birmanica (Mammalia: Perissodactyla: Deperetellidae) from the Eocene Pondaung Formation, Myanmar TAKEHISA TSUBAMOTO’, PATRICIA A. HOLROYD’, MASANARU TAKAI’, NOBUO SHIGEHARA’, AYE KO AUNG‘, TIN THEIN’, AUNG NAING SOE* and SOE THURA TUN‘ ‘Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan (e-mail: tsuba @ kueps.kyoto-u.ac.jp) “Museum of Paleontology, University of California, Berkeley, CA 94720, USA *Primate Research Institute, Kyoto University; Inuyama 484-8506, Japan *Department of Geology, Dagon University, Yangon, Myanmar Department of Geology, University of Pathein, Pathein, Myanmar °Department of Geology, University of Yangon, Yangon, Myanmar Received 20 October 1999; Revised manuscript accepted 8 May 2000 Abstract. Discovery of upper premolar dentitions of Deperetella birmanica (Mammalia: Perisso- dactyla: Deperetellidae) from the Eocene Pondaung Formation, central Myanmar (= Burma) throws a new light on previously confused species- and genus-level systematics of Deperetella and its re- lated genus Diplolophodon. Clarification of the relationship among the Deperetella species is par- ticularly important for correlation of Eocene mammal faunas in Asia. The newly discovered material show the characteristics of the previously unknown upper premolar dentition of D. birmanica, demonstrating that Deperetella similis (the type species of the genus Diplolophodon) from China is a junior synonym of Deperetella birmanica and that D. birmanica is clearly distin- guishable from all other species of Deperetella. The genus Diplolophodon, to which D. birmanica has often been allocated, is regarded conventionally as a junior synonym of Deperetella because this genus is not sufficiently distinct from Deperetella to warrant generic separation. The presence of D. birmanica and its comparable species in several Eocene deposits of Myanmar, China and Mongolia suggests that these deposits are roughly contemporaneous. Key words: Deperetella, Deperetellidae, Diplolophodon, Eocene, Myanmar, Pondaung Formation Introduction Deperetella is an Asian Eocene tapiroid perissodactyl genus and was proposed by Matthew and Granger (1925a) based on Deperetella cristata Matthew and Granger, 1925a as the type species. This genus and Teleolophus Matthew and Granger, 1925b, which together constitute the family Deperetellidae Radinsky, 1965, are among the most com- mon elements of the middle to late Eocene mammal fauna in Asia and important for correlation of Eocene mammal fau- nas in this area. Zdansky (1930) proposed Diplolophodon and described Diplolophodon similis as the type species. Of several species in the genus Deperetella, Deperetella birmanica (Pilgrim, 1925) from the Pondaung Formation, Myanmar has been sometimes referred to the genus Diplolophodon based on their small dental size and several of their dental characteristics (e.g. Ding et al., 1977). Previous classification of Deperetella birmanica and its re- lated species has been much confused because these spe- cies were described on the basis of different parts of dentitions. D. birmanica was originally described by Pilgrim (1925) as Chasmotherium? birmanicum based on two mandibular rami of a single individual from the Eocene Pondaung Formation, central Myanmar. This was the only species of the Deperetellidae from the Pondaung Formation, and was questionably referred to the genus Deperetella by Colbert (1938). On the other hand, Diplolophodon similis was described based on an upper dentition from the Heti Formation in the Yuanchu Basin of the Shanxi and Henan Provinces, China (Zdansky, 1930). Young (1937) reported 184 Takehisa Tsubamoto et al. Khoer Dzan CHINA Qufu Yuanchu X Pondaung * MYANMAR Andaman Sea Figure 1. Maps showing distribution of several deperetellid-bearing deposits in Asia, names of place mentioned in this paper, and collecting sites of NMMP-KU 0005 and 0006. Upper left map showing locations of deposits that yielded Deperetella birmanica (Pilgrim, 1925) or Deperetella sp. cf. D. birmanica (black stars). Data from Colbert (1938), Li and Ting (1983), Russell and Zhai (1987), Shi (1989), Dashzeveg and Hooker (1997), and Huang (1999). Upper right map is topographic map of Pondaung area in central Myanmar, showing some major cities (black circles). Lower map showing collecting sites (black squares) of NMMP-KU 0005 and 0006 in the Pondaung Formation. Deperatella birmanica from Myanmar 185 an additional upper dentition of D. similis from the same for- mation. Radinsky (1965) referred both Chasmotherium? birmanicum and Diplolophodon similis to the genus Deperetella, and established a new family Deperetellidae. He mentioned that D. birmanica was related to D. similis. Chow et al. (1974) first reported the lower and additional upper dentitions of D. similis from the Lumeiyi Formation in the Lunan Basin of Yunnan Province, China, distinguishing D. similis from D. birmanica on the basis of several morpho- logical differences in the lower dentitions. The upper dentition of D. birmanica was discovered in Pondaung Formation during paleontological field research by Myanmar researchers in 1997 (Pondaung Fossil Expedition Team, 1997). In this study, we describe two maxillary fragments with premolars of D. birmanica. This discovery provides new information on the relationship of D. birmanica and D. similis. Geological setting The Pondaung Formation (Pondaung Sandstones) distrib- uted in the central part of Myanmar (Figure 1) can be divided into “Lower” and “Upper” members for convenience: the “Lower Member’ is mainly composed of greenish sandstone and is about 1,500 m thick in the type section; and the “Upper Member’ is dominated by variegated-colored mudstone, about 500 m thick in the type section, and yields many mammalian and other vertebrate fossils (13 genera belonging to three orders; see Pilgrim and Cotter, 1916; Colbert, 1938; Holroyd and Ciochon, 1995; Jaeger et al., 1999), indicative of a freshwater lagoonal environment (Colbert, 1938; Aye Ko Aung, 1999; Aung Naing Soe, 1999; Figure 2). The present material was recovered from the middle part of the “Upper Member” of the Pondaung upper Eocene Discocyclina sella, Operculina cf. canalifera, Velates perversus, Nummulites yawensis Yaw Formation (Yaw Shale) Many vertebrate fossils Formation (Pondaung Sandstones) Occasional marine molluscs "Lower Member' Nummulites acutus i Indian Khirthar stage = Lutetian-equivalent = middle Eocene Tabyin Formation (Tabyin Clay) Figure 2. Generalized stratigraphy of middle to late Eocene deposits in central Myanmar and representative fossil species. Compiled from Stamp (1922), Eames (1951), Bender (1983), Holroyd and Ciochon (1994), and Aye Ko Aung (1999). Formation. The Pondaung Formation grades downward into the Tabyin Formation (Tabyin Clay), and the two forma- tions partially interfinger (Figure 2; Stamp, 1922; Bender, 1983). The Pondaung Formation is overlain by the Yaw Formation (Yaw Shale) with a distinct lithological break (Figure 2; Stamp, 1922; Bender, 1983). The Pondaung Formation is considered to date from middle to late Eocene based on the microfossil dating of the Tabyin Formation and the Yaw Formation (Bender, 1983; Figure 2). On the basis of the mammal fauna, the “Upper Member” of the Pondaung Formation has been considered most likely to be Bartonian age (late middle Eocene) (e.g. Russell and Zhai, 1987; Holroyd and Ciochon, 1994, 1995). Systematic paleontology Family Deperetellidae Radinsky, 1965 Genus Deperetella Matthew and Granger, 1925a Diplolophodon Zdansky, 1930, p. 35. Type species.—Deperetella cristata Matthew and Gran- ger, 1925a. Other species included.— Deperetella birmanica (Pilgrim, 1925); Deperetella depereti (Zdansky, 1930) Radinsky, 1965; Deperetella dienensis Chow et al., 1974; Deperetella khaitchinulensis Reshetov, 1979; Deperetella sichuanensis (Xu et al., 1979) Tong and Lei, 1983. Distribution and age.—Asia. Middle to late Eocene. Diagnosis.—“Deperetellids with premolar series longer than molars and posterior premolars molariform. P°* protolophs .and metalophs slightly convergent to parallel, and separated lingually. Pı and especially P; lengthened into shearing blades; Ps. with complete hypolophids. Molars relatively shorter and wider than those of Teleolophus. Manus tridactyl” (Radinsky, 1965, p. 222). Remarks.—The genus Diplolophodon was proposed by Zdansky (1930) based on an upper dentition of Diplolo- phodon similis from the Heti Formation in China. Radinsky (1965) regarded Diplolophodon as a junior synonym of Deperetella, although he recognized some characteristics that distinguished Diplolophodon from Deperetella. Ding et al. (1977), in contrast, viewed Diplolophodon as a distinct genus, in which Diplolophodon major Young, 1937 and Diplolophodon birmanicum were included. We follow Radinsky’s (1965) view, because it is difficult to judge based on such a scanty fossil record whether the above-mentioned differences are intra- or intergeneric variations. Deperetella birmanica (Pilgrim, 1925) Figures 3, 4C-D Chasmotherium? birmanicum Pilgrim, 1925, p. 25, pl. 2, fig. 9. Diplolophodon similis Zdansky, 1930, p. 35, pl. 1, fig. 35; Young, 1937, p. 419, fig. 5; Zong et al., 1996, p. 83, pl. 32, fig. 4; Huang, 1999, p. 129. Diplolophodon major Young, 1937, p. 421, fig. 6. Deperetella? birmanicum (Pilgrim, 1925). Colbert, 1938, p. 348, fig. 40. [sic] 186 Takehisa Tsubamoto et al. Figure 3. Deperetella birmanica (Pilgrim, 1925). A, A’. NMMP-KU 0005, stereo pair of fragmentary left upper jaw with broken P'* in occlusal view. B, B’. NUMP-KU 0006, stereo pair of fragmentary right upper jaw with broken P'* in occlusal view. Scale bar = 2 cm. 2 p’ p* Figure 4. Upper premolar dentitions of Deperetella cristata Matthew and Granger, 1925a, “Deperetella similis’ (Zdansky, 1930) and Deperetella birmanica (Pilgrim, 1925) in occlusal view. A. D. cristata, American Museum of Natural History (AMNH) No. 20290 with 20293, P**, after Radinsky (1965, fig. 14). B. “D. similis” (Shanxi specimen), P**, after Young (1937, fig. 5) and Radinsky (1965, p. 222, footnote 1). C. D. birmanica, NMMP-KU 0005, P'®. D. D. birmanica, NMMP-KU 0006, P'* (reversed). Scale bar = 2 cm. Deperatella birmanica from Myanmar 187 Deperetella similis (Zdansky, 1930). Radinsky, 1965, p. 226; Chow et al., 1974, p. 263, 272, pl. 1, fig. 3, 5-7. Deperetella birmanicum (Pilgrim, 1925). Radinsky, 1965, p. 227. [sic] Diplolophodon cf. similis Zdansky. Ding et al., 1977, p. 38, pl. 1, fig. 4. Diplolophodon birmanicum (Pilgrim, 1925). Ding et al., 1977, p. 44, 45. Diplolophodon qufuensis Shi, 1989, p. 91, 99, pl. 1, fig. 7. Material.—National Museum of the Union of Myanmar No. NMMP-KU 0005, a left maxillary fragment with roots of P', very heavily damaged P° and relatively complete P®; NMMP- KU 0006, a right maxillary fragment with roots of P', lingual one-third of P° and mesial margin of P°. Locality. —NMMP-KU 0005 was from Bahin, Myaing Township, central Myanmar; NMMP-KU 0006 was from Kyawdaw, Palé Township, central Myanmar (Figure 1). Horizon and age.—Middle part of the “Upper Member” of the Pondaung Formation (Figure 2), middle to late Eocene (most probably late middle Eocene). Revised diagnosis.—A small-sized Deperetella with half the size of the type species D. cristata. The dental morphol- ogy is most derived in the genus. The molar cingulum is absent or weakly developed. P? is relatively shorter and wider than that of D. cristata. On P**, the protoloph and metaloph are nearly parallel to each other, nearly perpen- dicular to the tooth row, and separated lingually. Description.—P' has two buccolingually widened roots. The distal root is larger than the mesial one. Judging from the roots, P' is longer than wide, and as long as and much narrower than P*. No P' crown is preserved in the present material. The crown of submolariform P? of each specimen is very poorly preserved. The protoloph and metaloph appear to be nearly parallel to each other and nearly perpendicular to the tooth row. These two are separated lingually by a groove. The distal cingula are present. There seems to be no lingual cingulum, although the tooth of each specimen is heavily worn. The existence of mesial and buccal cingula, and the characteristics of buccal structures in the tooth are uncertain. P? is relatively better preserved in NMMP-KU 0005 than in NMMP-KU 0006, where only the broken anterior part of the tooth is preserved. P° is more molariform and transversely larger than P*. The protoloph and metaloph are nearly par- allel to each other, nearly perpendicular to the tooth row, and separated lingually by a groove. The mesial and distal cingula are present. There seems to be no lingual cingulum, although the tooth of each specimen is heavily worn. The buccal structures are not preserved. The protoloph, paracone and metaloph form a slightly oblique, in- verted U-shape, and the metacone is located as buccally as the paracone. Dental measurements and comparison with other species are given in Table 1. Discussion NMMP-KU 0005 and 0006 possess submolariform premo- Table 1. Measurements (in mm) of upper premolars of NMMP-KU 0005 and 0006 and some other species of Deperetella. Henan and Shanxi specimens are those described by Zdansky (1930) and Young (1937), respectively. Data for “Deperetella similis", D. cristata and D. dienensis are from Ding et al. (1977), Radinsky (1965) and Chow et al. (1974), respectively. Abbreviations: L, anteroposterior length; W, buccolingually width; AMNH, American Museum of Natural History; IVPP, Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China. . P' p' pP? pP? pP’ pP? P* P* Specimen [E W L W L W L W Deperetella birmanica (Pilgrim) NMMP-KU 0005 Week 6.9' 9.8 12.2 9.9 14.1 NMMP-KU 0006 7.4' 7.1' 9.4? “Deperetella similis (Zdansky, 1930)” Henan specimen (Zdansky, 1930) 9.0 11.5 9.4 13.4 Shanxi specimen (Young, 1937) 9.0 10.8 9.0 12.3 9.5 13.0 IVPP V29 10.0 12.8 10.7 14.3 Deperetella cristata Matthew & Granger AMNH 20290 19.9 21.8 AMNH 20293 18.7 24.4 Deperetella dienensis Chow et al. IVPP V31.1 13.0 20.0 ‘The measurements are based on the roots, not on the crown. * Estimated value. 188 Takehisa Tsubamoto et al. lars (P°*) which are much wider than long and have a U- shaped crista that consists of a protoloph, paracone and metaloph. The protoloph and metaloph are arranged nearly parallel and lingually separated (Figures 3 and 4C-D). These characteristics of NMMP-KU 0005 and 0006 agree well with those of the upper premolar series of Deperetella diagnosed by Radinsky (1965). In Deperetella, the lower dentitions bear a diastema anterior to Pı (Matthew and Granger, 1925a, fig. 5; Radinsky, 1965, fig. 14). Base on this fact, the presence of a diastema anterior to P' in its upper dentitions can be expected, though P' and anterior part to P' have not yet been discovered in any species of the genus. The presence of a diastema anterior to the most an- terior tooth or tooth roots of botn NMMP-KU 0005 and 0006 strongly suggests that these tooth or tooth roots are identifi- able as P'. NMMP-KU 0005 and 0006 are referred to the nominal species Deperetella similis from China, based on the similar size and dental morphology of the protoloph and metaloph that are nearly parallel to each other and nearly perpendicu- lar to the tooth row on P? (Figure 4B-D and Table 1). Deperetella cristata has upper premolar dentitions much larger than the present specimens, and its protoloph and metaloph on P? are not parallel (Figure 4A). Deperetella khaitchinulensis and Deperetella depereti are similar to D. cristata in dental morphology (Dashzeveg and Hooker, 1997). The dental size of D. khaitchinulensis and D. depereti is larger than that of the present specimens. Deperetella dienensis is also similar to D. cristata in terms of dental morphology (Chow et al., 1974), and its dental size is intermediate between those of D. cristata and the present specimens. Deperetella sichuanensis is similar in dental size to the present specimens, but the dental morphology of the former is the most primitive among the genus (Tong and Lei, 1984). The only deperetellid previously recorded from the Pondaung Formation is D. birmanica, which has so far been represented only by lower dentitions. Radinsky (1965) no- ticed that D. birmanica is more closely related to D. similis than to other species of Deperetella based on the followings; the dentitions in D. birmanica and D. similis are nearly the same size, and lack the molar cingula, which are present in D. cristata and D. depereti. He did not synonymize D. similis to D. birmanica, because D. birmanica was repre- sented only by a lower dentition, while D. similis was repre- sented only by upper dentitions at that time. Ding et al. (1977) and Dashzeveg and Hooker (1997) also recognized the dental similarity between D. similis and D. birmanica. Chow et al. (1974) clearly distinguished D. similis from D. birmanica because D. similis lacks the posterior spur on P: and has broadly and posteriorly convex lophids on M,-s in the lower dentition. However, these differences indicated by Chow et al. (1974) are not useful characteristics for separat- ing the two species, since such are probably caused only by dental abrasion: the lower dentition in D. birmanica (Geological Survey of India (GSI) C348) is heavily worn, while the lower dentitions in D. similis (IVPP V713, V31) are almost intact (see Chow et al., 1974, pl. 1, figs. 3, 5-7). Diplolophodon major Young, 1937 from the Heti Formation in China was synonymized to Deperetella similis by Radinsky (1965), and Diplolophodon qufuensis Shi, 1989 from the Huangzhuang Formation in China was synonymized to Diplolophodon similis (= Deperetella similis) by Zong et al. (1996) and Huang (1999). Zong et al. (1996) and Huang (1999) did not discuss the relationship between D. birmanica and D. similis, despite the fact that the two spe- cies are very similar. Our discovery of the upper premolar dentitions of this form strongly suggests that D. similis and D. birmanica are conspecific. Deperetella birmanica is distinguished from the other spe- cies of Deperetella by its smaller dental size, by the absence or weak development of molar cingula, and by the high de- gree of molarization in its premolar series (the lingually separated and nearly parallel protoloph and metaloph are present both on P** and P?) (Figure 4). This high degree of molarization in its premolar series suggests that D. birmanica is the most derived species among the genus Deperetella. Radinsky (1965), however, interpreted this fact as a result of a greater elongation of the anterior premo- lars in Deperetella cristata in contrast to the higher degree of molarization of the premolars in Deperetella similis (=D. birmanica). The new synonymy enables us to correlate the Pondaung fauna with local middle to late Eocene mammal faunas in China, which yield D. birmanica, and Mongolia, which yield D. sp. cf. D. birmanica: Dongjun fauna of the Bose Basin, Guangxi Province, China; Lumeiyi fauna of the Lunan Basin and Xiangshan fauna of the Lijiang Basin, Yunnan Province, China; Heti fauna (from the Rencun Member) of the Yuanchu Basin, Shanxi and Henan Province, China; Huangzhuang fauna of Qufu County, Shandong Province, China; Ergilin Dzo fauna (from the Sevkhul Member) of Khoer Dzan, Mongolia (Figure 1; Li and Ting, 1983; Russell and Zhai, 1987; Shi, 1989; Zong et al., 1996; Dashzeveg and Hooker, 1997; Huang, 1999). The occurrences of D. birmanica and D. sp. cf. D. birmanica suggest that these de- posits are roughly contemporaneous to each other, and that these mammal faunas were mutually interchanged among them during middle to late Eocene. Acknowledgments We are grateful to the Myanmar Government for granting our study of the specimens. We thank Colonel Than Tun, Major Bo Bo and other personnel of the Office of Strategic Studies, Ministry of Defence, Union of Myanmar for guid- ance and help in the field, and curators of the National Museum of the Union of Myanmar for assisting of our work at that institution. The first author is indebted to Takeshi Setoguchi, Department of Geology and Mineralogy, Kyoto University for his kind help in studying at the laboratory of the department. This manuscript was improved by two anonymous referees and Tomoki Kase, one of the editors of this journal. This research was supported by the Overseas Scientific Research Funds (No. 09041161 to N. Shigehara) and by the Grant-in-Aid for JSPS Fellows (No. 9714 to T. Tsubamoto), both from the Ministry of Education, Science, Sports and Culture of Japan (Monbusho). 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(in Chinese with English abstract) 189 Te été tore hr = ren mW. ee ets Ni M ELLE une Alpe arr: u - eo Sr ene ar are fi : Kibale FRA VE nr ir Pe NE uf ey oR f Paleontological Research, vol. 4, no. 3, pp. 191-204, September 24, 2000 © by the Palaeontological Society of Japan Late Oligocene larger foraminifera from the Komahashi-Daini Seamount, Kyushu-Palau Ridge and their tectonic significance MIA MOHAMMAD MOHIUDDIN', YUJIRO OGAWA’ and KUNITERU MATSUMARU* ‘Marine Geology Department, Geological Survey of Japan, Tsukuba 305-8567 Japan; on study leave from Department of Geology and Mining, the University of Rajshahi, Rajshahi 6205 Bangladesh (e-mail: mohi@gsj.go.jp) ®Institute of Geoscience, University of Tsukuba, Tsukuba 305-8571 Japan “Department of Geology, Faculty of Education, Saitama University Urawa, 338-8570 Japan Received 26 August, 1999; Revised manuscript accepted 1 June 2000 Abstract. A larger foraminiferal assemblage consisting of Miogypsinella ubaghsi (Tan), Spiroclypeus margaritatus (Schlumberger) and other species is described from limestone blocks dredged at two sites on the Komahashi-Daini Seamount of the Kyushu-Palau Ridge. The fauna dates the limestone samples as Late Oligocene and is correlatable with the younger part of the Minamizaki Limestone on the Ogasawara (Bonin) Islands. These shallow-water benthic foraminifera give evidence for the shallow-water attitude of the Kyushu-Palau Ridge during the Oligocene, which has been rifted, submerged, and finally subsided to the present water depth. Key words: Komahashi-Daini Seamount, Kyushu-Palau Ridge, larger foraminifera, Late Oligocene Introduction The Kyushu-Palau Ridge is an about 3,000 km long sub- marine ridge with a general N-S trend which divides the sea floor into the Nankai Trough on the east and the Ryukyu Trench on the west (Figure 1). On the Kyushu-Palau Ridge, a series of isolated seamounts were discovered dur- ing the 1970’s (Shiki et al., 1974; Shiki et al., 1975). The Komahashi-Daini Seamount is located near the northern margin of this ridge. During the R/V Tansei-Maru KT94-10 Cruise, which operated July 5-12, 1994, we dredged lime- stone samples along with many intrusive, hypabyssal and volcanic rocks such as tonalite, andesite, tuff and pumice from the Komahashi-Daini Seamount. In this study, we de- scribe the larger foraminifera in the limestone samples and discuss the age assignment based on the foraminiferal data and their tectonic significance. Material During the KT94-10 cruise, samples were dredged at two sites of the Komahashi-Daini Seamount. DG-04 site is lo- cated on the northeastern slope of the north peak, and DG-05 site on the eastern slope of the major peak (Table 1 and Figure 2). Among the rock samples, one limestone sample (DG-04-01) from the northern site and two (DG- 05-01 and DG-05-02) from the southern site were studied. The limestone samples are indurated packstone or packstone to wackstone. All these samples are moderately hard to compact, and white to creamy white in color. They contain abundant larger and smaller benthic foraminifera, to- gether with coral biolithite, calcareous algae and mollusks. All of the described larger foraminiferal specimens are kept in the Geological Survey of Japan, under catalogue numbers GSJF 15418 to GSJF 15427. Results Thirteen foraminiferal species were identified (Figures 3- 8). Dominant species are Spiroclypeus margaritatus, Nephrolepidina praejaponica, N. angulosa, N. marginata, Eulepidina ephippioides, Heterostegina borneensis, Miogyp- sinella ubaghsi and Austrotrillina howchini. No distinct dif- ference in species composition was found among the three samples. This assemblage was assigned an age of Te 1-4 (Tertiary e 1-4) according to the system of Far East Letter Stages, equivalent to Late Oligocene (Hashimoto et al. 1980; Hashimoto and Matsumaru, 1984; Mohiuddin, 1997). Coexistence of M. ubaghsi and S. margaritatus along with H. borneensis, Eulepidina, Miogypsinoides and Spiroclypeus is indicative of a Late Oligocene age as seen in the Melinau Limestone of Sarawak, North Borneo (Adams, 1965). Moreover, Adams and Belford (1974) suggested that the as- sociation of S. margaritatus, H. borneensis and E. ephippioi- des is indicative of the Tertiary lower e, which is believed to be equivalent to the Upper Oligocene (Chattian) of Europe. 192 Mia Mohammad Mohiuddin et al. 130 1 32 134 LS 136 34 Shikoku J KT94-10 Site DG-04 KT94-10 Site DG-05 an aint Seamoun I DSDP Site 296 EN DSP eG % es D — > IN 100 km Index map of dredged samples used for this 28 Figure 1. study. The M. ubaghsi -S. margaritatus assemblage can be cor- related with the fauna of the upper member of the Minamizaki Limestone in Chichi-Jima and Minami-Jima, Bonin Islands. Miogypsinella boninensis (Matsumaru, 1996) described from the Bonin Islands is thought to be a junior synonym of Miogypsinella ubaghsi (Tan, 1936). This assemblage may be correlated with the assemblage of Te Stage limestones from 1210 to 1599 feet depth in Enewetok Atoll Drill Hole and with those from 1597.5 to 1671 feet depth in Bikini Atoll Drill Hole. The M. ubaghsi -S. margaritatus assemblage is also correlated with the fauna of the Bubton Limestone, Mindoro, Philippines (Hashimoto and Matsu- maru, 1984). The Te Stage is regarded as corresponding to Zone P. 21 of Blow’s (1969, 1979) planktonic foraminiferal zonation. Discussion Konda (1975) reported larger foraminifera in limestone samples dredged from the eastern slope near a peak of the 133° 20'E 133MI0:E > © © 94-10, DG-04 30° 00'N | | 29° 50'N Komahashi-Daini Seamoun | | | 10 km CS Figure 2. Location of dredge sites KT94-10 on Kyushu- Palau Ridge. Adopted from Ohara et al. (1999). Contours in meters. Komashashi-Daini Seamount, Kyushu-Palau Ridge and as- signed to the samples an age younger than Middle Miocene based on the foraminiferal assemblage. The northern half of the Kyushu-Palau Ridge was dated around 48 Ma by Ar- Ar dating of volcaniclastic and granitic rocks (Ozima et al. 1977). A similar age was also obtained from K-Ar age of augite-orthopyroxene andesite rocks in Haha-Jima of the Bonin Islands (Kaneoka et al., 1970). These age data sug- gest that the Izu-Ogasawara arc was juxtaposed with the northern Kyushu-Palau Ridge before the initiation of back- arc spreading in the Shikoku Basin. Moreover, larger foraminiferal age data in this study gave a Late Oligocene age for the limestone blocks of the Komahashi-Daini Table 1. Location of dredged samples on the Kyushu-Palau Ridge. Hi m Sample No. Location Latitude en Pere Latitude peer Be Dredged materials DG-04-01 KPR, Unnamed 30°02.983’N 133°19.880’E 3800 30°02.074’E 133°18.465E 2632 tuff, pumice and Seamount limestone DG-05-01 and KPR, Komahashi- 29°53.983’N 133°22.656’E 3334 29°53.160’N 133°20.992’E 2500 tonalite, andesite and DG-05-02 Diani Seamount limestone Larger foraminifera from Kyushu-Palau Ridge 193 Sample No. pee DG-05-01 | DG-05-02 Larger foraminiferal species ———— piroclypeus margaritatus (Schlumberger CN ee es izrerost tegina borneensis van der Vlerk Nephrolepidina angulosa (Provale Nephrolepidina marginata (Michelotti) FETT Tre 77 pidina praejaponica Matsumaru X Miogypsinella ubaghsi (Tan) Austrotrillina howchini (Schlumberger) x x X LT x ent dilatata (Michelotti Eulepidina ephippioides (Jones and Chapman) ichtel and Moll 4mphistegina radiata Eulepidina sp. zo Se one ee mn RÉ NET eee PTE ET Heterostegina sp. Figure 3. Occurrence of larger foraminiferal species in dredged samples. Seamount, which is consistent with the oldest age of the basement rocks in the Shikoku Basin (Watts and Weissel, 1975). The association of Late Oligocene coral-bearing limestone with benthic foraminifera of shallow-sea nature and igneous rocks recognized at the Komahashi-Daini Seamount has also been reported at DSDP Site 296, south of the seamount, at a depth of 2,920m (Figure 1). This evidence suggests that volcanogenic-calcareous sedimentary se- quences of Oligocene age are rather widely distributed in the northern part of the Kyushu-Palau Ridge, including the Komahashi-Daini Seamount. In view of the paleoenvironmental nature of the larger foraminiferal assemblage consisting of Miogypsinella, Spiroclypeus, Austrotillina, Eulepidina, Amphistegina and Heterostegina, an environment of the shallow open ocean at the shelf edge was suggested for the deposition of limestone beds of the Komahashi-Daini Seamount, as in the case of the limestone beds of the Minamizaki Limestone, Chichi- Jima (Matsumaru, 1996). Moreover, the presence of sev- eral species of Lepidocyclina (Eulepidina) associated with pyroclastic sediments in cores 56 and 57 at DSDP Site 296 indicates a neritic environment (Ujiié, 1975). In contrast to the cases of the Komahashi-Daini Seamount and of Chichi-Jima, where the Late Oligocene sediments are exposed near the seamount surface, a drill hole at DSDP Site 296 displays a considerably continuous sequence from in situ volcanic rocks through Late Oligocene shallow-water sediments. It includes larger foraminifera and pelagic cal- careous ooze, suggesting a subsidence of the Kyushu-Palau Ridge (Ujiié, 1975). It is noteworthy that the northern parts of the Kyushu- Palau Ridge and the Izu-Bonin Arc resemble each other in the timing of the cessation of volcanic activity and in the final paleoenvironment reaching a shallow-water depth. Since Uyeda and Ben-Avraham (1972) many authors have sup- posed that both ridges formed a single arc at the initial stage and then were divided into two arcs owing to the spreading of the Shikoku and Parce Vella Basins. This study offers a new line of supporting evidence for this hypothesis. Conclusion The oldest age of the Kyushu-Palau Ridge is Late Oligocene based on larger foraminifera. The benthic foraminiferal assemblage in the limestone samples is corre- lated with that from the upper part of the Minamizaki Limestone exposed on the Ogasawara (Bonin) Islands of the Izu-Bonin Arc. This fact suggests that the Kyushu-Palau Ridge and the Izu-Bonin Arc initially formed a single arc. Afterward the arc may have split by a spreading of the Shikoku and Parce Vella Basins. Systematic descriptions Family Lepidocyclinidae Scheffen, 1932 Genus Nephrolepidina Douvillé, 1911 Nephrolepidina praejaponica Matsumaru, 1989 Figures 6.1-6.4, 6.6, 6.7, 6.9, 6.10, 7.1, 7.6-7.9 Nephrolepidina praejaponica Matsumaru. In Matsumaru and Kimura, 1989, p. 265, 267, figs. 6.1-6.13; Matsumaru et al. 1993, p. 8, figs. 2.4, 3.6-3.8. Material.—Thirteen specimens (GSJF 15420-1—13) in- cluding one megalospheric specimen in a vertical section (GSJF 15420-1; Figure 6.1). Description.— Tests of megalospheric specimens, GSJF 194 Mia Mohammad Mohiuddin et al. 15420-1-8, are small lenticular with diameter of 3.5 to 5.5 mm and thickness of 1.5 to 2 mm. Conical pillars are from 80 um to 100 um in diameter, and distributed in the central part of the test surface. The embryonic chambers are of nephrolepidine type. The protoconch is subcircular wih a diameter of 240 um. The second large chamber, the deuteroconch embraces the protoconch and has an internal diameter of 320 um. The ratio of the inner diameter of the deuteroconch (Il) to that of the protoconch (I) is 1.3. The outer wall of the embryonic chambers is more than 25 mm thick. The equatorial chambers of arcuate form near the periembryonic chambers change from ogival to short hex- agonal near the periphery. The height of the equatorial layer near the center is about 200 um and at the periphery less than 100 um. The lateral chambers are rectangular in shape and are arranged in a tier of 10 to 12 layers over the center. Chambers over the central area of the test have a length of more than 160 to 200 um, a height of 45 to 60 um, and floors and roofs 20 to 25 um thick. Remarks.—The present specimen has the same features of small embryonic chambers and short hexagonal equato- rial chambers in as N. praejaponica Matsumaru from the Lower Member of the Misaki Formation, Tosa Shimizu City, Kochi Prefecture, Shikoku (Matsumaru and Kimura, 1989) and the Early Miocene (Aquitanian) Shimizu Formation (Matsumaru et al., 1993), Shikoku Island. Nephrolepidina praejaponica is similar to N. japonica (Yabe) in overall mor- phology, but differs from the latter in having a small test and small embryonic chambers, primitive form of the embryonic chambers, short hexagonal equatorial chambers, rectangu- lar lateral chambers and wavy floors and roofs. Nephrolepidina species have been reported from Zones N. 8 and N. 9 of Blow (1969) in the Japanese mainland (Yabe, 1906; Yabe and Hanzawa, 1922; Hanzawa, 1931a, b; 1964; Matsumaru, 1967, 1971a) except the Izu Peninsula and Shikoku Island (Matsumaru, 1971a; Matsumaru and Kimura, 1989). Nephrolepidina angulosa (Provale, 1909) Figure 6.5 Lepidocyclina tournoueri Lemoine and R. Douvillé var. angulosa Provale, 1909, p. 28, pl. 3, figs. 13-15. Lepidocyclina angulosa Provale. Rutten, 1912, p. 21, figs. 1-4. Lepidocyclina (Nephrolepidina) angulosa Provale. Hanzawa, 1957, p. 76, 77, pl. 20, figs. 1-9, pl. 21, fig. 5, pl. 22, figs. 4, 14. Nephrolepidina angulosa (Provale). Matsumaru, 1992, p. 259, 260, figs. 1.6, 1.7. Material.—One megalospheric specimen in a vertical sec- tion, GSJF 15421. Remarks.—This species is characterized by having a flat- topped central boss with stout pillars; equatorial chambers in the mature stage are hexagonal in shape; the roof and floor of the lateral chambers are straight; and the chamber cavi- ties are narrow and long. External appearance of the shell is similar to that of Nephrolepidina praejaponica Matsumaru, but it differs from the latter in possessing several conical pil- lars formed on the flat top of the central boss. Family Nummulitidae de Blainville, 1827 Genus Spiroclypeus H. Douvillé, 1905 Spiroclypeus margaritatus (Schlumberger, 1902) Figures 4.1, 4.2, 4.4, 4.5, 4.7, 4.9, 4.10, 5.1-5.13, 8.1 Heterostegerina margaritata Schlumberger, 1902, p. 152, 153, pl. 7, fig. 4. Spiroclypeus orbitoideus H. Douvillé, 1905, p. 460-462, pl. 14, figs. 1-6; Tan, 1937, p. 183, 184, pl. 1, figs. 2-4, pl. 2, figs. 1-13, pl. 3, figs. 1-7; Cole, 1957a, p. 332-333, pl. 95, figs. 6-12; Matsumaru, 1976a, p. 200, pl. 1, figs. 1, 8, 10; Hashimoto, Matsumaru and Sugaya, 1981, p. 59, pl. 13, fig. 8. Spiroclypeus leupoldi van der Vlerk, 1925, p. 14, 15, pl. 2, fig. 16; pl. 5, figs. 41, 48; Yabe and Hanzawa, 1929, p. 188, pl. 24, fig. 9; Cole, 1954, p. 577, 578, pl. 208, figs. 1-19; Hanzawa, 1957, p. 45, 46, pl. 5, figs. 7-13; Matsumaru, 1974, p. 108, pl. 15, figs. 1-4, 10, 13-15, 21-23, 28; Matsumaru, 1976a, p. 199, 200, pl. 1, figs. 4-7, 14, 15, 21, 23, 4. Spiroclypeus yabei van der Vlerk, 1925, p. 16, pl. 2, fig. 19, pl. 5, figs. 40, 50; Tan, 1937, p. 183, pl. 1, figs. 5, 6, pl. 3, figs. 10, 11, pl. 4, figs. 8-10, text-fig. 1; Cole, 1954, p. 580-581, pl. 207, figs. 1-14, pl. 208, figs. 20-26; Cole, 1957b, p. 764, pl. 239, figs. 9-10. Spiroclypeus tidoenganensis van der Vlerk, 1925, p. 16, 17, pl. 1, fig. 12, pl. 5, figs. 42, 47; Tan, 1937, p. 183, pl. 1, fig. 10, pl. 2, figs. 4-5, pl. 3, fig. 12, pl. 4, figs. 2-5, 19-21; Hanzawa, 1957, p. 46, 47, pl. 3, figs. 1-6, pl. 4, figs. 1, 8-10; Cole, 1957a, p. 332, pl. 95, figs. 13-15; Matsumaru, 1976a, p. 200, pl. 1, figs. 3, 9, 12, 18-20, 22, pl. 6, fig. 15; Hashimoto, Matsumaru and Sugaya, 1981, p. 60, 61, pl. 13, figs. 9, 12. Spiroclypeus margaritata (Schlumberger). Yabe and Hanzawa, 1925, p. 627-630, pl. 2, fig. 10, pl. 3, figs. 8, 9, pl. 4, figs. 3-8, text-figs. 1-4; Krijnen, 1931, p. 89, pl. 1, figs. 1-3; Tan, 1937, p. 182, 183, pl. 2, fig. 12, pl. 3, fig. 9, pl. 4, figs. 6, 7; Hanzawa, 1940, p. 789, 790, pl. 42, figs. 3-9; Cole, 1954, p. 578-580, pl. 206, figs. 10-25, pl. 207, figs. 15, 16; Matsumaru, 1974, p. 108, pl. 15, figs. 16, 24, 26; Hashimoto and Matsumaru, 1975, p. 122, pl. 13, figs. 11, 12; Hashimoto, Matsumaru and Sugaya, 1981, p. 59, 60, pl. 13, fig. 3; Matsumaru, Myint Thein and Ogawa, 1993, p. 10,11, figs. 2-1-9, 3-1. Spiroclypeus margaritata (Schlumberger) var. umbonata Yabe and Hanzawa, 1929, p. 187, 188, pl. 124, figs. 5-8. Spiroclypeus higginsi Cole. Hanzawa, 1957, p. 45, pl. 5, figs. 1-6, 14; Cole, 1957a, p. 332, pl. 95, figs. 1-5, pl. 109, fig. 16; Cole, = Figure 4. 1, 2, 4, 5, 7, 9, 10. Spiroclypeus margaritatus (Schlumberger), 1 (upper), 5, 9, 10: vertical sections, x 30, (GSJF 15418-1—4) 4, 7: oblique sections, x 30, (GSJF 15418-5—6), 2: megalospheric protoconch x 200, (GSJF 15418-7). 3. Heterostegina sp. vertical section, x 30. 6, 8. Amphistegina radiata (Fichtel and Moll), 6: vertical section, x 20, (GSJF 15427-1) 8: median section, x 20, (GSJF 15427-2) 11. Heterostegina borneensis van der Vlerk, vertical sec- tion, x 30, (GSJF 15419). Larger foraminifera from Kyushu-Palau Ridge 195 SY, ae “2 matten... nr 196 Mia Mohammad Mohiuddin et al. 1957b, p. 763, 764, pl. 239, figs. 11, 12, 14; Matsumaru, 1974, p. 108, pl. 15, figs. 1, 5, 8, 12, 18, 19; Matsumaru, 1976a, p. 199, pl. 1, figs. 2, 11, 16, 17. Spiroclypeus margaritatus (Schlumberger). Matsumaru, 1996, p. 104-108, pl. 32, figs. 1-8, pl. 33, figs. 1-9. Material.— Twenty specimens, GSJF 15418-1—20. Description.—Test small, inflated to lenticular, bordered by a rather thin flange, central area more than 3.5 mm in di- ameter and 1.5 mm in thickness. Low raised pustules dis- tributed in umbonal portion of the test having a diameter of less than 100 um. The megalospheric embryonic chambers consist of a spherical protoconch followed by a reniform deuteroconch. The inner diameters of protoconch (DI) and deuteroconch (DIl) vary from 200 to 250 um and 450 to 550 um, respectively with a (DII/Dl) ratio of 2.2. Remarks.—Tan (1937) divided the species of Spirocly- peus into the pustulate and the reticulate group. The former group is characterized by prominent pillars on the umbonal portion of the test, the later one by the development of an external reticulation of the septa at the central part of the test. Spiroclypeus margaritatus belongs to the pustulate group and is characterized by large and heavy pillars, thick roofs and floors in lateral chambers, and moderate sized operculine chambers. According to Matsumaru (1996), all the Spiroclypeus spe- cies reported from the West Pacific region are junior synonyms of Spiroclypeus margaritatus (Schlumberger). This species, known from Chichi-Jima, is restricted in occur- rence to the Upper Member of the Minamizaki Limestone. It has a comparatively short stratigraphic range in Te, from the top of the Heterostegina borneensis Zone to the base of the Miogypsinoides dehaartii Zone, in the Eniwetok Atoll Drill Holes (Cole, 1957b). Genus Heterostegina d’Orbigny, 1826 Heterostegina borneensis van der Vlerk, 1929 Figure 4.11 Heterostegina borneensis van der Vlerk, 1929, p. 16, figs. 6a-c, 25a-b; Cole and Bridge, 1953, p. 23, pl. 2, figs. 1-3, 5; pl. 4, figs. 16-18; Hanzawa, 1957, p. 95, pl. 26, figs. 11, 19; pl. 27, figs. 4-8; Matsumaru, 1976a, p. 199, pl. 3, figs. 17-19, 21-22; Matsumaru, 1996, p. 94-96, pl. 28, figs. 1-7. Material.—One microspheric specimen in a vertical sec- tion, GSJF 15419. Description.—Test small, initial part evenly lenticular with a moderately wide, thin flange on distal part. Test diameter ranges from 2.2 mm to 2.7 mm; test thickness ranges from 1.0 to 1.2 mm; thickness of pillars varies from 120 um at umbo to 100 um at tip of flange. In vertical section, embry- onic apparatus biloculine; initial protoconch subcircular; its diameter less than 100 um. Prominent pillars are present on the central boss of the test. Pillars penetrating to outer wall of embryonic apparatus and equatorial layer. Remarks. — Heterostegina borneensis and Spiroclypeus margaritatus co-occur in the Lower and Upper members of the Minaminizaki Limestone. In the Komahashi-Daini Seamount Limestone, H. borneensis is associated with Spiroclypeus margaritatus, the latter species being the more abundant one. H. borneensis has also been recognized as a marker species to distinguish Te1-4 from Te5 (Cole, 1957a; Adams, 1965; Matsumaru, 1974, 1978), since van der Vlerk (1925) regarded it to be a useful species for delim- iting Te1-4. Family Austrotrillinidae Loeblich and Tappan, 1986 Genus Austrotrillina Parr, 1942 Austrotrillina howchini (Schlumberger, 1893) Figure 8.11 Trillina howchini Schlumberger, 1893, p. 119, 120, text-figs. 1-2, pl. 3, fig. 6; Hanzawa, 1940, p. 791-793, pl. 42, figs. 1, 2. Austrotrillina howchini (Schlumberger). Cole and Bridge, 1953, p. 20, pl. 14, fig. 12; Cole, 1954, p. 573, pl. 210, figs. 6-9; Hanzawa, 1957, p. 38, pl. 22, figs. 12, 13; pl. 34, figs. 1, 2; Matsumaru, 1996, p. 214-216, pl. 84, figs. 3-7. Material.—One microspheric specimen in a longitudinal section, GSJF 15424. Remarks. — Austrotrillina howchini originally described from Saipan is also found in the Bikini Atoll Drill Holes asso- ciated with Spiroclypeus and Eulepidina in Te Stage (Cole, 1954). The stratigraphic range of this species has been given as Te through Tf1-2 (Glaessner, 1943) and as Te and Tf1 (van der Vlerk, 1948). Hanzawa (1940) stated that this species is found only in the Aquitanian stage in the West- ern Pacific. Hashimoto and Matsumaru (1984) suggested that A. howchini ranged from Te4 to Te5-Tf1. This spe- cies occurs in association with Miogypsinella boninensis and Spiroclypeus margaritatus in the Minamizaki Limestone, Chichi-Jima, assigned to Te 1-4 of the Far East Letter Stages (Hashimoto et al., 1980; Hashimoto and Matsumaru, 1984). Family Lepidocyclinidae Scheffen, 1932 Subfamily Eulepidininae Matsumaru, 1991 Genus Eulepidina H. Douvillé, 1911 Eulepidina ephippioides (Jones and Chapman, 1900) Figures 6.8, 7.3, 7.4 Orbitoides (Lepidocyclina) ephippioides Jones and Chapman, 1900, p. 251, 252, pl. 20, fig. 9. Lepidocyclina ephippioides Jones and Chapman. Grimsdale, 1952, p. 240-244, pl. 23, figs. 8, 17, 18. Lepidocyclina (Eulepidina) formosa Schlumberger. Cole, 1954, p. 594-597, pl. 216, figs. 1-16; pl. 217, figs. 9-11, pl. 218, figs. 1, 3, 4. Lepidocyclina (Eulepidina) gibbosa Yabe. 217, figs. 9-11. Cole, 1954, p. 597, pl. = Figure 5. 1-13. Spiroclypeus margaritatus (Schlumberger). 1-3, 5-10, 12, 13: vertical sections, x 30, (GSJF 15418-8—18), 4, 11: oblique sections, x 30, (GSJF 15418-19—20). Larger foraminifera from Kyushu-Palau Ridge 197 Mia Mohammad Mohiuddin et al. 198 Larger foraminifera from Kyushu-Palau Ridge 199 Lepidocyclina (Eulepidina) planata Oppenoorth. 597, 598, pl. 217, figs. 7, 8; pl. 218, figs. 5, 6. Lepidocyclina (Eulepidina) ephilppioides Jones and Chapman. Cole, 1957b, p. 346-337, pl. 108, figs. 4-13; pl. 109, figs. 11- 15: Eulepidina ephilppioides (Jones and Chapman). Matsumaru, 1996, p. 178-181, pl. 65, figs. 1-6, pl. 66, figs. 1-3; pl. 67, figs. 1-6; pl. 68, figs. 1-3; pl. 69, figs. 1-4; pl. 70, figs. 1-5, text-fig. 20-5. Cole, 1954, p. Material. — Three megalospheric specimens 15426-1—3). Remarks.— Eulepidina ephippioides is characterized by the possession of a small nucleoconch and hexagonal or spatulate equatorial chambers. The earliest name of this species was thought to be Orbitoides (Lepidocyclina) ephippioides Jones and Chapman. According to Grimsdale (1952), the American Oligocene species L. (E.) favosa Cushman should be a synonym of L. ephippioides (Jones and Chapman). (GSJF Eulepidina dilatata (Michelotti, 1861) Figure 8.1 (lower) Orbitoides dilatata Michelotti, 1861, p. 17, pl. 1, figs. 1-2. Eulepidina dilatata (Michelotti). Matsumaru, 1971b, p. 184, 185, pl. 22, figs. 28-38; Hashimoto and Matsumaru, 1975, p. 114, 115, pl. 12, figs. 10, 11; Matsumaru, 1996, p. 162-178, pl. 60, figs. 1-6; pl. 61, figs, 1-6; pl. 62, figs. 1-7; pl. 63, figs. 1-6; pl. 64, figs. 1-2, text-figs. 20-2, 4, text-fig. 30. Material. — One obliquely specimen, GSJF 15425. Remarks.—The present species is characterized by hav- ing a lenticular shape, polygonal outline, large nucleoconch, hexagonal equatorial chambers, low and long lateral cham- bers and thin roofs and floors. It differs in general shell shape from Eulepidina ephippioides (Jones and Chapman). Recently, Matsumaru (1996) investigated the size of the em- bryonic chambers of E. dilatata and E. ephippioides from the Minamizaki Limestone, Chichi-Jima and concluded that microspheric E. dilatata slightly differs in chamber budding formation from microspheric E. ephippioides. sectioned megalospheric Family Miogypsinidae Vaughan, 1928 Genus Miogypsinella Hanzawa, 1940 Miogypsinella ubaghsi (Tan, 1936) Figures 7.2, 8.2, 8.3 Miogypsinoides ubaghsi Tan, 1936, p. 47, 48, pl. 1, figs. 1-7; Cole, 1954, p. 603, 604, pl. 221, figs. 5, 9-18; pl. 222, figs. 13, 15. Miogypsinella ubaghsi (Tan). Hanzawa, 1940, p. 767, 768, text-fig. 4. Material.— Three melalospheric specimens; one in an equatorial section, GSJF 15423-3 (Figure 8.3), one in an axial section, GSJF 15423-1 (Figure 8.2), and one in a ver- tical section, GSJF 15423-2 (Figure 8.2). Description.— Test small, slightly wider than long, fan- shaped; 1.5 to 1.8 mm in diameter and 0.65 to 0.75 mm in thickness. Surface ornamentation consists of large pus- tules over the initial portion and finer, closer-spaced pustules over the distal portion. Embryonic chambers are bilocular, first chamber is nearly spherical and second chamber is reniform. Initial chambers are followed by subquadrate periembryonic chambers arranged so that they form virtually two coils. Periembryonic chambers gradually increase in length as they as added for about 1.5 volution at which point they decrease gradually in length to the end of the coil. Remarks.—The present species differs from Miogypsi- nella borodinensis Matsumaru, 1996, described from Minamizaki Limestone, Chichi-Jima, in having fewer equato- rial and embryonic chambers and a small apical angle. Family Amphisteginidae Cushman, 1927 Genus Amphistegina d’Orbigny, 1826 Amphistegina radiata (Fichtel and Moll, 1798) Figures 4.6, 4.8, 8.1 Nautilus radiatus Fichtel and Moll, 1798, p. 58, pl. 8, figs. 8a-d. Amphistegina lessoni d'Orbigny. Yabe and Hanzawa, 1925, p. 48, 49, pl. 8, figs. 9, 10; Hanzawa, 1931b, p. 156, pl. 24, fig. 7; pl. 25, figs. 5-8; pl. 10, fig. 4. Amphistegina radiata (Fichtel and Moll). Yabe and Hanzawa, 1929, p. 179, 180, pl. 18, fig. 6; Matsumaru, 1976b, p. 408, pl. 1, figs. 1-3, 5-13, 17, 23, 26-27, text-figs. 6-8. Matsumaru, 1996, p. 188, pl. 74, figs. 1-5. Material.— Three microspheric specimens (GSJF 15427-1 —3) Remarks.—The present specimens show a close similar- ity with those of A. radiata described from the Minamizaki Limestones (Matsumaru, 1996) and are characterized by many chambers in the last whorl, curvature of the spiral su- ture and septa and a large protoconch. Acknowledgments We acknowledge the help of the crew and scientific party on board the R/V Tansei Maru KT94-10 cruise, particularly T. Ishii. Thanks are also due to H. Ujiié, Takushoku University, for discussion on some larger foraminifera taxon- omy and for critical reading of the manuscript. We would like to thank A. Nishimura, Geological Survey of Japan, for extensive and fruitful discussions regarding geologic history of the Kyushu-Palau Ridge. References Adams, C.G., 1965: The foraminifera and stratigraphy of the « Figure 6. Chapman), vertical section, x 20, (GSJF 15426-1). 1-4, 6, 7, 9, 10. Nephrolepidina praejaponica Matsumaru. vertical sections, x 30, (GSJF 15420-1—8). 5 Nephrolepidina angulosa (Provale), vertical section, x 30, (GSJF 15421). 8. Eulepidina ephippioides (Jones and Mia Mohammad Mohiuddin et al. 200 Larger foraminifera from Kyushu-Palau Ridge Melinau Limestone, Sarawak, and its importance in Tertiary correlation. 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De Inge- nieur in Nederlandsche-Indié, Afd. IV, Mijnbouw en Geologie, Jaarg. 3, no. 3, p. 45-61, pls. 1-2. Tan, S.H., 1937: On the genus Spiroclypeus H. Douvillé with a description of Eocene Spiroclypeus vermicularis nov. sp. from Koetai in east Borneo. De Ingenieur in Neder! andsche-Indié, Afd. IV, Miinbouw en Geologie, Jaarg. 4, no. 10, p. 177-193. Ujiié, H., 1975: Planktonic foraminiferal biostratigraphy in the Western Philippine Sea. In, Karig, D.E., Ingle, J.C. et al., eds. Initial Reports of the Deep Sea Drilling Project, vol. 31, p. 677-691. U.S. Goverment Printing Office, Washington, D.C. Uyeda, S. and Ben-Avraham, Z., 1972: Origin and develop- ment of the Philippine Sea. Nature, vol. 240, p. 176. Vaughan, T.W., 1928: Subfamily Miogypsinidae Vaughan. In, Cushman, J.A., 1928, Foraminifera their classification and economic use, Special Publication of Cushman Laboratory for Foraminiferal Research, vol. 1, 401p. Vlerk, I.M. van der, 1925: A study of Tertiary foraminifera from the “Tidoengsche Landen” (E. Borneo). Dutch East Indies, Dienst van der Mijnbouw, Wetenschappelijke Mededelingen. Dienst van den Mijnbouw in Nederlana- 203 Figure 8. 1. Bioclastic packstone containing diagnostic species such as Spiroclypeus margaritatus (Schlumberger) (GSJF 15418-20), Nephrolepidina marginata (Michelotti) (GSJF 15422), Eulepidina dilatata (Michelotti) (GSJF 15425) and Amphistegina radiata (Fichtel and Moll) (GSJF 15427-3) x 20. 2,3. Miogypsinella ubaghsi (Tan). 2: axial section, x 20, GSJF 15423-2, 3: equatorial section, x 20, (GSJF 15423-3). 4-10, 12, 13. Ammonia sp., 4, 7, 9, 10, 12: oblique sections, x 20, 5: equatorial section, x 20, 6, 8, 13: axial sections, x 20. 11. Austrotrillina howchini (Schlumberger), lon- gitudinal section, x 20, (GSJF 15424). sch-Indie, no. 3, p. 13-32, pls. 1-6. Vlerk, I.M. van der, 1929: Groote foraminiferen van N.O. Borneo. Wetenschappelijke Mededelingen Dienst van der Mijnbouw in Nederlandsch-Indie no. 9, p. 5-30. Vlerk, I.M. van der, 1948: Stratigraphy of the Cenozoic of the East Indies based on Foraminifera. International Geological Congress, Report of 18th Session, Great Britain, pt. 15, p. 61-63. Watts, A. B. and Weissel, J.K., 1975: Tectonic history of the Shikoku marginal basin. Earth and Planetary Science Letters, vol. 25, p. 239-250. Yabe, H., 1906: On the orbitoid limestone from Nakakosaka and from Kuboi on the Lake Kawaguchi. Journal of Geological Society of Japan, vol. 13, no. 156, p. 317-320. Mia Mohammad Mohiuddin et al. (in Japanese) Yabe, H. and Hanzawa, S., 1922: Lepidocyclina from Naka- Kosaka, Province of Kodzuke, Japan. Japanese Journal of Geology and Geography, vol. 1, no.1 p. 45-50, pls. 5-8. Yabe, H. and Hanzawa, S., 1925: A Lepidocyclina-Limestone from Klias Peninsula, B. N. Borneo. Gedenkboek Verbeek, Verhandelingen Geologisch-Mijinbouw Genoots- tschap Nederland en Kolonien, Geology Series, vol. 8, p. 617-631, pls. 1-4. Yabe, H. and Hanzawa, S., 1929: Tertiary foraminiferous rocks of the Philippines. Science Reports of the Tohoku University, Second Series (Geology), vol.11, no. 3, p. 137-190, pls. 15-27. Paleontological Research, vol. 4, no. 3, pp. 205-225, September 29, 2000 © by the Palaeontological Society of Japan Kheraiceras Spath (Ammonoidea)—new forms and records from the Middle Jurassic sequence of the Indian Subcontinent SUDIPTA K. JANA, SUBHENDU BARDHAN and SUBRATA K. SARDAR Department of Geological Sciences, Jadavpur University, Calcutta 700-032, India (corresponding author: Bardhan, s_bardhan01 @yahoo.co.uk) Received 5 January 2000; Revised manuscript accepted 21 July 2000 Abstract. Kheraiceras Spath reached its peak during the Late Bathonian-Early Callovian and achieved a wide biogeographic distribution during that interval. The genus speciated rapidly and is represented in the fossil record by many species. The present endeavour provides a full taxo- nomic account of six species, of which five are from Kutch, western India. The sixth, K. noetlingi sp. nov., is based on the specimen described as ‘Sphaeroceras’ cf. bullatum d’Orbigny by Noetling (1896) from Baluchistan, Pakistan. Among the five Kutch species one has also been found in Baluchistan. We know little about specific dimorphism in Kheraiceras. In at least three instances dimorphic pairs have been matched. Of the six species of Kheraiceras described herein three are new and two are new records. They are: Kheraiceras cosmopolitum, K. bullatum, K. cf. hannoveranum, K. spathisp. nov., K. sp. A, and K. noetlingisp. nov. Like many other biota, includ- ing other ammonites, Kheraiceras speciation is marked by a high degree of endemism in the Kutch Sea, which extended up to Baluchistan. The endemism in this newly opened basin is due to the transgressions resulting from the fragmentation of Gondwanaland. Key words: endemism, Indian Subcontinent, Kheraiceras, Middle Jurassic, migration, sexual dimorphism Introduction The genus Kheraiceras Spath, 1924 of the family Tulitidae has been thought to evolve from Bullatimorphites Buckman, 1921. Unlike its probable ancestor, Kheraiceras has a wide biogeographic distribution along the margins of the Tethys and the Pacific including Indonesia, Mexico and South America (Donovan et al., 1981; Mangold, 1984; Riccardi et al., 1989; Sandoval et al., 1990; Westermann, 1993). The genus has not been reported, however, from the Boreal or Subboreal Provinces. From the distribution patterns it ap- pears that Kheraiceras is longitudinally widespread and latitudinally more restricted to the palaeotropics and subtrop- ics (see also Westermann and Callomon, 1988). It shows strong facies control, since most of its species are found mainly in calcareous facies deposited in shallow seas (Arkell, 1952; Bardhan et al., 1988). Kheraiceras is of great stratigraphic value because of its short temporal distribution, although its biostratigraphic potentialities have not been fully explored (see Bardhan et al., 1999). Kheraiceras ranges in age from Late Bathonian to Late Callovian (Hahn, 1969, 1971), but was at its peak during the Late Bathonian and Early Callovian when many other biostratigraphically impor- tant taxa, e.g. Macrocephalites Zittel, 1884 and Reineckeia Bayle, 1878 also flourished. In the present endeavour, we have made a taxonomic study of six Kheraiceras species, among which three are new and two have not been described previously from the subcontinent. Dimorphism is now considered to be very im- portant in understanding evolution within a lineage and must be taken into account in phylogeny. Although dimorphism in Kheraiceras is evident, little is known about specific di- morphic pairs (for details see Bardhan et al., 1994, 1999). In the present study we have distinguished dimorphic pairs in three species. Besides, there are two new microconchs and one macroconch species whose counterparts are still unknown. So far Kheraiceras is described in the literature mainly by macroconchs and microconchs are often rare. We have plentiful microconch specimens with a well pre- served peristome showing apertural modifications. They are described herein. The measurements of the types and other specimens of the present collection (abbreviated as below) are in mm. D=diameter; H=whorl height; W=whorl width; U=umbilical di- ameter. Repository. — Curatorial Division, Geological Survey of 206 Sudipta K. Jana et al. India, Calcutta (GSI); The Indian Museum, Calcutta; Department of Geological Sciences, Jadavpur University, Calcutta, India (JUM). Previous Study There are only a few reports of Kheraiceras from the Indian subcontinent. Waagen’s (1875) “Stephanoceras bul- latum” d’Orbigny, 1846 which Spath (1924) subsequently made the type species of Kheraiceras, i.e., K. cosmopoli- tum, comes from the Golden Oolite of Keera, Kutch. Recently many specimens of this species have been col- lected from Kutch, and the intraspecific variability and dimor- phism of this species have been firmly established (Bardhan et al., 1994). Noetling (1896) described a large single specimen as ‘Sphaeroceras’ cf. bullatum (pl. 6, figs. 2, 2a) from the Polyphemus Limestone bed of Mazardrik, Baluchi- stan. Although it resembles Kheraiceras hannoveranum (Roemer, 1911) from the Late Bathonian of Europe (Westermann and Callomon 1988), novel traits distinguish it and is described here as a new species. Spath (1931) re- ported K. aff. cosmopolitum from his Macrocephalus Zone of Jumara, Kutch, which is represented by a complete microconch resembling closely the one of our present spe- cies, K. spathi and has been synonymised with it. Kanjilal (1978) reported Kheraiceras probullatum from Kutch which is now considered to be a variant of Macrocephalites formosus (Sowerby, 1840) (see Pandey and Westermann, 1988). K. ex. gr. platystoma reported by Bardhan and Datta (1987) from Jumara is now considered to be an extreme de- pressed variant of K. cosmopolitum. Krishna et al. (1987) il- lustrated but did not describe a specimen as a microconch of K. cosmopolitum from the Golden Oolite of Keera. It ap- pears, however, from the figure to be an adult macroconch of K. bullatum with a partially preserved body chamber. Bardhan et al. (1988) described Bullatimorphites sp. from Jumara which is in fact a Kheraiceras species with a less de- pressed inner whorl and strong, coarse ribbing persisting on the adult body chamber. It has been redesignated here as K. cf. hannoveranum (see also Callomon, 1993; Jain et al., 1996). Panday and Westermann (1988) reported a single specimen of Bullatimorphites (Kheraiceras?) n. sp. A from the Middle (?) Bathonian of Patcham ‘island’, Kutch. It has peculiar Bullatimorphites-like inner whorls and a Kherai- ceras-like eccentrically coiled body chamber. The spatio-temporal distribution of Kheraiceras reveals its relatively narrow stratigraphic but wide biogeographic distri- butions. Yet little attention has been paid to its biostratigraphic potentialities except in Submediterranean France. In a previous attempt we have proposed a new biozonation scheme of the Upper Bathonian-Lower Callo- vian sequence of Kutch based on different stratigraphic ranges of Kheraiceras and other important time-diagnostic taxa such as Macrocephalites, Reineckeia etc. (Bardhan et al., 1999). An attempt has also been made for regional standard chronostratigraphy and interprovincial correlation. Stratigraphy Species of Kheraiceras are distributed throughout the en- tire Callovian sequence of the basal Chari Formation in Kutch. One species straddles into the uppermost Batho- = 2. a) ÆLMAINTAND ., Figure 1. Geographic location of Kutch with Keera and Jumara, the type area of the Chari Formation. The patterned area is the Rann of Kutch. Middle Jurassic Kheraiceras from India 207 nian bed in Jumara. The Chari Formation is a regionally persistent, highly fossiliferous unit and constitutes one of the four principal divisions of the Kutch Mesozoic (for details see Biswas, 1977; Mitra et al., 1979; Krishna, 1984). It repre- sents a near-continuous section ranging from the Upper Bathonian through the entire Callovian and Oxfordian. There are, however, reports of condensation of the se- CALLOVIAN FORMATION CHARI BATHONI AN FORMATION © PATCHAM m Figure 2. Key. 1. white, cream or brown-coloured limestone; 2. coral biostrome; 3. marl; 4. shale; 5. cross-stratified, lenticular, green, oolitic limestone; 6. grey shelly limestone with thin alter- nating bands of red or white limestone and grey shale; 7. bioclastic grainstone; 8. oolitic limestone. Occurrences of dif- ferent Kheraiceras species are indicated by horizon nos. (I-X). Stratigraphic sections at Jumara and Keera, quence and time-averaging of fauna during the Oxfordian (Fursich et al., 1992; Halder and Bardhan, 1996). The Chari Formation represents a heterolithic facies consisting of shale, limestone and sandstone. The carbonate facies which yields the present Kheraiceras specimens is occa- sionally oolitic and is more dominant in the lower part of the sequence. The partially exposed, underlying Patcham Formation at Jumara is on the other hand predominantly cal- careous, consisting of coral biostromes and limestone-marl alternations. Judging from the faunal associations and sedimentological evidence, these two formations are consid- ered to be the product of a shallow-marine environment (Biswas, 1991; Datta, 1992; Fürsich and Oschmann, 1993). The present Kheraiceras species have been systemati- cally collected from different limestone beds of Jumara and Keera in the mainland of Kutch (Figure 1). Jumara is the stratotype of the Chari Formation and Keera is the type lo- cality of Kheraiceras cosmopolitum. Stratigraphic occur- rences of Kheraiceras species in the Jumara and Kerra sections is shown in Figure 2. All species of Kheraiceras described herein restrictedly occur within the zones spanning Upper Bathonian to Lower Callovian (Figure 3). Although these zones are based mainly on endemic Kutch ammonites, discoveries (e.Q., Kayal and Bardhan, 1998) of some well time-diagonosed short-ranging taxa have made possible broad interprovincial correlation with other Kheraiceras-bearing provinces (for de- tailed discussion on age and correlation see Bardhan et al., 1999). Kheraiceras cf. [AGE | ZONE |suBzone | FAUNAL HORIZON | SPECIES Nothocephalites semilaevis M.formosus a Formosus | ORMOSUS| Kamptokephalites lamellosus Kampt. dimerus DIADE - K.bullatum MATUS I. diadematus Kheraiceras TORIUS TE I.transitorious MADAGAS- CARIENSIS hannoveranum is also known from EARLY CALLOVIAN K.spathi — < | cHRrsoo- es Z | LITHICUS |CHRYSOO- | Indocephalites |= € 2 LITHICUS | chrysoolithicus | 22 2 m Ele 5 TRIAN- |Macrocephalites |S $ w | TRIAN- | GULARrS | triangularis = = | GULARIS 2 Figure 3. Range chart of different species of Kheraiceras in Kutch. Zones and Subzones are after Bardhan et al. (1999). 208 Baluchistan. Another new species described here, Kherai- ceras noetlingi, has been found only in Baluchistan. Both come from the Polyphemus Limestone, Mazardrik, Baluchi- stan. Kheraiceras Faunal Associations Kheraiceras, though it ranges from Late Bathonian to Late Callovian (Hahn, 1969), is more diverse in Early Callovian, when other biostratigraphically important genera e.g., Macrocephalites Zittel and Reineckeia Bayle, also under- went adaptive radiation. In Submediterranean France Kheraiceras is closely associated with reineckeiids in the Lower Callovian beds, but macrocephalitids are rare (Cariou, 1984). In England, this part is marked by diverse macrocephalitid species but Kheraiceras and reineckeiids are absent (Callomon et. al., 1988). Kutch, on the other hand, includes ammonites of all these three groups and thus provides a unique opportunity for high resolution of biostrati- graphic zonation and interprovincial chronostratigraphic cor- relation. Recently Bardhan et. al. (1999) proposed biostratigraphic zonations within the Bathonian-Callovian Stages of Kutch (Figure 3). The faunal horizons are not found in every sec- tion, but the subzones are regionally persistent and can be easily recognised for their characteristic ammonite assem- blages in all the sections in the mainland of Kutch. Kheraiceras species are distributed throughout these as- semblages except for the lowest one, i.e., the Triangularis Sudipta K. Jana et al. biostratigraphic ranges and like macrocephalitids, they are more diverse in the lowest Early Callovian. A brief sum- mary of the faunal association of each Kheraiceras species is given here (Figure 4). The relative abundance of other important ammonite species is discussed and a possible age correlation based on time-diagnostic or equivalent taxa is indicated. The only Kheraiceras species described from outside Kutch is K. noetlingi sp. nov. It comes from the Polyphemus Limestone, Mazardrik, Baluchistan (Noetling, 1896). It is associated with Macrocephalites triangularis ‘group’, Clydo- niceras baluchistanense (Spath) and Choffatia (Homeo- planulites) (Spath). This faunal association indicates a Late Bathonian age (see also Westermann and Callomon, 1988). K. cf. hannoveranum first appeared in the Madagascarien- sis Subzone of the Chrysoolithicus Zone in Kutch. It resem- bles the lectotype coming from the Upper Bathonian Orbis Zone of Germany. In the Madagascariensis Subzone, Macrocephalites madagascariensis is particularly abundant. It resembles M. verus (Buckman) in Europe which comes from the lowermost Callovian (Cariou, 1984; Callomon et al. 1988). Another abundant macrocephalitid species is Indocephalites chrysoolithicus (Spath). Sivajiceras conge- ner is also abundant while Choffatia sp. and Oxycerites (Paroxycerites?) sp. are less common. K. cf. hannoveranum also continues to the next assemblage, i.e., the Transitorius Subzone of the lowest Early Callovian where it co-occurs with diverse macrocephalitids, e.g., Indocephalites transitorius, |. kheraensis, I. diadematus, Pleurocephaites Subzone. Different Kheraiceras species have different elephantinus, Kamptokephalites lamellosus and | Other important ammonite species | | | | 5 | | | | | = a | | | 3 S 3 5 | | | | le 3 | a ‘6 rs) 3 ES Sse lesa | 0 | = 2 à )3 | 3 s|s/&|3 8812|» 16181) | 3 12) a BE Er 2/2 | sa Fal (iS £ ah | A PVEVELEIRVEVEIEVEIEIEIEUE/§ E 4 oli 2 | 2 ESS |s lé ls |S 12a] 2 8 |& |L|E a SB 5 |2 = | = aegis) Bee. lego) elec 8 in 3 | 8/5 & 5 &| 8 OFS = | s 2/2 |3|3|8|s |2|2 Is |s|3 |2|2 | ® Eleleile|s 5 | 5 ° | 9 s/s 2 |2|=2:|=|3 2 £ | gi 2 = = & 3|2 6 & 3 E 3 A 8 | a 2 5 PIEIZIZ/Z 1/218 a siels le ele ARRIÈRE 3 S 8 $$$ 1818 (2/2/22) 8/88 ls lalgleselelels < < BIS lSléls ls ls ls ls lé els (Sl IE > | (ÉTÉ |E El EE la la lS|S|S|2|12l4 88 le |8l6|6|616|5|8 1 : —+— + {_—j 1 SANSEIE Nothocephalites | kK cosrnopolitum | @ 0o|0o|x |x }O;/O}O};X |@ |x |X |x|x |X |x|olole semilaevis | | | | | T T T + - a i Macrocephalites K. cosmopolitum | | | | ] formosus | K. sp. A | ® Le fe) ololele @ |x x x | | | | Macrocephalites | K. cosmopolitum | | seen | | | diadematus | K. bullatum | O loJo|je|je|o|ıo|®e|ıx x |X — - | + ——— — | | | 1 4 | IL: | Indocephalites | K. cosmopolitum | sian | | transitorius K. bullatum, K. spathi [0.101010 101|0|0 10 | x | K. cf. hannoveranum | | | | | | | t ln = = | + + — Le | Macrocephalites | K. cf. hannoveranum | | | | | | madagascariensis e | e } | | x lelx | er | u | | | L [Es | ® abundant, O common, x rare Figure 4. Biostratigraphic distribution of Kheraieras species in Kutch in association with other important ammonites. Middle Jurassic Kheraiceras from India 209 Dolikephalites subcompressus, Macrocephalites formosus. Besides, other Kheraiceras species e.g., K. cosmopolitum, K. bullatum, K. spathi are also found from this level. K. cosmopolitum is the most abundant species of Kheraiceras and an endemic form. It has a longer stratigraphic distribution spanning the entire Formosus Zone of the Lower Callovian. This zone can be approximately correlated with the Lower Callovian Macrocephalus and Gracilis Zones of France (see also Krishna and Westermann, 1987; Bardhan et. al., 1999). It is more fre- quent in the Formosus Subzone, where it is associated with abundant Macrocephalites formosus, Indocephalites kheraensis, Kamptokephalites dimerus, Kamptokephalites lammellosus, Dolikephalites subcompressus, and rare Choffatia recuperoi, Reineckeia tyrraniformis. In the superjacent Semilaevis Subzone, K. cosmopolitum is asso- ciated with abundant Nothocephalites semilaevis, Choffatia recuperoi. Collotia oxyptica, Eucyclocers eucyclum, Sub- kossmatia opis and Nothocephalites asaphus are rare at this level. Judging by this faunal association, the upper limit of K. cosmopolitum can reasonably be placed at the uppermost Early Callovian. K. spathi sp. nov. comes from the level im- mediately above the Bathonian-Callovian boundary. This horizon yields diverse Kheraiceras species e.g., K. cosmo- politum, K. cf. hannoveranum, K. bullatum. The important macrocephalitids are /. transitorius, I. chrysoolithicus, |. diadematus, P. elephantinus etc. K. bullatum appeared slightly above the base of the Lower Callovian, spanning the upper part of the Transitorius and the entire Diadematus Subzones. Here it is associated with K. cosmopolitum and typical members of the faunal assem- blage such as /. diadematus, P. elephantinus, K. dimerus, etc. This faunal association indicates a late appearance of K. bullatum in Kutch because it is already known from the Late Bathonian of Europe as well as South America (see Riccardi et al., 1989; Sandoval et al., 1990). We agree with Krishna and Cariou (1990) who correlated K. bullatum- bearing horizons of Kutch approximately with the upper Herveyi Zone and Bullatus Zone of France on the basis of common associated taxa. K. sp. A is represented by a single microconchiate speci- men from the Formosus Subzone, which marks the disap- pearance of K. bullatum. It is associated with K. cosmopolitum and abundant M. formosus, K. dimerus, K. lamellosus and D. subcompressus. Systematic Palaeontology Superfamily Perisphinctaceae Family Tulitidae Buckman, 1921 Genus Kheraiceras Spath, 1924 Type species.—Sphaeroceras cosmopolitum Parona and Bonarelli 1895; original desgination. Kheraiceras cosmopolitum (Parona and Bonarelli, 1895) Figures 5.1-5.4; 6c Holotype.—GSI Type No. 2009. Internal mould with par- tial shell remains, adult macroconch with last quarter of body chamber missing, from Golden Oolite of Keera. Material.—In addition to the holotype, one macroconch (JUM/J/5) and two microconchs (JUM/J/2 and JUM/J/6) have been studied. All of them come from Jumara. The macroconch is an adult specimen with thin shell and last quarter of the body chamber missing, from Horizon V, Bed 5. The microconchs are almost complete, both coming from Bed 7; JUM/J/2 with terminal constriction present at flank and abraded on one side, from Horizon IX; JUM/J/6 with thin shell, from Horizon X. Diagnosis.— Sphaeroconic, whorls extremely depressed and to a maximum in phragmocone, W/H ratio=2.8; body chamber occupies more than three-fourths of last whorl; be- ginning of body chamber marked by sudden whorl contrac- tion and umbilical uncoiling following first a straight centrifugal line and then turning suddenly inwards; ribbing feeble in internal mould, disappears more rapidly near um- bilicus than venter on body chamber, last seen at a diameter of 58 mm; umbilicus small, deep, umbilical wall gradually be- comes steeper; flanks extremely short; septal suture with typically shallow tulitid Us. Description.— Detailed systematic description of macro- conch, microconch, their synonymy and stratigraphic distri- bution have already been given in Bardhan et al. (1994). Occurrence.— Kheraiceras cosmopolitum is an endemic Kutch species. The holotype comes from the Golden Oolite (Bed 2), Keera. JUM/J/5 is collected from Horizon V, Bed 5, Jumara. JUM/J/2 and JUM/J/6 come from Horizon IX and X respectively of Bed 7, Jumara. Kheraiceras bullatum (d’Orbigny, 1846) Figures 5.5a,b; 6a,b; 7.1-7.6; 8.1a-c; 9 Macroconch.— 1846 Ammonites bullatus d’Orbigny, pl. 142, fig. 1, 2. 1954 Bullatimorphites bullatus (d’Orbigny). Arkell, text-fig. 34. 1958 Kheraiceras bullatus (d’Orbigny). Westermann, pl. 22, fig. 1a-b. 1984 Bullatimorphites (Kheraiceras) bullatus (d’Orbigny). Wester- mann, Corona and Carrasco, pl. 2, fig. 8a-b. 1987 Kheraiceras cosmopolita Krishna, Cariou and Enay, p. 4, pl. 1, fig. 6. 1990 Kheraiceras bullatum (d’Orbigny). Krishna and Cariou, p. 112. Macroconch and microconch.— 1999 Kheraiceras bullatum (d’Orbigny). Bardhan, Sardar and Jana, pl. 1, figs. 5-6. Material. — Seven macroconch specimens, mostly adults, internal moulds with aperture missing. All come only from Bed 2, Keera; JUM/K/8-12, JUM/K/17 from lower horizon (Horizon I) and a near complete small variant, JUM/K/13, from upper level (Horizon Il). Four microconchs with shell remains come only from Jumara; JUM/J/12 and JUM/J/13 with flared collar from Bed 6 (Horizon VII); JUM/J/14 with last quarter of body chamber missing, from Bed 5 (Horizon VI); JUM/J/11 near complete, abraded on one side, from basal part of Bed 7 (Horizon IX). 210 Sudipta K. Jana et al. Middle Jurassic Kheraiceras from India 211 Table 1. Measurements for Kheraiceras bullatum (d’Orbigny, 1846) (in mm) Specimen D U H W Holotype aperture 78 31 25 40 JUM/K/8 body chamber 61 20 24 33 56(ca) 13 26 32 52 8 28 38 JUM/K/9 body chamber 57 18 23) 33 54 17 24 32 end-phragmocone 42(ca) 9 26 36 JUM/K/10 body chamber 59(ca) 13 21 22 49 11 24 28 JUM/K/11 body chamber 57 20 22 23(ca) end-phragmocone 41 12 23 38(ca) JUM/K/12 aperture 60 20 24 32 end-phragmocone 40 12 22 40 JUM/K/13 aperture 47 14 18 275 body chamber 43 10.5 19 26 37 8 19 30 end-phragmocone 34(ca) 8 14 23 JUM/K/17 aperture 67 20 29 38 end-phragmocone 53(ca) 12 28 42 JUM/J/11 aperture 41 11 14 19 body chamber 34 10 16 21 JUM/J/12 aperture 43 14 15 23 body chamber 36 10 15 21 34 9 16 21 JUM/J/13 aperture 35 12 16 20 body chamber 30 7 13 19 29 = 14 19 JUM/J/14 body chamber 28 8 1117 Figure 6. Septal sutures of Kheraiceras. a, b. Adult septal sutures of Kheraiceras bullatum (d’Orbigny) , a: = : ae i JUM/K/17 and b: JUM/K/9. c. Penultimate septal suture of the 23 holotype (GSI type no. 2009) of Kheraiceras cosmopolitum (Parona and Bonarelli) , after Spath 1928. d. Adult septal Sans : " suture of Kheraiceras cf. hannoveranum (Roemer) , ellipticonic, phragmocone spindle-shaped. Early whorls JUM/J/10. involute, relatively depressed (W/H=1.04-1.65), one inflated variant (JUM/K/12) having W/H=1.8. Maximum diameter observed is 67 mm, the specimen (JUM/K/17, Figure 7- 2a,b) was still larger as evident from the trace of the last Measurements.—To record the remarkable modification quarter of body chamber. Body chamber occupying almost of the adult body chamber, multiple measurements at differ- whole of the last whorl. It partially occludes umbilicus at di- ent positions are given for a few specimens (Table 1). ameter 41 mm-55 mm immediately after end-phragmocone Description. — Macroconch: Mostly internal mould, stage and shows a strong deviation from regular spiral, thin shell remains are rarely preserved. Body chamber where it becomes straight initially and then egresses out ec- @ Figure 5. Dimorphs of Kheraiceras. (All natural size). 1-4. Kheraiceras cosmopolitum (Parona and Bonarelli). 1a, b. Holotype 2009, from Golden Oolite of Keera Bed 2, mostly internal mould, adult with incompletely preserved body chamber, highly depressed variant, lateral (a) and frontal (b) views. 2a-c. Adult with last quarter of body chamber missing, from Horizon V, Bed 5, Jumara, JUM/J/5, lateral (a), frontal (b) and ventral (c) views. 3a-c. Almost complete , from Horizon X, Bed 7, Jumara, JUM/J/6, lateral (a), frontal (b) and ventral (c) views. 4. Adult , body chamber fully preserved, but broken near venter, from Horizon IX, Bed 7, Jumara, JUM/J/2, note terminal constriction preserved at the flank, lateral view. 5a, b. Kheraiceras bullatum (d’Orbigny), , mostly internal mould with shell remains. Adult with almost completely preserved body chamber, from Horizon |, Bed 2, Keera, JUM/K/12, lateral (a) and frontal (b) views. x: base of body chamber. 212 Sudipta K. Jana et al. Middle Jurassic Kheraiceras from India 233 centrically, resulting in a wider umbilicus near peristome. Umbilicus varies ontogenetically (U/D=0.22 — 0.35), holotype being more evolute (U/D=0.40) relatively narrow, shallow to moderately deep in inner whorls; umbilical margin distinct and wall steeper throughout adult body chamber. Flanks short to slightly wide, flat to gently curved with rounded ventrolateral margin. Venter rounded, broad. Adult phragmocone diameter ranges from 40 to 53 mm and even less in a small variant, where the figure is about 34 mm. Maximum width of shell attained just at beginning of adult body chamber. Width of body chamber contracts maximally at middle part from where it gradually increases again. Whorl height on the other hand gradually decreases with in- creasing shell diameter. Aperture missing. Whorl de- pressed, semicircular to semielliptical in apertural outline. Ribbing not well discernible as shell is mostly internal mould. Ribs appear to be dense and fine on inner whorls, while broad, distant and restricted on venter and seen at least up to diameter 57 mm in the adult body chamber. The number of secondaries on first half of outer whorl is about 24. Both lobes and saddles not deeply incised. Both external and lateral lobes are frilled, but former are more slender. Incipient internal lobes less frilled. External saddle weakly bifid, first lateral saddle shallow, broad (Figure 6-a, b). Microconch : Mostly shell remains, strongly resem- bles macroconch in many morphological features (Figure 9) except being smaller in size (M : m~1.42). Beginning of adult body chamber is marked by sudden egression of um- bilical seam and maximum inflation (W/H=1.25 - 1.65) oc- curs just after it. Body chamber occupies nearly entire last whorl. Diameter of adult shell ranges from 35 to 43 mm. Apertural shape variable, elliptical to ovate. Peristome with slightly flared collar followed immediately by terminal con- striction which cuts ribs obliquely. At middle part of body chamber of diameter 29 mm to 35 mm, apertural contraction is maximum, after which shell width again gradually in- creases towards aperture. Venter broad, strongly curved in inner whorls, becoming narrow and gently curved in body chamber. Laterals highly reduced, rounded up to end- phragmocone but widens and flattens later. Both primary and secondary ribs are conspicuous, persis- tent up to peristome. Ribs fine and closely spaced in the early stage, becoming coarse and distant in outer whorl. Primaries rising from umbilical wall slightly rursiradiately, bi- furcate irregularly at mid-flank or slightly higher. Secon- daries and occasional solitaries go straight over venter. Number of secondaries in half whorl varies from 27 to 30. Septal suture not discernible. Discussion.—Macroconchs of the present form are closely allied to the type specimens of K. bullatum (d’Orbigny, 1846) (see Arkell, 1954, text-fig. 34). They show strong resem- blance in shell shape, whorl outline and nature of uncoiling of the umbilical seam. Ribbing pattern and the number of secondaries in the Kutch variant also agree more closely with the Lower Callovian K. bullatum s.s. The ribbing in the present macroconchs, however, is less conspicuous since most of them are internal moulds, and Arkell (1954) also pointed out that it is exaggerated in d’Orbigny’s figure. However, d’Orbigny’s species differs by its slightly larger adult shell diameter and relatively more inflated form. The stratigraphic and geographic distribution of K. bullatum is now better known. It is found in Europe, South America and Mexico, and ranges in age from Late Bathonian to Early Callovian (Cariou, 1984; Westermann et al., 1984; Riccardi et al., 1989; Sandoval et al., 1990). The stratigraphic distri- bution of K. bullatum both in Kutch and France shows a phyletic size decrease (see also Krishna and Cariou, 1990). The relatively smaller adult size of the Kutch forms in com- parison to those of Europe may, therefore, actually repre- sent a smaller variant of a higher stratigraphic level or may be due to geographic variation (Bardhan et al., 1999). The microconch described here under the present species strongly resembles the macroconch of K. bullatum of both Kutch and European forms. Its phragmocone is similarly cadiconic but not much inflated like that of K. cosmopolitum, body whorl with typical bullatum-like uncoiling. The microconch, however, is characterised by much smaller adult size and apertural modification. In the microconch ribs are fine, dense, continuing all through the body whorl. Interestingly, in Kutch, although both dimorphs come from coeval stratigraphic horizons, they do not occur together. Macroconch specimens come from different stratigraphic levels within the Golden Oolite of Keera whereas the microconchs are found in different but coeval horizons of Jumara. Microconch shows strong resemblance to different spe- cies of Bomburites. B. devauxi (de Grossouvre, 1891) (see Arkell, 1952, text-fig. 27), though similar in nature of shell shape and uncoiling, differs mainly by its smaller size, more depressed aperture and presence of strongly flared collar behind the terminal constriction. B. globuliforme (Gemmellaro, 1872) (see Arkell, 1952, text-fig. 27) has a shell size comparable to one of the variants of the present form (Figures 7-4a-c), but it is coarsely ornate and charac- terized by a peristome with a much flared collar. K. prahecquense of France also resembles the present form in shell diameter and K. bullatum-like other features. In Kutch both dimorphs are found at the same stratigraphic levels, but K. prahecquense appears only after the disappearance of K. « Figure 7. Kheraiceras bullatum (d’Orbigny). (All natural size). 1a-c. Adult , internal mould, body chamber fully pre- served, from Horizon |, Bed 2, Keera, JUM/K/8, lateral (a) frontal (b) and ventral (c) views. 2a, b. Adult , internal mould, al- most completely preserved body chamber, from Horizon |, Bed 2, Keera, JUM/K/17, lateral (a) and frontal (b) views. 3. Almost completely adult , internal mould, aperture missing, from Horizon |, Bed 2, Keera, JUM/K/9, lateral view. 4a-c. Adult , with terminal constriction preserved near the flank, from Horizon VII, Bed 6, Jumara, JUM/J/12, lateral (a), ventral (b) and frontal (c) views. JUM/J/14, lateral (a), ventral (b) and frontal (c) views. 5a-c. Almost completely adult , with partially preserved body chamber, from Horizon VI, Bed 5, Jumara, 6a-d. Complete adult specimen , from Horizon VII, Bed 6, Jumara, JUM/J/13, lateral (a,b), frontal (c) and ventral (d) views. Note terminal constriction in 6b. x: base of body chamber. Sudipta K. Jana et al. 214 Middle Jurassic Kheraiceras from India 215 W/H % Macroconch 11 = Microconch 0 10 20 30 40 50 60 70 80 D Figure 9. Best-fit growth curves of whorl section of macroconch and microconch of Kheraiceras bullatum (d’Orbig- ny). bullatum, thus making two distinct subzones (Cariou, 1984). Recently, Ammonites microstoma d’Orbigny (see Arkell, 1954, text-fig. 35) has been considered as a possible microconch of K. bullatum (Westermann and Riccardi, 1979 and Westermann and Callomon, 1988). A. microstoma, though, with a less depressed phragmocone, has a gradual Bullatimorphites-like uncoiling of the body chamber. It ap- pears that the present microconchiate forms are the better candidates to match to the true, i. e., macrochonchiate form of K. bullatum. The present macroconch closely resembles K. cf. hannoveranum , described here, but the latter is larger and strongly ornate. Detailed comparison, however, is given in the discussion part of K. cf. hannoveranum. Noetling’s (1896) ‘Sphaeroceras’ cf. bullatum is a giant Kheraiceras and considered as K. cf. bullatum by Pandey and Westermann (1988) and Westermann and Callomon (1988). Arkell (1954) also compared it with the European K. bullatum s.s. Noetling described the species from the Upper Bathonian Polyphemus Limestone, Baluchistan. We have inspected the only monotypic specimen reposited in the Geological Survey of India, Calcutta (Type No. 2915). Admittedly it is comparable with the European K. bullatum in coiling and ribbing pattern, but it is exceptionally large for the genus, having a diameter of 158 mm. Its body whorl is highly contracted and the aperture is barely in contact with the ventral surface of the preceding whorl. Besides, the phragmocone does not become depressed as much as in K. bullatum and ribs disappear much earlier in the inner flank on the body chamber. The Baluchistan specimen is de- scribed here as a new species, K. noetlingi sp. nov. K. cosmopolitum (Parona and Bonarelli, 1895), the type species, comes also from Kutch and stratigraphically over- laps the present species in the lower part of its range. This species and K. bullatum are closely related and their microconchs are also known. The nature of dimorphism is quite distinct and speaks for their specific separation. Both morphs of K. cosmopolitum have much inflated phrag- mocone, more depressed aperture and more eccentrically coiled body chamber than those of the present species. Microconchs of the two species are ornate to the end and characterised by apertural modification, but the microconch of K. bullatum has relatively fine, denser ribbing and more secondaries in the outer whorl than in K. cosmopolitum. Septal sutures are well discernible in macroconchs only, which are mainly represented by internal moulds. K. cosmopolitum has a more complex sutural pattern (Figure 6-c) at the same growth stage. Interestingly, both the spe- cies differ in macroconch-microconch size ratio which is greater in K. cosmopolitum (M : m=2.05). Kheraiceras spathi sp. nov. described later, is readily distinguishable from the microconch of the present species by its elliptically coiled body chamber, less depressed and less evolute early whorls, and pronounced terminal constric- tion. Microconch of the present species differs from Kheraiceras sp. A , described later, in being larger with coarse ornamentation and widely spaced ribbing. Westermann et al. (1984) described B. (K.) bullatum from Mexico based on a full-grown and almost complete speci- men (pl. 2, fig. 8a-b). Its obsolete ribbing on the body chamber and number of secondaries agree closely with some of our specimens of the present species. However, this Mexican form is slightly larger and may be an older geo- graphic variant since it comes from the Upper Bathonian ho- rizon. Bullatimorphites (Kheraiceras) v-costatus from the Upper Bathonian of Caracoles, Chile is a large and coarsely ornate form (Riccardi et al., 1989, pl. 8, figs. 3, 4). This form is even larger than true K. bullatum (d’Orbigny, 1846) of Europe and the Kutch form. Its ribbing is strong, distant and seems to persist on most of the outer whorl, and thus per- haps agrees closely with contemporary K. hannoveranum (Roemer). Recently Géczy and Galacz (1998) described a new Late Bathonian species Bullatimorphites (Bullatimorphites) dietli from South Hungary. The paratype of the species (Géczy @ Figure 8. Dimorphs of Kheraiceras. (All natural size). 1a-c. Kheraiceras bullatum (d’Orbigny) , internal mould, small variant, complete adult specimen, from Horizon Il, Bed 2, Keera, JUM/K/13, lateral (a), frontal (b) and ventral (c) views, note ob- solete ribbing restricted on the venter. 2-5. Kheraiceras cf. hannoveranum (Roemer) and . 2a-c. Adult with last 1/3 of the body chamber missing, from Horizon IV, Bed 4, Jumara, JUM P-2, lateral (a), frontal (b) and ventral (c) views. 3. Adult , one half is damaged, last part of the body chamber crushed, from Horizon V, Bed 5, Jumara, JUM/J/10, lateral view. 4. Almost complete adult specimen , one side damaged, from the Polyphemus Limestone, Mazardrik, Baluchistan, kept in Indian Museum, Calcutta, type no. H. 48.607, lateral view. 5a-d. Almost complete adult specimen , peristome missing, from Horizon |, Bed 2, Keera, JUM/K/7, lateral (a,b), frontal (c) and ventral (d) views. Note retention of coarse, distant ribbing to the end. x: base of body chamber 216 Sudipta K. Jana et al. and Galacz, 1988, pl. Ill, fig. 7) resembles our smaller, younger variant (Figure 8.1a-c) from the late Early Callovian in nature of umbilical uncoiling and adult body whorl length. Sandoval et al. (1990) recently established dimorphism in K. bullatum from the Upper Bathonian of Mexico. They synonymised their microconch with Bomburites microstoma, but the Mexican form differs from that of d’Orbigny. It, in fact, is very closer to the present microconch and one Mexican variant (ibid. pl. 9, 3a-c) is barely distinguishable. Occurrence. — Kheraiceras bullatum has a wide biogeographic distribution. Besides Kutch, it occurs in Europe, South America and Mexico from the Late Bathonian to Early Callovian. In Europe the species is abundant in France. The lectotype (see Arkell, 1954, text-fig. 34) comes from the Upper Bathonian. The species is common in the Bullatum Subzone of the Lower Callovian (Cariou, 1984). K. cf. bullatum is reported from the East Pacific faunal prov- ince. In Mexico it appears in the lower part of the Steinmanni Zone (=upper part of Restrocostatum Zone or Aspidoides Zone of Europe), and is associated with Epistrenoceras histricoides, indicating a Late Bathonian age (Westermann et al, 1984; Sandoval et al., 1990). In Argentina it comes from the Vergarensis Zone, which is equivalent to the Macrocephalus Zone of Submediterranean France (Riccardi et al., 1989). All seven macroconchs from Kutch localities come from different horizons within Bed 2, Keera. JUM/K/8 - 12, JUM/K/17 from Horizon | and JUM/K/13 from Horizon Il. Four microconchs come from Jumara. JUM/J/14 from Horizon VI, Bed 5; JUM/J/12-13 from Horizon VII, Bed 6 and JUM/J/11 from Horizon IX, Bed 7. Kheraiceras cf. hannoveranum (Roemer) Figures 6d; 8.2-8.5 Macroconch.— 1911 Sphaeroceras quenstedti var. hannoverana n.v. Roemer, p. 42, pl. 7, figs. 16, 21, pl. 8, fig. 1. 1915 Sphaeroceras bullatum d’Orbigny. Löczy, p. 351, text-fig. 79. 1925 Kheraiceras ? stansfieldi Spath, pl. I, fig. 2a-b. 1952 Bullatimorphites hannoveranus (Roemer). Arkell, p. 108. 1958 Bullatimorphites bullatus hannoveranus (Roemer). Westermann, p. 65, pl. 21, figs. a-b. 1970 Bullatimorphites (Bullatimorphites) cf. hannoveranus (Roemer). Mangold, p. 303, figs. 96-97. 1971 Bullatimorphites cf. hannoveranus (Roemer). Hahn, pl. 7, fig. 3. 1988 Bullatimorphites sp. Bardhan, Datta, Khan and Bhaumik, pl. 1, fig. 1a-c. 1993 Kheraiceras sp. nov. A. Callomon, p. 235. 1994 Bullatimorphites (Kheraiceras) hannoveranus (Roemer). Dietl, p. 10, pl. 1, fig. 2. 1997 Bullatimorphites (Kheraiceras) hannoveranus (Roemer). Mangold and Rioult, pl. 18, fig. 6. 1998 Bullatimorphites (Bullatimorphites) hannoveranus (Roemer). Géczy and Galacz, pl. Ill, figs. 1a-b, 2a-b, text-fig. 9. Macroconch and microconch.— 1999 Kheraiceras cf. hannoveranum (Roemer). Bardhan, Sardar and Jana, pl. 1, figs. 7-9. Material. — The present collection includes three macroconchs and one microconch. Two macroconchs (JUM P-2, JUM/J/10) are collected from Beds 4 and 5 of Jumara (Horizons IV and V in Figure 2), Kutch, and the other one is from the Polyphemus Limestone, Mazardrik, Baluchistan, and now kept in the Indian Museum (H 48.607), Calcutta. The only microconch, JUM/K/7 comes from the lower part ofthe Golden Oolite (Bed 2, Horizon | in Figure 2) of Keera. Measurements.—See Table 2. Description.—Macroconch : Shell elliptoconic, moder- ately inflated, involute up to adult phragmocone stage and then becomes evolute with rapid uncoiling of umbilical seam. Whorl section depressed, ovate. Adult phragmocone di- ameter ranges from 45 to 60 mm. Adult body chamber cov- ering more than 3/4 of the last whorl. Maximum shell diameter observed is about 100 mm. Maximum inflation (W/H=1.27-1.76) occurs at or just after end-phragmocone; both width and height show negative allometry afterwards. Umbilicus shallow and umbilical margin is steep up to end- phragmocone diameter or early part of body chamber but later gradually becoming less inclined. Sudden egression of umbilical seam coincides with beginning of body chamber; first it goes straight up to about 18 mm length occluding par- tially umbilicus of inner whorl, then turns inwards eccentri- cally towards aperture resulting in a ‘hook-shaped’ body chamber. Flank short, barely existing in inner whorl but with ontogeny becomes broad and gently curved. Venter broad, highly curved at early stage but becomes gently rounded on adult body chamber. Ventrolateral margin is always rounded. Shell coarsely ornate on body chamber. Phragmocone with relatively fine and dense secondaries; primaries short, regular and bifurcating on inner flank, and originating from umbilical margin. They disappear, resulting in smoothening of inner flank of body chamber while secondaries suddenly become coarse, distant and traced up to end of body cham- ber. Secondaries assume a broad, convex pattern aborally and then flex forward near ventrolateral margin and go over venter with slight forward projection. Number of second- aries on first half of outer whorl is 24. Both external and lateral saddles are large, frilled. Table 2. Measurements for Kheraiceras cf. hannoveranum (Roemer) (in mm). Specimen D U H W JUM/J/10 body chamber 72(ca) 19 27 38 61 20 34 44 end-phragmocone 51 = 26 40 JUM P-2 body chamber 60 14 24 40 49 7 25 44 end-phragmocone 45 7 24 40 H 48.607 aperture 99(ca) 33 27(ca) = end-phragmocone 60(ca) EL. 34 JUM/K/7 aperture 48 1261; 27 body chamber 42 13 22 28 35(ca) S23 33 Middle Jurassic Kheraiceras from India 217 External saddle bifid with deeply incised secondary lobes, lateral lobe deep, narrow (Figure 6-d). Microconch : It replicates macroconch in all major as- pects barring size. Body chamber occupies almost whole of last whorl. Maximum diameter observed is 48 mm. Maximum inflation (W/H=1.59) occurs on adult body cham- ber at diameter 35 mm followed by sudden contraction with decrease of both height and width. Aperture missing. Body chamber, initially after deviating from the regular spiral, goes straight for a distance of about 12 mm and then turns centrifugally towards the aperture. Ornamentation similar to that on macroconch but both pri- maries and secondaries retained without losing strength up to end of preserved body chamber. Number of secondaries on first half of outer whorl is about 30. Discussion.—The present species can be readily distin- guished from other Kutch forms by its coarsely ornate rib- bing which persists to the end of adult conch, sutural pattern and nature of dimorphism. However, it occupies morpho- metrically an intermediate position between highly de- pressed K. cosmopolitum and relatively compressed K. bullatum (see Figure 10). The present species differs from K. cosmopolitum by its less contracted body chamber and less inflated phragmocone, relatively simple sutural pattern and more dis- tant, coarse ribbing persistent up to the end of the body chamber. Moreover, in K. cosmopolitum, the growth of shell width relative to shell diameter shows negative allometry, while in the present species both width and height of the body chamber decrease with increasing shell diame- ter. Flanks are wider than in K. cosmopolitum. Moreover, dimorphic size ratio between these two species also differs. The lectotype of K. hannoveranum from the Upper Bathonian Orbis Zone of Germany matches well with the macroconchs of the present species in having a less inflated phragmocone and coarse ribbing which persists to the end. Jain et al. (1996) also compared one of the variants (JUM P- cosmopolitum hannoveranum===== bullatum ET W/H 8 28 48 68 D(mm) Figure 10. Growth curve of whorl section of both macroconch and microconch of three species of Kheraiceras in Kutch. Continuous line graph shows developmental change in a specimen. 2, Figures 8-2a-c) of the present Kutch form with Bullatimorphites cf. hannoveranus (Roemer, 1911, pl. 8, fig. 1 ; Hahn, 1971, pl. 7, fig. 3) and B. (Bullatimorphites) cf. hannoveranus (Mangold, 1970, p. 303, figs. 96-97) from the Upper Bathonian Restrocostatum Zone of the Southern Jura. Callomon (1993) also noticed a similarity between the same Kutch specimen (JUM P-2) and B. costatus Arkell (Lissajous, 1923, p. 18, fig. 2), and K. suivecum (Roemer) (pl. 7, fig. 21). The latter species has now been regarded as a microconch of the present species (Géczy and Galacz, 1998) and the type specimens of K. suivecum (see Arkell, 1952, text-fig. 36) are quite comparable with the microconch of the present speceies (JUM/K/7) described herein (Figure 8-5a-d). All of them are characterised in having strongly ornate outer whorl and ribbing which continues to the end without losing strength. The European macroconchs of the present species are larger in size and come from the older stratigraphic horizons. The present forms come from beds ranging in age from Late Bathonian to earliest Callovian. It appears that their smaller adult size may be due to geographic variation as well as younger straitigraphic age, since phyletic size decrease is found in many species of Kheraiceras. The macroconch of the present species is a close ally of that of K. bullatum, but differs in relatively large adult size and less contracted and less aberrantly coiled body cham- ber. Besides, in K. bullatum ribs are finer, more numerous, restricted mainly on the venter, and disappear finally near the aperture, while coarse, distant ribs which persist throughout the last whorl characterise the present species. Remarkably, these differences are also observed in microconchs. Kheraiceras? stansfieldi described by Spath (1925, pl. |, fig. 2a-b) from the ‘Lower Callovian’ Macrocephalus Zone of Madagascar, which is represented by an adult steinkern with crowded septal sutures and an incomplete body chamber, matches well with one of our specimens (Figures 8-2a-c) coming from the Madagascariensis Horizon. Both Kutch and Madagascan forms are similarly less depressed in apertural outline and have a rounded umbilical margin, and prorsiradiate ribs. Interestingly, the Madagascan form comes from the same locality and horizon which yield Macrocephalites madagascariensis. We believe that Kheraiceras? stansfieldi and the present K. cf. hannove- ranum are conspecific. Occurrence.—The lectotype of K. hannoveranum comes from the Upper Bathonian Orbis Zone of Germany. It closely resembles the Kutch form. The other Upper Bathonian specimens of the present species e.g., Bullatimorphites cf. hannoveranus (Roemer, 1911, pl. 8, fig. 1; Hahn, 1971, pl. 7, fig. 3), and B. (Bullatimorphites) cf. hannoveranus (Mangold, 1970, figs. 96-97, cited in Jain et al., 1996) come from the Upper Bathonian Restrocostatum Zone of the Southern Jura. Among our three macroconchs, JUM P-2 comes from Horizon IV, Bed 4, Jumara and JUM /J/10 from Horizon V, Bed 5, Jumara. The other one (H 48.607) comes from the Polyphemus Limestone, Mazardrik, Baluchistan. The only microconch (JUM/K/7) comes from Horizon |, Bed 2, Kerra. 218 Sudipta K. Jana et al. Middle Jurassic Kheraiceras from India 219 Kheraiceras spathi sp. nov. Figures 11.2a, b Microconch.— 1931 Kheraiceras aff. cosmopolita, Spath, pl. XCVI, fig. 8a-b. 1999 Kheraiceras sp. B. Bardhan, Sardar and Jana, pl. 1, fig. 12. Material.—The present species is represented only by the holotype specimen (JUM/J/15) collected from Horizon V, Bed 5 of Jumara. Diagnosis. — Shell small, compressed; inner whorls evolute, umbilical wall © overhanging, depressed phragmocone, much contracted body chamber; width de- creases during ontogeny, while height remains constant on outer whorl; retaining ancestral Bullatimorphites-like gradual uncoiling of body chamber, but characterised by flared peristome and highly contracted body chamber. Etymology.—In honour of L.F. Spath, England, who first studied this species. Measurements.—See Table 3. Description.—Microconch : Mostly internal mould, small, slender in shape (W/D=0.84 to 0.41, during ontogeny of outer whorl). Inner whorl sphaeroconic, gradually un- coiled to ellipticonic outer whorl. Body chamber occupies almost whole of last whorl. Maximum diameter observed is 36 mm. Beginning of body chamber at about 22 mm, marked by slightly inward curving of outer whorl, thus oc- cludes partially inner umbilicus (U/D=0.21) and followed thereafter by gradual eccentric coiling, so that at aperture body chamber is in contact only with ventral surface of pre- ceding whorl (U/D=0.33). Inner whorl relatively evolute, de- pressed with laterals barely existing. Venter broad, strongly curved. Umbilical margin sharp, angular with overhanging umbilical wall. Inner flanks gradually flatten and umbilical margin becomes rounded near aperture. Maximum inflation (W/H=1.9) of shell is attained after beginning of adult body chamber. Width decreases from the early part of adult body chamber with increase of shell size, but height remains al- most unchanged. Laterals widen and venter narrows ontogenetically on body chamber; whorl section depressed, ovate (at aperture, W/H=1.5). Aperture with deep, broad terminal constriction which rises very sharply in rursiradiate Table 3. Measurements for Kheraiceras spathi sp. nov. (in mm). manner near inner margin, then proceeds with a broad for- ward projection towards outer margin. Peristome projected forward at venter. Aperture immediately next to the con- striction appears to be slightly flared in internal mould. Ribbing fine, feeble on internal mould but appears to be persistent up to aperture. Suture not well discernible. Discussion.—The microconchiate affinity of the present specimen is obvious in its smaller size and contracted adult body chamber with modifications at the peristome. The present species strongly recalls ‘Bomburites’, a genus which is now considered as microconchs of Kheraiceras. It is a close match of the holotype of the type species Bomburites devauxi (de Grossouvre, 1891) (Arkell, 1954, text-fig. 27). However, the present species differs mainly by its gradual uncoiling of the body chamber, fine ribbing, rela- tively larger adult size and absence of any prominent flared collar at peristome. Spath’s (1931) Kheraiceras aff. cosmopolita (pl. XCVI, figs. 8a-b) which comes from the same stratigraphic horizon (Bed 5) and same locality at Jumara, resembles so strikingly the present species that they appear to be conspecific. The present species differs from microconchs of all other Kheraiceras spp. of Kutch by its compressed form, gradual uncoiling of umbilical seam and inwardly sloping umbilical wall. It differs from K. bullatum by its gradual uncoiling of umbilical seam, elliptoconic body chamber and less or- nate shell. K. cosmopolitum is the most tumid species (W/D= 0.69-1.03) of the present group, with an eccentrically coiled body chamber. It has a more depressed phragmocone and aperture than those of K. spathi. Besides, ribs in K. cosmopolitum are coarser and more distant. Microconch of K. cf. hannoveranum is readily distinguish- able from the present form in having larger shell diameter, strong ornamentation, highly contracted and aberrantly un- coiled body chamber. The original figure of Ammonites microstoma described by d’Orbigny (1846, pl. 142, figs. 3-4) which was refigured by Arkell (1954, text-fig. 35) is closely comparable with the pre- sent form, particularly with respect to gradual uncoiling of the body chamber and presence of a deep terminal constriction. A. microstoma d’Orbigny, 1846 is now considered as a microconch of Kheraiceras. It, however, differs from the present form in its larger size, strongly ornate shell and dis- tinct collar. Spath (1931) compared the present form with K. globuliformi (Gemmellaro, 1872) (Parona and Bonarelli, 1895, pl. VI, fig. 1) but the latter species is larger in size and characterized by coarse ribbing, more eccentrically coiled body chamber and highly flared peristome. Occurrence.—The monotypic holotype (JUM/J/15) comes from a horizon (HorizonV, Bed 5, Jumara) which lies just Specimen D U H W Holotype, aperture 36 12 10 15 JUM/J/15 body chamber 29 8 10 17 near end- 23 5 10 19.5 phragmocone @ Figure 11. Dimorphs in Kheraiceras. (All natural size). 1. Kheraiceras noetlingi sp. nov. , holotype, (type no. 2915), complete adult, from the Polyphemus Limestone, Mazardrik, Baluchistan, now kept in Curatorial Division, Geological Survey of India, Calcutta, lateral view. 2a, b. Kheraiceras spathi sp. nov. , holotype, internal mould, complete adult specimen with deep terminal constriction from Horizon V, Bed 5, Jumara, JUM/J/15, lateral (a) and frontal (b) views. 3a-c. Kheraiceras sp. A. , adult with almost completely preserved body chamber, abraded near the last part, from Horizon Ill, Bed 2, Keera, JUM/K/16, lateral (a), frontal (b) and ventral (c) views ; note fine, dense ribbing. x: base of body chamber. 220 Sudipta K. Jana et al. above the Bathonian-Callovian boundary. Kheraiceras sp. A Figures 11.3a-c Microconch.— 1999 Kheraiceras sp. A. Bardhan, Sardar and Jana, pl. 1, fig. 11. Material. —Only one specimen (JUM/K/16) collected from the Golden Oolite (Bed 2, Horizon Ill in Figure 2), Keera. Measurements.—See Table 4. Description.—Microconch : Shell small, elliptoconic? Table 4. Measuremetns for Kheraiceras sp. A (in mm). Specimen D U H W JUM/K/16 aperture ?30 7(ca) 11.5 14 body chamber 31 7(ca) 12 19 26 45 11 20 (W/D=0.46); strongly involute inner whorls. Adult phrag- mocone at about 21 mm. Maximum inflation (W/H=1.8) is attained after beginning of body chamber at 26 mm. Width of body whorl decreases rapidly with ontogeny while height Figure 12. Kheraiceras noetlingi sp. nov. , same as figure 11.1, frontal (a) and ventral (b) views. (All natural size) Middle Jurassic Kheraiceras from India 221 remains more or less same. Body chamber occupies more than 3/4 of last whorl, largest shell diameter being 31 mm, which occurs near middle part of body chamber. After- wards shell diameter decreases slightly which may be due to secondary crushing of specimen. Aperture missing. Initially, umbilical seam deviates from regular spiral and goes straight in direction of largest shell diameter; then it suddenly turns inward and barely touches ventral surface of penultimate whorl. Venter broad, rounded and narrows down gradually towards aperture. Flanks short, less curved near mature phragmocone; both ventrolateral and umbilical margins gradual. Ribs fine, dense, persisting till end. Primaries originating from umbilicus, straight to slightly rursiradiate near inner margin, and furcate irregularly either at or sligtly above mid- flank. Secondaries feebly sinuous or straight across venter, about 34 on first half of outer whorl. Septal suture not discernible. Discussion.—The present species differs from K. cosmo- politum by its smaller size, less depressed early whorls and more fine and dense ribbing. It is smaller than K. bullatum and body chamber is more contracted and aberrantly uncoiled. Besides, they dif- fer in ribbing pattern and number of ribs per half whorl. The described specimen also strongly recalls the holotype of ‘Bullatimorphites’ uhligi (Popovichi-Hatzeg, 1905, pl. 6, fig. 7) (see Arkell, 1954, text-fig. 36). They both are characterised by fine dense ribbing and strongly involute phragmocone and may be conspecific if enough material is available. Unfortunately, the holotype of ‘B.’ uhligi has an incomplete body chamber. The unique holotype of K. spathi sp. nov. has a compara- ble adult shell diameter and fine, dense ribbing. It has, on the other hand, characteristic Bullatimorphites-like gradual uncoilding of body chamber and compressed shell shape. Besides, the present form differs also by its strongly involute inner whorls and less contracted aperture. Occurrence.—Single speciment (JUM/K/16) from Horizon Ill of Bed 2, Keera. Kheraiceras noetlingi sp. nov. Figures 11.1 ; 12a, b Macroconch.— 1896 ‘Sphaeroceras’ cf. bullatum d’Orbigny, Noetling, pl. 6, fig. 2, 2a. 1933 Kheraiceras quenstedti (J. Roemer). Spath, p. 808. 1999 Sphaeroceras bullatum Bardhan, Sardar and Jana, pl. 1, fig. 10. Material.—The holotype, a unique specimen described by Noetling (1896, pl. 6, fig. 2, 2a) from the Polyphemus Limestone, Mazar Drik, now reposited in GSI (Type No. 2915) and refigured here (Figures 11.1; 12a, b). Diagnosis.—Unusually large for the genus; less cadiconic phragmocone, aperture highly contracted, inner whorls involute, body chamber eccentrically uncoiled and barely in contact with the ventral surface of the preceding whorl, apertural whorl section elliptical; ribbing coarse, distant, be- coming obsolete in the first half of the body chamber. Table 5. Measurements for Kheraiceras noetlingi sp. nov. (in mm). Specimen D U H W Holotype, aperture 158 49 55 60 GSI Type body chamber 132 34 51 60 No.2915 end- 127 17 50 90 phragmocone Etymology.—In honour of F. Noetling, who first studied this species. Measurements.—See Table 5. Description.—Macroconch : Internal mould, large, relatively compressed (W/D=0.7). Complete adult speci- men with maximum diameter 158 mm. Shell involute in early whorls, but becoming evolute in last whorl. Umbilical seam turns inward occuluding partially umbilicus of inner whorls, end-phragmocone diameter 103 mm. _ Thereafter adult body chamber, which occupies more than 3/4 of last whorl, coils eccentrically and becomes very narrow at aper- ture, resulting in a wide umbilicus. Maximum inflation at- tained at end-phragmocone stage (W/H=1.8) followed by rapid contraction of body chamber which is maximum at about diameter 132 mm (W/H=1.17), thereafter height in- creases relative to width and at aperture W/H=1.09. In inner whorls, umbilical wall steep with umbilical margin rela- tively sharp to rounded but gradually becomes inclined with rounded umbilical margin on outer whorl. Flanks short and rounded in inner whorls, increase and tend to become less curved ontogenetically. Venter relatively broad and gently rounded up to end phragmocone, narrowing and arching strongly during later ontogeny. Apertural whorl section strongly depressed, ovate near beginning of body chamber and at aperture relatively compressed and elliptical. Primary ribs prominent up to end phragmocone stage. They originate from umbilical wall slightly rursiradiately and furcate below midflank. Secondaries strong and distant, become gradually indistinct and restricted near venter and persist up to 3/4 of last whorl. Number of secondaries in first half whorl is about 30. Discussion.—As far as we know the present species rep- resents the largest Kheraiceras in the world. From its size alone it matches many Bullatimorphites species. Bullati- morphites and Kheraiceras form an evolving lineage and there exist several species which show morphologic overlap- ping (Sandoval, 1983; Pandey and Westermann, 1988). The affinity of the present species towards Kheraiceras is nevertheless unequivocal, based on its inflated phrag- mocone, eccentric coiling of umbilical seam and rapidly con- tracted body chamber. Although it comes from the Upper Bathonian sequence of Baluchistan (Noetling, 1896; Arkell, 1956), it is known that both Bullatimorphites and Kherai- ceras overlap stratigraphically in the Upper Bathonian. Bullatimorphites has a very restricted geographic distribution and comes mainly from the Mediterranean Province. Both Noetling (1896) and Arkell (1952) found the present holotype conspecific with the European Kheraiceras bullatum (d’Orbigny, 1846). Admittedly, the present species [897 [897 [557 resembles K. bullatum which ranges from the Late Bathonian to the earliest Callovian (Riccardi et al., 1989), but the adult size difference between them is remarkable. Besides, d’Orbigny’s type specimen of K. bullatum (see Arkell, 1952, text - fig. 34) has a more eccentrically coiled and less contracted adult body chamber and more de- pressed phragmocone. The present species also differs from the Indian form of K. bullatum , described here, mainly by its adult size and coarser and distant ribbing. Bullatimorphites cf. hannoveranus (Roemer, 1911) , now known from both Europe and India, is also a larger form with coarser ornament and strongly recalls the present spe- cies. The present species, however, differs in having cadiconic, spindle-shaped inner whorls, highly contracted body chamber and less strong ribbing on the body whorl which becomes indistinct in the first half of body chamber and disappears thereafter. Study of K. cf. hannoveranum reported here, makes the difference more apparent. Its body chamber is strongly ribbed and ribbing persists to the end without losing strength. Occurrence. —The holotype comes from the Polyphemus Limestone bed, Mazardrik, Baluchistan. Judging from the faunal association which includes Macrocephalites triangu- laris ‘group’, Clydoniceras baluchistanense (Spath) and Choffatia (Homeoplanulites) (Spath), a Late Bathonian age of K. noetlingi is certain (see also Westermann and Callomon, 1988). Remarks Kheraiceras is a stratigraphically important genus of near circum-global distribution. The genus evolved from Bullatimorphites, presumably during the Middle Bathonian. It underwent a speciation burst during the Late Bathonian to Early Callovian. After this peak, the genus declined and was reduced to a few stragglers by the Middle and Late Callovian (Hahn, 1969, 1971). Its early radiation was ac- companied by a spectacular dispersion of Kheraiceras spe- cies to almost all biogeographic provinces. The Upper Bathonian of Europe yielded at least seven species includ- ing both micro- and macroconchs (Arkell, 1952). Among them, two important macroconchiate species, i.e., K. hannoveranum and K. bullatum had wide biogeographic dis- tributions. K. bullatum, besides Europe, is also reported from Mexico (Westerman et al., 1984; Sandoval et al., 1990), South America (Riccardi et al., 1989) and India (Bardhan et al., 1999). K. hannoveranum on the other hand, is so far known to occur only in Europe and India. However, a speci- men reported as ‘Bullatimorphites (Kheraiceras) bullatus’ by Sandoval et al. (1990, pl. 9, fig. 4a-c) is known from South Mexico. It comes from the Upper Bathonian Steinmanni Zone. It has a marked similarity to the macroconch of Indian K. cf. hannoveranum (for details see Bardhan et al. 1999). Bullatimarphites (Kheraiceras) v-costatus from the Upper Bathonian of Caracoles, Chile is a large and similarly coarsely ornate form (Riccardi et a/. 1989, pl. 8, figs. 3, 4). It is larger in size than true K. bullatum of Europe and Kutch. Its ribbing is strong, distant and seems to persist on the body chamber for a greater distance and thus agrees more closely with contemporary K. hannoveranum of Sudipta K. Jana et al. Europe. Both K. hannoveranum, the putative ancestor, and the de- scendant K. bullatum continued to the Lower Callovian beds in Europe. While the former is restricted to the basal Lower Callovian horizon in Southern Germany and the Northern Jura (Kepplerites keppleri horizon of Callomon et al., 1988), K. bullatum proceeded further up to the Cadoceras suevicum fannal horizon of Subtethyan France (Cariou, 1984). Subsequently six new species of Kheraiceras ap- peared during the Early Callovian in these parts of Europe. This paper describes six species of Kheraiceras of which three are new and four are endemic to Kutch and adjoining areas. Besides, Pandey and Westermann (1988) reported another Bathonian species of this genus from Kutch ‘island’. The diversity falls in line with the Late Bathonian-Early Callovian radiation of the genus elsewhere, but a high de- gree of endemism may be attributed to the newly opened-up basin which was yet to establish well developed sea routes with other faunal provinces. Kutch was a pericratonic basin developed at the northwestern margin of the Indian plate with the beginning of fragmentation of Gondwanaland during the Bathonian (Biswas, 1991). The newly formed Kutch basin was immediately occupied by organisms which mi- grated from other areas and the basin acted as a cradle of evolution. The organisms that migrated here evolved rap- idly to colonise the virgin ecospace (Halder, in press) and gave birth to a distinct faunal assemblage unique to India, Madagascar, East Africa and Baluchistan, all of which con- stitute what is known as the Indo-Madagascan or Ethiopian faunal province. Endemism and speciation events are all pervasive, affecting all major taxa. For example, corals showed a spectacular radiation; about seventy new species appeared in Kutch during Late Bathonian time (Gregory, 1900; Panday and Fursich, 1993). Many new gastropods (Das et al., 1999), brachiopods (Mukherjee et al., in press) and nautiloids (Halder, in press) originated. Among am- monites, another circum-global genus, Macrocephalites Zittel, 1884, was also a product of Bathonian innovation and followed a course of spectacular Late Bathonian-Early Callovian radiation and migration (Datta et al., 1996; Jain et al., 1996). Kutch macrocephalitids are diverse and marked similarly by a high degree of endemism (Spath, 1927-33). However, in both cases, ecologically better adapted species spread to various faunal provinces in a fleeting manner (sensu Ager, 1984) and their first appearances seem to be isochronous everywhere. Such bioevents are of great value in intercontinental chronostratigraphic correlation and in establishing stage boundaries (Callomon, 1993). The precise place of origin of Kheraiceras is unclear. The oldest species known until recently, K. hannoveranum, ap- pears to be isochronous everywhere during the Late Bathonian. It is now generally believed that Kheraiceras evolved from Bullatimorphites through a complex hetero- chronic process involving neoteny (for details see Bardhan et al., 1994). Evolutionary novelties were introduced, for example, sudden increase in degree of involution, inflation of phragmocone and occlusion of umbilicus by aberrantly- coiled, highly contracted body chamber, etc. (see also Westermann and Callomon, 1988). Two Kheraiceras spe- cies older than K. hannoveranum have been reported from Middle Jurassic Kheraiceras from India 223 Kutch. The Kheraiceras species from Baluchistan, K. noetlingi, is associated with some time-diagnostic ammon- ites indicating Late (? basal) Bathonian age (Westermann and Callomon, 1988). It is already a fully realised Kheraiceras with the synapomorphies (sensu Eldredge and Cracraft, 1980) such as inflated phragmocone, occluded um- bilicus, excentrically coiled and contracted body chamber without ribbing towards the aperture. K. noetlingi nonethe- less still has a Bullatimorphites-like large adult size. Unfortunatlely little is known about its inner whorls. Interestingly, inner whorls are Bulllatimorphites - like in an- other Kutch species, Bullatimorphites (? Kheraiceras) sp. A described from the (?) Middle Bathonian by Pandey and Westermann (1988). Itis a remarkable species showing a curious combination of many symplesiomorphies in the early whorls and advanced evolutionary features in the body chamber. Ifthe age assignment is correct, it is the oldest Kheraiceras known to date. Hence, in all probability, Kutch is a rare allopatric site (cf. Gould and Eldredge, 1977) where an immigrant ancestor, Bullatimorphites, gave rise to Kheraiceras. The newly emerged Kutch basin subse- quently prompted speciational and migrational events when sea - routes became well established. Acknowledgements A. Kayal, D. Mukherjee and S. Das (J. U.) helped at vari- ous stages both in the field and laboratory works, T. Chakraborty, Geological Survey of India, Calcutta, helped in computer study. The Director of the Geological Survey of India granted permission for studying the holotype and other materials kept at the Repository while P. H. Bhatti (Bhuj) provided the logistical and administrative support in Kutch. One of the authors (S. B. ) received financial aid from Department of Science and Technology, India (ESS/23/VES/ 022/98). References Ager, D. V., 1984: The nature of the stratigraphical record, 122 p. Macmillan Publishers Ltd., Hong Kong. Arkell, W. J., 1952-54: Monograph of the English Bathonian ammonites. Palaeontographical Society London, vol. 106-107 (3, 4), p. 73-128. Arkell, W. J. 1956: Jurassic Geology of the World, 806 p. 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Handbuch der Palaeonto- logie, vol. 1, p. 329-522. 225 Paleontological Research, vol. 4, no. 3, pp. 227-228, September 29, 2000 © by the Palaeontological Society of Japan SHORT NOTES Replacement names for Permian stauraxon radiolarians Kazuhiro Sugiyama Marine Geology Department, Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, Ibaraki 305-8567, Japan Received 6 April 2000; Revised manuscript accepted 21 July, 2000 Abstract. New names are proposed for two genera of Permian stauraxon radiolarians to correct existing homonymy; the replacement names are Raciditor Sugiyama for Nazarovella De Wever and Caridroit and Kimagior Sugiyama for Deflandrella De Wever and Caridroit. This action makes the family Deflandrellidae De Wever and Caridroit invalid according to Art. 39 of ICZN (1999), therefore the family Kimagioridae is established to replace Deflandrellidae. Key words: Deflandrella, Nazarovella, replacement name, Permian, stauraxon radiolarians Introduction Radiolarians are diverse marine zooplankton having a long evolutionary history beginning, to our knowledge, with the Cambrian period (e.g., Won and Below, 1999). When discussing the evolution, phylogenetic classification and systematics of the Radiolaria of a particular period or era (e.g. Permian, Mesozoic), it is essential to establish a geo- logical-historical context by examining materials of the pre- ceding and subsequent geologic ages. This approach to research will ensure correct knowledge of the characteristics of each period or era. However, most radiolarian researchers tend to specialize throughout their careers in the radiolarians of a particular geologic age. For example, those working on Paleozoic ra- diolarians generally do not have a basic knowledge of Cenozoic radiolarians. At the least, when we establish new taxa, it is necessary to consult a variety of monographic studies on radiolarians of other geologic time periods to avoid taxonomic confusion created by the creation of homo- nyms and synonyms. In this short paper, | introduce new names for two genera of Permian stauraxon radiolarians which are junior homo- nyms. The invalid names were originally in honor of famous radiolarian researchers. When creating such names, par- ticular attention should be paid to the likely posssibility of the names aleady having been employed by other researchers. Systematic paleontology Superfamily Ruzencevispongacea Kozur, 1980 Remarks. — Some researchers have used the name Latentifistulidea Nazarov and Ormiston, 1983, for this superfamily (e.g. Nazarov and Ormiston, 1983; Sashida and Tonishi, 1986). However, this is obviously an invalid name according to Art. 36 of ICZN (1999), as mentioned in detail by Kozur and Mostler (1989). Family Ormistonellidae De Wever and Caridroit, 1984 Genus Raciditor Sugiyama, new name Not Nazarovella Kozur and Mostler, 1979, p. 68 (type spe- cies: N. tetrafurcata Kozur and Mostler, 1979). Nazarovella De Wever and Caridroit, 1984, p. 101 (type speceis: N. gracilis De Wever and Caridroit, 1984). Type species.—Raciditor gracilis (De Wever and Caridrot) =Nazarovella gracilis De Wever and Caridrot, 1984. Remarks.—The generic name Nazarovella was first used by Kozur and Mostler (1979) for Triassic spherical radiolari- ans (spumellarian or entactinarian) possessing isometrically arranged spines with a quadrifurcated tip. Based on Arts. 23 and 60 of ICZN (1999), therefore, the replacement name Raciditor is given herein for Nazarovella proposed by De Wever and Caridroit (1984), who studied Permian stauraxon spumellarians from the Ultra-Tamba terrane of SW Japan, and named those stauraxon spumellarians having one short horn and three, long and grooved arms forming a flattened- tetrahedral structure as Nazarovella. Etymology.—Named by use of an anagram of the family name of Dr. M. Caridroit, who first made excellent studies on the Ulta-Tamba terrane, SW Japan, using radiolarians. This name is of masculine gender. Family Kimagioridae Sugiyama, new name Deflandrellidae De Wever and Caridroit, 1984. Type genus.—Kimagior Sugiyama, described below as a new name for Deflandrella De Wever and Caridroit, 1984. Remarks. — Since the type genus of the family Deflandrellidae De Wever and Caridroit, 1984, is a junior homonym as discussed below, a replacement name for the 228 Kazuhiro Sugiyama family is called for based on Art. 39 of ICZN (1999). Genus Kimagior Sugiyama, new name Not Deflandrella Loeblich and Tappan, 1961, p. 227 (type species: Campylacantha cladophora Jorgensen, 1905). Deflandrella De Wever and Caridroit, 1984, p. 99 (type species: D. manica De Wever and Caridroit, 1984). Type species. — Kimagior manicus (Dewever and Caridroit) = Deflandrella manica De Wever and Caridroit, 1984. Remarks.—Since the generic name Campylacantha had already been used, Loeblich and 1 appan (1961) introduced a replacement name Deflandrella for a homonymous name, Campylacantha Jorgensen, 1905, which was established for a plagiacanthid nassellarian from Norwegian plankton mate- rials. Some radiolarian researchers have regarded Def- landrella Loeblich and Tappan as a junior subjective synomym of Neosemantis Popofsky, 1913 (e.g. Goll, 1979), whereas others have treated Deflandrella and Neosemantis as independent genera (e.g. Petrushevskaya, 1981). In any event, Deflandrella proposed by Loeblich and Tappan (1961) still remains valid taxonomically, which means that the identical name Deflandrella used by De Wever and Caridroit (1984) for Permian stauraxon spumellarian with three coplanar tubes is invalid. Etymology.—Named by creating an anagram of a local place name, Kamigori, Hyogo Prefecture, SW Japan, near the type locality of the type species. This name is of mas- culine gender. References De Wever, P. and Caridroit, M., 1984: Description de quelques nouveaux Latentifistulidea (Radiolaires Polycystines) Pa- leozoiques du Japon. Revue de Micropaleontologie, vol. 27, no. 2, p. 98-106. Goll, R. M., 1979: The Neogene evolution of Zygocircus, Neosemantis and Calimitra: their bearing on nassellarian classification. Micropaleontology, vol. 25, no. 4, p. 365- 396, pls. 1-5. ICZN (International Commission on Zoological Nomenclature), 1999: International Code of Zoological Nomenclature, Fourth edition, 306 p. The International Trust for Zoologi- cal Nomenclature, London. Jorgensen, E., 1905: The protist plankton and the diatoms in bottom samples. Bergens Museum Skrift, 1905, ser. 1 (7), p. 49-151, 195-225, pls. 6-18. Kozur, H., 1980: Ruzhencevispongidae, eine neue Spumellaria-Familie aus dem Oberen Kungurian (Leonardian) und Sakmarian des Vorurals. Geologisch- Paläontologische Mitteilungen Innsbruck, vol. 10, p. 235-242. Kozur, H. and Mostler, H., 1979: Beiträge zur Erforschung der mesozoischen Radiolarien. Teil Ill: Die Oberfamilien Actinommacea HAECKEL 1862 emend., Artiscacea HAECKEL 1882, Multiarcusellacea nov. der Spumellaria und triassische Nassellaria. Geologisch-Paläontologische Mitteilungen Innsbruck, vol. 9, p. 1-132. Kozur, H. and Mostler, H., 1989: Radiolarien und Schwammskleren aus dem Unterperm des Vorurals. Geologisch-Paläontologische Mitteilungen Innsbruck, Sonderband 2, p. 147-275. Loeblich, A. R., Jr. and Tappan, H., 1961: Remarks on the systematics of the Sarkodina (Protozoa), renamed homo- nyms and new and validated genera. Proceedings of the Biological Society of Washington, vol. 74, p. 21-234. Nazarov, B. B. and Ormiston, A. R., 1983: A new superfamily of stauraxon polycystine Radiolaria from the Late Paleozoic of the Soviet Union and North America. Senckenbergiana Lethaea, vol. 64 (2/4), p. 363-379. Petrushevskaya, M. G., 1981: Radiolyarii otryada Nassellaria Mirovogo Okeana. Opredeliteli po Faune SSSR. Izdavaemye Zoologicheskim Institutom Akademii Nauk SSSR, no. 128, p. 1-406. Popofsky, A., 1913: Die Nassellarien des Warm- wassergebietes. Wissenschaflichte Ergebnisse der Deutschen SYdpolar-Expedition 1901-1903 auf dem Schiff “Gauss,” vol. 14 (Zool. 6), no. 1, p. 217-416, pls. 28-38. Sashida, K. and Tonishi, K., 1986: Upper Permian stauraxon polycystine Radiolaria from Itsukaichi, western part of Tokyo Prefecture. Science Reports of the Institute of Geoscience, University of Tsukuba, Section B, vol. 7, p. 7-13, pls. 1-4. Won, M.-Z. and Below, R., 1999: Cambrian Radiolaria from the Georgina Basin, Queensland, Australia. Micro- paleontology, vol. 45, no. 4, p. 325-363. 229 The Palaeontological Society of Japan has revitalized its journal. Now entitled Paleontological Research, and published in English, its scope and aims have entirely been redefined. The journal now ac- cepts and publishes any international manuscript meeting the Society’s scientific and editorial standards. 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A., 1989: Lower Miocene to Quatemary diatom biostratigraphy of Leg 57, off northeastern Japan, Deep Sea Drilling Project. In, Scientific Party, Initial Reports of the Deep Sea Drilling Project, vols, 56 and 57, p. 641-685. U. S. Govt. Printing Office, Washington, D. C. Burckle, L. H., 1978: Marine diatoms. In, Hag, B. U. and Boersma, A. eds., Introduction to Marine Micropaleon- tology, p. 245-266. Elsevier, New York. Fenner, J. and Mikkelsen, N., 1990: Eccene-Oligocene diatoms in the westem Indian Ocean: Taxonomy, stratigraphy, and paleoecology. /n, Duncan, R. A., Backman, J., Peterson, L. C., et al., Proceedings of the Ocean Drilling Program, Scientific Results, vol. 115, p. 433-463. College Station, TX (Ocean Drilling Program). Kuramoto, S., 1996: Geophysical investigation for methane hy- drates and the significance of BSR. The Journal of the Geological Soclety of Japan, vol. 11, p. 951-958. (in Japanese with English abstract) Zakharov, Yu. D., 1974: Novaya nakhodka chelyustnogo apparata ammonoidey (A new find of an ammonoid jaw ap- paratus). Paleontologicheskii Zhurnal 1974, p. 127-129. (in Russian) N N N + N % N N N % + + + % , % + + N + N s + N % N N % N % N % ’ % N + N + $ + + + N , % + ’ + N + , % N + N sy ’ N 5 , 5 % N + N + ’ NU N + > 5 + IT BE FT TE mm &&150Efl&1&, 20012 1 H27H (+) &28H (A) CAMARA) CHES NES. 27810 RDA THERKAHMEEMF OR OH HEN: He] + ASF - BABS - Mee — | SFTHDHETS. FAO LAS HUA It2000112H 1 H (4) TE. ©2001 FF& - Kid, 2001 6 A29H (2), 6ASOH (4), 7H148 (A) x [Esty vey 7 LÉDERE CY 7 —] CHEAHET. AHHKNOESTIDOT, [21H00 LAVE] Æ— 7 — VEL, 2QAIHA-YYEYOA, 80H € 1 BITITHORBA YY ROY ADTTONZTFTETE. HE SAO HRHHEBS| ICKATFTUISADOHEMEURHTH. RER AY — RAT ICTE > TEIHNHEF. OSRERERICLA-HRMISHKOERADCCHB PSY. HZ 9 -HRBOBLIA AU) A lt2001F 5 À 9A OK) CH. OF15S1ElPIZ (20027 1 A FARE E) OF HALAS, SOL ERA, O2PFFL - BS (20027 6 A FIBRE) (CSHB HEIL Be > D BAER LIA ZE 0 ELK. OHEHMEZTIE, /P\ARCHHEANZI-FPVY¥ayvT7TRVYa-hIA-AEEHLTHV ETF, FEDS SRASTEHENNILZEDTRLEFOT, SAL KHEOAILTHRE CHMUAH FAW, (ABB - VV RYO ABOHLIASSE BHASEOË LAB REE BHREAYO FSW. e-mail P77 » 2 2 TORLAAIX, HAE L TZUNGTBUEHA,. 7240-0067 MAHRLY AKBHGATI-2 REA VASAR ANS BAB SE TEL 045-339-3349 (i818) FAX 045-339-3264 (ub t5 =) E-mail majima@edhs.ynu.ac.jp NÉE TER HAL ERÉ, TÉRD FROTÉREE CHAE PSU. T250-0031 /j HE AAA 499 PEAS) [AE AO + HIERÉ MIRE TEL 0465-21-1515 FAX 0465-23-8846 E-mail taru@pat-net.ne.jp fe ll (ER) AEDT IRS ZB, BAOSRUA, MRR SOA AMD D UIC BAAD 5 OLR BATSNCWETS, HEDEHZALTELDOEN TE, AYFAVTANHAR LH Ballen Nr HR EYE AHBHEMHFMRAZH FH À MH KL SH KERTIAEHBAROBME $2-YT4AN-7RHBAREOE (7197 = # JE) ORR AAFHA Eth bse (DEAR A BAER) ICK 2, Em aie un As ts ee 200097225 Fl iil 113-8622 HRA HK ABYIAS-16-9 2000-9 29H % ff HARPAHRBe vy ¥ -A BG 03-5814-5801 4 & Ww KK: mM À KR EB HEHE PRE HR A KE El ll 4 SARÉMRMAAISH BH BR 2,500 T176-0012 KAHHEREEI2D1ID1 BG 03-3991-3754 ISSN 1342-8144 Paleontological Research BAB, #35 Paleontological Research September 29, 2000 “; Be Re R CONTENTS Naoki Ikegami, Wexandgr W av. À: Keiner and Yukimitsu Tomida: The presence of an azhdarchid pterosaur in the Creed en open Bean a ER BOs alam tional ee ee 165 Ritsuo Nomura and Yokichi Takayanagi: The suprageneric classification of the foraminiferal genus Murrayinella and a new species from Japan -::::--::::-:-.................................. 171 Takehisa Tsubamoto, Patricia A. Holroyd, Masanaru Takai, Nobuo Shigehara, Aye Ko Aung, Tin Thein, Aung Naing Soe and Soe Thura Tun: Upper premolar dentitions of Deperetella birmanica (Mammalia: Perissodactyla: Deperetellidae) from the Eocene Pondaung Formation, Myanmar --------..........................ieeeeceesseesesseeeeeeeesesc + 183 Mia Mohammad Mohiuddin, Yujiro Ogawa and Kuniteru Matsumaru: Late Oligocene larger foraminifera from the Komahashi-Daini Seamount, Kyushu-Palau Ridge and their tectonic Significance "Hr eee eee sise 191 Sudipta K. Jana, Subhendu Bardhan and Subrata K. Sardar: Kheraiceras Spath (Ammonoidea) -new forms and records from the Middle Jurassic sequence of the Indian subcontinent ** 205 SHORT NOTES Kazuhiro Sugiyama: Replacement names for Permian stauraxon radiolarians * "tree: 007 PROCEEDINGS ee a oF eo oe 0 le lee ele ale wie ele ete 8 we ccc es's en v0 tee ce vps este 60 00s eee) oie) elahe e.e/eia le aletlofele feet eiele 229 ISSN 1342-8144 Formerly Transactions and Proceedings of the Palaeontological Society of Japan | WAR 28 090) 1) Vol. 4 No.4 December 2000 The Palaeontological Society of Japan Co-Editors Kazushige Tanabe and Tomoki Kase Language Editor Martin Janal (New York, USA) Associate Editors Jan Bergström (Swedish Museum of Natural History, Stockholm, Sweden), Alan G. Beu (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Satoshi Chiba (Tohoku University, Sendai, Japan), Yoichi Ezaki (Osaka City University, Osaka, Japan), James C. Ingle, Jr. (Stanford University, Stanford, USA), Kunio Kaiho (Tohoku University, Sendai, Japan), Susan M. Kidwell (University of Chicago, Chicago, USA), Hiroshi Kitazato (Shizuoka University, Shizuoka, Japan), Naoki Kohno (National Science Museum, Tokyo, Japan), Neil H. Landman (Amemican Museum of Natural History, New York, USA), Haruyoshi Maeda (Kyoto University, Kyoto, Japan), Atsushi Matsuoka (Niigata University, Niigata, Japan), Rihito Morita (Natural History Museum and Institute, Chiba, Japan), Harufumi Nishida (Chuo University, Tokyo, Japan), Kenshiro Ogasawara (University of Tsukuba, Tsukuba, Japan), Tatsuo Oji (University of Tokyo, Tokyo, Japan), Andrew B. Smith (Natural History Museum, London, Great Britain), Roger D. K. 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Phone: (978)750-8400, Fax: (978)750-4744, www.copyright.com Cover: Idealized sketch of Nipponites mirabilis Yabe, a Late Cretaceous (Turonian) nostoceratid ammonite. Various reconstructions of the mode of life of this species have been proposed, because of its curiously meandering shell form (after T. Okamoto, 1988). All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN c/o Business Center for Academic Societies, Honkomagome 5-16-9, Bunkyo-ku, Tokyo 113-8622, Japan Visit our society website at http://ammo.kueps.kyoto-u.ac.jp/palaeont/ Paleontological Research, vol. 4, no. 4, pp. 231-234, December 30, 2000 © by the Palaeontological Society of Japan Gyronautilus, a new genus of Triassic Nautilida from South Primorye, Russia YURI D. ZAKHAROV' and YASUNARI SHIGETA? ‘Federal Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Science, Viadivostok 690022, Russia (e-mail: zakharov @ fegi.ru) *Department of Geology and Paleontology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo, 169-0073 Japan (e-mail: shigeta @kahaku.go.jp) Received 25 April 2000; Revised manuscript accepted 10 August 2000 Abstract. A new genus of Triassic Nautilida, Gyronautilus, is proposed for material from the Lower Triassic of South Primorye, Russia. The new genus differs from previous known genera of the family Grypoceratidae by its gyroconic shell with subrectangular whorl sections and a near-marginal siphuncle. A new subfamily, Gyronautilinae, within the Grypoceratidae is also proposed. Key words: Early Triassic, Gyronautilus, Nautilida, Olenekian, South Primorye Introduction The Triassic deposits in South Primorye, Far East of Russia, yield well-preserved nautilids, some of which spe- cies have been described by previous authors (Diener, 1895; Kiparisova, 1954, 1961; Zakharov, 1978). Syringo- ceras praevolutum was proposed by Kiparisova (1961) on the basis of a single small specimen collected by N.K. Trifonov in 1948 from the Lower Triassic of the Abrek Bay area, about 45 km southeast of Vladivostok. The exact lo- cality and horizon of the specimen were not described, but recently we found a large and complete specimen identified as S. praevolutum from the type locality (Figure 1). In this paper we describe the early to adult features of the species, and propose a new subfamily and genus based on the specimen. The specimen utilized herein is deposited in the National Science Museum, Tokyo (NSM). Note on Stratigraphy The Lower Triassic strata exposed along the eastern coast of Abrek Bay are lithostratigraphically divided into two formations, the Lazurnaya Bay and Zhitkov Formations in upward sequence, as defined by Zakharov (1996, 1997) along the shore of Lazurnaya (= Shamara) Bay and the east coast of Russian Island near Vladivostok. The Lazurnaya Bay Formation unconformably overlies the Permian Abrek Formation and consists of basal conglomer- ate and gray, fine-grained, bedded sandstone with lenses of coquinoid calcareous sandstone. Its thickness is 57.9 m in the section surveyed. It contains the ammonoids Gyronites subdharmus Kiparisova and Koninckites? sp., the brachio- pod Lingula sp., the bivalves Promyalina vetusta Bencke and Eumorphotis multiformis (Bittner) in the middle part, and the cephalopods Hedenstroemia sp., Meekoceras boreale Diener, M. subcristatum Kiparisova, Ambites sp. indet., and Gyronautilus praevolutum (Kiparisova), as well as the brachiopods Abrekia sulcata Dagys and Lingula borealis Bitner in the upper part (Zakharov and Popov, 1999). These fossils suggest the Upper Induan in the middle part and the Lower Olenekian (lower part of the Hedenstroemia bosphorensis Zone) in the upper part ofthe formation. The Induan/Olenekian boundary is located at 55 m above the base of the formation. The overlying Zhitkov Formation consists mainly of dark grey siltstone with calcareous nodules and intercalations of fine-grained sandstone. The formation is more than 87.3 m thick in the section studied. The ammonoids Inyoites spicini Zakharov, Parahedenstroemia conspicienda Zakharov, Prosphingitoides magnumbilicatus (Kiparisova), Dienero- ceras Sp., Meekoceras boreale Diener, M. subcristatum Kiparisova, Koninckites aff. timorense Wanner, K. varaha (Diener), Arctoceras septentrionale (Diener), and Flemingi- tes sp., as well as the bivalves Phaedrysmocheilus sp. and Promyalina putiatinensis (Kiparisova) were found in the lower part of the formation, suggesting an early Olenekian age (upper part of the Hedenstroemia bosphorensis Zone). Paleontological description Order Nautilida Agassiz, 1847 Superfamily Trigonocerataceae Hyatt, 1884 Family Grypoceratidae Hyatt in Zittel, 1900 232 Yuri D. Zakharov and Yasunari Shigeta Fossil locality Nakhotka € ne Sea of Japan Figure 1. Map showing the fossil locality in South Primorye, Far East Russia. Subfamily Gyronautilinae, subf. nov. Diagnosis. — Gyroconic shell with flattened venter. Suture with distinct ventral and lateral lobes. Composition.—One genus: Gyronautilus Zakharov and Shigeta. Remarks. — Kiparisova (1961) described “Syringoceras” praevolutum in 1961 from the Lower Triassic of South Primorye and included it in the family Syringonautilidae. Shimansky (1962) recognized four subfamilies in the family Grypoceratidae: Domatoceratinae, Grypoceratinae, Syringo- nautilinae and Clymenonautilinae. During our investigation of Kiparisova’s species we experienced problems with deter- mination of its subfamily assignment, and concluded that it seems to be a representative of a new, previously unknown subfamily of the family Grypoceratidae. However, the nomenclatural and taxonomic history around the type genus of Grypoceratidae, Grypoceras Hyatt, 1883 is very compli- cated (T. Engeser, 2000, personal communication) and was not completely correctly investigated by Engeser and Reitner (1992). Distribution.—Lower Triassic in South Primorye, Russia. Genus Gyronautilus, gen. nov. Type species.— Gyronautilus praevolutum (Kiparisova). Diagnosis.—Gyroconic shell with subrectangular whorl- sections and a near-marginal siphuncle. Suture with shal- low ventral lobe, broad lateral lobe, and deep dorsal lobe. Discussion.—The new genus is discussed with Gyronauti- lus praevolutum. Geological distribution.—Lower Olenekian. Gyronautilus praevolutum (Kiparisova, 1961) Figures 2-4 Syringoceras praevolutum Kiparisova, 1961, p.25, pl.4, fig. 2. S . m 1c — = Figure 2. Whorl cross sections of Gyronautilus praevolutum (Kiparisova), NSM PM16132, at whorl height of 18.0 mm (1) and 39.3 mm (2). S: siphuncle. Venter | Figure 3. Suture line of Gyronautilus praevolutum (Kiparisova), NSM PM16132, at whorl height of 25 mm. Holotype.—CGM 12/5504 figured by Kiparisova (1961, pl.4, fig.2) from the Lower Triassic (Olenekian?) of Abrek Bay in South Primorye, Russia. Material.—One specimen, NSM PM16132. Description.—Shell moderately large, reaching 92.6 mm in diameter, rapidly expanding gyroconic conch, consisting of 1.7 whorls. Embryonic shell 18.2 mm long, exogastrically curved, consisting of 0.4 whorl, attaining 7.4 mm height and 7.0 mm width at nepionic constriction. First whorl sub- quadrate in cross section, with near-marginal siphuncle, at- taining 18.1 mm height and 14.7 mm width: umbilical opening 8.2-13.4 mm across. Adult whorl subrectangular in cross-section with rounded-inflated venter, well-rounded shoulder and concave dorsal side, with near-marginal siphuncle, attaining 39.7 mm height and 36.1 mm width at last septum. Body chamber partly preserved, attaining 45.2 mm height and 36.6 mm width at adoral end. Shell surface not preserved. Suture consisting of shallow ventral lobe, broad lateral lobe, and deep dorsal lobe. Discussion. —Kiparisova described the only previously known middle stage of Gyronautilus praevolutum on the basis of a fragment of the phragmocone reaching 17.0 mm height and 15.0 mm width at the last septum. The speci- men described herein is a large and nearly complete one from the embryonic shell to a part of the adult body chamber. Characteristic features described by Kiparisova (1961) are also observed in the middle stage of specimen NSM PM16132. Gyronautilus praevolutum is placed within the family Grypoceratidae because of its flattened venter and suture with ventral and lateral lobes. Among the previously de- A new Triassic Nautilida from Russia 233 Fugure 4. Gyronautilus praevolutum (Kiparisova), NSM PM16132. Right lateral (1), back (2), left lateral (3) and frontal (4) views, x1.0. Arrow marks indicate the position of the preserved last septum. 234 Yuri D. Zakharov and Yasunari Shigeta scribed genera of the family, the shape of the conch and the suture of Gyronautilus show closest affinities with the Permian Domatoceras. The sutures of both are similar, with rounded ventral and lateral lobes (Kummel, 1964). Gyronautilus shows some affinities to Triassic Grypoceras and Menuthionautilus, but the latter two differ in the propor- tions of sutural elements, in general forms of the conch, and in the siphuncle position (Kummel, 1953, 1964). It seems best to consider that Gyronautilinae is an offshoot of Domatoceratinae. Occurrence.—NSM PM16132 was collected from the up- permost part of the Lazurnaya Bay Formation in the Abrek Bay area, Hedenstroemia bosphorenses Zone of the Lower Olenekian. Acknowledgments We are very grateful to A. M. Popov (Federal Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Science, Vladivostok) for his kind help and cooperation throughout the field survey. Thanks are extended to J. W. Haggart (Geological Survey of Canada, Vancouver) and T. Engeser (Institut für Paläontologie, Frei Universität Berlin, Berlin) for their helpful suggestions. This study was sup- ported by RFBR Project (no. 97-05-65832) to Y. D. Zakharov and the JSPS Fellowships for research in NIS countries and Grant-In-Aid for Scientific Research from JSPS (No. 12440141 for 2000) to Y. Shigeta. References Diener, C., 1895: Triadische Cephalopoden der ostsibirischen Kustenprovinz. Mémoires Comité Geologique St. Peters- bourg, vol. 14, no. 3, p. 1-59, pls. 1-5. Engeser, T and Reitner, J., 1992: Description of the first Rhaetian nautiloid (Grypoceras rhaeticum n.sp.) from the Kössen Beds of the Fonsjoch area near Achensee (Austria). Neues Jahrbuch für Geologie und Paläontolo- gie Monatshefte, 1992, p. 231-241. Kiparisova, L. D., 1954: Polevoj atlas kharakternykh komplek- sov fauny i flory triasovykh otlozhenij primorskogo kraya. 125 p. Gosgeoltekhizdat, Moscow. [Field atlas of typical complexes of fauna and flora of Triassic deposits in Primorye region.] (in Russian) Kiparisova, L. D., 1961: Paleontologicheskoe obosnovanie stratigrafii triasovykh otlozhenij primorskogo kraya. 1. Golovonogie mollyuski. Transactions of All-Union Geo- logical Research Institute (VSEGEI), New Series, vol. 48, p. 1-278. [Paleontological basis of Triassic stratigraphy of Primorye region. 1. Cephalopods.] (in Russian) Kummel, B., 1953: American Triassic coiled nautiloids. U.S. Geological Survey Professional Paper, 250, p. 1-104, pls. 1-19. Kummel, B., 1964: Nautiloidea-Nautilida. In, Moore, R. C. ed., Treatise on Invertebrate Paleontology. Part K. Mollusca 3, p. K383-457, The Geological Society of America and the University of Kansas Press. Shimansky, V.N. 1962: Order Nautilida. In, Orlov, Y. A. ed. Osnovy paleontologii. Mollyuski-golovonogiye.1, p. 115- 154, Izdatel'stvo Akademii Nauk SSSR, Moscow. [Fundamentals of Paleontology. Mollusca-Cephalopoda. 1.] (in Russian) Zakharov, Y. D., 1978: Rannetriasovye ammonoidei Vostoka SSSR. 224 p, Nauka, Moscow. [Lower Triassic ammo- noids of East USSR.] (in Russian) Zakharov, Y. D., 1996: The Induan-Olenekian boundary in the Tethys and Boreal realm. Supplemento agli Annali dei Musei Civici di Rovereto Sezione Archeologia, Storia e Scienze Naturali, vol. 11, p. 133-156. Zakharov, Y. D., 1997: Ammonoid evolution and the problem of the stage and substage division of the Lower Triassic. Mémoires de Géologie (Lausanne), vol. 30, p. 121-136. Zakharov, Y. D. and Popov, A. M., 1999: New data on Induan/Olenekian boundary in South Primorye. Alber- tiana, vol. 22, p. 19. Paleontological Research, vol. 4, no. 4, pp. 235-238, December 30, 2000 © by the Palaeontological Society of Japan Discovery of Early Cretaceous (Barremian) decapod Crustacea from the Arida Formation of Wakayama Prefecture, Japan HIROAKI KARASAWA Mizunami Fossil Museum, Yamanouchi, Akeyo, Mizunami, Gifu 509-6132, Japan (e-mail: GHA06103 @nifty.ne.jp) Received 17 May 2000; Revised manuscript accepted 14 August 2000 Abstract. Hoploparia sp. (Astacidea, Nephropidae) and Callianassa (s. |.) sakakuraorum sp. nov. (Thalassinidea, Callianassidae) are described from the Lower Cretaceous Arida Formation in Wakayama Prefecture, Japan. Cretaceous (Barremian) deposits of Japan. Both genera are recognized for the first time from Lower These occurrences indicate that Hoploparia and Callianassa reached Japan—the west side of the North Pacific region—by the Barremian. Key words: Arida Formation, Cretaceous, Crustacea, Decapoda, Japan Introduction Early Cretaceous decapod Crustacea from Japan previ- ously were only known from the Aptian Miyako Group, north- western Japan (Takeda and Fujiyama, 1983). The purpose of this paper is to describe two species of decapods, Hoploparia sp. (Astacidea, Nephropidae) and Callianassa (s. |.) sakakuraorum sp. nov. (Thalassinidea, Callianassidae) from the Lower Cretaceous Arida Formation of Wakayama Prefecture, southwestern Japan. Hitherto, Hoploparia from the Lower Cretaceous of the North Pacific region has been known from the Hauterivian of Oregon (Feldmann, 1974), while Callianassa (s.|.) has not been found in Lower Cretaceous deposits of that region. The specimens were collected from sandy mudstone ex- posed at Suhara [Loc. 02 of Komatsu (1999)], Yuasa-cho, Wakayama Prefecture. Obata and Ogawa (1976) and Matsukawa and Obata (1993) indicated that the geologic age of the formation is Barremian. Komatsu (1999) studied the depositional environments and molluscan assemblages of the Arida Formation in the area and divided the formation into four depositional facies. The decapod fossils occurred in his facies 3, which is characterized by the predominant occurrence of Nanonavis yokoyamai and seems to indicate an inner-shelf paleoenvironment (Komatsu, 1999). The described specimens are deposited in the Mizunami Fossil Museum (MFM). Systematic paleontology Infraorder Astacidea Latreille, 1802 Superfamily Nephropoidea Dana, 1852 Family Nephropidae Dana, 1852 Subfamily Homarinae Huxley, 1879 Genus Hoploparia McCoy, 1849 Hoploparia sp. Figure 1.1, 1.2 Description. — Hoploparia with small-sized body. Carapace laterally compressed. Anterior half of carapace poorly preserved. Rostrum lacking. Surface finely granu- lated. Postcervical groove deep dorsally, obliquely extend- ing ventrally. Hepatic groove obscurely defined, curving to join antennal and cervical grooves. Cervical groove deep, slightly arcuate, extending ventrally to join antennal groove. Antennal groove nearly straight. Gastro-orbital groove shal- low, extending to near upper part of cervical groove. Antennal region with antennal ridge. Dorsal and supraorbital ridges well developed. Intermediate carina weakly developed. Branchial region finely punctuate. Abdominal somites 1-6 smooth. Pleuron of somite 1 somewhat reduced; posteroventral corner with posterovent- rally directed spine. Pleuron of somite 2 subrectangular; anteroventral corner rounded; ventral margin gently convex; posteroventral corner with posteroventrally directed spine; posterior margin gently concave; surface with marginal fur- rows joining transverse furrow on anterior part of tergum. Pleura of somites 3 and 4 with sharp, posteroventral cor- ners; surfaces with shallow, broad marginal furrow along posterior margin. Pleuron of somite 6 reduced. Telson, uropod and pereiopods unknown. Discussion.—The carapace with dorsal, supraorbital and antennal ridges readily distinguishes the species from two known Japanese species, Hoploparia miyamotoi Karasawa, 1998 from the Maastrichtian Izumi Group and Hoploparia kamuy Karasawa and Hayakawa, 2000 from the Turonian- Santonian part of the Upper Yezo Group. Hoploparia sp. possesses characters most like those of Hoploparia collignoni (Van Straelen, 1949) from the Albian of Madagascar and Hoploparia riddlensis Feldmann, 1974 236 Hiroaki Karasawa Figure 1. men; 2: lateral view. 3-5. chelipeds and abdomen, x2.0, lateral view. 4: MFM247015 (holotype), abdomen, x2.0, dorsal view. 5: MFM247015 (holotype), carapace, cheliped, pereiopods and abdomen, x2.0, lateral view. from the Hauterivian of Oregon. However, the present species has well developed supraorbital and antennal ridges on the carapace. Hoploparia sp. is similar to Hoploparia longimana (Sowerby, 1826) from the Barremian of Argentina and the Aptian-Cenomanian of England, and Hoploparia mesembria Etheridge, 1917 from the Albian of Australia, but differs in the presence of an obscurely defined hepatic groove and a well developed antennal ridge. Hoploparia longimana and H. mesembria possess a dentate supraorbi- tal ridge and an antennal region with three large projections. Hoploparia, earliest known from the Neocomian of Europe, U. S. A and Argentina (Aguirre-Urreta, 1989), has been recorded from Cretaceous-Palaeogene deposits in Europe, U. S. A, Japan, Argentina, Australia, New Zealand, and Antarctica (Aguirre-Urreta, 1989; Karasawa and Hayakawa, 2000). Material examined.—MFM247111 collected by Y. Mizuno. Infraorder Thalassinidea Latreille, 1831 Superfamily Callianassoidea Dana, 1852 Family Callianassidae Dana, 1852 Genus Callianassa Leach, 1814 Callianassa (s. |.) sakakuraorum sp. nov. Figure 1.3-1.5 1,2. Hoploparia sp., MFM247111, carapace and abdomen. x2.0. 1: Latex cast of external mould of the speci- Callianassa (s. |.) sakakuraorum sp. nov. 3: MFM247016 (paratype), external mould of both Diagnosis.—Moderate-sized callianassid. Pereiopods 1 chelate, equal-sized, dissimilar. Palm of right cheliped, equal to fixed finger length, slightly longer than high; carpus short, about 1/4 propodus length, height 3/4 length; merus slightly longer than carpus, rhomboidal in lateral view, dorsal and ventral margins strongly convex without meral hook and spines. Propodus of left cheliped about equal to right propodus length, rather slender; palm slightly longer than fixed finger, height about 4/5 length. Description.— Moderate sized callianassid. Only right branchial region of carapace preserved. Abdominal somite 1 poorly preserved. Somite 2 slightly longer than 3. Pleura of somites 2-5 well developed with rounded posteroventral corner. Pleuron of somite 6 reduced with convergent lateral margins. Telson about equal to length of somite 6 with lon- gitudinal ridge on dorsal surface. Uropod unknown. Pereiopods 1 chelate, equal-sized, dissimilar. Dactylus of right cheliped strongly curved ventrally with acutely pointed tip; dorsal and occlusal margins smooth. Fixed fin- ger slightly longer than dactylus with acutely pointed tip; occlusal and ventral margins smooth. Palm rectangular in lateral view, equal to fixed finger length, slightly longer than high, with longitudinally convex lateral surface; dorsal and ventral margins smooth. Carpus short, about 1/4 propodus length, height 3/4 length, with nearly straight dorsal margin and strongly curved ventral margin. Merus slightly longer Early Cretaceous (Barremian) decapods 237 than carpus, rhomboidal in lateral view, dorsal and ventral margins strongly convex without meral hook; lateral surface strongly vaulted. Ischium poorly preserved, slender without marginal teeth or spines. Propodus of left cheliped about equal to major propodus length, rather slender in outline, occupying about 3/4 major propodus height. Dactylus gen- tly curved ventrally with acutely pointed tip; dorsal and occlusal margins smooth. Fixed finger slightly shorter than dactylus with acutely pointed tip; occlusal and ventral margin smooth. Palm rectangular in lateral view, slightly longer than fixed finger, height about 4/5 length, with smooth dorsal and ventral margins. Pereiopod 2 not preserved. Carpus and merus of pereiopod 3 preserved; carpus flattened, slender, tapering proximally; merus flattened, about twice length of carpus with straight dorsal and gently convex ventral margins. Propodus, carpus, merus and ischium of pereiopod 4 pre- served; propodus small, broken; carpus slender; merus about twice length of carpus; ischium about half carpus length. Pereiopod 5 unknown. Discussion.—Manning and Felder (1991) recognized two families, seven subfamilies and 21 genera for taxa previ- ously assigned to the extant Callianassidae, whilst Sakai (1999) reexamined all known extant members in the family and recognized four subfamilies and 10 genera. The ge- neric placement of the present species awaits the discovery of better material bearing the maxilliped 3 and the telson, and it is considered best to place the specimen in Callianassa (s. |.) for the time being. The genus Callianassa from the Cretaceous of Japan is represented by two species, “Callianassa" ezoensis Nagao, 1932 from the Maastrichtian Hakobuchi Sandstone and Callianassa (s. |.) masanorii Karasawa, 1998 from the Maastrichtian Izumi Group. Callianassa (s. |.) sakakura- orum differs from “C.” ezoensis in that pereiopods 1 have dissimilar chelipeds, smooth ventral margins of propodi, and a rhomboidal merus. Equal-sized pereiopods 1 with short fingers and carpi readily distinguish C. (s. |.) sakakuraorum from C. (s. |.) masanorii. The new species most resembles “Callianassa valida Rathbun, 1935 from the Lower Cretaceous of Texas, but differs in having a shorter propodus of pereiopod 1 with a smooth dorsal margin and a rhomboidal merus of pereiopod 1. In C. (s. |.) sakakura- orum the dactylus of pereiopod 1 has a smooth dorsal mar- gin whilst in “C.” valida it has a serrated dorsal margin. The earliest known members of Callianassa (s. |.) have been recorded from the Neocomian of Europe (Glaessner, 1929) and the Valanginian of Argentina (Aguirre-Urreta, 1989). The Jurassic members of the genus were removed to the axiid genus Etallonia Oppel, 1861, by Förster (1977). The known distribution of Callianassa (s. |.) is from Upper Cretaceous-Recent worldwide (Glaessner, 1969). Etymology.—The name is dedicated to Fujio and Norihiko Sakakura. Material examined.—MFM247015 (holotype) collected by M. Chiba; MFM247016 (paratype) collected by N. Sakakura. Acknowledgements | thank J. S. H. Collins (London) for reading the manu- script and M. Chiba (Nagoya), Y. Mizuno (Nagoya), N. Sakakura (Kyoto University) and F. Sakakura (Nagoya), for allowing access to specimens in their collections. References Aguirre-Urreta, M. B., 1989: The Cretaceous decapod Crustacea of Argentina and the Antarctic Peninsula. Palaeontology, vol. 32, p. 499-552. Dana, J. D., 1852: Crustacea. In, United States Exploring Expedition during the Years 1838, 1839, 1840, 1841, 1842 Under the Command of Charles Wilkes, U.S.N., vol. 13, 1620 p. Etheridge, R., 1917: Description of some Queensland Palaeozoic and Mesozoic fossils. 1. Queensland Lower Cretaceous Crustacea. Publications, Geological Survey of Queensland, no. 260, p. 7-10. Feldmann, R. M., 1974: Hoploparia riddlensis, a new species of lobster (Decapoda: Nephropidae) from the Days Creek Formation (Hauterivian, Lower Cretaceous) of Oregon. Journal of Paleontology, vol. 48, p. 586-593. Forster, R., 1977: Untersuchungen an jurassischen Thalassinoidea (Crustacea, Decapoda). Mitteilungen der Bayerischen Staatssammlung für Paläontologie und historische Geologie, vol. 17, p. 137-156. Glaessner, M. F., 1929: Crustacea Decapoda, In, Pompeckii, F. J. ed., Fossilium Catalogus, p. 1-464, W. Junk, Berlin. Glaessner, M. F., 1969: Decapoda, /n, Moore, R. C. ed., Treatise on Invertebrate Paleontology, Part R, Arthropoda 4, p. R399-651, Geological Society of America and University of Kansas Press. Huxley, T. H., 1879 [1878]: On the classification and the distri- bution of the crayfishes. Proceedings of the Scientific Meetings of the Zoological Society of London, vol. for 1878, p. 752-788. Karasawa, H., 1998: Two new species of Decapoda (Crustacea) from the Upper Cretaceous Izumi Group, Japan. Paleontological Research, vol. 2, no. 4, p. 217- 223. Karasawa, H. and Hayakawa, H., 2000: Additions to Cretaceous decapod crustaceans from Hokkaido, Japan— Part 1. Nephropidae, Micheleidae and Galatheidae. Paleontological Research, vol. 4, no. 2, p. 139-145. Komatsu, T., 1999: Depositional environments and bivalve fossil assemblages of the Lower Cretaceous Arida Formation, southwest Japan. The Journal of the Geological Society of Japan, vol. 105, p. 643-650. Latreille, P. A., 1802-1803: Histoire naturelle, générale et particuliére, des crustacés et des insectes, volume 3, 468 p. F. Dufart, Paris. Latreille, P. A., 1831: Cours d’Entomologie, ou de l'histoire naturelle des Crustacés, des Arachnides, des Myriapodes et des Insectes, etc. Annales |. Atlas, 26 p. Roret, Paris. Leach, W. E., 1814: Crustaceology. In, Brewster, D., Edinburgh Encyclopedia, vol. 7, p. 385-437. McCoy, F., 1849: On the classification of some British fossil Crustacea with notices of new forms in the University Collection at Cambridge. Annals and Magazine of Natural History, Series 2, vol. 4, p. 161-179, 330-335. 238 Hiroaki Karasawa Manning, L. B. and Felder, D. L., 1991: Revision of the American Callianassidae (Crustacea: Decapoda: Thala- ssinidea). Proceedings of the Biological Society of Washington, vol. 104, p. 764-792. Matsukawa, M. and Obata, I, 1993: The ammonites Crioceratites and Shasticrioceras from the Barremian of southwest Japan. Palaeontology, vol. 36, p. 249-266. Nagao, T., 1932: Two new decapod species from the Upper Cretaceous deposits of Hokkaid6, Japan. Journal of the Faculty of Science, Hokkaido Imperial University, series 4, vol. 2, p. 207-214. Obata, |. and Ogawa, Y., 1976: Ammonites biostratigraphy of the Cretaceous Arida Formation, Wakayama Prefecture. Bulletin of the National Science Museum, Series C (Geology & Paleontology), vol. 2, p. 93-110. Oppel, A., 1861: Die Arten der Gattungen Eryma, Pseudas- tacus, Magila und Etallonia. Jahreshefte des Vereins für Vaterländische Naturkunde in Württemberg, vol. 17, p. 355-364. Rathbun, M.J., 1935: Fossil Crustacea of the Atlantic and Gulf coastal plain. Geological Society of America, Special Papers, no. 2, p. 1-160. Sakai, K., 1999: Synopsis of the family Callianassidae, with keys to subfamilies, genera and species, and the descrip- tion of new taxa (Crustacea: Decapoda: Thalassinidea). Zoologische Verhandelingen, no. 326, 152 p. Sowerby, J., 1826: Description of a new species of Astacus, found in a fossil state at Lyme Regis. Zoological Journal, vol. 2, p. 493-494. Takeda, M. and Fujiyama, I., 1983: Three decapod crusta- ceans from the lower Cretaceous Miyako Group, northern Japan. Bulletin of the National Science Museum, Series C (Geology & Paleontology), vol. 9, p. 129-136. Van Straelen, V., 1949: Crustacés. In, Collignon, M, Recherches sur les faunes albiennes de Madagascar. I. L’Albien d’Ambarimaninga. Annales Geologiques du Service des Mines Madagascar, vol. 16, p. 99. Paleontological Research, vol. 4, no. 4, pp. 239-253, December 30, 2000 © by the Palaeontological Society of Japan Palaeogene decapod Crustacea from the Kishima and Okinoshima Groups, Kyushu, Japan HIROAKI KARASAWA' and YASUHIRO FUDOUJI? ‘Mizunami Fossil Museum, Yamanouchi, Akeyo, Mizunami, Gifu 509-6132, Japan (e-mail: GHA06103 @nifty.ne.jp) “Kouda 1754-2-214, Karatsu, Saga 847-0824, Japan Received 20 May, 2000, Revised manuscript accepted 14 August, 2000 Abstract. rocks of Nagasaki and Saga Prefectures, Twelve species in 11 genera of decapod crustaceans are recorded from Palaeogene Kyushu, Japan. Carinocarcinoides gen. nov. (Goneplacidae) is proposed to accommodate Carinocarcinoides carinatus sp. nov. and Varuna angustifrons Karasawa from the lower Oligocene Kishima Group. A new monotypic genus, Cicarnus (Portunidae), is erected with Cicarnus fumiae sp. nov. from the middle Eocene Okinoshima Group. Neocallichirus sakiae sp. nov. (Callianassidae) is described from the lower Oligocene Kishima Group. Axius (s. |.) sp. and Euphylax ? sp. from the Kishima Group represent the first records for both genera from the Oligocene of Japan. The occurrence of Minohellenus macrocheilus Kato and Karasawa extends the known geologic range of this species back to the lower Oligocene. A new description is given for Collinsius simplex Karasawa. Key words: Crustacea, Decapoda, Japan, Kyushu, Palaeogene Introduction Previous contributions describing and illustrating decapod species from Palaeogene rocks of Kyushu are rather limited. Yokoyama (1911) was the first to describe two new species, Xanthilites pentagonalis and Homolopsis japonicus, from the Palaeogene of the Miike Coalfield. Nagao (1941) recorded and illustrated an unnamed Callianassa sp. indet. from the Palaeogene of the Asakura Coalfield. Five species in five genera were described from the lower Oligocene Kishima Group in Saga and Nagasaki Prefectures by Imaizumi (1958) and Karasawa (1993, 1997). Inoue (1972) intro- duced an abundant occurrence of unnamed crabs from the lower Oligocene Kishima Group distributed in the Karatsu Coalfield. Karasawa (1992) described five species from the middle Eocene Manda Group, moved Xanthilites pentagona- lis to Branchioplax Rathbun, 1916 and erected a new monotypic genus Prohomola for Homolopsis japonicus. Kato and Karasawa (1994) described a new portunid, Minohellenus macrocheilus from the upper Oligocene Ashiya Group and additional material of the species was re- corded (Kato and Karasawa, 1996). The purpose of this paper is to describe 12 species in 11 genera, including two new genera and three new species, of decapods from the middle Eocene-lower Oligocene rocks in Saga and Nagasaki Prefectures, Kyushu. New descriptions are given for Carinocarcinoides angustifrons (Karasawa, 1993) comb. nov. and Collinsius simplex Karasawa, 1993. The specimens described in the paper are housed in the Mizunami Fossil Museum (MFM). Localities Kosasa area (Figure 1A) Imaizumila sexdentata Karasawa, 1993 occurred in sand- stone of the Nagashima Sandstone Member, Haiki Formation, Kishima Group exposed at Takasakiyama (Loc. KSM-1), Usunoura, Kosasa-cho, Kitamatsura-gun, Nagasaki Prefecture. The Haiki Formation was correlated with the Hatatsu Sandstone Member and Yukiaino Sandstone Member of the Kishima Group distributed in the Karatsu- Taku areas (Matsui et al, 1989). According to Okada (1992), the Hatatsu Sandstone Member and Yukiaino Sandstone Member are assigned to Zone CP17 (early Oligocene) of Okada and Bukry’s (1980) scale of nannofossils. Karatsu-Taku areas (Figure 1B) Eight species in seven genera of decapods (Figure 2) were collected from the Kishima Formation and Yukiaino Sandstone Member of the Kishima Group from 15 localities distributed in the eastern part of Saga Prefecture. Okada (1992) assigned the Kishima Formation to Zone CP 16a of Okada and Bukry's nannozones and the Yukiaino Sandstone to Zone CP17. Details of localities are shown in Table 1. 240 Hiroaki Karasawa and Yasuhiro Fudouji Okinoshima area (Figure 1C) Three species in three genera of decapods (Figure 2) were collected from sandstone of the Okinoshima Formation of the Okinoshima Group exposed at Aze, lojima-cho, Nagasaki City. The Okinoshima Formation is correlated with the lower part of the Sakasegawa Group in the Amakusa Coalfield and the Nougata Group in the Chikuho Coalfield (Ozaki and Hamasaki, 1991). According to Ozaki and Hamasaki, the formation seems to be assigned to Zones CP13-14 (middle Eocene) by Okada and Bukry’s Are RIvee (1980) nannozone. fe 2 KS KSM-15 i Summary of the Palaeogene decapod fauna of Kyushu Izen-cno Okinoshima The decapod fauna from the Okinoshima Group com- & prises three species, Callianassa (s. |.) sp., Raninoides nodai Karasawa, 1992 and Cicarnus fumiae gen. et sp. nov. (Figure 2). Previously known decapods from the middle Eocene rocks are recorded from the Dosi and Kawamagari River Formations (Nagao, 1941) and the Manda Group v/ 2 (Yokoyama, 1911; Karasawa, 1992). Callianassa (s. |.) sp. is known from the Dosi and Kawamagari Formations and R. nodai from the Manda Group. Cicarnus is only known from the Okinoshima Group. The middle Eocene decapod fauna has close affinities with those of the western-central Tethys KSM-3 KSM-4 region, based on the occurrences of Prohomola, Portunites 5 Ohmachi-cho and Branchioplax from the Manda Group (Karasawa, 1992, “em, Mitagata-cho- OQ KSM-2 1999). © Yamauchi-cho N The early Oligocene decapod fauna from the Kishima Arita-cho Takeo City Group is represented by nine species in eight genera (Figure 2). The fauna from the Kishima Formation is characterized by the abundant occurrence of Collinsius simplex Karasawa, 1993, whilst from the Yukiaino Sandstone Member it is char- OKN-1 - Kyuuragi Taku River Figure 1. Map showing decapod localities of the studied areas. Age] Middle Eocene| Early Oligocene = Nanno Zone by Okada & Bukry (1980) Formation) Okinoshima G. Okinoshima F. Locality Species OKN-1 22123 [al Axius (s.l.) sp. _ an Ctenocheles sujakui_|Imaizumi, 1958 xX | X Callianassa (s.|.) sp. x ii Neocallichirus sakiae sp. nov. —- Raninoides nodai Karasawa, 1992 x Imaizumila sexdentata Karasawa, 1993 Minohellenus macrocheilus Kato and Karasawa, 1994 Cicarnus fumiae_gen. et sp. nov. X 5 Euphylax ? sp. Tre Carinocarcinoides angustifrons (Karasawa, 1993) comb. nov. x Carinocarcinoides carinatus gen. et sp. nov. EM Collinsius simplex Karasawa, 1993 XI XIX1X Figure 2. List of fossil decapods from the studied areas. Locality numbers are shown in Figure 1. Palaeogene decapod Crustacea from Kyushu 241 Table 1. List of decapod-bearing localities of the Karatsu-Taku areas. Loc. no. Locality Formation KSM-2 Hatada, Ohmachi, Ohmachi-cho, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-3 Magami, Osaki, Kitagata-cho, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-4 SE of Magami, Osaki, Kitagata-cho, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-5 Tatsugawa, Okawa-cho, Imari City, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-6 Shimohirano, Kitahata-mura, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-7 Shimohiranotoge, Kitahata-mura, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-8 Sarajuku, Takeo City, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-9 Wakagi, Takeo City, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-10 Takatori, Kitagata-cho, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-11 Oubounotoge, Arita-cho, Saga Prefecture Sandy mudstone of the Kishima Formation, Kishima Group KSM-12 Komanaki, Okawa-cho, Imari City, Saga Prefecture Sandstone of the Yukiaino Sandstone Member, Kishima Group KSM-13 Shige, Kitahata-mura, Saga Prefecture Sandstone of the Yukiaino Sandstone Member, Kishima Group KSM-14 Tuzumi, Minamihata-cho, Imari City, Saga Prefecture Sandstone of the Yukiaino Sandstone Member, Kishima Group KSM-15 Kirigo, Hizen-cho, Saga Prefecture Sandstone of the Yukiaino Sandstone Member, Kishima Group KSM-16 Sosorogawachi, Genkai-cho, Saga Prefecture Sandstone of the Yukiaino Sandstone Member, Kishima Group acterized by the frequent occurrence of Neocallichirus sakiae sp. nov. Among the known genera from the Kishima Group, Carinocarcinoides and Collinsius are Japanese early Oligocene endemic genera; /maizumila is only known from the Oligocene of Japan and the Eocene-Miocene of Chile (Schweitzer and Feldmann, 2000); Minohellenus occurs out- side of Japan in Oligocene-Miocene rocks of Washington and Oregon (Schweitzer and Feldmann, 2000). Axius (s. |.), Ctenocheles, Callianassa (s. |.) and Neocallichirus are cosmopolitan. Euphylax occurs in the Caribbean and East Pacific Ocean at the present day, but the fossil record seems to extend to the lower Oligocene of Japan. Karasawa (1999) suggested that the Tethyan genera Prohomola, Portunites and Branchioplax disappeared by the Oligocene and that the decapod fauna of southwest Japan appears to become endemic in the early Oligocene. Systematic paleontology Infraorder Thalassinidea Latreille, 1831 Superfamily Axioidea Huxley, 1879 Family Axiidae Huxley, 1879 Genus Axius Leach, 1814 Type species.—Axius stirhynchus Leach, 1814 by mono- typy. Geologic range.—Oligocene to Recent. Axius (s. |.) sp. Figure 3.1a-c Description.— Anterior half of carapace preserved but lacks rostrum. Anterolateral margin unarmed. Gastric re- gion convex; median carina smooth, well marked, extending from anterior margin to posterior fourth of gastric region; lat- eral carinae weak, extending from anterior margin to anterior third of gastric region. Cervical groove well developed, reaching anteroventrally to hepatic region. Postcervical re- gion of carapace glabrous. Pereiopods 1-3 preserved. Meri of both pereiopods 1 flattened laterally, lateral surface smooth, dorsal and ventral margins pitted, without spines. Palm and carpus of pereiopod 2 compressed laterally; lat- eral surface, dorsal and ventral margins smooth. Carpus and merus of pereiopod 3 cylindrical in cross section, with- out marginal spines. Discussion.—Poore (1994) recognized four families and 32 genera for taxa previously assigned to the extant Axiidae. The definition of the extant axiids includes detailed charac- ters of eyes, antennae, pleopods, and uropods, which are not available for study in fossil specimens. The present species is assigned to Axius (s. |.) by having a carapace with a well defined cervical groove and without linea thalassinicae. The single incomplete specimen renders ge- neric placement obscure and it is considered best to place the specimen in Axius (s. |.). Previously known fossil members of Axius (s. |.) are re- corded from the Oligocene of Panama and the Pliocene of France (Glaessner, 1969). Material examined.—MFM218633 from KSM-6. Superfamily Callianassoidea Dana, 1852 Family Ctenochelidae Manning and Felder, 1991 Subfamily Ctenochelinae Manning and Felder, 1991 Genus Ctenocheles Kishinoue, 1926 Type species.— Ctenocheles balssi Kishinoue, 1926 by monotypy. Geologic range.—Late Cretaceous to Recent. 242 Hiroaki Karasawa and Yasuhiro Fudouji Figure 3. 1a-c. Axius (s. |.) sp., MFM218633, x1.8; 1a: carapace, dorsal view; 1b: carapace and pereiopod 1, lateral view; 1c: carapace and pereiopods 1-3, lateral view. 2, 4. Callianassa (s. |.) sp., x1.2; 2, carpus of major cheliped, lateral view; 4: propodus of major cheliped, mesial view. 3. Ctenocheles sujakui Imaizumi, 1958, MFM218631, fixed finger of major cheliped, x1.8, lateral view. 5-8, 10, 11. Neocallichirus sakiae sp. nov.; 5: MFM218516 (paratype), major cheliped, x1.5, lateral view; 6: MFM218515 (holotype), minor cheliped, x2.5, lateral view; 7: MFM218519 (paratype), major cheliped, x1.5, lateral view; 8, MFM218515 (holotype), major cheliped, x1.5, lateral view; 10: MFM218518 (paratype), major cheliped, x1.5, lateral view; 11, MFM218517 (paratype), major cheliped, x1.5, lateral view. 9: Raninoides nodai Karasawa, 1992, MFM218636, carapace, x1.5, dorsal view. Ctenocheles sujakui Imaizumi, 1958 Remarks.—Imaizumi (1958) originally described the spe- Fiqure 3.3 cies from the lower Oligocene Kishima Formation of Nagao, g i Taku City, Saga Prefecture. Ctenocheles sujakui Imaizumi, 1958, p. 301, pl. 44, figs. 2-5; Material examined. — MFM218631 and 218632 from Karasawa, 1997, p. 31, pl. 3, figs. 5, 7. KSM-3; referred specimens from KSM-2, 4, 7. Palaeogene decapod Crustacea from Kyushu 243 Family Callianassidae Dana, 1852 Subfamily Callianassinae Dana, 1852 Remarks.—Manning and Felder (1991) recognized two families, seven subfamilies and 21 genera for taxa previ- ously assigned to the extant Callianassidae. According to Manning and Felder’s (1991) classification, Poore (1994) gave keys to 20 genera in the extant Callianassidae. Since then, four genera, Grynaminna Poore, 2000, Necallianassa Heard and Manning, 1998, Nihonotrypaea Manning and Tamaki, 1998, and Pseudobiffarius Heard and Manning, 2000, have been described. Fossil taxa have traditionally been assigned to Callianassa (s. |.); however, recent studies have employed the classification of Manning and Felder (Karasawa, 1992, 1993, 1997; Karasawa and Goda,1996; Kato, 1996; Schweitzer Hopkins and Feldmann,1997; Stilwell et a/., 1997; Vega et al., 1995). Sakai (1999) reex- amined all known extant members in the family Callianassidae and recognized four subfamilies and 10 gen- era in the family. The classification of Callianassidae by Sakai is quite different from Manning and Felder’s (1991) system. After that, Sakai and Türkay (1999) erected a new subfamily Bathycalliacinae with a new genus Bathycalliax. Therefore, the fossil species referred to the Callianassidae are in need of reexamination. Genus Callianassa Leach, 1814 Type species.—Cancer (Astacus) subterraneus Montagu, 1808 by monotypy. Geologic range.—Cretaceous to Recent. Callianassa (s. |.) sp. Figure 3.2, 3.4 Callianassa sp. indet.; Nagao, 1941, p. 85, pl. 26, figs. 8, 9. Description.—Propodus and carpus of major cneliped pre- served. Fixed finger short, about 0.3 propodus length, with acutely pointed tip. Palm subrectangular in lateral view, longer than high, with distally convergent dorsal and ventral margins. Carpus subrectangular in lateral view, equal to palm length; dorsal and ventral margins divergent distally. Discussion.—The generic placement of the present spe- cies awaits the discovery of better material and it is consid- ered best to place the species in Callianassa (s. |... The known Japanese Palaeogene species formerly placed in the genus Callianassa comprise five species, Callianassa elongatodigitata Nagao, 1941, Callianassa isikariensis Nagao and Otatume, 1938, Callianassa kushiroensis Nagao, 1941 and Callianassa muratai Nagao, 1932 of Hokkaido, and Callianassa sp. indet. (Nagao, 1941) of Kyushu. Among these, C. muratai and C. elongatodigitata were moved to the genus Callianopsis De Saint Laurent, 1973 in the family Ctenochelidae by Kato and Karasawa (1994). The present species differs from C. ishikariensis and C. kushiroensis in that the major cheliped has a short fixed finger and a palm with distally convergent dorsal and ventral margins. The species is identical with Callianassa sp. indet. described from the middle Eocene Dosi and Kawamagari Formations of Fukuoka Prefecture by Nagao (1941). Material examined. — MFM218634 and 218635 from OKN-1. Subfamily Callichirinae Manning and Felder, 1991 Genus Neocallichirus Sakai, 1988 Type species. — Neocallichirus horneri Sakai, 1988 by original designation. Geologic range. —Oligocene to Recent. Neocallichirus sakiae sp. nov. Figure 3.5-3.8, 3.10, 3.11 Etymology.—The specific name is in honor of Miss Saki Fudouji. Diagnosis.—Chelipeds large, unequal, dissimilar. Dorsal margin of dactylus of major cheliped smooth; occlusal mar- gin with broad tooth on midlength. Fixed finger shorter than dactylus; occlusal margin with broad tooth on proximal half. Palm rectangular, about 1.3 times longer than high, 1.3 propodus length, with serrated distal margin. Carpus subrectangular, about 0.6 palm length, slightly higher than long. Merus equal to palm length, about 0.6 times higher than long; ventral margin strongly convex without ventral hook. Ischium with dentate ventral margin. Description.—Chelipeds large in size, unequal, dissimilar. Dactylus of major cheliped curved ventrally with acutely pointed tip; dorsal margin smooth with 4 setal pits; occlusal margin bearing broad tooth at midlength; lateral surface in- flated with 4 setal pits parallel to occlusal margin. Fixed fin- ger about 0.75 dactylus length with acutely pointed tip; occlusal margin bearing broad tooth on proximal half; ventral margin smooth; lateral surface slightly convex with row of setal pits parallel occlusal and ventral margins. Palm rec- tangular in lateral view, about 1.3 times longer than high, 1.3 propodus length; dorsal margin slightly convex; ventral mar- gin nearly straight; distal margin gently convex, serrate; lat- eral surface longitudinally inflated with row of setal pits parallel to ventral margin. Carpus subrectangular in lateral view, about 0.6 palm length, slightly higher than long, taper- ing proximally, with convex lateral surface. Merus equal to palm length, about 0.6 times higher than long; dorsal margin gently convex; ventral margin strongly convex without ven- tral hook; lateral surface with longitudinal ridge. Ischium poorly preserved, about as long as merus, ventral margin dentate. Fingers of minor cheliped poorly preserved. Palm rectan- gular in lateral view, occupying about half palm length of major cheliped, slightly longer than high, with convex lateral surface; dorsal margin smooth, ventral margin pitted. Carpus rectangular, about 0.75 palm length, with convex lat- eral surface, its length equal to height. Discussion.—The Japanese fossil Neocallichirus is repre- sented by three species, Neocallichirus bona (Imaizumi, 1959) from the Miocene Moniwa Formation and Mizunami Group (Karasawa, 1993, 1997), Neocallichirus grandis Karasawa and Goda, 1996, from the middle Pleistocene Atsumi Group (Karasawa and Goda, 1996) and the middle- 244 Hiroaki Karasawa and Yasuhiro Fudouji upper Pleistocene Shimosa Group (Kato and Karasawa, 1998), and Neocallichirus okamotoi (Karasawa, 1993) from the upper Oligocene Hioki Group (Karasawa, 1993, 1997). Among these, the new species most resembles N. okamotoi but differs in that the major cheliped has broad teeth on the occlusal margin of both fingers, a longer palm with a ser- rated, convex distal margin and a shorter carpus. The merus on the major cheliped without marginal denticules and a short merus readily distinguish N. sakiae from N. bona and N. grandis. Material examined.—MFM218515 (holotype) and 218516 (paratype) from KSM-12; MFM218517 (paratype) and 218518 (paratype) from KSM-16; MFM218519 (paratype) from KSM-14; referred specimens from KSM-13, 14, 15. Infraorder Brachyura Latreille, 1802 Section Podotremata Guinot, 1977 Superfamily Raninoidea De Haan, 1841 Family Raninidae De Haan, 1841 Subfamily Raninoidinae Lörenthey in Lörenthey and Beurlen, 1929 Genus Raninoides H. Milne Edwards, 1837 Type species.— Ranina loevis Latreille, 1825 by mono- typy. Geologic range.—Palaeocene to Eocene. Raninoides nodai Karasawa, 1992 Figure 3.9 Raninoides nodai Karasawa, 1992, p. 1252, figs. 4.2-4.8; Karasawa, 1997, p. 39, pl. 7, figs. 7, 9, 11. Laeviranina nodai (Karasawa); Tucker, 1998, p. 351. Remarks. — Tucker (1998) provisionally placed Raninoides nodai in Laeviranina Lorenthey in Lorenthey and Beurlen, 1929. However, this species should be assigned to Raninoides based upon the absence of the postfrontal ridge on the carapace. Material examined.—MFM218636 from OKN-1. Section Heterotremata Guinot, 1977 Superfamily Portunoidea Rafinesque, 1815 Family Portunidae Rafinesque, 1815 Subfamily Carcininae MacLeay, 1838 Genus Cicarnus gen. nov. Type species.—Cicarnus fumiae sp. nov. by monotypy. Etymology.—Cicarnus is an anagram of Carcinus Leach, 1814; masculine gender. Diagnosis.—Carapace transversely hexagonal in outline, length about 0.8 its width. Orbitofrontal margin wide. Front with 3 rounded lobes, separated from small, bluntly triangu- lar supraorbital angle by shallow V-shaped notch. Upper orbital margin with 2 open fissures. Anterolateral margin convex, bearing 4 well developed teeth. Dorsal surface smooth, moderately convex. Regions well defined. Epigastric region transversely raised anteriorly. Proto- gastric region inflated with transverse ridge on each side. Mesogastric region bearing anterior transverse ridge. Cervical groove well defined. Epibranchial region more in- flated. Branchiocardiac grooves poorly defined. Discussion.—The subfamily Carcininae is defined by the following characters: The carapace is not broad with four or five anterolateral teeth; chelae are short; pereiopods 2-5 are similar and rather stout, and the pereiopod 5 has a lanceolate dactylus [modified from Glaessner (1969)]. Although carapace characters of Carcininae overlap those of the subfamily Polybiinae Ortmann, 1893, Polybiinae are dis- tinguished from Carcininae by having a paddle-like pereiopod 5 (Glaessner, 1969; Schweitzer and Feldmann, 2000). The Recent Carcininae comprises six genera, Benthochascon Alcock and Anderson, 1899, Brusinia Steveic, 1991, Carcinus Leach, 1814, Nectocarcinus A. Milne Edwards, 1860, Portumnus Leach, 1814 and Xaiva MacLeay, 1838 (Moosa, 1996). Three extinct genera, Portunites Bell, 1858, Pleolobites Remy, 1960 and Mioxaiva Miller, 1979, were previously assigned to the subfamily (Glaessner, 1969; Muller, 1979). Schweitzer and Feldmann (2000) and Schweitzer et al. (2000) removed Portunites to Polybiinae based upon the presence of a paddle-like pereiopod 5. The position of Pleolobites and Mioxaiva within Carcininae is doubtful (Glaessner, 1969; Müller, 1984). The present new genus and species are represented by a single carapace specimen, and chelipeds and pereiopods are not preserved. However, Cicarnus possesses carapace characters most like those of Benthochascon, Carcinus and Nectocarcinus, and may be assigned to Carcininae. Cicarnus is most similar to Nectocarcinus, but differs in hav- ing well developed anterolateral teeth, the frontal margin composed of three rounded lobes, and a smooth dorsal carapace. The mesogastric region in Cicarnus has a trans- verse ridge interrupted by a shallow median groove. With respect to the front which is composed of three rounded lobes, the new genus resembles Benthochascon and Carcinus. Cicarnus differs from Carcinus in having four anterolateral teeth and well defined dorsal regions. Although Cicarnus together with Benthochascon bears four anterolateral teeth, in Cicarnus the dorsal regions are well defined and a wide anterolateral margin bears well sepa- rated teeth. Cicarnus fumiae sp. nov. Figure 4.2a-c Etymology.—The specific name is in honor of Mrs. Fumie Karasawa. Diagnosis.—As for the genus. Description.—Carapace hexagonal in outline, length about 0.8 its width. Orbitofrontal margin wide, occupying 0.6 carapace width. Front composed of 3 rounded lobes, occupying about 0.3 carapace width, separated from small, bluntly triangular supraorbital angle by shallow V-shaped notch; median frontal lobe small and laterals broad. Upper orbital margin concave, bearing shallow fissure at about midwidth of orbit and shallower fissure anterior to outer or- bital tooth. Anterolateral margin convex, occupying about 0.45 carapace width, bearing 4 well separated teeth includ- ing outer orbital tooth; outer orbital tooth acutely triangular, 245 Palaeogene decapod Crustacea from Kyushu Figure 4. 1. Imaizumila sexdentata Karasawa, 1993, MFM218507 (holotype), carapace, x1.2, dorsal view. 2a-c. Cicarnus fumiae gen. et sp. nov., MFM218512 (holotype), x1.5, 2a: frontal view; 2b: dorsal view; 2c: lateral view. 3a-c. Euphylax ? sp., MFM218639, x1.0; 3a: both chelipeds, lateral view; 3b: carapace, cheliped and pereiopods, dorsal view; 3c: thoracic sternum, chelipeds and pereiopods, ventral view. 4a, b, 5. Minohellenus macrocheilus Kato and Karasawa, 1994, x1.2; 4a: MFM218637, carapace, dorsal view; 4b: MFM218637, right cheliped, lateral view; 5: MFM218638, carapace, dorsal view. 246 Hiroaki Karasawa and Yasuhiro Fudouji directed anteriorly; second broadly triangular, slightly di- rected anterolaterally and dorsally; third acutely triangular, directed anterolaterally and dorsally; last lacking tip, but di- rected laterally and dorsally. Posterolateral margin sinuous, slightly longer than anterolateral margin. Posterior margin nearly straight, slightly longer than posterolateral margin. Dorsal surface smooth, moderately convex, with well de- fined regions. Epigastric region transversely raised anteriorly. Protogastric region inflated, well separated from narrow anterior mesogastric process, with transverse ridge on each side. Mesogastric region convex, pentagonal in outline, bearing anterior transverse ridge divided into two by shallow median depression. Urogastric region narrow, de- pressed. Cervical groove well defined. Cardiac region slightly convex, hexagonal in outline, bearing two nodes transversely arranged. Intestinal region depressed. Hepatic region slightly convex. Epibranchial region more inflated, shallowly separated from mesobranchial region. Meso- and metabranchial regions also inflated. Branchio- cardiac grooves poorly defined. Discussion.—As for the genus. Material examined.—MFM218512 (holotype) from OKN- 1. Subfamily Polybiinae Ortmann, 1893 Genus Imaizumila Karasawa, 1993 Type species.— Imaizumila sexdentata Karasawa, 1993 by monotypy. Geologic range.—Eocene to Middle Miocene. Imaizumila sexdentata Karasawa, 1993 Figure 4.1 Imaizumila sexdentata Karasawa, 1993, p. 52, pl. 11, figs. 1-3; Karasawa, 1997, p. 48, pl. 11, figs. 8, 12. Remarks. — Previously specimens were recorded only from the lower Oligocene Haiki Formation of the Kishima Group (Karasawa, 1993). Schweitzer and Feldmann (2000) described an additional species, /maizumila araucana (Philippi, 1887) from the Eocene-Miocene of Chile. Material examined.—MFM218507 (holotype) and 218508 (paratype) from KSM-1. Genus Minohellenus Karasawa, 1990 Type species.—Charybdis (Minohellenus) quinquedentata Karasawa, 1990 by monotypy. Geologic range.—Early Oligocene to Middle Miocene. Minohellenus macrocheilus Kato and Karasawa, 1994 Figure 4.4a, b, 4.5 Minohellenus macrocheilus Kato and Karasawa, 1994, p. 55, fig. 2; pl. 4, figs. 1-4; Kato and Karasawa, 1996, p. 31, pl. 10, figs. a-c; Karasawa, 1997, p. 49, pl. 14, figs. 2-7. Remarks.—Previously known specimens were recorded from the upper Oligocene Ashiya Group (Kato and Karasawa, 1994, 1996). The discovery of M. macrocheilus from the Kishima Group extends the geologic range for the species back to the early Oligocene. Material examined. —MFM218637 from KSM-16; MFM 218638 from KSM-6. Subfamily Podophthalminae Miers, 1886 Genus Euphylax Stimpson, 1860 Type species.—Euphylax dovii Stimpson, 1860 by mono- typy. Geologic range.—Oligocene to Recent. Euphylax ? sp. Figure 4.3a-c Description.— Right half of carapace poorly preserved; upper orbital margin wide, gently convex; anterolateral mar- gin narrow with laterally directed stout spine; posterolateral margin sinuous. Thoracic sternum wide, sternites 4-7 pre- served. Chelipeds similar. Dactylus slender, elongate, with smooth dorsal margin and irregularly dentate opposing mar- gin. Fixed finger elongate, about 0.3 times higher than long proximally, with acutely pointed tip; occlusal margin straight, irregularly dentate; ventral margin convex, smooth. Palm short, about 0.75 fixed finger length, about 0.6 times longer than high, converging proximally; dorsal surface tuberculated; ventral margin smooth. Meri of pereiopods 2 and 3 ovate in cross section. Discussion.—There is, in the general outline of chelipeds, similarity between the species and Euphylax domingensis (Rathbun, 1919) from the lower Miocene? of Haiti, but this species has a slender dactylus and a short palm without carinae on the lateral margin. However, a well preserved carapace of this species is needed to qualify the systematic position. Material examined.—MFM218639 from KSM-3. Superfamily Xanthoidea MacLeay, 1838 Family Goneplacidae MacLeay, 1838 Subfamily Carcinoplacinae H. Milne Edwards, 1852 Carinocarcinoides gen. nov. Type species.— Carinocarcinoides carinatus sp. nov. by present designation. Etymology.—The genus is named in allusion to its close resemblance to Carinocarcinus Lörenthey, 1898; masculine gender. Diagnosis.—Carapace transversely hexagonal to roundly quadrate in outline, widest at anterolateral angle. Orbitofrontal margin wide. Front nearly straight with sharply squared corners. Upper orbital margin concave with trian- gular, forwardly directed outer orbital spine and without fis- sures. Inner suborbital tooth sharp, projecting anteriorly. Anterolateral margin strongly convex with 2 small, anterolaterally directed spines exclusive of outer orbital spine. Dorsal surface smooth, moderately vaulted trans- versely and weakly vaulted longitudinally. Regions distinct. Protogastric, cardiac and epigastric ridges present. Palaeogene decapod Crustacea from Kyushu 247 Anterior mesogastric process poorly defined. Cervical and branchiocardiac grooves well defined. Thoracic sternum narrow, longer than wide, tapering anteriorly and posteriorly. Chelipeds large; dactylus, palm and carpus finely granulate on dorsal and lateral surfaces. Discussion. — Carinocarcinoides possesses characters most like those of the extant genera Carcinoplax H. Milne Edwards, 1852 and Homoioplax Rathbun, 1914. However, Carinocarcinoides has a dorsal carapace with well defined regions and several ridges. The thoracic sternum of the new genus is much narrower than that of Carcinoplax. Of the extinct genera within Carcinoplacinae, Carinocarcinoides is most similar to Carinocarcinus Lörenthey, 1898, a monotypic genus from the middle Eocene of Hungary, but differs in having a straight front with sharp lateral corners, three anterolateral teeth including the outer orbital spine, and a protogastric ridge. The new genus is represented by two species, Carinocarcinoides angustifrons (Karasawa, 1993) comb. nov. and Carinocarcinoides carinatus sp. nov., from the lower Oligocene Kishima Group. Carinocarcinoides angustifrons (Karasawa, 1993) comb. nov. Figure 5.3 Varuna angustifrons Karasawa, 1993, p. 81, pl. 23, fig. 13; Karasawa, 1997, p. 69, pl. 27, fig. 8. Revised diagnosis. — Carinocarcinoides with rounded- quadrate carapace and with epigastric, protogastric, cardiac and epibranchial ridges. Revised description.— Carapace roundly quadrate in out- line, about as long as wide, widest at midlength. Orbitofrontal margin 0.75 carapace width. Front straight, occupying about 0.3 carapace width, with sharp lateral cor- ners. Upper orbital margin wide, concave, rimmed, with small, forwardly directed outer orbital spine. Anterolateral margin gently convex, about 0.4 carapace width, with two small spines excluding outer orbital spine. Posterolateral margin also strongly convex, about 1.4 times as long as anterolateral margin. Posterior margin straight, about 0.4 carapace width. Dorsal surface smooth, moderately vaulted transversely and weakly vaulted longitudinally. Regions somewhat dis- tinct. Epigastric region with weak, transverse ridge on each side. Protogastric regions inflated with broad, transverse ridge interrupted by narrow anterior mesogastric process. Anterior mesogastric process poorly defined. Mesogastic region slightly convex. Cervical groove distinct, sinuous. Cardiac region gently inflated transversely, hexagonal in out- line, bearing two nodes transversely arranged, with anterior transverse ridge. Intestinal region poorly defined. Hepatic region depressed. Branchiocardiac grooves _ shallow. Branchial regions convex; each epibranchial region inflated with broad ridge extending in convex-forward arc from mesogastric region to last anterolateral spine. Discussion.—The present species was originally placed in Varuna H. Milne Edwards, 1852 in the family Grapsidae. However, the species is moved here from Varuna to Carinocarcinoides on the basis of its inflated dorsal cara- pace with several ridges and three anterolateral spines. Members of Varuna have a flattened dorsal surface with a wider frontal margin and three broadly triangular anterolateral teeth. Material examined.—MFM218501 (holotype) from KSM- 2. Carinocarcinoides carinatus sp. nov. Figure 5.1a-d, 5.2, 5.4 Diagnosis.— Carinocarcinoides with transversely hexago- nal carapace and with anterior frontal, protogastric, urogastric, cardiac and epigastric ridges dorsally. Etymology.—From Latin carina (= keel), in reference to dorsal ridges on the carapace. Description.—Carapace transversely hexagonal in outline, length 0.8 its width, widest at anterolateral angle. Orbito- frontal margin occupying about 0.75 carapace width. Front nearly straight, about 0.4 carapace width, weakly protruded medially, with well developed ridge parallel to anterior mar- gin and with sharply squared corners. Upper orbital margin concave, rimmed, with weak, central projection and broadly triangular, forwardly directed outer orbital spine. Inner suborbital spine sharp, projecting anteriorly, visible in dorsal view. Anterolateral margin strongly convex, about 0.35 carapace width, with two small, anterolaterally directed spines exclusive of outer orbital spine. Posterolateral mar- gin also strongly convex, about 1.8 times as long as anterolateral margin. Posterior margin short, about 0.3 carapace width. Dorsal surface smooth, moderately vaulted transversely and weakly vaulted longitudinally. Regions distinct. Protogastric region inflated with broad, arcuate ridge on each side. Anterior mesogastric process poorly defined. Mesogastic region slightly convex. Urogastric region with transverse ridge. Cervical groove well defined, sinuous. Cardiac region gently vaulted transversely, hexagonal in out- line, bearing two nodes transversely arranged, with trans- verse ridge anteriorly. Intestinal region small, poorly defined. Hepatic region flattened. Branchiocardiac grooves fairly deep. Branchial regions convex; each epibranchial region most strongly inflated with broad ridge extending in convex-forward arc from mesogastric region to last anterolateral spine. Infraorbital region with weak, granulated ridge parallel to lower orbital margin. Pterygostomian region bearing finely granulated ridge below and parallel to pleural suture. Maxilliped 3 poorly pre- served. Thoracic sternum longer than wide, tapering anteriorly and posteriorly, occupying about 0.4 carapace width, widest at sternite 6. Sternites 1 and 2 fused, triangular. Sternite 3 twice as wide as long with shallow median depression; ante- rior margin weakly concave, posterior margin broadly V- shaped, lateral margin straight, converging anteriorly. Sternites 4-7 with blunt episternal projections. Sternite 4 about 1.5 times wider than long, narrower anteriorly, wider posteriorly; anterior and posterior margins broadly V- shaped, lateral margins convex. Sternite 5 wider than long, becoming narrower anteriorly; anterior margin broadly V- 248 Hiroaki Karasawa and Yasuhiro Fudouji Figure 5. 1a-d. Carinocarcinoides carinatus gen. et sp. nov., MFM218513 (holotype) , x2.0; 1a: carapace and left cheliped, frontal view; 1b: carapace and left cheliped, dorsal view; 1c: carapace, thoracic sternum, abdomen of male, and left cheliped, ventral view; 1d: carapace, lateral view. 3. Carinocarcinoides angustifrons (Karasawa, 1993) comb. nov., MFM218501 (holotype), carapace, x2.5, dorsal view. 2, 4. Carinocarcinoides carinatus gen. et sp. nov., MFM218514 (paratype) , 2: pleopods, x3.0, ventral view; 4: carapace and thoracic sternum, x1.5, ventral view. shaped, posterior margin sinuous, lateral margin convex. Sternites 6 and 7 wider than long, narrowing posteriorly; an- terior and posterior margins sinuous, lateral margin convex. Sternite 8 directed strongly posterolaterally with weak lateral projections. Pleopods poorly preserved. Abdomen of male narrow. Telson triangular, as long as wide at base. Somites 4-6 preserved, widest at posterior part of somite 4, with straight, anteriorly convergent lateral margins; somite 6 about as long as wide; somites 4 and 5 wider than long. Left cheliped large, poorly preserved. Dorsal surface of dactylus and lateral surface of palm finely granulate. Lateral surface of carpus also finely granulate with finely granulated ridge parallel to proximal margin; dorsal margin with forwardly directed spine. Discussion.—A transversely hexagonal carapace with transverse frontal and urogastric ridges readily distinguishes C. carinatus from C. angustifrons. In C. carinatus the cara- pace length occupies about 80 % of the width, while in C. angustifrons a roundly quadrate carapace is about as long as wide. Material examined.—MFM218513 (holotype) and 218514 (paratype) from KSM-9. Subfamily Chasmocarcininae Seréne, 1964 Genus Collinsius Karasawa, 1993 Type species.— Collinsius simplex Karasawa, 1993 by monotypy. Geologic range.—Early Oligocene. Revised diagnosis.—Carapace slightly wider than long, widest at posterolateral angle. Orbitofrontal margin occupy- ing about half carapace width. Front narrow, bilobed, pro- jecting anteriorly, with squared lateral corner. Upper orbital margin narrow, concave, rimmed, with broadly triangular outer orbital angle. Lateral margin rounded, divergent posteriorly. Posterior margin short, straight. Dorsal sur- face smooth, gently convex longitudinally and transversely. Epigastric region poorly defined. Cervical groove becoming obsolete in advance of hepatic region. Urogastric region Palaeogene decapod Crustacea from Kyushu 249 narrow, depressed. Cardiac region transversely convex. Intestinal region narrow. Branchiocardiac grooves well de- fined. Branchial regions inflated. Thoracic sternum wide, wider than long, widest at sternite 6. Sternite 8 of male with supplementary sternal plate. Abdomen of male narrow; somites 3-5 fused. Chelipeds unequal. Discussion. — Karasawa (1993) originally placed the genus in the family Goneplacidae, but did not assign it to any known subfamily. Later, Karasawa (1997) assigned Collinsius to the subfamily Chasmocarcininae by recognising the presence of supplementary sternal plates of the thoracic sternite 8 in the male. The subfamily Chasmocarcininae comprises five extant genera, Chasmocarcinus Rathbun, 1898, Camatopsis Alcock and Anderson, 1899, Chasmocarcinops Alcock, 1900, Hephthopelta Alcock, 1899 and Scalopidia Stimpson, 1858, and the Eocene Falconoplax Van Straelen, 1933 (Davie and Guinot, 1996). Among these genera, Collinsius resembles Chasmocarcinus, Hephthopelta and Falconoplax in that ab- dominal somite 3 of the male fuses to somites 4 and 5. However, the genus differs from Chasmocarcinus by having a narrow front and lacking the posterolateral expansion of the carapace; Hephthopelta has a wider front and a strongly inflated dorsal carapace; the carapace of Falconoplax has well defined epibranchial regions, protogastric tubercles, deep branchiocardiac grooves and epibranchial ridges. Collinsius is only known from the lower Oligocene Kishima Formation of Kyushu, Japan. Collinsius simplex Karasawa, 1993 Figure 6.1-6.9 Collinsius simplex Karasawa, 1993, p. 73, pl. 21, figs. 3-8; Karasawa, 1997, p. 61, pl. 23, figs. 4-6, 8-10. Revised description.—Carapace slightly wider than long, widest at posterolateral angle. Orbitofrontal margin occupy- ing about half of carapace width. Front narrow, projecting anteriorly with shallow median depression dorsally; anterior margin nearly straight, interrupted by weak median notch with sharply squared lateral corner; lateral margin rimmed. Upper orbital margin concave, rimmed, occupying about 0.2 carapace width, with weak, central projection and broadly tri- angular outer orbital angle. Lateral margin rounded, diver- gent posteriorly. Posterior margin short, straight. Dorsal surface smooth, gently convex longitudinally and trans- versely. Epigastric region poorly defined, but visible. Protogastric region separated from anterior mesogastric process by shallow groove. Cervical groove becoming ob- solete in advance of hepatic region. Urogastric region nar- row, depressed. Cardiac region transversely hexagonal in outline, transversely convex. Intestinal region narrow. Branchiocardiac grooves well defined. Branchial regions in- flated. Thoracic sternum wide, wider than long, widest at sternite 6. Sternites 1 and 2 fused, narrow, broadly triangular in out- line, with deep median depression. Sternite 3 about 0.3 as long as wide with median depression; anterior margin nearly straight, posterior margin broadly V-shaped, lateral margin straight, strongly converging anteriorly. Sternites 4-7 with blunt episternal projections. Sternite 4 about 0.4 times longer than wide, narrower anteriorly, wider posteriorly; an- terior and posterior margins broadly V-shaped; lateral mar- gins convex. Sternite 5 wider than long, narrower anteriorly, wider posteriorly; anterior margin broadly V- shaped, posterior margin sinuous, lateral margin convex. Sternite 6 wider than long; anterior and posterior margins sinuous, lateral margin convex. Sternite 7 wider than long, wider anteriorly, narrower posteriorly; anterior and posterior margins sinuous, lateral margin convex. Sternite 8 wider than long, wider anteriorly, narrower posteriorly, directed posterolaterally; supplementary sternal plate developed in male; shallow, transverse groove in female surface. Abdomen of male narrow. Telson triangular, slightly longer than wide at base. Somite 6 wider than long with straight, anteriorly convergent lateral margins. Somites 3-5 fused, wider than long, widest at base, with slightly concave, anteriorly convergent lateral margins; posterior lateral ex- pansions covering mesial ends of supplementary plates. Somite 2 narrow. Somite 1 unknown. Telson of female ab- domen rounded, wider than long at base. Somites 1-6 nar- row, much wider than long, widest at somite 3, longest at somite 6. Chelipeds unequal. Fixed finger short on major cheliped; palm with smooth, inflated lateral surface. Dactylus elon- gate on minor cheliped, curving ventrally, with acutely pointed tip; fixed finger also elongate, about as long as dactylus, occupying about half of propodus length, slightly deflexed ventrally, with acutely pointed tip; palm longer than high, distal margin much wider than proximal margin, with smooth, inflated lateral surface. Pereiopods 1-4 of female poorly preserved. Propodi of pereiopods 2-4 elongate, cylindrical in cross section. Coxa and ischium fused to basis short. Discussion.—As for the genus. Material examined. — MFM218502 (holotype), 218503 (paratype), and 218601-218610 from KSM-2; MFM218505 (paratype), 218506 (paratype), and 218613-218620 from KSM-4; MFM218504 (paratype), 218621-218630, 218640, 218641 from KSM-5; MFM218612 from KSM-3; MFM 218642, 218643 and 218644 from KSM-6; referred speci- mens from KSM-7, 8, 9, 10, 11. Acknowledgements We thank J. S. H. Collins (London) for reading our manu- script, Y. Okumura (MFM) for assisting in the senior author's field work in 1995 and 1999 and Mr. T. Yamada (Kyoto Umiversity) for offering fossil crab specimens for study. This work was partly supported by the Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture (no. 1663) for Karasawa. 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Yokoyama, M., 1911: Some Tertiary fossils from the Miike Van Straelen, V., 1933: Sur les Crustacés Décapodes cénozo- coalfield. Journal of the College of Science, Imperial iques du Venezuela. Bulletin du Musée Royal d’Histoir University of Tokyo, vol. 27, p. 1-16. e Naturelle de Belgique, vol. 9, no. 10, p. 1-14. 1 D © il he ER pa PRE TOT. A a | | | En Si | “re ine lh ental we For wee Pere pe Pond a Pape i vy) oe hin ae © ct € oh ces 1 Paleontological Research, vol. 4, no. 4, pp. 255-260, December 30, 2000 © by the Palaeontological Society of Japan New cephalopod material from the Bashkirian (Middle Carboniferous) of the Ichinotani Formation, Central Japan SHUJI NIKO Department of Environmental Studies, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashihiroshima, 739-8521, Japan (niko @hiroshima-u.ac.jp) Received 5 June 2000; Revised manuscript accepted 23 August 2000 Abstract. Three Bashkirian (Middle Carboniferous) species of orthocerid cephalopods, the orthoceratid Hidamichelinoceras bandoi gen. et sp. nov. and the pseudorthoceratids Mooreoceras sp. and Adnatoceras ichinotaniense Niko and Hamada, 1987, are described (or redescribed) from the Ichinotani Formation, Central Japan based on new material. The siphuncular structure of Hidamichelinoceras is shared with Michelinoceras, but this new genus is characterized by its broadly cone-shaped initial camera and rapid shell expansion. The discovery of Mooreoceras, which previously had been known only from the Hikoroichi Formation in Japan, supports a paleobiogeographic link between the Fukuji and southern Kitakami areas in the Carboniferous. The apical shell diagnosis of Adnatoceras ichinotaniense is added. Key words: Bashkirian (Middle Carboniferous), Hidamichelinoceras gen. nov., Ichinotani Forma- tion, Orthocerida. Introduction Recent research on Far Eastern Carboniferous orthocerids and bactritids has shown that at least two iso- lated faunal provinces were present through the period in the area, i. e., the Taishaku-Akiyoshi-South China Province with the Bogoslovskya and Bactrites lineage (Niko et al., 1987, 1991, 1995, 1997; Niko and Ozawa, 1997) and the southern Kitakami-Fukuji Province with the Adnatoceras lineage (Niko and Hamada, 1987; Niko, 1990). Nevertheless, our knowl- edge of Carboniferous orthoconic cephalopods is too limited to permit detailed paleobiogeographic reconstruction. Descriptive works are still critical also for providing phylogenetic information about these groups. As an addi- tional account of orthocerid cephalopods in the Fukuji area, Central Japan, this work documents a new collection from the Bashkirian (Middle Carboniferous) limestone of the Ichinotani Formation. Details of the geologic setting and stratigraphic position of the collection have already been given by Niko and Hamada (1987). The abbreviation UMUT for the repository stands for the University Museum of the University of Tokyo. Systematic paleontology Order Orthocerida Kuhn, 1940 Superfamily Orthocerataceae M’Coy, 1844 Family Orthoceratidae M’Coy, 1844 Subfamily Michelinoceratinae Flower, 1945 Genus Hidamichelinoceras gen. nov. Type species.—Hidamichelinoceras bandoi sp. nov., by monotypy. Diagnosis.—Orthoconic michelinoceratinid with rapid shell expansion, 9°-13° in angle, for subfamily, circular cross sec- tion, and probably endogastric early juvenile portion; shell surface ornamented by transverse lirae; initial camera broadly cone-shaped with rounded apex, shallow; early siphuncle central then becoming subcentral in position; septal necks very long and orthochoanitic, forming very wide septal foramen; cameral deposits weakly developed, episeptal-mural and hyposeptal; auxiliary deposits absent. Etymology.—The generic name is derived from Hida, which is a historic provincial name of the type locality, and Michelinoceras. Hidamichelinoceras bandoi sp. nov. Figures 1.1-1.6, 2.1 256 Shuji Niko Diagnosis.—Same as for the genus. Description.—Based on single incomplete phragmocone of orthoconic shell with circular cross section; early juvenile shell indicates probable endogastric curvature; shell expan- sion rapid as for subfamily, its angle approximately 13° apically, then decreases to approximately 9° adorally; di- ameter of adoral shell attains 6.2 mm. Surface ornamenta- tion consists of transverse and somewhat distant lirae forming weak sinuations. Sutures not observed, but obvi- ous obliquity not recognized in dorsoventral section. Initial camera broadly cone-shaped with rounded apex, shallow and relatively small with 0.9 mm+ (slightly deformed) in maximum diameter and 0.3 mm in length between both apexes of initial and second camerae; cameral length abruptly increases in following camerae, then re-shortened adorally; maximum diameter/length ratios of adoral camerae range from 1.7 to 2.2; septal curvature moderate to relatively deep in seven apical septa, then becomes shallower in adoral septa. Siphuncular position nearly central in early ju- venile shell, then slightly shifts in ventral direction, subcentral; minimum distance of central axis of siphuncle from shell surface versus shell diameter decreases to 0.4; caecum weakly inflated; siphuncle consists of orthochoanitic septal necks and nearly cylindrical connecting rings in sec- ond to seventh camerae; connecting rings missing in adoral camerae where septal necks are orthochoanitic, very long, 0.65-0.79 mm in length, attaining 0.3 in ratio of septal neck length/cameral length; diameters of septal necks are 0.61- 0.71 mm; septal foramen cylindrical, very wide for subfamily, 0.52-0.63 mm in diameter; ratio of septal neck diameter to corresponding dorsoventral shell diameter attains 0.13. Cameral deposits weakly developed, restricted to apical 10 camerae, episeptal-mural and hyposeptal, slightly thicker in venter than dorsum; circumsiphuncular ridges of episeptal and hyposeptal deposits partly extend onto ventral side of connecting rings and septal necks, respectively. Endo- siphuncular deposits, including auxiliary ones, are absent. Discussion.—The siphuncular structure of Hidamichelino- ceras bandoi gen. et sp. nov. suggests a close relationship to the widespread genus Michelinoceras (Foerste, 1932; type species Orthoceras michelini Barrande, 1866). The most important distinctive feature is the morphology of the initial camera. In contrast to the broadly cone-shaped initial camera of this new genus, the longitudinally elongated bul- bous form of the type species of Michelinoceras was con- firmed by Ristedt (1968, pl. 1, fig. 1). The rapid shell expansion (9°-13° in angle) of Hidamichelinoceras in com- parison with the much slenderer shell shape of Michelino- ceras (1°-2° in angle of shell expansion of M. michelini ) is also regarded as enough to be of generic significance. Hidamichelinoceras differs from the Devonian to Carboniferous genus Bogoslovskya (Zhuravleva, 1978; type species, B. perspicua Zhuravleva, 1978) in having a less ec- centric siphuncular position with a wider septal foramen and in lacking auxiliary deposits. The Triassic genus Tremato- ceras (Eichwald, 1851, not seen by the author; its generic di- agnosis, including apical shell morphology, comes from citation by Schindewolf, 1933; type species, Orthoceratites elegans Munster, 1841) has a cone-shaped initial camera but the shape of the septal necks of Hidamichelinoceras is quite unlike that of Trematoceras, whose septal necks are very short and suborthochoanitic. In addition, the cameral deposits of Trematoceras are characterized by the promi- nent lamellae. The circular shell cross section of Hidamichelinoceras clearly separates it from the Devonian genus Arkonoceras (Flower, 1945; type species, Orthoceras arkonense Whiteaves, 1898), which has a much slenderer shell characterized by its subquadrangular cross section. The Ordovician genus Sinoceras (Shimizu and Obata, 1935; type species, Orthoceras chinense Foord, 1888) was erroneously assigned to the Michelinoceratinae (e. g., Sweet, 1964) owing to its orthoconic shell shape and its Michelinoceras-like very long septal necks indicating orthochoanitic forms. However, the enveloping cameral- endosiphuncular deposits on the septal neck and on both the adoral and apical surfaces of the septum, recognized in the type species of Sinoceras in Woodward's (1856, pl. 6, fig. 1) illustration, undoubtedly place Sinoceras in the family Lituitidae within the order Tarphycerida. Material examined and occurrence.—Holotype, UMUT PM 27849, 28.0 mm in length from the uppermost part of the Lower Member, Ichinotani Formation. Etymology.—The specific name refers to the late Dr. Yuji Bando, in recognition of his contributions to the study of fos- sil cephalopods. Superfamily Pseudorthocerataceae Flower and Caster, 1935 Family Pseudorthoceratidae Flower and Caster, 1935 Subfamily Pseudorthoceratinae Flower and Caster, 1935 Genus Mooreoceras Miller, Dunbar and Condra, 1933 Type species.—Mooreoceras normale Miller, Dunbar and Condra, 1933. Mooreoceras sp. Figures 1.7-1.9, 2.7 Description.—Orthoconic phragmocone with gradual shell expansion and dorsoventrally depressed, oval cross section; diameter of apical end is 5.2 mm in dorsoventral direction and 5.8 mm in lateral direction, giving a form ratio of ap- proximately 1.1. Surface ornamentation absent. Sutures transverse, nearly straight, or strongly oblique in rare cases; septal curvature shallow. Cameral length moderate for genus, cameral ratios of maximum dorsoventral diameter/ maximum length are 0.2-0.4. Siphuncle subcentral, con- sists of cyrtochoanitic septal necks and subcylindrical con- necting rings whose inflation is weak for genus. Cameral deposits not detected. Endosiphuncular deposits form annulosiphonate rings. Discussion.—Although this species is known from a single specimen of a probable juvenile shell judging from the rela- tively weak inflation of the connecting rings, the oval cross section of the shell, subcentral siphuncular position with the cyrtochoanitic septal necks, annulosiphonate rings formed of endosiphuncular deposits and the lack of cameral deposits warrant generic assignment to Mooreoceras. Unsuccessful attempts to make a well-oriented thin section preclude a specific determination. Bashkirian cephalopods from Japan Figure 1. 1-6. Hidamichelinoceras bandoi gen. et sp. nov., holotype, UMUT PM 27849. 1: Lateral view of silicone rubber cast, venter on right, x4; 2: Details of shell surface, showing ornamentation of transverse lirae, x8; 3: Polished cross section, venter down, x4; 4: Longitudinal thin section of apical shell, venter on left, slightly deformed, x14; 5: Longitudinal thin section of adoral shell, venter on left, x14; 6: Details of the three most apical camerae, note cone-shaped initial camera, ventral shell slightly deformed, x30. 7-9. Mooreoceras sp., UMUT PM 27850. 7: Dorsal view, x4; 8: Septal view of apical end, venter down, x4; 9: Longitudinal thin section, venter on right, x5. 257 258 Shuji Niko Figure 2. 1. Hidamichelinoceras bandoi gen. et sp. nov., holotype, UMUT PM 27849, longitudinal thin section, venter on left, x5. 2-6. Adnatoceras ichinotaniense Niko and Hamada, 1987. 2-4: UMUT PM 27852; 2: Longitudinal thin section of apical shell, venter on right, x14; 3: Longitudinal thin section of adoral shell, venter on right, x14; 4: Longitudinal thin section, venter on right, x5; 5,6: UMUT PM 27851; 5: Ventral view, x2; 6: Longitudinal thin section, details of adoral siphuncular structure, venter on left, x14. 7. Mooreoceras sp., UMUT PM 27850, longitudinal thin section, venter on right, showing siphuncular struc- ture, x14. Bashkirian cephalopods from Japan 259 Previously, this genus had been represented in Japan solely by Mooreoceras kinnoi Niko, 1990, from the Visean (Early Carboniferous) of the Hikoroichi Formation in the southern Kitakami area, Northeast Japan. The present dis- covery of Mooreoceras sp. from the Fukuji area supports a paleobiogeographic link in the Carboniferous between the Fukuji and southern Kitakami areas, of which the similarity has also been suggested by the common occurrence of Adnatoceras in both areas. Material examined and occurrence.—Single incomplete phragmocone, UMUT PM 27850, 15.0 mm in length. Stratigraphic horizon is identical with Hidamichelinoceras bandoi. Subfamily Spyroceratinae Shimizu and Obata, 1935 Genus Adnatoceras Flower, 1939 Type species.—Orthoceras spissum Hall, 1879. Adnatoceras ichinotaniense Niko and Hamada, 1987 Figure 2.2-2.6 Adnatoceras ichinotaniensis Niko and Hamada, 1987, p. 225, 227, figs. 3-1-6. Adnatoceras ichinotaniense Niko and Hamada. 557; Kamiya and Niko, 1992, fig. 1-E. Niko, 1990, p. Additional diagnosis.—Early siphuncle central in position with suborthochoanitic septal necks and cylindrical connect- ing rings. See Niko and Hamada (1987, p. 225) for diagno- sis of adult shell. Description.—Orthoconic shells with dorsoventrally de- pressed subcircular cross section up to nearly 4 mm in di- ameter and with a mean form ratio of approximately 1.1, then circular cross section attaining 9.1 mm in diameter; shell expansion moderate for genus, its angle approximately 4° in apical shell, then decreases to 2°-3° in adoral shell. Surface ornamentation absent; ventral wall slightly thicker than dorsal wall. Sutures straight, slightly oblique with ap- proximately 5° to rectangular direction of shell axis, toward aperture on venter; septa relatively shallow; cameral length moderate to relatively short for genus; maximum width/ length ratio of apical camerae ranges from 1.3 to 2.0, and ratio increases to 2.9-5.8 with 3.9 mean in adoral camerae. Early siphuncle central in position, composed of very short suborthochoanitic septal necks, 0.13 mm in length for a well- preserved one, and cylindrical connecting rings having weak constrictions at septal foramen; siphuncular position shifts towards a ventral one as shell grows, subcentral; ratio of minimum distance of central axis of the most adoral siphuncle from shell surface per shell diameter decreases to 0.3, where septal necks are asymmetrical, suborthochoanitic to cyrtochoanitic on dorsal side, with a length of 0.31 mm, and strongly recurved cyrtochoanitic on ventral side, with a length of 0.22 mm; adoral connecting rings subcylindrical, nearly parallel-sided and abruptly constricted at septal fora- men; maximum diameter/length ratio of adoral siphuncle 0.5 -0.7; adnation area very wide for family. Cameral deposits usually episeptal-mural and hyposeptal, but the latter are ab- sent in some camerae, thicker in venter than dorsum. Endosiphuncular parietal deposits restricted on ventral siphuncular wall, thin, not fused. Adoral camerae lack both cameral and endosiphuncular deposits. Discussion.—The description above is the same as in Niko and Hamada (1987) except that the apical shell mor- phology and most adoral siphuncular structures are added based on new specimens. The weaker cameral and endosiphuncular deposits of one specimen (UMUT PM 27852), compared to the holotype, probably result from its immaturity. Material examined and occurrence.—Holotype, UMUT PM 18068; paratype, UMUT PM 18069. In addition, two newly collected incomplete phragmocones were examined: UMUT PM 27851, which includes more of the adoral shell than the type specimens, 38.3 mm in length, and UMUT PM 27852, which represents more of the apical shell than the type specimens, 23.0 mm in length. Stratigraphic horizon is identical with Hidamichelinoceras bandoi. Acknowledgments The author is grateful to Takashi Hamada for his helpful comments in the early stages of this study and to Hisayoshi Igo who provided locality information for the present cepha- lopods. Toshiaki Kamiya collected most of the specimens utilized in this study. References Barrande, J., 1866: Systéme silurien du centre de la Boheme, Premiere Partie: Recherches paléontologiques. Volume 2, Classe des Mollusques, Ordre des Céphalopodes, part 7, pls. 108-244, Praha. Eichwald, E. von, 1851: Naturhistorische Bemerkungen, als Beitrag zur vergleichenden Geognosie, auf einer Reise durch die Eifel, Tyrol, Italien, Sizilien und Algier gesammelt. Nouveaux Memoires de la Societe Imperiale des Naturalistes de Moscou, vol. 9, p. 1-464, pls. 1-4. (not seen) Flower, R.H., 1939: Study of the Pseudorthoceratidae. Palaeontographica Americana, vol. 2, p. 1-214, pls. 1-9. Flower, R.H., 1945: Classification of Devonian nautiloids. American Midland Naturalist, vol. 33, p. 675-724, pls. 1- 5. Flower, R.H. and Caster, K.E., 1935: The stratigraphy and pa- leontology of northeastern Pennsylvania. Part Il: Paleon- tology. Section A: The cephalopod fauna of the Cone- wango Series of the Upper Devonian in New York and Pennsylvania. Bulletins of American Paleontology, vol. 22, p. 199-271. Foerste, A.F., 1932: Black River and other cephalopods from Minnesota, Wisconsin, Michigan, and Ontario (Part 1). Denison University Bulletin, Journal of the Scientific Laboratories, vol. 27, p. 47-136, pls. 7-37. Foord, A.H., 1888: Catalogue of the Fossil Cephalopoda of the British Museum (Natural History), part 1, 344 p., London. Hall, J., Palaeontology of New York. Volume 5, Descriptions of the Gastropoda, Pteropoda and Cephalopoda of the Upper Helderberg, Hamilton, Portage and Chemung .Groups, part 1, 492 p., part 2, 113 pls., New York Geological Survey, C. van Benthysen and Sons, Albany. Kamiya, T. and Niko, S., 1992: Color markings on Devonian 260 Shuji Niko orthochonic cephalopod from Fukuji, Gifu Prefecture. Chigakukenkyu, vol. 41, p. 149-153. (in Japanese) Kuhn, O., 1940: Paläozoologie in Tabellen, 50 p. Fischer, Jena. M'Coy, F., 1844: A Synopsis of Characters of the Carboniferous Limestone Fossils of Ireland, 274 p. Privately published. (reprinted by Williams and Norgate, London, 1862). Miller, A.K., Dunbar, C.O. and Condra, G.E., 1933: The nautiloid cephalopods of the Pennsylvanian System in the Mid-Continent region. Nebraska Geological Survey, Bulletin 9, Second Series, p. 1-240, pls. 1-24. Münster, G., 1841: Beiträge zur Geognosie unt Petrefacten- Kunde des südöstlichen Tirols vorzüglich der Schichten von St. Cassian, Volume 4, 152 p., 16 pls., Buchner, Bayreuth. (not seen) Niko, S., 1990: Early Carboniferous (Visean) cephalopods from the Hikoroichi Formation, southern Kitakami Mountains. Transactions and Proceedings of the Pala- eontological Society of Japan, New Series, no. 159, p. 554-561. Niko, S. and Hamada, T., 1987: Adnatoceras from Middle Carboniferous of the Ichinotani Formation, Fukuji district, Central Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 148, p. 223-227. Niko, S., Nishida, T. and Kyuma, Y., 1987: Middle Carbonifer- ous Orthoceratidae and Pseudorthoceraceae (Mollusca: Cephalopoda) from the Akiyoshi Limestone, Yamaguchi Prefecture (Molluscan paleontology of the Akiyoshi Limestone Group-VIll). Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 148, p. 335-345. Niko, S., Nishida, T. and Kyuma, Y., 1991: Middle Carboniferous Bactrioidea (Mollusca: Cephalopoda) from the Akiyoshi Limestone Group, Yamaguchi Prefecture (Molluscan Paleontology of the Akiyoshi Limestone Group-X). Transactions and Proceedings of the Pala- eontological Society of Japan, New Series, no. 161, p. 714-719. Niko, S., Nishida, T. and Kyuma, Y., 1995: A new Carbonifer- ous cephalopod Bogoslovskya akiyoshiensis from Southwest Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 179, p. 193-195. Niko, S., Nishida, T. and Kyuma, Y., 1997: Moscovian (Carboniferous) orthoconic cephalopods from Guizhou and Guangxi, South China. Paleontological Research, vol. 1, p. 100-109. Niko, S. and Ozawa, T., 1997: Late Gzhelian (Carboniferous) to early Asselian (Permian) non-ammonoid cephalopods from the Taishaku Limestone Group, Southwest Japan. Paleontological Research, vol. 1, p. 47-54. Ristedt, H., 1968: Zur Revision der Orthoceratidae. Abhandlungen der Mathematisch Naturwissenschaftli- chen Klasse, no. 4, p. 211-287, pls. 1-5. Schindewolf, O.H., 1933: Vergleichende Morphologie und Phylogenie der Anfangskammern tetrabranchiater Cephalopoden. Eine Studie Uber Herkunft Stammesent- wicklung und System der niederen Ammoneen. Abhandlungen der Preussischen Geologischen Landesanstalt, Neue Folge, no. 148, p. 1-115, pls. 1-4. Shimizu, S. and Obata, T., 1935: New genera of Gotlandian and Ordovician nautiloids. The Journal of the Shanghai Science Institute, Section 2, Geology, Palaeontology, Mineralogy and Petrology, vol. 2, p. 1-10. Sweet, W.C., 1964: Nautiloidea-Orthocerida. In, Moore, R.C. ed., Treatise on Invertebrate Paleontology. p. K216- K261. The Geological Society of America and the University of Kansas Press. Whiteaves, J.F., 1898: On some additional or imperfectly un- derstood fossils from the Hamilton Formation of Ontario, with a revised list of the species therefrom. Geological Survey of Canada, Contributions to Canadian Paleontology, vol. 1, p. 361-427, pls. 48-50. Woodward, S.P., 1856: On an Orthoceras from China. The Quarterly Journal of the Geological Society of London, vol. 12, p. 378-381, pl. 6. Zhuravleva, F.A., 1978: Devonskiye ortoserodei, Nadotryad Orthoceratoidea (Devonian orthoceratids, superorder Orthoceratoidea). Akademiya Nauk SSSR, Trudy Paleontologicheskogo Instituta, vol. 168, 223 p. (in Russian) Paleontological Research, vol. 4, no. 4, pp. 261-273, December 30, 2000 © by the Palaeontological Society of Japan Further notes on the turrilitid ammonoids from Hokkaido- Part 1 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXIX) TATSURO MATSUMOTO! and TAKEMI TAKAHASHI’ ‘c/o Kyushu University Museum, Fukuoka 812-8581, Japan *28-109 Hanazono-cho, Mikasa, 068-2124, Japan Received 25 May 2000; Revised manuscript accepted 18 September 2000 Abstract. This paper contains the descriptions of Ostlingoceras (Ostlingoceras) bechei (Sharpe, 1857), O. (O.) aff. bechei, and Neostlingoceras carcitanense (Matheron, 1842), all from the lower Cenomanian of the Mikasa and Kotanbetsu areas; also those of two new species Neostlingoceras asiaticum and N. cobbani from the middle Cenomanian of the Mikasa area. A new genus Hypostlingoceras is established, with descriptions of two new species, H. japonicum (type species) and H. mikasaense, from the lower Cenomanian of the same area. Key words: Carthaginites, Cenomanian, Turrilitidae Introduction Recently ten species of Mariella and a few species of Mesoturrilites, Hypoturrilites and Pseudhelicoceras from the Cretaceous of Hokkaido have been described (Matsumoto et al., 1999; Matsumoto and Kawashita, 1999; Matsumoto and Kijima, 2000; Matsumoto and Inoma, 1999; Matsumoto et al., 2000). Sources of the material for these investiga- tions are collections from the upper Albian and lower Cenomanian of the Soeushinai area of northwestern Hokkaido and the Shuparo and Hobetsu areas of central Hokkaido. In this and succeeding papers additional species of the Turrilitidae are to be described. The material for this paper depends mainly on the collections from the celebrated Ikushunbetsu Valley of the Mikasa area. For a general ac- count of the stratigraphy and the locality data readers may refer to Matsumoto (1991, p. 3-5; 21-24). Supplementary notes may be added to the particular cases concerned. The purpose of our series of papers is to present precisely the systematic descriptions of the turrilitid ammonoids from the Cretaceous Yezo Group of Hokkaido, with confirmation or revision of previously known species and also establish- ment of new taxa. The described species could be useful for biostratigraphic subdivision and interregional correlation. As the faunal characteristics of the subdivided units of the Albian and the Cenomanian in the North Pacific region be- come clearer, the results could improve the knowledge of its palaeogeography and palaeoenvironments. Hypostlingoceras, Neostlingoceras, Ostlingoceras, Repository.—The specimens described in this paper are to be stored in the Kyushu University Museum, Fukuoka, 812-8581, Japan, which is indicated by the letters GK at the head of a register number. To each specimen collected by T. T. a personal number was provisionally given. This num- bering was set in accordance with the date of his field work. Although not official register numbers, they should not be ig- nored, because they are written clearly in red ink on each specimen and because they are tied to his field notes and will enable readers to get useful information. In this paper such numbers are indicated in brackets, as for instance, GK. H8531 [= previous S. 37:7:17] (Figure 1 D-F). Herein S. means Showa, a reign style in Japan and S. 37 = 1962. A few specimens which were housed in the Geological Collections, Faculty of Culture and Education, Saga University, Saga, 840-8502, Japan (abbreviated as GS), are transferred to GK. Systematic descriptions Order Ammonoidea Zittel, 1884 Suborder Ancyloceratina Wiedmann, 1966 Superfamily Turrilitaceae Gill, 1871 Family Turrilitidae Gill, 1871 Genus Ostlingoceras Hyatt, 1900 Subgenus Ostlingoceras (Ostlingoceras) Hyatt, 1900 Type species.— Turrilites puzosianus d’Orbigny, 1842 (p. 587, pl. 143, figs. 1, 2) by original designation (Hyatt, 1900, 262 Tatsuro Matsumoto and Takemi Takahashi p. 587). Diagnosis.—See Wright and Kennedy, 1996, p. 320. Remarks.—Wright and Kennedy (1996, p. 320) treated Parostlingoceras Breistroffer (1953, p. 1350) as a subgenus of Ostlingoceras. No example of O. (Parostlingoceras) has been found in Hokkaido. In addition to O. (O.) puzosianum ten species were assigned to O. (Ostlingoceras) by Wright and Kennedy (1996, p. 321). Moreover, Turrilites cf. colcanapi of Pervinquiére (1910, p. 50, pl. 14, fig. 4) from Algeria was revised to O. (O.) collignoni Wright and Kennedy (1996, p. 340, text-fig. 138E), although it deviates from the normal species of O. (Ostlingoceras) in its larger apical angle. The available material of O. (Ostlingoceras) from Hokkaido is not numerous but fairly good in showing the characters that enable us to define more clearly previously named species. There are a few other indefinite taxa which are temporarily placed in this subgenus. One of them is de- scribed in this paper. Ostlingoceras (Ostlingoceras) bechei (Sharpe, 1857) Figures 1A-C, D-F; 2A, B Turrilites bechei Sharpe, 1857, p. 66, pl. 26, fig. 13 [as bechii on p. 66] Ostlingoceras bechei (Sharpe, 1857). Wright and Wright, 1951, p. 18; Marcinowski, 1970, p. 435, pl. 3, fig. 5; Kennedy, 1971, p. 25 (pars), pl. 8, figs. 9, 13. Ostlingoceras (Ostlingoceras) bechii (Sharpe, 1857). Atabekian, 1985, p. 50, pl. 14, fig. 6. Ostlingoceras (Ostlingoceras) bechei (Sharpe, 1857). Wright and Kennedy, 1996, p. 321, pl. 96, figs. 6, 14-16, 18, 23. Name of the species.—Two names have been used for this single species since Sharpe’s (1857) original paper: Turrilites Bechii in the heading of the description (p. 66) and Turrilites Bechei in the explanation to plate 26, fig. 13a, b. Sharpe noted that the specimen was found by Sir H. T. de la Beche, and that it was named in his memory. We agree with Wright and Wright (1951, p. 18) in regarding T. Bechii as an obvious misprint for T. Bechei. Holotype. — By monotypy, BMNH 88, the original of Sharpe, 1857, pl. 26, fig. 13, from the ‘Cenomanian Lime- stone’ near Lyme Regis, Devon (southern England). Material —GK.H8529 (Figure 1A, B, C), found by Tamotsu Omori near Loc. IK1065b of the Shimo-ichino-sawa, a tribu- tary of the River Ikushunbetsu; GK. H1381 (not figured), ob- tained in 1955 by T. M. at Loc. Ik1065b; GK.H8531 [previous Figure 1. (C) views of GK.H8529; similar views (D, E, F) of GK. H8531. (G) and undeveloped (H) states of GK. H8530; two lateral (I, J) and basal (K) views of GK. H8555. All figures are x2, except for H (x2.5). A-C, D-F. Ostlingoceras (Ostlingoceras) bechei (Sharpe, 1857). G-H, I-K. Ostlingoceras aff. bechei (Sharpe, 1857). Two lateral (A and B, 180° apart) and basal Extracted Photos courtesy of M. Noda (D-F, H) and T. Nishida (others). Notes on the Turrilitidae-Part 1 263 Table 1. Measurements of Ostlingoceras (O.) bechei (Sharpe). Specimen NW Hp Ht D ap h d h/d R r/h GK. H8529 5 38.0 58.0 17.5 20° 7.4 13.8 0.54 32 6-7 GK. H8531 5 27.0 40.0 12.5 232 6.1 11.5 0.53 30 6 BMNH88 4 50.0 75.0 29.8 20° 11.5 Pls) 0.53 = U/ NW = number of the preserved whorls, Hp = total height of the preserved whorls, Ht = total shell height from the preserved last whorl to the estimated apex, D = diameter of the preserved last whorl, ap = estimated apical angle, h = height of an exposed outer face [= flank] of a late whorl, d = diameter of the same whorl, R = number of ribs on the same whorl, r/h = number of ribs in the interval equal to h. Linear dimension is in mm. S. 37-7-17] (Figure 1D, E, F), collected by T. T. in 1962 at a locality on the Onkonosawa, a branch of the River Ponbetsu, which is a major tributary of the River Ikushunbetsu. Description.—The two illustrated specimens preserve five whorls but are dissimilar in size. Their dimensions are shown in Table 1. As the youngest part is lacking, the api- cal angle is estimated from the preserved part. It is fairly low but seems to vary to some extent between individuals (20°-23°). The shell is turreted, sinistral, and the whorls are tightly in contact. The outer exposed whorl face is rounded, and its main part (= flank) is gently inflated and has a weak shoulder on its upper margin. Transverse ribs are numerous, some- what prorsiradiate, and moderately distinct. They are much weakened at (or interrupted by) a shallowly concave, narrow spiral zone in the lower part of the flank. They may be faintly swollen above this zone, showing sinuous curvature. Still lower, parallel to the lower whorl seam, there are two rows Of spirally elongated tubercles, that correspond in num- ber to the transverse ribs. The two rows tend to form nar- row ridges, with an intervening, narrow groove between them. The lower ridge runs along the lower whorl seam. In other words it forms the outer outline of the basal surface, where the ribs extend to run with an anteriorly convex curva- ture to the narrow umbilicus. On the marginal part of the basal surface close to the second row of clavate tubercles there is another (i. e., fourth) row of small tubercles resting on the basal ribs. The number of ribs seems to vary to some extent with growth and also between individuals. Where the shelly Figure 2. A, B. Ostlingoceras bechei (Sharpe, 1857). layer is preserved the ribs are more distinct than on the inter- nal mould. In the preserved last part of GK. H8529, the largest speci- men of the three, a few ribs tend to strengthen and curve more markedly than the other ones (Figure 1B, C). This could be inferred as flaring near the peristome, although the interpretation is uncertain. Septal sutures are exposed on some parts of the flank, showing a fairly broad E-L saddle, L, and a narrower L-U saddle. These elements show minor incisions (Figure 2). Comparison.—The specimens from Hokkaido are essen- tially similar to the holotype and other specimens from the ‘Lower Chalk’. GK.H8529 surprisingly resembles the partly restored illustration of the holotype (Sharpe, 1857, pl. 26, fig. 13). Actually the holotype was in part enclosed by rock ma- trix, when one of us (T. M.) examined it at the Natural History Museum, London. Its characters are, however, well ex- pressed by Sharpe’s figure. The differences from the two il- lustrated specimens from Hokkaido are in the somewhat larger size and more delicate ribbing of the holotype. As the shelly layer is not preserved in the British specimen and as the number of ribs tend to increase with growth, the above differences are quite natural and would not invalidate the identification. Discussion.—As described above, GK. H8529 may be al- most adult, whereas the holotype, despite its larger shell, does not show the feature that should occur near the adult apertural end. This may suggest a difference in size. Wright and Kennedy (1996) pointed out the presence of size dimorphs in many species of the Turrilitidae, although they did not discuss this problem with respect to O. (O.) bechei. B A: External suture on the-whorl flank of GK. H8531 at h = 4.5 mm. Figure is about x7.5. B: Ditto on the flank of successive whorls of GK. H8529 at h = 4.5 mm and 6.0 mm. Figure is about x 7. Straight line: whorl seam, dotted line: tubercles; E: external lobe; L: lateral lobe; U: umbilical lobe. Drawing by T. M. 264 Tatsuro Matsumoto and Takemi Takahashi Table 2. Measurements of Ostlingoceras (O.) aff. bechei (Sharpe). Specimen NW Hp Ht D ap h d h/d R r/h GK. H8530 6 12.0 13.3 5.5 30° 2.2 5.0 0.44 25 4-5 GK. H8537 5 13.3 16.5 6.2 30° 3.0 6.2 0.48 27 5 Legend as for Table 1. In fact, the available specimens are not numerous enough to determine whether the size difference mentioned above is an indication of individual variation or implies dimorphism. The question is left for further investigation. Occurrence.—As for material. On the basis of the loca- tion, lithology and associated species, the described three specimens came from the lower part of the Member IIb of the Mikasa Formation and are of early Cenomanian age. Distribution. — Ostlingoceras (O.) bechei has been re- ported to occur in the lower Cenomanian of England, Poland and Azerbaidjan (see Wright and Kennedy, 1996, p. 322). Its occurrence in Hokkaido of the North Pacific region sug- gests a more extensive distribution of this species. Ostlingoceras (Ostlingoceras) aff. bechei (Sharpe, 1857) Figure 1G, H; I-K Material. — Two small specimens: GK.H8530 (Figure 1G, H) collected by T. M. at Loc. IK1065b of the Shimo-ichino- sawa, a tributary of the River Ikkushunbetsu; GK. H8555 [= previous GS.G058] (Figure 11, J, K) collected by Tamio Nishida and T. M. at Loc. R735 pl in the upper reaches of the River Oku-futamata, a branch of the River Kotanbetsu (see Nishida et al., 1993, fig. 1 for the location). The second specimen is probably derived from the upper part of the lower Cenomanian on the basis of its location and associ- ated /noceramus cf. virgatus Schlüter. Description.—These two specimens are generally similar to the typical specimens of Ostlingoceras (O.) bechei (Sharpe, 1857) described above, but the young part, at the same size as the former, is lacking or poorly preserved in the latter. As is shown in Table 2, the estimated apical angle is somewhat larger and the ribs are less numerous and seem to be relatively coarser and shorter in the former in compari- son with the latter. Moreover, the preserved earliest whorl (diameter = 1.3 mm in GK. H8530) shows an inflated flank. Tentatively, we call this taxon Ostlingoceras (O.) aff. bechei (Sharpe), although the above difference might imply a change with growth in ©. (O.) bechei. It seems to resemble the taxon from Germany which was described under ‘O. (O.) aff. bechif by Lehmann (1998, p. 37, without figure), but as we have not examined the actual specimen, we hesitate to confirm the identity. Genus Neostlingoceras Klinger and Kennedy, 1978 Type species.— Turrilites carcitanensis Matheron, 1842 -(p. 267, pl. 41, fig. 4) by original designation (Klinger and Kennedy, 1978, p. 14). Diagnosis.—Sinistrally coiled turrilicone, with low apical angle (less than 20°) and roughly flat flank of the whorl; or- namented by coarse tubercles in an upper row and more nu- merous finer tubercles in lower 2 or 3 approximated or coalesced rows, with a shallowly concave zone below the upper row; faint transverse riblets may extend upward and/- or downward and scarcely cross the concave belt. Siphuncle runs along the upper shoulder or still higher im- mediately below or along the upper whorl seam, depending on the species. Discussion.—The type species and its allied species N. oberlini (Dubourdieu, 1953) have been regarded as being well defined. The available specimens are, however, mostly fragmentary, without showing the details of the early growth stage or those of the last stage. The origin of this genus has been sought in Ostlingoceras (Klinger and Kennedy, 1978, p. 15). In addition to the above two species from the lower Cenomanian, Cobban and Hook (1981) and Cobban et al. (1989) described five species from the middle and upper Cenomanian of New Mexico, of which one species, N. virdenense Cobban, Hook and Kennedy, occurs also in the upper Cenomanian of England (Wright and Kennedy, 1996). Furthermore, there are two new species (described below) in the middle Cenomanian of Hokkaido. Some of these species are represented by very small specimens, as shown by N. procerum Cobban, Hook and Kennedy, 1989 (p. 60, figs. 62, 95, O, P) and N. asiaticum sp. nov. (to be estab- lished below). They are, in their early growth stage, very similar to Carthaginites kerimensis (Pervinquiére, 1907) (p. 101, pl. 4, figs. 18, 19) or C. krorzaensis Dubourdieu, 1953 (p. 66, pl. 4, figs. 49-52). Hence, the question might arise that Neostlingoceras is a junior synonym of Carthaginites. Until the characters of the later growth stages in Carthaginites can be made clear, Neostlingoceras should be used in accordance with the current difinition. Occurrence.—The genus has been recorded to occur in the Cenomanian of France, England, Germany, Poland, Romania, Turkmenistan, Kazakstan, Iran, Israel, Tunisia, Algeria, Madagascar, South Africa, New Mexico, Colorado, Wyoming, Texas and Japan. Although the type species and its allied species occur characteristically in the lower Cenomanian, other species are recorded from the middle and upper parts of the Cenomanian. Neostlingoceras carcitanense (Matheron, 1842) Figure 3A-C, D-F Turrilites carcitanensis Matheron, 1842, p. 261, pl. 41, fig. 4; Fabre, 1940, p. 242, pl. 5, fig. 7. Turrilites morrisii Sharpe, 1857, p. 65 (pars), pl. 26, figs. 4, 6-7. Hypoturrilites carcitanensis (Matheron). Kennedy, 1971, p.59 (pars), pl. 6, figs. 1, 2, 4-6, 9, 10. Notes on the Turrilitidae-Part 1 265 Figure 3. A-C, D-F. Neostlingoceras carcitanense (Matheron, 1842). Two lateral (A and B, 180° apart) and basal (C) views of GK. H8534, without whitening; similar views (D, E, F) of the same specimen with whitening. x1. Photos courtesy of M. Noda (A-C) and T. Nishida (D-F). Turrilites (Hypoturrilites) carcitanensis (Matheron). Immel, 1979, p. 635, pl. 4, fig. 1. Neostlingoceras carcitanense (Matheron). Klinger and Kennedy, 1978, p. 15 (pars), pl. 3, fig. G; Wright and Kennedy, 1996, p. 326, pl. 99, figs. 1-7, 9-15, 18, 19, 22; pl. 100, fig. 8; text-fig. 140B (with full synonymy). Holotype.—By monotypy, the original of Matheron, 1842, pl. 41, fig. 4. We have not seen the specimen, which seems to be fragmentary as shown by Fabre’s (1940, pl. 5, fig. 7) reillustration. The type locality is in southern France. Its present repository is uncertain (see Wright and Kennedy, 1996, p. 327). Material.—GK. H8534 [= previous S. 40-8:15] (Figure 3A-C, D-F), collected by T. T. in 1965 at Loc. Ik1054 below the bridge called ‘Katsura-Ohashi’. It was found in the dark green silty fine-grained sandstone of the Zone of Mantelliceras japonicum. Another crushed specimen, GK. H8556, was found by T. M. at Loc. R82 of the Soeushinai- Kontanbetsu area (for the location see Matsumoto and Okada, 1973, fig. 7). It was from the mudstone in the lower part of the Member My5. One of us (T. M.) examined the specimens from England (see above synonymy) at the Natural History Museum, London to compare them with ours. Description.—Six continuous whorls are preserved in GK. H8534, which is 47 mm high altogether and 15.6 mm in di- ameter of the last whorl. The ratio of height to diameter in the exposed part of each whorl is roughly 5:9. The apical angle estimated from the preserved part of the shell is as low as 13°. The early part of the shell is lacking. Each whorl is ornamented by an upper row of larger tuber- cles, 13 to a whorl, and a lower row of smaller, double tuber- cles 18 or 19 per whorl, above the lower whorl seam. The upper tubercle is pointed at the top and its base is bullate upward, whereas a concave spiral zone runs at about the carcitanense External suture of GK. H8534 on the flank at h = 7.8 mm. Figure is about x5.5. Symbols as for Figure 2. Drawing by T. M. Figure 4. Neostlingoceras (Matheron, 1842). 266 Tatsuro Matsumoto and Takemi Takahashi midflank immediately below the row of major tubercles. The double tubercle of the lower row consists of a small subrounded upper one and rather clavate lower one which are closely set. Some of the upper ones are bullate up- ward, whereas the lower ones form the outer edge of the basal surface. The suture is exposed on a part of the flank, showing L in the middle part of the flank, with saddles on either side of L. They are moderately incised at the middle growth stage (Figure 4). Remarks.—When the genus Neostlingoceras was intro- duced, Klinger and Kennedy (1978, p. 15) considered that N. carcitanense (Matheron, 1842) is so variable that N. oberlini (Dubordieu, 1953) and some others were within its variation or might be subspecies in a successive sequence. Such an interpretation has been recently denied by Wright and Kennedy (1996, p. 327-328), with whom we agree. Comparison.—The described specimen shows clearly the morphological characters of this species. It quite well re- sembles a specimen called SAS SM (Klinger and Kennedy, 1978, pl. 3, fig. G) from the Mzinene Formation, Ceno- manian Il, of the Skoenburg, Zululand. Occurrence.—As for material. This species marks the basal zone of the Cenomanian in England, but it occurs in the beds of the next and still higher levels in Hokkaido. Neostlingoceras asiaticum sp. nov. Figures 5 A-C, D-F, G-l; 6 Material.—Holotype is GK. H8536 [= previous S. 36-8-26] (Figure 5A, B, C) collected by T. T. in 1961 at Loc. Ik1103 from the middle part of the Cenomanian in the Mikasa area on the western wing of the Ikushunbetsu anticline. Two other specimens (paratypes) are GK. H8537 [= previous S. Figure 5. A-C, D-F, G-I. Neostlingoceras asiaticum, sp. nov. Two lateral (A and B, 180° apart) and basal (C) views of GK. H8536 (holotype). Similar views (D, E, F) of GK. H8537 and ditto (G, H, |) of GK.H8538. J-L. Neostlingoceras cobbani sp. nov. of M. Noda. Two lateral (J and K, 180° apart) and basal (L) views of GK. H8535 (holotype). Figures are all x3. Photos courtesy Notes on the Turrilitidae-Part 1 267 Table 3. Measurements of Neostlingoceras asiaticum sp. nov. Specimen NW Hp Ht D ap h d h/d il; t GK. H8536 745 28.0 45.3 10.0 13° 3.8 8.7 0.44 15 30 GK. H8537 6+a 14.2 21.0 4.7 14° 2.2 4.7 0.47 — — GK. H8538 7 16.2 26.0 5.3 1152 2.5 5.5 0.48 16 32 T = number of upper tubercles, t = number of lower tubercles, 6 + a= somewhat over 6. See Table 1 for other abbreviations. Figure 6. Neostlingoceras asiaticum sp. nov. External suture on the flank of two successive young whorls of GK. H8537 at h = 1.4 mm and 1.9 mm. Figure is about x16. Symbols as for Figure 2. Drawing by T. M. 55-3-10A] (Figure 5D, E, F) and GK. H3538 [= S. 55:3: 10B] (Figure 5G, H, I) collected by T. T. in 1980 at the type locality (Ik1103). This locality belongs to the Abunance Zone of Calycoceras (Newboldiceras) asiaticum. Diagnosis.—Shell slender with a low apical angle; whorl at early growth stage rather flat-sided, with rounded upper shoulder and shallow groove at midflank. Later, blunt nodes are developed on the upper shoulder and numerous minute tubercles are aligned along the lower edge of the flank. Suture fundamentally similar to that of Ostlingoceras (O.) bechei, but apparently simple on account of the small size of the shell (Figure 6). Description.—The three specimens are all small as shown in Table 3. They preserve the shell layer for the most part. In GK.H3537, the smallest specimen, the suture is well shown at its preserved middie stage (2.3 mm in whorl height). It is rather simple, but the elements (L and the sad- dies on either side) exposed on the next whorl show more clearly minor indentations. L is situated on the concave zone of the midflank. The holotype is the largest of the three specimens. Its earlier part is lacking. If its preserved last part be assumed to reach a part of the last whorl, the restored outline of the shell would be roughly 45 mm in height. In every specimen the whorl junction is clearly impressed. The ratio of height to diameter in each whorl is low (less than 0.5). A gradual change of ornament with growth is evidently shown by the holotype. Two paratypes generally follow the holotype in this regard. In young whorls a shallow and narrow, spiral groove runs at about the midflank and a low, spiral elevation above the groove forms a rounded shoulder in the upper part of the flank. In the next step of growth, the upper elevation is faintly un- dulated and the lower edge of the whorl has numerous, tiny tubercles. Soon this is followed by broadening of the upper elevation on which bluntly raised and upward bullate nodes are developed. The spiral groove below the upper elevation is somewhat shifted downward from the midflank and nu- merous small tubercles become distinct on the lower edge. The upper tubercles are 15 or 16 per whorl and the lower ones are twice as numerous as the upper ones. Both tuber- cles become gradually distinct with growth and a short riblet extends upward from each of the lower tubercles. Finally on the preserved last whorl narrow transverse ribs run obliquely downward (i. e., adorally) from some of the upper tubercles. Underneath the row of lower tubercles there is a train of narrowly clavate tubercles, which defines the margin of the basal surface of the whorl. Comparison.—This species is unique among the nine species of Neostlingoceras in that its younger part is similar to Carthaginites krorzaensis Dubourdieu, 1953 (p. 66, pl. 4, figs. 49-52, text-fig. 20), from the upper Cenomanian of eastern Algeria, also to C. cf. krorzaensis, from the upper Cenomanian of England (Wright and Kennedy, 1996, p. 361, pl. 98, fig. 11), whereas its later whorls show the general characters of Neostlingoceras. The present species somewhat resembles N. bayardense Cobban, Hook and Kennedy, 1989 (p. 60, figs. 95R, 96R), from the Zone of Calycoceras canitaurinum in New Mexico, but the latter has a still lower apical angle (11°), distinctly flatter flank and finer and more numerous tubercles in the upper row. N. procerum Cobban, Hook and Kennedy, 1989 (p. 60, figs. 62, 95 O-Q, S), from the upper Cenomanian Metoicoceras mosbyense Zone in New Mexico, is also simi- lar to the younger part of the present species. Its shell is, however, more slender with a lower apical angle (10°). In later growth stages the nodes in the upper row are more dis- tinct and coarser in N. asiaticum. It should be noted that transverse ribs occur at the late growth stage in both spe- cies. Occurrence.—As for material. It should be noted that the present species is fairly close in geological age to N. bayardense mentioned above. Neostlingoceras cobbani sp. nov. Figure 5J-L Material.— Holotype, designated herein, is GK. H8535 [= previous S.36-3-28] (Figure 5J, K, L), collected by T. T. in 1961 at loc. Ik1103 of Nishikatsurazawa, from the middle Cenomanian part of the Mikasa Formation on the western wing of the Ikushunbetsu anticline. At present it is the sole available material for this rare but noteworthy species. Specific name.—In honor of William A. Cobban, who has 268 Tatsuro Matsumoto and Takemi Takahashi Table 4. Measurements of Neostlingoceras cobbani sp. nov. Specimen NW Hp Ht D GK. H8535 6+a 20.0 25.5 8.8 20° 3.5 7.5 0.47 10 25 Abbreviations as for Table 3. made a remarkable contribution to palaeontology and biostratigraphy. Diagnosis.—A species of Neostlingoceras that shows a comparatively less acute apical angle for the genus, dis- tantly disposed and rather bluntly elevated tubercles of the upper row, shallower concave zone at midflank and numer- ous, small tubercles of the lower row. Small size of the shell appears to be diagnostic, but is not necessarily definite. Description.—This specimen preserves six whorls, but its very apex and late whorls are unpreserved. It is small, as shown in Table 4, although the true size of the completely preserved original shell is not known. The proportion of height to diameter of each whorl is less than 0.5. The apical angle as estimated from the preserved part of the shell is 20°. The upper part of the outer exposed whorl face slopes down to the upper row of tubercles where a shoulder is formed. The tubercles of this row are distant and not nu- merous; 10 per whorl on average. Each of them is a bluntly pointed node which is broadened but lowered upward. A shallowly concave spiral zone runs below the upper row of major tubercles. Minor tubercles of the lower row are nu- merous, 25 per whorl. They are arranged in a single row immediately above the lower whorl seam, but each of them seems to be double, as it is granular in lateral view but is rather clavate in lower view, forming the outer edge of the lower face of the whorl. In other words the lower tubercles may be those of united 2nd and 3rd rows. Sometimes faint riblets may extend upward from the lower tubercles across the concave zone below the row of major tubercles. On the lower face of the whorl ribs are scarcely discernible. The suture is not well traced. The preserved last whorl is still septate, showing minor indentation on the lobes of L, U and adjacent saddles. Comparison.—Although the specimen is small, it shows the generic charcters of Neostlingoceras. It is distinguished from N. carcitanense by the diagnosis (see above). Although the ratio of height to diameter of each whorl may vary to some extent within a species, it is generally smaller in the present species than in the cases of N. carcitanense, N. oberlini and also N. kottlowskii Cobban and Hook, 1981 (p. 26, pl. 4, figs. 1-28; Cobban, 1984, p. 17, pl. 4, fig. 9; Cobban et al., 1989, p. 60, fig. 95 A-F). N. kottlowskii is closer in geological age to the present species than the other two. Occurrence and distribution.—As for material; unique at present. Genus Hypostlingoceras nov. Type species.—Hypostlingoceras japonicum sp. nov. (de- scribed below). Figure 7. A, B. Hypostlingoceras japonicum gen. et. sp. nov. Lateral (A) and basal (B) views of GK.H8542 (holotype). are x2. Photos courtesy of M. Noda. Figures Notes on the Turrilitidae-Part 1 269 Diagnosis. —Turrilitid ammonoids which show peculiar change of characters with growth. Whorls in early growth stages have coarse or strong tubercles at about the midflank and numerous, minute tubercles in at least two lower rows. Sooner or later the tubercles at midflank gradually weaken and become sparse, whereas transverse ribs intervene be- tween the tubercles. Finally the midflank tubercles disap- pear, while numerous transverse ribs predominate, and thus the ornamentation as well as the whorl shape becomes quite similar to that of Ostlingoceras. Discussion.—On account of its more or less slender shell shape and small size, this genus resembles Neostlingoceras rather than Hypoturrilites in its youth. In more or less later growth stages it is quite similar to Ostlingoceras. The stage at which the characters of the Neostlingoceras type change to those of the Ostlingoceras type varies to some extent, and the change occurs more or less gradually. Based on the above facts, we presume that Hypostlingoceras may have been derived from Ostlingoceras in parallel with Neostlingoceras. The type specimens are never artificial chimeras. Occurrence.—At present this genus is represented by two species from the lower Cenomanian in the Mikasa area of Hokkaido. More material should be searched for to deter- mine clearly the geological and geographical distribution as well as the phylogenetic relationships of this genus. Hypostlingoceras japonicum sp. nov. Figures 7A, B; 8A-E; 9A-E; 10 Material.—Holotype, designated herein, is GK. H8542 [= previous S. 36-7-25] (Figures 7A, B; 8A, B, C, D, E), col- lected by T. T. in 1961 from the lower part of the Mikasa Formation exposed on the Ganseki-zawa, i. e., the eighth branch of the Kami-ichino-sawa, a tributary of the River Ikushunbetsu. Paratype is GK. H8541 [= previous S. 39- 9-11] (Figure 9A, B, C, D, E) collected by T. T. in 1964 at Loc. 7045 of T. T. in the Suido-no-sawa, a short branch of the River Ikushunbetsu. The beds at the above two locali- ties are referred to the Mantelliceras japonicum Zone, and are early Cenomanian in age. Diagnosis.—Shell shape is slender, with low apical angle, and rather small. Whorls in youth subtrapezoid in lateral view, with square shoulder at midflank where coarse and strong tubercles are disposed at intervals. Then comes a transitional stage, where whorl is subrounded, midflank tu- bercles weaken and extend upward to ribs and additional in- tervening ribs occur. Whorls in later growth stages gently inflated on side and ornamented densely by numerous transverse ribs. Minute tubercles are aligned on the lower two narrow ridges throughout growth. Description.—The two specimens, GK. H8542 and GK. H8541, are much different in size but similar in their slender Figure 8. A-E. Hypostlingoceras japonicum gen et sp. nov. Four lateral (A, B, C, D, successively 90° apart clockwise) and basal (E) views of GK.H8542 (holotype). Figures are x1.2. Photos courtesy of T. Nishida. 270 Tatsuro Matsumoto and Takemi Takahashi Table 5. Measurements of Hypostlingoceras japonicum sp. nov. Specimen NW Hp Ht D ap h d h/d R ili t GK. H8542 8+a 69.0 80.0 20 18° 11.0 19.0 0.58 40 16 30 GK. H8541 7+a 26.5 34.0 8.5 18° 4.2 7.4 0.57 32 15 = Abbreviations as for Tables 1 and 4. T and t are measured on the whorl at 2 volutions earlier than that where h, d, and R are measured. Figure 9. A-E. Hypostlingoceras japonicum gen. et sp. nov. Four lateral (A, B, C, D, successively 90° apart clockwise) and basal (E) views of GK.H8541 (paratype). shell shape with a low apical angle (about 18°) and the pro- portion of the flank height and diameter of each whorl is slightly above 0.5 (see Figures 7-9 and Table 5). The stage characterized by strong midlateral tubercles is manifested by several young whorls in the two specimens, although the youngest part is destroyed or unpreserved. The change in the whorl shape and ornamentation is evident in both speci- mens, but it occurs in the whorl at a diameter of about 15 mm in GK. H8542, whereas it occurs at a diameter of about 5 mm in GK. H8541. An Ostlingoceras-like late stage con- tinues for fully 3 whorls in the smaller specimen (GK. H8541) and for 2.5 whorls in the larger one (GK. H8542). In the larger specimen the longitudinal ribs become denser and more numerous on the whorl of the later growth stage (Figure 8). However, near the preserved last part a few ribs strengthen and markedly curve on the convex basal surface (Figure 7B). However, as the last whorl is partly de- stroyed, we cannot confirm the real peristome. In the smaller specimen the ribs do not become particularly dense and numerous in the preserved last whorl. They curve rather moderately on the convex lower surface (Figure 9). Almost throughout growth, in both specimens, small tuber- cles are aligned in two rows on the narrowly raised ridges which are separated by a narrow groove. At first these minor tubercles correspond in number and disposition to the major ones, but soon they become more numerous and clavate. These two rows of minor tubercles correspond to Figures are x2. Photos courtesy of M. Noda. Figure 10. Hypostlingoceras japonicum gen. et sp. nov. External suture of GK. H8541 (paratype) on the preserved last whorl ath = 5 mm and d = 8.2 mm. Figure is about x9. Symbols as for Figure 2. Drawing by T. M. the second and third rows in certain species of Ostlingoceras (Ostlingoceras). The second row forms the lower edge of the flank and the third row runs along the lower whorl seam. In the early stages there is a concave spiral zone below the subangular zone of strong tubercles. In the transitional and later stages, the concave zone shifts downward and the ribs have more or less weakened smaller tubercles above this zone. These minor tubercles may be so reduced that they may be sometimes expressed as faint swellings. The ribs extend further to run across the concave zone with gen- tle sinuosity and weakening and are connected with minor tubercles of the second row. In addition to the tubercles of Notes on the Turrilitidae-Part 1 271 Figure 11. A-E. Hypostlingoceras mikasaense gen. et sp. nov. Four lateral (A, B, C, D, successively 90° apart clockwise) and basal (E) views of GK.H8540 (holotype). Table 6. Measuremenis of Hypostlingoceras mikasaense sp. nov. All figures are x 2.1. Photos courtesy of T. Nishida (A-C) and M. Noda (D, E). Specimen NW Hp Ht D ap GK. H8540 6 26.0 32.0 13.0 30° Abbreviations as for Table 5. the third row, those of the fourth row may be discernible on some ribs of the basal surface. A septal suture is observed on the preserved last whorl of the smaller specimen (see Figure 10). Discussion.—The specimen, OM.II-497, illustrated as Turrilites cf. costatus Lamarck’ by Ikegami and Omori (1957, pl. 14, fig. 3), from their Unit MK1 (= Member Ilb of Matsumoto, 1965, fig. 4; 1991, p. 22-24), was listed under Ostlingoceras (O.) aff. colcanapi (Boule, Lemoine and The- venin, 1907) by Wright and Kennedy (1996, p. 323). Its fig- ure shows, however, a more slender shell shape with a lower apical angle and its younger whorls have a row of coarse tubercles at about midflank. It is probably another example of this species. Regrettably, the original specimen is missing at present. Occurrence.—As for material. ‘ Hypostlingoceras mikasaense sp. nov. Figure 11A-E Material.—Holotype is GK. H8540 [= previous S. 51:74] (Figure 11A, B, C, D, E), collected by T. T. in 1976 at a local- ity on the northeastern rivulet [‘Migimata’] of the Ganseki- zawa, i. e., the eighth branch of the Kami-ichi-no-sawa, a tributary of the River Ikushunbetsu. The exposed rock of the type locality is referred to the Mantelliceras japonicum Zone of the Mikasa Formation. Diagnosis. — Shell small, with a moderate apical angle, about 30° as estimated from the preserved part. Whorls in Figure 12. Hypostlingoceras mikasaense gen et sp. nov. External suture of a young stage at h = 4.2 mm. Figure si about x9.5. Symbols as for Figure 2. Drawing by T. M. youth subtrapezoid in lateral view with shoulder at about the midflank, where coarse and strong tubercles are aligned. Change of ornament at transitional growth stage generally follows that of the type species. Later whorls show moder- ately to gently convex flanks and ornamentation like that of Ostlingoceras (O.) bechei (Sharpe, 1857). Description.—The holotype consists of about 6 whorls, but its apical part is lacking. The preserved part of the shell is 26 mm high and its diameter at the last whorl is 13 mm. The apical angle estimated from the preserved part of the shell is about 30°. Whorls are tightly in contact, with a fairly deeply impressed junction. The ratio between flank height and diameter in each whorl is about 0.45 (see Table 6). 272 Tatsuro Matsumoto and Takemi Takahashi The shape of a young whorl in lateral view is trapezoid, with an angular shoulder at about the midflank, where strong tubercles are aligned at moderate intervals, numbering 12 per whorl. Another row of smaller tubercles runs on a nar- row ridge slightly above the lower whorl seam. On the pre- served first whorl these lower tubercles are fairly coarse and correspond in number and disposition to the upper tuber- cles. Soon the upper strong tubercles are bullate and the lower tubercles become finer and tend to be clavate. In the transitional stages the upper tubercles are weak- ened, transversally elongated and distantly arranged, whereas a few nodeless ribs occur in the intervening space. The minor tubercles on the lower spiral ridge are disposed approximately on the extension of the elongated tubercles and intervening ribs. Throughout the above-described stages there is another row of clavate tubercles along the lower whorl seam. There is a narrow but distinct spiral groove between the two lower rows of minor tubercles. In the late stages, including the late transitional substage, the whorl develops a more rounded shape, showing a gently convex flank. It is ornamented by numerous transverse ribs, numbering 32 in the preserved last whorl. Above the second row of minor tubercles there is a shallowly concave spiral zone. The ribs run across this concave zone with slight weakening and sinuousity. In the preserved last whorl the third row of minor tubercles is not clavate but ele- vated at the markedly curved point of the ribs on the mar- ginal part of the basal surface. Some of the tubercles seem to be doubled, suggesting incorporation of the remnants of the tubercles of the fourth row (Figure 11E). The ribs ex- tend further toward the narrow umbilicus with a gentle curva- ture. The septal suture is partly exposed on the flank of a rather young whorl, showing half of E, the E-L saddle, entire L and a part of the L-U saddle. L is situated on the concave zone below the upper row of the tubercles. These elements are indented (Figure 12). Comparison.—With respect to the general change of char- acters with growth, this species is assigned to the genus Hypostlingoceras. It is distinguished from H. japonicum in having a larger apical angle, smaller ratio of h/d in each whorl, stronger midflank tubercles in youth and somewhat coarser and less numerous ribs on the later whorls. The whorls of this species in late growth stages are fairly similar to Ostlingoceras (Ostlingoceras) bechei (Sharpe) in shell shape and ornamentation, although this does not nec- essarily imply a direct phylogenetic relationship. Occurrence and distribution.—As for material. At present this species is known solitarily in the lower part of the Cenomanian of Hokkaido. Acknowledgments Tamotsu Mori generously provided the specimens of his collection for this study. Tamio Nishida helped us in various ways. C.W. Wright, W. A. Cobban and W. J. Kennedy dis- cussed various points with one of us (T. M.). Masayuki Noda photographed the majority of the specimens. Kazuko Mori assisted us in preparing the manuscript. Two anony- mous referees helped us to improved the manuscript. We thank all of these persons for their kindness. References Atabekian, A. A., 1985: Turrilitids of the late Albian and Cenomanian of the southern part of the USSR. Academy of Sciences of the USSR, Ministry of Geology of the USSR, Transactions, vol. 14, p. 1-112, pls. 1-34. (in Russian) Boule, M., Lemoine, P. and Thévenin, A., 1907: Céphalopod- es crétacés des environs de Diégo Suarez. Annales de Paléontologie, vol. 2, p. 1-58, pls. 1-8. Breistroffer, M., 1953: L’evolution des Turrilitides albiens et cénomaniens. Compte Rendus Hebdomadaires des Sciences de l'Académie des Sciences, vol. 237, p. 1349-1351. Cobban, W. A., 1984: Molluscan record from a mid- Cretaceous borehole in Western County, Wyoming. U. S. Geological Survey, Professional Paper, no. 1271, p. 1-24. Cobban, W. A. and Hook, S. C., 1981: New turrilitid ammonite from the mid-Cretaceous (Cenomanian) of southwestern New Mexico. New Mexico Bureau of Mines and Mineral Resources, Circular 180, p. 22-29. Cobban, W. S., Hook, S. C., and Kennedy, W. J., 1989: Upper Cretaceous rocks and ammonite faunas of southwestern New Mexico. New Mexico Bureau of Mines and Mineral Resources, Memoir 45, p. 1-137. Dubourdieu, G., 1953: Ammonites nouvelles des Monts du Mellegue. Bulletin du Service de la Carte Géologique de l'Algérie. 1re Série, Paléontologie, no. 16, p. 1-76, pls. 1-4. Fabre, S., 1940: Le Crétacé supérieur de la Basse-Provence occidentale. 1. Cenomanien et Turonien. Annales de la Faculté de Sciences de Marseille, série 2, vol. 14, pl 1- 355, pls. 1-10. Gill, T., 1871: Arrangements of the families of Mollusks. Smithsonian Miscellaneous Collections, no. 227, p. i-xvi, 1-49. Hyatt, A., 1900: Cephalopoda, /n, Zittel, K. A. : Text book of Palaeontology, 1st English edition translated by C. R. Eastman, p. 502-592. Macmillan, London and New York. Ikegami, S. and Omori, T., 1957: On the so-called “Mikasa Formation” in the Katsurazawa-dam site area near the Ikushunbetsu River, Mikasa, Hokkaido. Journal of the Hokkaido Gakugei University, ser. 2, vol. 8, no. 1, p. 70- 89, pls. 1-14. (in Japanese with English explanation of plates) Immel, H., 1989: Cenoman-Ammoniten aus den Losensteiner Schichten der Bayerischen Alpen. /n, Wiedmann, J., ed., Aspekte der Kreide Europas. International Union of Geological Sciences, ser. A, no. 6, p. 607-644, pls. 1-4. Schweizerbartische Verlagsbuchhandlung, Stuttgart. Kennedy, W. J., 1971: Cenomanian ammonites from southern England. Special Papers in Palaeontology, vol. 8, p. 1- 133, pls. 1-64. Klinger, H. C. and Kennedy, W. J., 1978: Turrilitidae (Cretaceous Ammonoidea) from South Africa, with a dis- cussion of the evolution and limits of the family. Journal of Molluscan Studies, vol. 44, p. 1-48, pls. 1-9. Lehmann, J., 1988: Systematic palaeontology of the ammo- nites of the Cenomanian-Lower Turonian (Upper Cretaceous) of northwestern Westphalia, north Germany. Tubinger Geowissenschaftliche Arbeiten, Reihe A, vol. Notes on the Turrilitidae-Part 1 37, p. 1-58, pls. 1-5. Marcinowski, R., 1970: The Cretaceous transgressive depos- its east of Czestochowa (Polish Jura Chain). Acta Geologica Polonica, vol. 20, p. 413-449, pls. 1-6. Matheron, P., 1842: Catalogue methodique et descriptif des corps organises fossiles du Departement des Bouche-du- Rhone et lieux circonvoisins, 269 p., 41 pls. Marseille. Matsumoto, T., 1965: A monograph of the Collignoniceratidae from Hokkaido. Part 1. Memoirs of the Faculty of Science, Kyushu University, ser. D, vol. 16, no. 1, p. 1-80, pls. 1-18. Matsumoto, T. (compiled), 1991: The mid-Cretaceous am- monites of the family Kossmaticeratidae from Japan. Palaeontological Society of Japan, Special Papers, no. 33, p. i-vi, 1-143, pls. 1-31. Matsumoto, T. and Inoma, A., 1999: The first record of Mesoturrilites (Ammonoidea) from Hokkaido, Paleontological Research, vol. 3, no. 1, p. 36-40. Matsumoto, T., Inoma, A. and Kawashita, Y., 1999: The turrilitid ammonoid Mariella from Hokkaido-Part 1. Pale- ontological Research, vol. 3, no. 2, p. 106-120. Matsumoto, T. and Kawashita, Y., 1999: The turrilitid ammonoid Mariella from Hokkaido-Part 2. Paleontologi- cal Research, vol. 3, no. 3, p. 162-172. Matsumoto, T. and Kijima, T., 2000: The turrilitid ammonoid Mariella from Hokkaido-Part 3. Paleontological Resear- ch, vol. 4, no. 1, p. 33-38. Matsumoto, T. and Okada, H., 1973: Saku Formation of the Yezo geosyncline. Science Reports of the Department of Geology, Kyushu University, vol. 11, no. 2, p. 275-309. (in Japanese with English abstract) Matsumoto, T., Takashima, R. and Hasegawa, K., 2000: Some turrilitid ammonites from the Cretaceous of the Shuparo Valley, central Hokkaido. Bulletin of the Mikasa City Museum, Natural Science, no. 4, p. 1-13. Nishida, T., Matsumoto, T., Yao, A. and Maiya, S., 1993: Towards the integrated mega- and micro- biostratigraphy on the Cenomanian (Cretaceous) sequence in the Kotanbetsu Valley, Hokkaido, including the C-T boundary problem. Journal of the Faculty of Education, Saga University, vol. 40, no. 3, p. 95-125. (in Japanese with English abstract) Orbigny, A. d’, 1842: Paléontologie française. Terrains cret- aces. 1. Céphalopodes, p. 431-662. Masson, Paris. Pervinquiere, L., 1907: Etudes de paléontologie tunisienne. 1. Céphalopodes des terrains secondaires. Carte Géologi- que de la Tunisie, 438p., atlas (27 pls.). Rudeval, Paris. Pervinquiére, L., 1910: Surquelques ammonites du Crétace algérien. Mémoires de la Sociéte Géologique de Fran- ce, vol. 17, mémoir 42, p. 1-86, pls. 1-7. Sharpe, D., 1857: Description of the fossil remains of Mollusca found in the Chalk of England. Cephalopoda, part 3. Palaeontographical Society, London, 1856, p. 37-70, pls. 17-27. Wiedmann, J., 1966: Stammesgeschichte und System der posttriadischen Ammonoideen, ein Überblick, 1 Teil. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, vol. 125, p. 49-79, pls. 1-2. Wright, C. W. and Kennedy, W. J., 1996: The Ammonoidea of the Lower Chalk, part 5. Monograph of the Palaeonto- graphical Society, London, 1996, p. 320-403, pls. 95- 124. Wright, C. W. and Wright, E. V., 1951: A survey of the fossil Cephalopoda of the Chalk of Great Britain. Palaeontographical Society, London, 1950, p. 1-40. Zittel, K. A. von, 1884: Cephalopoda, In, K. A. Zittel: Handbuch der Paläontologie, vol. 1, p. 329-522, Oldenbourg, München & Leibzig. 273 Ws Ne er Me ie dé Va Fo 8 \ f a) ave L ; ate rs 4 De 4 PET A | " " h à baa 0 ‘ TEA 5 Ware PET AN Der RAT EE { ur eas i ea ONE LE hi eee = Ê PA ‘ i Paleontological Research, vol. 4, no. 4, pp. 275-301, December 30, 2000 © by the Palaeontological Society of Japan Late Paleocene to early Eocene planktic foraminiferal biostratigraphy of the Dungan Formation, Sulaiman Range, central Pakistan MUHAMMAD YOUSAF WARRAICH', KENSHIRO OGASAWARA’ and HIROSHI NISHI? ‘Institute of Geoscience, University of Tsukuba, Tennodai 1-1-1, 305-8571 Japan (yousaf56 @strati.geo. tsukuba.ac.jp; ogasawar @arsia.geo.tsukuba.ac.jp) *Department of Earth Science, Graduate School of Social and Cultural Studies, Kyushu University 4-2-1 Ropponmatsu, Chuo-Ku, Fukuoka, 810-8560 Japan (hnishi@rc.kyushu-u.ac.jp) Received 16 April 1999; Revised manuscript accepted 6 November 2000 Abstract. The Paleogene marine sequences of the Dungan, Shaheed Ghat, Baska and Kirthar Formations are exposed at several places in the Sulaiman fold and thrust belt in central Pakistan. The lowermost Dungan Formation unconformably overlies the open marine Maastrichtian Pab Sandstone, being distributed widely along both limbs of the Zinda Pir Anticline area and in the Rakhi Nala area. The Dungan Formation is composed mainly of black-colored siltstone with some intercalations of sandstone in the base and many interbeds of limestone in the upper part. The strata from all three sections have yielded abundant and well-preserved Paleocene-Eocene planktic foraminifers and about 50 species belonging to nine genera are identified from this sequence. Zones P3 to P7 of the tropical zonal schemes were recognized, furthermore, Zones P3 and P4 are subdivided into two subzones (Subzones A and B), respectively. These assemblages contain a new species Globanomalina rakhiensis in the Rakhi Nala section. A late Paleocene through early Eocene age is assigned to the Dungan Formation. The quantitative data of each species indicates that the Dungan Formation was deposited in a relatively deep to open marine environment, proba- bly forming a continental slope dipping from east to west. Key words: Biostratigraphy, Dungan Formation, Pakistan, Paleocene-Eocene, paleoenvironment, planktic foraminifera, Sulaiman Range Introduction A Mesozoic to Paleogene sedimentary sequence is widely exposed along the northwestern margin of the Indian Subcontinent in central Pakistan. These strata were depos- ited during the closing of the Tethys Ocean and form several fold-and-thrust belts of over 100 km width along a series of lobes in the Kirthar, Sulaiman, and Salt Ranges from south to north (Cheema et al., 1977; Humayon et al., 1991; Warwick et al., 1998). The Paleogene sequence of the Sulaiman Range which overlies the Mesozoic marine shelf sediments consists of the Paleocene to Eocene Dungan Formation, the early Eocene Shaheed Ghat and Baska Formations, and the middle to late Eocene Kirthar Formation. Latif (1961) and Samanta (1973) reported many Paleocene-Eocene planktic foraminifers and their zonation from the Rakhi Nala section located in the eastern Sulaiman Range (Figure 1). Jones (1997) also showed the age of the Dungan Formation using the planktic foraminifers recovered from three samples from the northern part of the Sulaiman Range. Warraich and Natori (1997) also established the Paleocene-Eocene planktic foraminiferal biostratigraphy on the western side of the Zinda Pir Anticline region, and recog- nized the following nine zones: the Morozovella angulata, Globanomalina pseudomenardii, Morozovella velascoensis, M. subbotinae, M. formosa formosa, M. aragonensis, M. spinulosa/Truncorotaloides topilensis, Catapsydrax howei and Globigerina officinalis zones. However, this biostrati- graphic work is still preliminary and further detailed work is needed for correlation with the recently revised standard zonal schemes of Berggren et al. (1995) and Olsson et al. (1999). The main objectives of this paper are to establish a com- plete biostratigraphic zonation of the Dungan Formation dis- tributed in the Zinda Pir Anticline and the Rakhi Nala regions of the Sulaiman Range, and to correlate zones established in these regions with standard zones of the tropical- subtropical latitudes, and with those recognized in the other 276 Muhammad Yousaf Warraich et al. INDEX MAP OF PAKISTAN Figure B Figure À : - Ne Si te: nat an ays | Hot Spring Zinda Pir Scale (km) Chitarwata Formation +40 Dip & Strike Shaheed Ghat Formation Height (m) Dungan Formation © Locality Barren sample Pab Sandstone Sample containing Alluvial deposit planktic foraminifers Figure 1. Route maps of the Rakhi Nala and the Zinda Pir sections of the eastern Sulaiman Range, central Pakistan. Late Paleocene to early Eocene planktic foraminiferal biostratigraphy regions of the Indus Basin. We also discuss the faunal changes and depositional environment of the Dungan Formation using quantitative foraminiferal data. Materials and methods We carried out systematic sampling along both sides of the Zinda Pir Anticline and in the Rakhi Nala section cover- ing the entire sequence of the Dungan Formation (Figure 1). Some 54 samples (22 samples coded ZPW and 32 samples coded ZPE) were obtained along the western and the east- ern limbs of the Zinda Pir Anticline, and 41 samples (coded R) were collected from the Rakhi Nala section. These sam- ples were collected at 1-to 5-meter intervals. Because siltstone samples were very hard, all samples (each weigh- ing 100g) were first treated with sodium sulfate (Na:So.), and later with tetraphenylborate (NaTPB). The disaggregated samples were washed using a 63 um sieve. Population counts for planktic foraminifers are based on random splits of 200 to 300 specimens. To remove juvenile forms, specimens over 150 um were picked and identified; however, the smaller fractions were also scanned for recog- nition of small-sized species. The faunal reference list is given in Appendix 1. Lithostratigraphy The Paleogene sequences exposed in the Zinda Pir and Rakhi Nala sections of the investigated areas consist of the Dungan and the Shaheed Ghat Formations in ascending order (Figure 1). The Dungan Formation forms the basal part of the Paleogene sequence, unconformably overlying the Maastrichtian Pab Sandstone (Kazmi, 1995, Nomura and Brohi, 1995, this study). Eames (1952) was the first who described the lithostratigraphy of the lower Paleogene strata of both the Zinda Pir and Rakhi Nala areas in detail. He divided this sequence into four lithological units in both areas (Figure 2). Cheema etal. (1977) and Kazmi (1995) summarized his several units and gave the name of the Dungan Formation to the mudstone-dominated sequences. For example, Kazmi (1995) included many lithological units Eames (1952) Rakhi Nala Zinda Pir Upper Rakhi Gaj Shales Lower Rakhi Gaj Shales Gorge Beds Venericardia hale Pab Sandstone Quartzose Sandstone Ghazij Shales Ghazij Fm. Shaheed Ghat Zinda Pir Ls. (upper part Formation Zinda Pir Ls. (lower part) Zinda Pir Shales DunganıEm. Khadro Fm Pab Sandstone|Pab Sandstone 277 defined by many previous workers into the Dungan Formation (Figure 2). We divided the strata distributed in the studied area into three formations according to the lithology of Kazmi (1995). The lowermost strata of the Maastrichtian Pab Sandstone consist of white, cream-to brown-colored, thick- to massive- bedded, medium to coarse-grained quartzose sandstone with intercalations of shale and argillaceous limestone in the study areas. The Dungan Formation overlying the Pab Sandstone represents dark-black colored siltstones inter- beded with hard quartzitic-glauconitic sandstone beds in the lower part and thin-to thick-bedded, dark-gray limestone weathering brown-buff in the upper part. The interbeds of sandstone are abundant in the Rakhi Nala, while those of limestone are common in the Zinda Pir. It is noteworthy that the thickness of the Rakhi Nala section (312 m) is twice that of the Zinda Pir sections (135 m). In the Sulaiman Range, while contact of the Dungan Formation with the overlying Shaheed Ghat Formation is de- scribed as conformable (Cheema et al., 1977; Shah, 1990, Kazmi, 1995). However, we describe this contact as unconformable based on the presence of the conglomeratic to brecciated limestone bed in the lowermost part of the Shaheed Ghat Formation (Figures 3-6). Previous workers (Eames, 1952; Cheema et al., 1977; Shah, 1990, Kazmi, 1995) did not report this conglomeratic to brecciated lime- stone bed. Moreover, this result is also supported by the nonexistence of Zone P6 (Figures 3-6). Thickness of the conglomeratic to brecciated limestone bed is 16 m in the Zinda Pir sections that pinches out at Rakhi Nala. However, in the Rakhi Nala section, there is another conglomeratic to brecciated bed (1 m) which is strati- graphically younger than those of the Zinda Pir sections (Figure 6). This limestone contains shallow marine fossils such as larger foraminifers and bivalves (Vasticardium and Chlamys species) embedded in a calcareous matrix contain- ing a pelagic fauna. Biostratigraphy Among 32 and 22 samples collected from the Dungan Shaheed Ghat Formation Cheema et al. (1977) Dungan N Dungan Formation Formation Pab Sandstone Figure 2. Lithostratigraphic subdivisions and correlation of the early Tertiary strata exposed in the Sulaiman Range pro- posed by different workers. 278 Formation |Columnar| Samples Planktic foraminiferal species Muhammad Yousaf Warraich et al. Shaheed Ghat ee ' ais e—e— M. occlusa o.+- à A. coalingens e R S E G S. velascoensis S. triangularis A. soldadoensis soldadoensi: G. chapmani 4 |. tadjikistanensis vee G. pseudomenardii oe M. conicotruncata € e Morozovella velascoensis IZ ilcoxensis @ igerina wi M. subbotinae TRZ Paleocene lobanomalina seudomenardii er. eee M. apanthesma M. angulata G. ehrenbergi Igorina albeari Igorina pusilla Legend _ ——) Siltstone Pab Sandstone | Conglomeratic- brecciated limestone Eastern side Scale Limestone intercalated with siltstone ® Larger foraminifers Sandstone e Occurrence of planktic foraminifers Ben CSSSLSA Quartzose sandstone Ne Limestone Unconformity Figure 3. Measured columnar section along the eastern limb of the Zinda Pir Anticline showing lithostratigraphic se- quences, sample locations, and biostratigraphic distribution of the recovered planktic foraminifers. samples containing planktic foraminifers. Formation along the eastern and western limbs of the Zinda Pir Anticline, 7 and 11 samples yielded planktic and benthic foraminifers, respectively. The individual specimens of the planktic foraminifers recovered from the western side of the Zinda Pir Anticline are abundant and better preserved than those from the eastern side. Some 30 species belonging to 7 different genera of planktic foraminifers were identified in the Zinda Pir sections (Appendix 3). In the Rakhi Nala section, 16 samples out of 41 yielded abundant and well-preserved foraminifers. The planktic foraminiferal assemblage recovered from this section com- prised 51 species belonging to 10 genera (Appendix 3). Two standard Paleogene zonal schemes have been es- tablished in the low-latitude regions. One is represented by Bolli's zonation and its revisions (Bolli, 1957, 1966; Toumarkine and Luterbacher, 1985). The other one is the P-zonation of Blow (1979) and its modifications (Berggren and Miller, 1988; Berggren et al, 1995). Recently, Berggren and Norris (1997) and Olsson et a/. (1999) have The numbers indicate the published updated versions of the Paleocene P-zonal sys- tem and the phylogeny. The Paleogene fauna recovered from the Dungan Formation included abundant tropical and subtropical indica- tors, suggesting a habitat of tropical-subtropical Tethyan wa- ters. Hence, the Paleogene international zonal schemes proposed by Berggren et al. (1995) and Olsson et al. (1999) are basically applicable to the faunal assemblage of the Dungan Formation (Figure 7). This formation is divided into five biostratigraphic intervals that correspond to Zones P3 to P7 of Berrgren’s zonation (Figure 7). However, we have subdivided Zone P4 of Berggren and Norris (1997) and Olsson et al. (1999) into two subzones instead of three as an extension of the stratigraphic range of A. subsphaerica is re- corded in this region. Moreover, we have used some differ- ent datum levels as boundaries of subzones due to sporadic occurrence of index species in the lower portions of all three sections. Late Paleocene to early Eocene planktic foraminiferal biostratigraphy Columnar | Samples Formation section |(ZPW) Planktic foraminiferal species 279 Shaheed Ghat + © 600 0e 0 000 000000 “0000 + ++ ee — 666 6e + + © A. nitida@ 00 0 4-6 + e A. coalingensis : 0 —— 4 4 — —@ G. chapmani S. velascoensis 00-000 69 A. soldadoensis soldadoensis @—@—@-@ Dungan nl Als wo M. occlusa S. triangularis LA e = = : M. velascoensis eS = e x “s S = SG © Ss — ——a ——-5 ! ] ES = A Western side S. triloculinoides e Eocene | Age M. subbotinae -@ Pseudohastigerina wilcoxensis | @ A. wilcoxensis @ eo. + 00000 |. tadjikistanensis CO + eo @ + + © 'Globanomalina | Morozovella pseudomenardii | velascoensis M. formosa gracilis | @ 00 6 + © ee A. mckannai G. pseudomenardii |« A. subsphaerica Igorina albeari ee: A. strabocella @-@ | M. acutispira @ Paleocene apanthesma Globanomalina pseudomenardii |Z M. conicotruncata G. ehrenbergi I. pusilla Morozovella angulata- M. angulata Parasubbotina varianta gr © e e © Globanpmalina compressa seems Limestone intercalated with siltstone @ ES Limestone Siltstone Conglomeratic-brecciated limestone Be] ® Larger foraminifers oO Unconformity XG Trace fossil Sandstone SLLLLA Quartzose sandstone Occurrence of planktic foraminifers Figure 4. Measured columnar section along the western limb of the Zinda Pir Anticline showing lithostratigraphic se- quences, sample locations and biostratigraphic distribution of the recovered planktic foraminifers. samples containing planktic foraminifers. Paleocene Zones of the Dungan Formation P3. Morozovella angulata/Globanomalina pseudomenar- dii Interval Zone Zone P3 of Berggren and Norris (1997) and Olsson et al. (1999) is defined as the interval zone between the first ap- pearance datum (FAD) of Morozovella angulata and the FAD of Globanomalina pseudomenardii. They also have subdivided Zone P3 into Subzones P3a and P3b using the FAD of /gorina albeari. In this paper, however, we cannot use their subzones because of the sporadic occurrence of /. albeari (Figures 3-5). Instead, we defined two regional subzones as described below, using the FAD of M. acuta. P3A. Morozovella angulata -M. acuta Interval Subzone Definition.—The lower boundary of this zone is not de- fined because of the missing sequence in the Zinda Pir and nonoccurrence of any planktic foraminifers in the Rakhi The numbers indicate the Nala. The upper boundary is placed at the FAD of Morozovella acuta (Figure 4). Occurrence.—This subzone is found restrictedly in the western section of the Zinda Pir Anticline (Figures 1, 4). Planktic foraminifers in this zone are not abundant, with the total number of specimens per sample ranging from 20 to 76 per sample. The rare occurrence of M. angulata is ob- served in Sample ZPW-1, associated with Globanomalina imitata, G. compressa, and Subbotina triloculinoides. Correlation and age.—The FAD of M. acuta is a reliable datum in the tropical regions, being placed within Subzone P3b of Berggren and Norris (1997) and within the Planorotalites pusilla pusilla Zone of Toumarkine and Luterbacher (1985). The other index species of the Dungan Formation is G. compressa, which disappears within Zone P3a of Berggren and Norris (1997). The absence of M. acuta and cooccurrence of M. angulata and G. compressa 280 Muhammad Yousaf Warraich et al. Shaheed r—50 m Zone | Dominance Diversity P-ratio P7 P4B P4A P3B : SSF esgs 0 20 40 60% RES = 1 5 3 SESS SESS i 8 N RSS ROA 9 Dominance BR SRÈ CSSS) | et 2 8 IS 38 4 FOS TY Sy = a9 v : RICH ASRS n Fr 8 gy DEISE: ge SDS Diversity 2 58 Sus s : SL ass 90 96 100 ca SR = 5 cn 58 dsl tı ti S B : NS N P-ratio È = So S 3 IS 2 = I 2 Ss Ss oi à = 3 = à 2 N S 5 Dungan Formation £ La 6 > \ 0 [N Parasub, G. pseudo i =. Ch. trin 7 J LEGEND Rage za! S. tri ar Sy | M. i I. tad, 1 PD Scale a Conglomeratic/ = brecciated limestone ss Limestone — Siltstone Sandstone Quartzose sandstone Larger foraminifers Mollusca Unconformity Ripple mark Trace fossil >77 Cross-bedding Pab Sandstone | (Section-1) Figure 5. Measured columnar section along the Rakhi Nala (river) showing lithostratigraphic sequences, sample locations and biostratigraphic distribution of the recovered planktic foraminifers. In addition, the results of quantitative analysis consisting of dominance (the most abundant species), diversity and foraminifers. the P-ratio are shown in this figure. indicate that Subzone P3A corresponds to the interval from Subzone P3a to the lower part of Subzone P3b of Berggren and Norris (1997) (Figure 7). Hence, the age of Subzone P3A is assigned to the late Paleocene (Selendian). P3B. Morozovella acuta-Globanomalina pseudomenardii Interval Subzone Definition.—The interval of this zone ranges from the FAD of M. acuta to the FAD of the Globanomalina pseudo- menardii. Occurrence.—This subzone is observed in the interval from Samples ZPW-5 to ZPW-16 in the western section of the Zinda Pir Anticline and from Samples R23 to R28 in the Rakhi Nala (Figures 4, 5). Correlation and age.—The dominant faunas of this subzone are Morozovella forms (acuta, apanthesma, occlusa, and velascoensis). These species and another three species (Globanomalina ehrenbergi, Igorina pusilla, and Subbotina triangularis) appear first in Sample ZPW-5 of the Zinda Pir west section and R23 of the Rakhi Nala. This The numbers indicate the samples containing planktic subzone is correlated with the upper part of Subzone P3b of Berggren and Norris (1997), Olsson et al. (1999), and with the P. pusilla pusilla Zone of Toumarkine and Luterbacher, 1985 (Figure 7). The age of this zone is late Paleocene (Selendian). P4. Globanomalina pseudomenardii Total Range Zone The total range of Globanomalina pseudomenardii (Zone P4) is recognized as an excellent stratigraphic marker in many tropical regions (e.g. Bolli and Krasheninnikov, 1977; Toumarkine and Luterbacher, 1985). In the studied sec- tions, the FAD of Globanomalina pseudomenardii has been placed at Sample ZPW-15 in the western section of the Zinda Pir Anticline, and at Sample R25 from the Rakhi Nala (Figures 4, 5). The last appearance datum (LAD) of G. pseudomenardii was observed in all three sections. Samples ZPE-20, ZPW-21 of the Zinda Pir Anticline and Sample R32 of the Rakhi Nala show the LAD of G. pseudomenardii. Some 25 species belonging to five gen- era were identified in this zone. Late Paleocene to early Eocene planktic foraminiferal biostratigraphy 281 Shaheed setae Ghat Fm. ne R-14 ST : = is 5 RE R29 = = 28 | = (Supplimentary — section) Ei een R-23 © | == = : \ Pr oO | €: i E — LZR.22 Je Ss oO : ==) | 2 | DZ 5 —_, —= ln 50 m ey SS — ——— | a: = Be eS SS —— En | Vy ii N = LÉ | = | —— Be Ni = —— 0 — — Scale = = = AT a sy Et — = Ie N SA [7) IT ze GA LT Q ZA 2 Rakhi Nala 2 section Shaheed ht Shaheed Ghat Fm. a ieee | Conglomeratic to brecciated limestone bed taken as the base of the Shaheed Ghat Les Formation 18°, =, 1 7 à D SS Glauconite LS1 À 21 correlation line = Ë 2 S 5 oy) € = 3 = a ee a Zi J N = Zinda Pir ~\_ section \ western side 2 (ZPW) Zinda Pir section eastern side(ZPE) Figure 6. Lithostratigraphic and biostratigraphic correlation between measured columnar sections from the Rakhi Nala and the Zinda Pir area. The numbers indicate the samples containing planktic foraminifers. Berggren and Norris (1997) have used the FADs of A. soldadoensis soldadoensis overlap in the Zinda Pir west Acarinina subsphaerica and A. soldadoensis soldadoensis section and in the Rakhi Nala (Figures 3-5). Olsson et al. to subdivide their Zone P4 into three subzones (P4a, P4b (1999) has demonstrated that the stratigraphic range of and P4c). We cannot apply their definition in this area, be- Acarinina subspaerica may extend upwards, close to Zone cause the stratigraphic ranges of both A. subsphaerica and P4/P5 boundary. Therefore, we used only the FAD of A. 282 Muhammad Yousaf Warraich et al. Berggren et al., 1995; A ¢ à 4 A Berggren & Noriss (1997) International zonal schemes in tropical and subtropical regions c Berggren | Berggren et al.(1995); 8 © [and Miller] Berggren & Noriss (1997); i a 2 | (1988) | Olsson et al. (1999) Pa | M. aragonensis PRZ M. aragonensis / M. formosa formosa CRZ M. formosa formosa M. formosa formosa; orM. lensiformis -M. aragonensis CRZ M. velascoensis - M. formosa formosa ; or M. lensiformis ISZ M. aragonensis (FAD) be M. velascoensis PRZ Ac. soldadoensis/ Gib. pseudomenardii 1SZ M. velascoensis (LAD) 4 Ac. subsphaerica - Ac. soldadoensis ISZ THANETIAN M. subbotinae (FAD) HF Gib. pseudomenardii - Ac. subsphaerica CRSZ Ac. soldadoensis (FAD) H Glb. pseudomenardii TRZ + Gib. pseudomenardii — Paleocene Ig. albeari -Gib. pseudomenardii ISZ SELANDIAN H Ig. albeari (FAD) M. angulata - Ig. albeari 1SZ pseudomenardil |Z Ac, subsphaerica =] = Unrecognized zone Figure 7. Correlation of planktic foraminiferal zones of the studied area with international low latitude zones. Datums Markers Ac. pentacamerata (FAD) H Eastern Sulaiman Range, Pakistan (This Work) Bolli (1957; 1966); premoli Silva & Bolli (1973); Toumarkine & Luterbacher (1985) Blow (1979) M. aragonensis |Z G. (M.) aragonensis / G. (M.) formosa M.formosa formosa |Z M.formosa formosa |Z G. (M.) formosa/ G. (M.) lensiformis : M.subbotinae PRZ ? M.velascoensis |Z Mur. sold. soldadoensis/ G. (M.) velascoensis pasionensis A. sold. soldadoensis- 4BlG. pseudomenardii G. pseudomenardii-A 4|P4Alsold. soldadoensis ISZ G. (G) P. pseudomenardii pseudomenardii Globanomalina pseudomenardii TRZ P. pusilla pusilla M. acuta- G. 3 Globorotalia P3B| pseudomenardii ISZ (M.) angulata M lata . angulata- angulata M. angulata pan M. acuta ISZ M. angulat. G. pseudom- Senardii |Z AAW =Unconformity Here IZ: Interval Zone, TRZ: Total Range Zone, PRZ: Partial Range Zone, CRSZ: Concurrent Range Subzone, ISZ: Interval Subzone. A; Ac: Acarinina, Gib; G: Globanomalina, Ig; I: Igorina, M: Morozovella, P: Planorotalites; S: Subbotina. Age and epoch bounda- ries are adopted from Berggren et a/. (1995) and Berggren and Norris (1997). soldadoensis soldadoensis as an index marker, and subdi- vided Zone P4 into two subzones P4A and P4B as follows (Figure 7). P4A. Globanomalina pseudomenardii-Acarinina solda- doensis soldadoensis Interval Subzone Definition.—This subzone is defined as the interval zone between the FAD of G. pseudomenardii and the FAD of A. soldadoensis soldadoensis. Occurrence.—This subzone is recognized in both sides of the Zinda Pir Anticline (Samples ZPE-14 to 15 in the east and ZPW-17 to 18 in the west) and in the Rakhi Nala (Samples R25 to R29). Correlation and age.—The FAD of A. soldadoensis solda- doensis is one of the distinctive bioevents in the late Paleocene and is placed at Zones P4a/P4b boundary by Berggren and Norris (1997) and Olsson et al. (1999) or within the Planorotalites pseudomenardii (= Globorotalia pseudomenardii) Zone by Toumarkine and Luterbacher (1985). This subzone corresponds to the joint interval of P4a and P4b (Figure 7) of Berggren and Norris (1997), and Olsson et al. (1999). The age span of this zone is late Paleocene, from the latest Selendian to early Thanetian. In the Dungan Formation, two species of /gorina (albeari, pusilla) and Parasubbotina varianta disappear within this subzone. P4B. Acarinina soldadoensis soldadoensis/Globa- nomalina pseudomenardii Concurrent range Subzone Definition.—Subzone is defined as the interval between the FAD of A. soldadoensis soldadoensis and the LAD of G. pseudomenardii. Occurrence.—This subzone ranges from Samples ZPE- 15 to 20 in the east section of the Zinda Pir Anticline, ZPW-19 to 21 in the west section of the Zinda Pir Anticline, and R29 to R32 in the Rakhi Nala (Figures 3-5). Correlation and age.—This subzone is equivalent to Subzone P4c of Berggren and Norris (1997) and Olsson et al. (1999). The age of this subzone is late Paleocene (Thanetian). In the Dungan Formation, Morozovella Late Paleocene to early Eocene planktic foraminiferal biostratigraphy 283 Formation Dominance | Diversity P. Columnar, Samples : = : (Shannon Section | (ZPE) Planktic foraminiferal species Woaner % Functor) Shaheed Ghat u on Morozovella velascoensis 50 100% A. nitida u = I. albeari |. pusilla G. ehrenbergi >= S. triloculinoides æ— Dungan G. imitata —————_——= G. chapmani ——— - G. pseudomenardii ———— A. Mekannäl ——— M. angulata —-- M. apanthesma S. velascoensis S. triangularis |. tadjikistanensis A. coalingensis M. subbotinae A. wilcoxensis : M. conicotruncata —— — EN œ Globanomalina | pseudomenardii M. velascoensis A. soldadoensis soldadoensis : Parasubbotina varianta M. formosa gracilis Pseudohastigerina wilcoxensis Legend —— = Es Larger foraminifers e Siltstone Limestone intercalated Sandstone 5 Occurrence of planktic with siltstone wun 2 r £ foraminifers = SEG HESS CLLLL LA Vee Sandstone | Conglomeratic- Limestone Quartzose A ; Unconformi Eastern side brecciated limestone sandstone ty Figure 8. Results of the quantitative analysis of dominance (the most abundant species), diversity, P-ratio and the relative abundances of the characteristic planktic foraminiferal species along the eastern limb of the Zinda Pir Anticline. The numbers indicate the samples containing planktic foraminifers. Fm. Dominance Diversity P-ratio Columnr Hi 1 SE sf __| Section samples Planktic foraminiferal species 0 10 20 30% ER 20 ae Morozovella velascoensis | _ Globanomalina pseudomenardii TRZ G ehrenbergi M. apanthesma M. conicotruncata A. mckannal S. triloculinoides M. acuta 1. pusilla A. soldadoensis soldadoensis Pseudohastigerina wilcoxensis : M. occlusa M. velascoensis S. triangularis A. wilcoxensis M. subbotinae M. formosa gracilis G. imitata G. pseudomenardii S. velascoensis A. coalingensis G. chapmani Globanomalina pseudomenardii |Z Morozovella angulata- | Pab |Sandstone ® Larger foraminifers Unconformity EE Siltstone Limestone intercalated with siltstone Sandstone z e > be ena en aan LLLLL) Occurrence of planktic Trace fossil Conglomeratic-brecciated limestone Limestone Quartzose sandstone foraminifers Figure 9. Results of the quantitative analysis of dominance, diversity, P-ratio and relative abundances of the most abun- dant characteristic planktic foraminiferal species along the western limb of the Zinda Pir Anticline. The numbers indicate the samples containing planktic foraminifers. 284 Muhammad Yousaf Warraich et al. Shaheed Ghat Fm. 2 IR BESS Ad 1 S388 Bes à ae ul u = SS g = -2 3 i À SR. Kb 3 po ioc G 5 = à à | 3 : So Be s P- = = LE zei: = SA = = 8 Er ae ; wet E 5 u ge 8 = 3 = 5 = à II o> 5 8 À —— 3 o° v 5 STEISS à a8 ee bo 8378 S ss PS 2 3 5| ac. 5 Say SS ES 3 8 AL er 2 3 x = a 3 r—50m x € +5 Conglomeratic/ in: = ERS ecciated limestone ® a Li <> Mollusca ie 5 EE amestone Mu Unconformity 0 a siltstone “oO Ripple mark Scale ET Sandstone sais ace fossil = Cross-bedding ULLZ77/]Quarizose sandstone — Pab Sandstone | (Section-1) Figure 10. Results of the quantitative analysis of the relative abundances of the most abundant characteristic planktic foraminiferal species from the Rakhi Nala section. The numbers indicate the samples containing planktic foraminifers. For quantitative results of dominance, diversity, and the P-ratio see Figure 5. angulata and Globanomalina ehrenbergi disappear within Subzone P4B. P5. Morozovella velascoensis Interval Zone Definition.—The definition of Zone P5 is the interval zone between the LAD of G. pseudomenardii and the LAD of Morozovella velscoensis (e.g. Berggren and Norris, 1997). The base of this zone has been found in all three sections. The upper limit of this zone was placed at the level of Sample R26 in the Rakhi Nala, but its boundary is not clear in the Zinda Pir Anticline, because the hard siltstone of the uppermost part of the Dungan Formation contains no planktic foraminifers (Figures 3, 4). Occurrence.—This zone ranges from Samples ZPE-20 to 26 in the east and from Samples ZPW-21 to 22 in the west of the Zinda Pir Anticline, and from Sample R32 to R33 in the Rakhi Nala. Correlation and age.—This zone corresponds exactly to Zone P5 of Berggren and Norris (1997) and Olsson et al. (1999). The assemblages of planktic foraminifers in the Dungan Formation contain abundant index species of latest Paleocene to early Eocene age such as Morozovella subbotinae, M. formosa gracilis, Acarinina wilcoxensis and Pseudohastigerina wilcoxensis. In particular, the last spe- cies is a marker for recognizing the Paleocene/Eocene (P/E) boundary, appearing first just above the P/E boundary (Berggren, 1969; Stainforth et al., 1975; Berggren and Aubry, 1998). The FAD of this species has been recorded in Samples ZPW-21 and ZPE-26 in the Zinda Pir, and in Sample R27 in the Rakhi Nala. The chemo- and biostratigraphic events of a negative ex- cursion of ô *C (CIE) and the benthic foraminiferal extinc- tion event (BEE) are used as the P/E boundary markers by many workers (e. g. Berggren and Aubry, 1998; Berggren et al., 1998). The BEE in the investigated area is recog- nized between Samples R32 and R33 of the Rakhi Nala sec- tion (personal communication by Ritsuo Nomura, Shimane University, Japan). Hence, the P/E boundary can be placed between Samples R27 and R26 in the Rakhi Nala section. The P/E boundary in the Zinda Pir sections can be drawn tentatively between the Samples ZPE-20 and 26 in the east and ZPW-21 and 22 in the west, respectively. The age of this zone ranges from the latest Paleocene to earliest Eocene. Eocene Zones of the Dungan Formation In the study area, the siltstone sequence of the Dungan Formation is overlain by the conglomeratic to brecciated limestone beds present in the basal part of the Shaheed Ghat Formation. This field observation implies an Late Paleocene to early Eocene planktic foraminiferal biostratigraphy 285 Figure 11. grains from the Zinda Pir western section, Sample LS3 (scale bar = 0.5mm). unconformable relationship between the two formations. The biostratigraphic data from the Dungan Formation sup- ports this interpretation because the age of the siltstone beds in the uppermost part of the Dungan Formation in the Zinda Pir sections is latest Paleocene to earliest Eocene (Zone P5), whereas such beds in the Rahki Nala section are early Eocene in age (Zone P7). Two early Eocene zones described here are recognized from the Rakhi Nala section. P6. Morozovella subbotinae Partial Range Zone Definition.—This zone is defined as an interval zone be- tween the LAD of M. velascoensis and the FAD of M. aragonensis. Occurrence.—None occurred in the intervening samples between the Sample R27 and the Sample R34 in the study area. P7. Morozovella aragonensis/M. formosa formosa Con- current-Range Zone Definition.—This zone is defined by the interval from the FAD of M. aragonensis to the LAD of Morozovella formosa formosa. The upper boundary of this zone probably lies within the overlying Shaheed Ghat Formation. Occurrence.—The interval of this zone is recognized be- tween the Samples R34 and R41 that include many early Eocene species such as Morozovella aragonensis, M. A. Pelagic limestone (wakestone) containing abundant planktic foraminifers from the Rakhi Nala section, Sample R37 (scale bar = 0.5mm). B. Limestone (wakestone) showing squashed (compacted) larger foraminifers and glauconitic G stands for glauconite grain. formosa formosa, Subbotina inaequispira, and S. lozanoi. Two species (Acarinina nitida and Morozovella aequa) dis- appear close to the top of this interval (Figure 5). Correlation and age.—Zone P7 of Blow (1969, 1979) has been revised by Berggren and Miller (1988), who used the FAD of M. aragonensis as the lower boundary of this zone and the LAD of M. formosa formosa as the top. This zone corresponds to the joint interval of the M. formosa formosa Zone and the lower part of the Acarinina pentacamerata Zone of Toumarkine and Luterbacher (1985). The age of this zone is early Eocene (middle to late Ypresian). Quantitative analysis of planktic assemblages For calculation of quantitative indices (plankton ratio, dominance and species diversity), we used the samples containing over 100 individuals. In the Rakhi Nala, all sam- ples from Zone P3 to P7 yielded abundant and well- preserved foraminifers (Appendix 2). However, the total number per samples of individuals recovered from Zone P3 of the Zinda Pir sections amounted to less than 100. The number of specimens in the other samples in the Zinda Pir exceeded 200 individuals per sample. 286 Muhammad Yousaf Warraich et al. Figure 12. Sample R41, all x270. Paratype, (IGUT coll. cat. no. 50103) side, spiral and umbilical views. Results and discussion 1. Plankton-ratio The plankton-ratio (P-ratio) is expressed by the following formula: P-ratio = [P/(P+B)] x 100 Here P and B represent the number of specimens of planktic and benthic foraminifers, respectively. The trend of P-ratios differs between the eastern and western sections of the Zinda Pir Anticline (Figures 8, 9). In the east, the P- ratios of Zone P4A are as high as 90%, decreasing gradually to a minimum (39%) in Zone P4B, and then recovering to 89% in Zone P5. In the west, the P-ratios are consistently high (80-90%) during Zones P3B to P5, except for a figure of 31% in Sample ZPW-17 in the lowermost part of Zone P4A. In the Rakhi Nala section, the P-ratios of all samples show high values of more than 95% (Figure 5). 2. Species compositions The morozovellid species are common to abundant throughout the studied sequences, exceeding about 30- 40% of the total number of specimens (Figures 8-10). The dominant morozovellids are M. angulata in Zone P3B, M. acuta and M. velascoensis in Zone P4 and three species (M. Globanomalina rakhiensis sp. nov. 1-3: Holotype, (IGUT coll. cat. no. 50101) umbilical, side and spiral views, 4, 5: Paratype, (IGUT coll. cat. no. 50102 ), umbilical and side views, Sample R41, all x330. 6-8: This specimen has more compressed peripheral margin on umbilical side, more limbate intercameral sutures on spiral side and more developed keel in side view, Sample R41, all x300. 9: An enlarged view of specimen (as illustrated in Figure 4) shows smooth wall surface with some pustules (scale bar = 10um) acuta, M. subbotinae, and M. aequa) in Zone P5 in the Zinda Pir area. In the Rakhi Nala region, the assemblage of Zone P3B is dominated by M. acuta and M. angulata (40-60%), whereas that of Zones P4 and P5 is dominated by M. acuta, M. conicotruncata, M. occlusa, and M. velascoensis (30- 35%). The relative abundance of Acarinina and Subbotina during Zones P3 to P5 is relatively high, fluctuating between 10 and 20% of the total for each genus. Those of the other genera (/gorina, Globanomalina, and Parasubbotina) are less than 10% for each genus. The replacement of the Paleocene morozovellid group (M. velascoensis, M. angulata, M. conicotruncata and M. apanthesma) by early Eocene forms (M. formosa gracilis, M. formosa formosa, M. lensiformis, M. subbotinae, M. marginodentata and M. edgari) occurred during Zones P5 to P6 (Figure 5). The acarininids (A. pentacamerata, A. solda- doensis soldadoensis, A. wilcoxensis) and subbotinids (S. patagonica, S. inaequispira, S. prolata) increased within Zone P7, accompanied by a decrease in the abundances of the morozovellid forms (Figure 10). This increase in the abundance of acarininid and subbotinid forms is probably re- lated to a temperature decrease after the Paleocene-Eocene boundary. In the late Paleocene, the period spanning latest zone P4 to P5 is of maximum warmth (LPTM), with Zones Late Paleocene to early Eocene planktic foraminiferal biostratigraphy Figure 13. Muhammad Yousaf Warraich et al. 288 Figure 14. Late Paleocene to early Eocene planktic foraminiferal biostratigraphy 289 Figure 15. Muhammad Yousaf Warraich et al. 290 Figure 16. Late Paleocene to early Eocene planktic foraminiferal biostratigraphy Figure 17. Muhammad Yousaf Warraich et al. Figure 18. Late Paleocene to early Eocene planktic foraminiferal biostratigraphy 293 P6b and P7 becoming slightly cooler (e.g., Stott et al., 1990; Bralower et al., 1995). This cooling event is probably re- sponsible for the increase in percentage of Acarinina and Subbotina species in Zone P7. 3. Diversity and dominance trends We calculated the species diversity in both sections of the Zinda Pir (Zones P3B to P5) and in the Rakhi Nala section (Zones P3 to P7) using the Shannon-Wiener Function by the following mathematical expression. H (S) = =%. piln pi (from i= 1 to S) Where pi is the relative abundance of the th species in a sample and S is the number of species. Dominance index is expressed as percentages of the most abundant species. The relationship between the Shannon-Wiener diversity index and dominance index display distinct opposite trends (Figures 8-10). In the east of the Zinda Pir, the species richness de- creases gradually from 20 to 15 species during Zones P4A to P5 (Appendix 2). The diversity index is, however, rela- tively constant (1.9 and 2.0), with generally lower values than in the western samples. The lowest value (15 species) was recorded from the earliest Eocene Sample ZPE-26, but this figure is not the overall minimum (Figure 8). Figure 13. (p.287) 1-3. Globanomalina chapmani (Parr), umbilical, side and spiral views, Sample ZPW-17, all x250. 4, 5,9. Acarinina wilcoxensis (Cushman and Ponton), umbilical, side and spiral views, Sample ZPW-21, all x230. 6-8. Parasubbotina varianta (Subbotina), umbilical, side and spiral views, Sample ZPW-5, all x500. 10, 14, 18. /gorina albeari (Cushman and Bermudez), umbilical, side and spiral views, Sample ZPW-15, all x230. 11-13. /gorina tadjikistanensis (Bykova), umbilical, side and spiral views, Sample ZPW-17, all x220. 15-17. Acarinina strabocella (Loeblich and Tappan), umbilical, side and spiral views, Sample ZPW-16, all x230. 19-21. /gorina pusilla (Bolli), umbilical, side and spiral views, Sample ZPW-17, all x300. Figure 14. (p.288) 1-3. Acarinina mckannai (White), umbilical, side and spiral views, Sample ZPW-17, all x180. 4-5, 10. Acarinina nitida (Martin), side, umbilical and spiral views, Sample ZPW-20, all x220. 6, 11-12. Acarinina soldadoensis soldadoensis (Bronnimann), umbilical, side and spiral views, Sample ZPW-20, all x170. 13-15. Acarinina soldadoensis soldadoensis (Bronnimann) spiral, side and um- bilical views, Sample ZPW-20, all x200. 7-9. Acarinina subsphaerica (Subbotina), spiral, side and umbilical views, Sample ZPW-19, all x220. 16, 20, 21. Subbotina velascoensis (Cushman), spiral, umbilical and side views, Sample ZPW-17, all x200. 17-19. Acarinina coalingensis (Cushman and Hanna), umbilical, side and spiral views, Sample ZPW-20, all x200. 22-24. Subbotina triangularis (White), spi- ral, side and umbilical views, Sample ZPW-17, all x180. 25-27. Subbotina triloculinoides (Plummer), umbilical, side and spiral views, Sample ZPW-17, all x300. Figure 15. (p.289) 1-3. Morozovella angulata (White), umbilical, side and spiral views, Sample ZPE-15, all x150. 4, 5, 10. Morozovella subbotinae (Morozova), umbilical, side and spiral views, Sample ZPE-26, all x150. 6, 11, 12. Pseudohastigerina wilcoxensis (Cushman and Ponton), apertural face, lateral views, Sample ZPW-22, all x270. 7-9. Morozovella conicotruncata (Subbotina), spiral, side and umbilical views, Sample ZPW-16, all x200. 13-15. Globanomalina imitata (Subbotina), umbilical, side and spiral views, Sample ZPW-18, all x250. 16, 17, 21. Globanomalina pseudomenardii (Bolli), umbilical, side and spiral views, Sample ZPW-17, all x170. 18-20. Globanomalina ehrenbergi (Bolli), umbilical, side and spiral views, Sample ZPW-17, all x170. 22-24.Globanomalina imitata (Subbotina), spiral, side and umbilical views, Sample ZPW-18, all x200. Figure 16. (p.290) 1-3. Morozovella acuta (Toulmin), side, umbilical and spiral views, Sample ZPW-17, all x100. 4-5, 10. Morozovella acuta (Toulmin), side, umbilical and spiral views, Sample ZPW-19, all x160. 6, 11, 12. Morozovella apanthesma (Loeblich and Tappan), um- bilical, side and spiral views, Sample ZPW-21, all x200. 7-9. Morozovella acutispira (Bolli and Cita), spiral, side and umbilical views, Sample ZPW-15, all x150. 13-15. Morozovella gracilis (Bolli), spiral, side and umbilical views, Sample ZPE-26, all x130. 17-19. Morozovella velascoensis (Cushman), umbilical, side and spiral views, Sample ZPE-15, all x140. 20, 21, 25. Morozovella aequa (Cushman and Renz), spiral, side and umbilical views, Sample ZPW-21, all x220. 22-24. Morozovella occlusa (Loeblich and Tappan), spiral, side and umbilical views, Sample ZPW-15, all x160. Figure 17. (p.291) 1-3. Morozovella edgari (Primoli Silva and Bolli), umbilical, side and spiral views, Sample R33, all x270. 4, 5, 10. Morozovella marginodentata (Subbotina), umbilical, side and spiral views, Sample R40, all x200. 6, 11, 12. Morozovella aragonensis (Nuttall), side, spiral and umbilical views, Sample R41, all x130. 7-9. Morozovella lensiformis (Subbotina), umbilical, side and spiral views, Sample R40, all x170. 13-15. Acarinina quetra (Bolli), umbilical, side and spiral views, Sample R41, all x180. 16-18. Acarinina pentacamerata (Subbotina), umbilical, side and spiral views, Sample R40, all x150. 19, 20, 26. Acarinina soldadoensis angulosa (Bolli), um- bilical, side and spiral views, Sample R38, all x200. 21-23. Morozovella formosa formosa (Bolli), umbilical, side and spiral views, Sample R41, all x130. 24, 25. Chiloguembelina trinitatensis (Cushman and Renz), lateral views, Sample R30, all x350. Figure 18. (p.292) 1-3. Subbotina lozanoi (Colom), umbilical, side and spiral views, Sample R41, all x170. 4, 5, 11. Subbotina patagonica (Todd and Knicker), umbilical, spiral and side views, Sample R38, all x150. 6-8. Subbotina inaequispira (Subbotina), umbilical, side and spiral views, Sample R41, all x150. 9-10. Chiloguembelina crinita (Glaessner), lateral views, Sample R30, all x370. 12-14. Subbotina prolata (Bolli), umbilical, side and spiral views, Sample R41, all x170. 15-17. Acarinina pseudotopilensis (Subbotina), umbilical, side and spiral views, Sample R39, all x160. 18-20. /gorina broedermanni (Cushman and Bermudez), umbilical, side and spiral views, Sample R41, all x200. 21, 22, 26. Acarinina esnaensis (LeRoy), umbilical, spiral and side views, Sample R41, all x190. 23-25. Planorotalites pseudoscitula (Glaessner), umbilical, side and spiral views, Sample R39, all x450. 27, 28. Chiloguembelina wilcoxensis (Cushman and Ponton), lateral views, Sample R33, all x180. 294 Muhammad Yousaf Warraich et al. In the western section, the species richness during Zones P3B to P4 is consistently high (17 to 20 species), except for sample ZPW-18 (Zone P4A, 16 species) (Appendix 3). The species diversity fluctuates between 2.1 and 2.6. The mini- mal values of both richness (15 species) and diversity (2.1) are yielded by the earliest Eocene Sample ZPW-22 (Figure 9). In the Rakhi Nala section, the species richness during the Paleocene (Zones P3B to P4) is high and nearly constant (19 to 22 species), excepting Sample R23 (8 species, Zone P3B). The diversity of two samples (Samples R23 and R25) of Zone P3B-P4 is about 1.6 but varies to 2.5 in Sample R30 (Zone P4B). The Eocene species richness during Zones P5 to P7 ranges from 16 to 20 species, and the diversity index is constant at close to 2.5 (Figure 10). The diversity during the earliest Eocene is consistently high (2.2-2.3), differing from the trends in the Zinda Pir. 4. Depositional environment The sequence of the Dungan Formation is characterized by a remarkable change of lithology in the studied regions. During the late Paleocene (Zone P3), the strata of both re- gions (Zinda Pir and Rakhi Nala) consist of siltstone subordi- nate to sandstone. The interbeds of sandstone show the westward-thickening trend as sandstone beds are abundant and thick in the Rakhi Nala (Figure 6). In Zone P4, two ba- sins were filled with siltstone, with rarely intercalating thin limestone beds containing larger foraminifers. After Zone P5, the limestones became thicker in the eastern section of the Zinda Pir, and the lithology changed from a siltstone- dominant facies to a limestone-dominant one in the eastern area. As a whole, limestone deposits thinned to the west- ward from the Zinda Pir to the Rakhi Nala, while siltstone deposition went on in the Rakhi Nala basin, located in the western region. As a rule, plankton-ratios (P-ratios) increase from the shelf to the open-ocean environment, and exceed 50% in the deeper environment beyond the outer shelf in both modern and ancient sediments (e.g. Ingle, 1980; Gibson, 1989). The high P-ratios of all three sections of the Dungan Formation strongly indicate an open marine environment in the studied area. The highest P-ratios (98 to 99%), high values of species richness and diversity index in the Rakhi Nala suggest that the paleodepth of the Rakhi Nala basin was greater than that of the Zinda Pir. Furthermore, the planktic foraminiferal assemblage of the western section in the Zinda Pir Anticline also represents higher species rich- ness and P-ratios than does that of the eastern one. Hence, the sedimentary basin of the Dungan Formation, as a whole, is thought to constitute a continental slope dipping from east to west. The westward-deepening basin is ascertained by lithological evidence, as mentioned above, namely, that the thickness of the limestone beds intercalated with the Paleocene siltstone in the Zinda Pir area are thinner in the western section than in the eastern ones (Figure 6). Moreover, petrographic studies of these intercalated limestones from the Rakhi Nala show an abundant pelagic faunas (Figure 11A), while some limestone bands from the Zinda Pir area contain deformed or broken specimens of larger foraminifers along with many glauconite grains (Figure 11B), indicating a shallow marine environment. Actually, these thin limestone bands are of turbidite origin and were emplaced in the deep-water siltstone sequence, possibly due to unstable tectonics in tectonic episodes. Our inter- pretation is also supported by Humayon et al. (1991), who have reported the westward-deepening-basin structure of the Sulaiman fold belts using seismic reflections and drilling core data. Conclusions Five biostratigraphic zones P3 to P7 of the tropical zones were recognized in the Dungan Formation exposed in the eastern Sulaiman Range. Zones P3 and P4 are subdivided into two subzones (Subzones A and B). The Dungan Formation is assigned to the late Paleocene to early Eocene. Based on quantitative analysis of planktic species of P-ratios, species richness and species diversity, the Dungan Formation is thought to have been deposited in a relatively deep-water environment, forming a westward- dipping continental slope during the late Paleocene to early Eocene. Systematic description Superfamily Rotaliporacaea Sigal, 1958 Family Hedbergellidae Loeblich and Tappan, 1961 Genus Globanomalina Haque 1956 Globanomalina rakhiensis sp. nov. Figure 12 Description.—Test very small, spiral side flat to slightly convex, umbilical side low convex; equatorial periphery elon- gate, distinctly lobulate; peripheral margin acute, strongly to moderately compressed with a keel; 14 or 15 chambers ar- ranged in 3 whorls, all visible from spiral side; commonly five (rarely six) chambers in the last whorl increase very rapidly in size; on umbilical side intercameral sutures depressed and weakly curved whereas strongly recurved and limbate on spiral side; surface finely perforate; umbilicus narrow and shallow; aperture low arch-shaped, interiomarginal, umbili- cal- extraumbilical with distinct lip. Type and material.—Holotype, IGUT (Institute of Geo- sciences, University of Tsukuba) coll. cat. no, 50101, from Sample R41, Dungan Formation, Rakhi Nala section, maxi- mum diameter 0.27 mm, width 0.20 mm. Paratype, IGUT coll. cat. no. 50102, Sample R41, Dungan Formation, Rakhi Nala section, maximum diameter 0.27 mm, width 0.20 mm. Paratype, IGUT coll. cat. no. 50103, Sample R41, Dungan Formation, Rakhi Nala section, maximum diameter 0.26 mm, width 0.21 mm. Remarks.—The species is common in Sample R41. The largest specimen is 0.27 mm in diameter, but specimens are usually less than 0.15 mm. Globanomalina rakhiensis sp. nov. is a small but very distinctive species and might have been overlooked previously due to its small size. It can be missed if using the 150 um size fraction. This species shows variation in size and degree of compression of the pe- ripheral margin. The holotype (Figure 12.1-12.3) is less Late Paleocene to early Eocene planktic foraminiferal biostratigraphy 295 compressed than the paratype (Figure 12.6 - 12.8). Planorotalites pseudoscitula (Glaessner, 1937) is very simi- lar to G. rakhiensis sp. nov. but differs in having more cham- bers in the last whorl (6 or 7) and a circular periphery, and in being more lenticular. Globanomalina rakhiensis sp. nov. is a homeomorph of the late Paleocene Globanomalina pseudomenardii (Bolli, 1957) as both forms possess a compressed planoconvex test, 5 chambers in the last whorl, and a low-arched umbilical-extraumbilical aperture that bears a lip. G. rakhiensis sp. nov. is easily distinguished from G. pseudo- menardii by its small size and relatively weak keel. The stratigraphic range of G. pseudomenardii is restricted to Zone P4 (late Paleocene) in many works (Toumarkine and Luterbacher, 1985; Berggren and Miller, 1988, Berggren et al., 1995; Berggren and Norris, 1997; Olsson et al., 1999, etc). However, Blow (1979) extended the age range of this species to his Zone P7 (early Eocene). We suggest that Globorotalia (G.) pseudomenardii identified by Blow (1979) from his Zone P7 (pl. 111, figs. 1-4; pl. 112, figs. 2, 3; 9-10) is quite similar to our new species (G. rakhiensis). Therefore, he might have misidentified G. rakhiensis sp. nov. This new species is named after a local river, Rakhi Nala, along which this section is exposed. Stratigraphic range.— Globanomalina rakhiensis sp. nov. yielded by Sample R41 is assigned to the M. formosa formosa Zone (P7), corresponding to Zone P7 of Berggren and Miller (1988) and Berggren et al. (1995). Therefore, the stratigraphic range of this species is within the middle lower Eocene. Acknowledgments We are thankful to Abdul Majeed and Muhammad Shafique Akram of the Pakistan Atomic Energy Commission for their assistance during field works in Pakistan. Thanks are extended to G. Eseller (presently at University of Tsukuba, Japan) for his valuable comments. The authors wish to express their sincere gratitude to Hiroshi Noda and Hiroo Natori of the University of Tsukuba for their helpful suggestions during the initial stage of this study. We appre- ciate the kind help of Y. Ohno in taking scanning electron mi- croscope (SEM) photographs. 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F. et al., Proceedings of the Ocean Drilling Program: Scientific Results, vol. 113, College Station, TX: Ocean Drilling Program, P. 849-863. Subbotina, N. N., 1947: Foraminifery datskikh i paleogenovykh otlozhenii severnogo Kavkaza [Foraminifera of the Danian and Paleogene deposits of the northern Caucasus]. /n, Mikrofauna neftyanykh mestorozhdenii Kavkaza, Emby | Srednei Azii. Trudy Vesesoyuznogo Nauchno-lssledovatel'skogo Geologo-Razvedochnogo Neftyanogo Instituta, Novaya Seriya (VNIGNI), p. 39-160, pls. 1-9. (in Russian) Subbotina, N. N., 1953: Iskopaemye foraminifery SSSR (Globigerinidy, Khantkenininidy i Globorotaliidy) [Fossil foraminifera of the U.S.S.R., Globigerinidae, Hantkenini- dae and Globorotaliidae]. Trudy Vsesoyuznogo Neftyanogo Nauchno-Issledovatel'skogo Geologo- Razvedochnogo Instituta (VNIGRI), vol. 76, p. 1-296. (in Late Paleocene to early Eocene planktic foraminiferal biostratigraphy Russian) Todd, R. and Kniker, H. T., 1952: An Eocene foraminiferal fauna from the Agua Fresca shale of Magallanes prov- ince, southernmost Chile. _ Cushman Foundation for Foraminiferal Research Special Publication, no. 1, p. 26. Toulmin, L. D., 1941: Eocene smaller foraminifera from the Salt Mountain limestone of Alabama. Journal of Paleontology, vol. 15, 567-611. Toumarkine. M. and Luterbacher. H., 1985: Paleocene and Eocene planktic foraminifera. In, Bolli, H. M., Saunders, J. B. and Perch-Nelson, K. eds., Plankton Stratigraphy, p. 87-154. Cambridge University Press, Cambridge. Warraich, M. Y. and Natori, H., 1997: Geology and planktonic foraminiferal biostratigraphy of the Paleocene-Eocene succession of the Zinda Pir section, Sulaiman Range, Southern Indus Basin, Pakistan. Bulletin of the Geological Survey of Japan, vol. 48, p. 595-630, pls. 1-15. Warwick, P. D., Johnson, E. A. and Khan, I. H., 1998: Collision-induced tectonism along the northwestern mar- gin of the Indian subcontinent as recorded in the Upper Paleocene to Middle Eocene strata of central Pakistan (Kirthar and Sulaiman Ranges). Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 142, p. 201-216. White, M. P., 1928: Some index foraminifera of the Tampico embayment area of Mexico, Part | and Part Il. Journal of Paleontology, vol. 2, p. 177-215, 280-317. 297 298 Muhammad Yousaf Warraich et al. Appendix 1: Faunal reference list The classification of the planktic foraminifera adopted in this paper is based on Berggren et al. (1995), Berggren and Norris (1997) and Olsson et al. (1999). The synonymies of the planktic foraminifers are restricted to original descriptions. The SEM photographs of marker species are presented in Figures 13 to 18. Acarinina coalingensis (Cushman and Hanna) (Figure 14.17- 14-19) Globigerina coalingensis Cushman and Hanna, 1927, p. 205, pl.14, fig. 4. Acarinina esnaensis (LeRoy) (Figure 18.21, 18.22, 18.26) Globigerina esnaensis LeRoy, 1953, p. 31, pl. 6, figs. 8-10. Acarinina mckannai (White) (Figure 14.1-14.3) Globigerina mckannai White, 1928, p. 194, pl. 27, figs. 16a-c. Acarinina nitida (Martin) (Figure 14.4-14.5, 14.10) Globigerina nitida Martin, 1943, p. 115, pl. 7, figs. 1a-c. Acarinina quetra (Bolli) (Figure 17.13-17.15) Globorotalia quetra Bolli, 1957, p. 79-80, pl. 19, figs. 1-6. Acarinina pentacamerata (Subbotina) (Figure 17.16-17.18) Globorotalia pentacamerata Subbotina, 1947, p. 128-129, pl. 12-17, figs. 24-26. Acarinina pseudotopilensis Subbotina (Figure 18.15-18.17) Acarinina pseudotopilensis Subbotina, 1953, p. 227-228, pl. 21, figs. 13. Acarinina soldadoensis angulosa (Bolli) (Figure 17.19-17.20, 17.26) Globigerina soldadoensis angulosa Bolli, 1957, p. 71, pl. 16, figs. 46. Acarinina soldadoensis soldadoensis (Bronnimann) (Figure 14.6, 14.11-14.15) Globigerina soldadoensis Bronnimann, 1952, p. 7, 9, pl. 1, figs. 19 Acarinina strabocella (Loeblich and Tappan) (Figure 13.15- 13.17) Globorotalia strabocella Loeblich and Tappan, 1957, p.195, pl. 61, figs. 6a-c. Acarinina subsphaerica (Subbotina) (Figure 14.7-14.9) Globigerina subsphaerica Subbotina, 1947, p. 108, pl. 5, figs. 26-28. Acarinina wilcoxensis (Cushman and Ponton) (Figure 13.4, 13.5, 13.9) Globorotalia wilcoxensis Cushman and Ponton, 1932, p. 71, pl. 9, figs.10a-c. Chiloguembelina crinita (Glaessner) (Figure 18.9-18.10) Guembelina crinita Glaessner, 1937, p. 383, pl.4, figs. 34a, b. Chiloguembelina trinitatensis (Cushman and Renz) (Figure 17.24-17.25) Guembelina trinitatensis Cushman and Renz, 1942, p. 8, pl. 2, figs. 8a, b Chiloguembelina wilcoxensis (Cushman and Ponton) (Figure 18.27-18.28) Guembelina wilcoxensis Cushman and Ponton, 1932, p. 66, pl. 8, figs. 16, 17. Globanomalina chapmani (Parr) (Figure 13.1-13.3) Globorotalia chapmani Parr, 1938, p. 87, pl. 3, figs. 8, 9. Globanomalina compressa (Plummer) Globigerina compressa Plummer, 1926, p. 135, pl. 8, figs. 11a-c. Globanomalina ehrenbergi (Bolli) (Figure 15.18-15.20) Globorotalia ehrenbergi Bolli, 1957, p. 77, pl. 20, figs. 18-20. Globanomalina elongata (Glaessner) Globanomalina pseudoscitula var. elongata Glaessner, 1937, p. 33, pl. 1, figs. 3d-f. Globanomalina imitata (Subbotina) (Figure15.13 - 15.15; 15.22-15.24) Globorotalia imitata Subbotina, 1953, p. 206-207, pl. 16, figs. 14-16. Globanomalina pseudomenardii (Bolli) (Figure 15.16-15.17, 15.21) Globorotalia pseudomenardii Bolli, 1957, p. 77, pl. 20, figs. 14 -17. Igorina albeari (Cushman and Bermudez) (Figure 13.10, 13.14, 13.18) Globorotalia albeari Cushman and Bermudez, 1949, p. 33, pl. 6, figs. 13-15. Igorina broedermanni (Cushman and Bermudez) (Figure 18.18-18.20) Globorotalia (Truncorotalia) broedermanni Cushman and Bermudez, 1949, p. 40, pl. 7, figs. 22-24. Igorina pusilla (Bolli) (Figure 13.19-13.21) Globorotalia pusilla pusilla Bolli, 1957, p. 78, pl. 20, figs. 8-10. Igorina tadjikistanensis (Bykova) (Figure 13.11-13.13) Globorotalia tadjikistanensis Bykova, 1953, p. 86, pl. 3, figs. 5a-c. Morozovella acuta (Toulmin) (Figure 16.1-16.3; 16.4-16.5, 16.10) Globorotalia wilcoxensis Cushman and Ponton var. acuta Toulmin, 1941, p. 608, pl. 82, figs. 68. Morozovella acutispira (Bolli and Cita) (Figure 16.7-16.9) Globorotalia acutispira Bolli and Cita, 1960, p. 15, pl. 33, figs. 3a-c. Morozovella aequa (Cushman and Renz) (Figure 16.20- 16.21, 16.25) Globorotalia crassata (Cushman) var. aequa Cushman and Renz, 1942, p. 12, pl. 3, figs. 3a-c. Morozovella aragonensis (Nuttall) (Figure 17.6, 17.11, 17.12) Globorotalia aragonensis Nuttall, 1930, p. 288, pl. 24, figs. 6-11. Morozovella angulata (White) (Figure 15.1-15.3) Globigerina angulata White, 1928, p. 191, 192, pl. 27, figs. 13a —C. Morozovella apanthesma (Loeblich and Tappan) (Figure 16.6, 16.11, 16.12) Globorotalia apanthesma Loeblich and Tappan, 1957, p. 187, pl. 48, figs. 1a-c, pl. 55, figs.1a-c, pl. 58, figs. 4a-c; pl. 59, figs. 1a-c. Morozovella conicotruncata (Subbotina) (Figure 15.7-15.9) Globorotalia conicotruncata Subbotina, 1947, p. 115-117, pl. 4, figs. 11-13; pl. 9, figs. 9-11. Morozovella edgari (Primoli Silva and Bolli) (Figure 17.1-17.3) Globorotalia edgari Primoli Silva and Bolli, 1973, p. 526, pl. 7, figs. 10-12, pl. 8, figs. 1-12. Late Paleocene to early Eocene planktic foraminiferal biostratigraphy Morozovella formosa formosa (Bolli) (Figure 17.21-17.23) Globorotalia formosa formosa Bolli, 1957, p. 76, pl. 18, figs. 1-3. Morozovella formosa gracilis (Bolli) (Figure 16.13-16.15) Globorotalia formosa gracilis Bolli 1957, p. 75, 76, pl. 18, figs. 4-6. Morozovella lensiformis (Subbotina) (Figure 17.7-17.9) Globorotalia lensiformis Subbotina, 1953, p. 214, pl. 18, figs. 4,5. Morozovella marginodentata (Subbotina) (Figure 17.4, 17.5, 17.10) Globorotalia marginodentata Subbotina, 1953, p. 212, 213, pl. 17, figs. 14-16, pl.18, figs. 1-3. Morozovella occlusa (Loeblich and Tappan) (Figure 16.22- 16.24) Globorotalia occlusa Loeblich and Tappan, 1957, p. 191, pl. 64, figs. 3a-c. Morozovella subbotinae (Morozova) (Figure 15.4, 15.5, 15.10) Globorotalia subbotinae Morozova, 1939, p. 80, pl. 2, figs. 16,17. Morozovella velascoensis (Cushman) (Figure 16.17-16.19) Pulvinulina velascoensis Cushman, 1925, p. 19, pl. 3, figs. 5a-c. Parasubbotina varianta (Subbotina) (Figure 13.6-13.8) Globigerina varianta Subbotina, 1953, p. 63, pl. 3, figs. 5-7, 10-12. Planorotalites pseudoscitula (Glaessner) (Figure 18.23-18.25) Globorotalia pseudoscitula Glaessner, 1937, p. 32, figs. 3a-c. Pseudohastigerina wilcoxensis (Cushman and Ponton) (Figure 15.6, 15.11, 15.12) Nonion wilcoxensis Cushman and Ponton, 1932, p. 64, pl. 8, figs. 11a, b. Subbotina inaequispira (Subbotina) (Figure 18.6-18.8) Globigerina inaequispira Subbotina, 1953, p. 69, pl. 6, figs. 1-4. Subbotina lozanoi (Colom) (Figure 18.1-18.3) Globigerina lozanoi Colom, 1954, p.149, pl. 2, figs. 1-48. Subbotina patagonica (Todd and Kniker) (Figure 18.4, 18.5, 18.11) Globigerina patagonica Todd and Kniker, 1952, p. 26, pl. 4, figs. 32a-c. Subbotina prolata (Bolli) (Figure 18.12-18.14) Globigerina prolata Bolli, 1957, p. 72, pl. 15, figs. 24-26. Subbotina triangularis (White) (Figure 14.22-14.24) Globigerina triangularis White, 1928, p. 195, pl. 28, figs. 1a-c. Subbotina triloculinoides (Plummer) (Figure 14.25-14.27) Globigerina triloculinoides Plummer, 1926, p. 134, 135, pl. 8, figs. 10a-c. Subbotina velascoensis (Cushman) (Figure 14.16, 14.20, 14.21) Globigerina velascoensis Cushman, 1925, p. 19, pl. 3, figs. 6a-c. Turborotalia praecentralis Blow Globorotalia (Turborotalia) praecentralis Blow, 1979, p. 1094, pl. 135, figs. 7-9; pl. 136, figs. 1-6; pl. 233, fig. 6. 299 300 Muhammad Yousaf Warraich et al. Appendix 2: Stratigraphic distribution and relative abundance (%) of planktic foraminiferal species in the Dungan Formation exposed at the Rakhi Nala section. Here x = less than 1 %. arinina coalingensis Dungan Formation 2] Planktic H 3 | foraminiferal Rzs|r2e [R25 R30 R26 |R27 |R33 |R34 R38 Rag| R40] R41] 3 | species BE 3 | oO BER S| Bees Poa bd Er ze) ER ee Be DER EN REST A. esnaensis (i a nd EEE fa a a „ mekannai Feen . nitida n n =E n » n wo fl > . pentacamerata il ea a 2]x[1|1{|1]21]4] 1 | 3 [A pseudotopiensis > 5 BLS 2 2 2 he] > D g à o wo 4 7 JA. wilcoxensis a (Eee tn Chiloguembelina crinita I [| | [| |] [| Ten. trinitatensis ee ie Ch. wilcoxensis Sr ns ee er Globanomalina chapmani A ER PE QE RS er] rer RE A | a | BE AN EP D DE EC RE ER TEE] EE CN ES A [SEN A En] DR RE EE EE ee BEE] en EC EN EG SN EN ES En Igorina albeari = = | 1 4 3 2 3 2 4 |l. broedermanni 7 1. pusilla 3 LE EN I. tadjikistanensis me Morozovella acuta x M. acutispira 7 | 8 | | u a) n = Q © 2 S 2 SI [= 3 oO D m 2 4 |Pseudohasti. wilcoxensis 1 5 |Subbotina inaequispira DE DE a a a EEE re DB ne] 243| 301 [Total Counts | 18 | 19 | 20 | 22 [15 | 18 [17 | 19 | 16 | 17 | 20 | 18 | 19 P3B P4A| P4B P5 P7 Zones N nN oa w oO oO wo oO oO wo œ [A] & oO wo nn wo œ w > [A] A] on nN oO œ [a] oO a @ “ [87 nm nN wo wo ao oO B 301 Late Paleocene to early Eocene planktic foraminiferal biostratigraphy Stratigraphic distribution and relative abundance (%) of planktic foraminiferal species in the Dungan Formation Appendix 3 exposed along the eastern and western lims of the Zinda Pir Anticline. Here x = less than 1 %. | ZT = RTS sauoz | Sd gtd vtd ged WEd| Sd dtd Ved T T- JSQUUNNIS2198 dS 1h01) Gs RO ES ee NS 2 Bra | oa ee ee alelclslelslslelelslolalslslalelels| sungoeoL|S RS (S/S Si Sls5]/k/S/"/Bl]2/e/ six) s/s SISU909SE/8A S | a + lo x M) = | © = RK - on |o w wo Red tt sueınduem Ss |" | = | = | |Jo|;- |. + EEE } pf} EEE EEE EEE S8pIOuIN20/11} BULJOGGNS al PCI o |w are 11 sisuaxogim Bunaßuseyopnasg | « o BJUBLIEA BuNoggnseled x o AFS | sisuaoosejan we |\- I|zx |}/2}z}]e2]}]-]a * -~-lo}lglelolaloa en ern a Ber seunoggns 'W| = | > = BSNn/220 'W | * MIE r a + - + + a a sti | PALO || et. a a en ae ea sıoeıb esouuoy 'W | = = EJEOUNNOOLLOO ‘NN HE w lol | TRI euseyuede ‘jy - |< lo Jo |a|a|a |w | Sia al BJeinDue 'W + + Gy zone CREME + a | «a — enbse | oe |* |- |- Jo | *| «|» lo wlaol-|als+s | s | e1ds}n2e ‘W © eınze Byaaozojoy | a |? IR | |35 | Jaıa | ayer 8/8)/Flal/ag]/a]e? sısuaue)siyılpe] ‘| + f= Tu Silissed earls le eyisnd :] See a o 7 ms! = lueaqe eul1oB] = | Sul ıpieuswopnasd ‘9 Te Aer er a | —- | w | - ane a BE on | = DE Sa eee a |[o |- 1B1equeiys ‘9 - [al-|al+ o - | + lo essa/du09 “5 w it wewdeys eugewouegog | x |x [om |+ |n | «io ie SEHR | = SISUAXOD|IM ‘ty x = eouaeydsgans 'W x |= = x eIIBs00gENS ‘Y ola | sısusopppjos sisuaopepjos Y|o |alz|r CA ESS ES por) fe epqu Ya Io le Ja || ala |- zu aa FE FR a | revi lee IBUUBYOW “yy | a l-|-|-|- o|-|olo x sjsuabuljeoo euuue2ty | - | w | a | x A Salis r | w aT | ANR /S]2 12 (Sig isles ejzjeiei: saiseds ElZie 2 2 228 2 la ale Eee le ie le jesayluıweıogy DININININININININ ININININININININININ 21} 4UeId | apıs UI19]S9M apis u19}S2 uonewio4 ueßung 303 The Palaeontological Society of Japan has revitalized its journal. Now entitled Paleontological Research, and published in English, its scope and aims have entirely been redefined. 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However, figures will be returned upon request by the authors after the paper has been pub- lished. Ager, D. V., 1963: Principles of Paleoecology, 371p. McGraw- Hill Co., New York. Barron, J. A., 1983: Latest Oligocene through early Middle Miocene diatom biostratigraphy of the eastern tropical Pacific. Marine Micropaleontology, vol. 7, p. 487-515. Barron, J. A., 1989: Lower Miocene to Quatemary diatom biostratigraphy of Leg 57, off northeastern Japan, Deep Sea Drilling Project. In, Scientific Party, Initial Reports of the Deep Sea Drilling Project, vols, 56 and 57, p. 641-685. U. S. Govt. Printing Office, Washington, D. C. Burckle, L. H., 1978: Marine diatoms. In, Haq, B. U. and Boersma, A. eds., Introduction to Marine Micropaleon- tology, p. 245-266. Elsevier, New York. Fenner, J. and Mikkelsen, N., 1990: Eccene-Oligocene diatoms in the westem Indian Ocean: Taxonomy, stratigraphy, and paleoecology. /n, Duncan, R. A., Backman, J., Peterson, L. C., et al., Proceedings of the Ocean Drilling Program, Scientific Results, vol. 115, p. 433-463. College Station, TX (Ocean Drilling Program). Kuramoto, S., 1996: Geophysical investigation for methane hy- drates and the significance of BSR. The Journal of the Geological Soclety of Japan, vol. 11, p. 951-958. (in Japanese with English abstract) Zakharov, Yu. D., 1974: Novaya nakhodka chelyustnogo apparata ammonoidey (A new find of an ammonoid jaw ap- paratus). Paleontologicheskii Zhurnal 1974, p. 127-129. (in Russian) 305 List of reviewers The coeditors are indebted to the following persons who acted as reviewers during the editing of volumes 3-4 of Paleontological Research. Aitchison, J. Amano, K. Anderson, O. R. Ando, H. Bandel, K. Chiba, S. Chinzei, K. Collette, B. B. Crick, R. E Debenay, J. -P. Endo, K. Engeser, T. Farrell, J. Feldmann, R. M. Fryxell, G. A. Furutani, H. Gröcke, D. R. Haggart, J. Hayami, |. Hirano, H. Hirayama, R. Histon, K. Hottinger, L. Houart, R. Igo, H. Iryu, Y. Ishizaki, K. Kaiho, K. Kato, H. Kennedy, W. J. Kidwell, S. M. King, A. King, G. M. Kitazato, H. Kuwahara, K. Landman, N. H. Maas, M. C. Maeda, H. Majima, R. Marincovich, L. Martin, T. Matoba, Y. Matsuoka, A. McLean, D. Muller, P. H. Nishida, H. Nishida, T. Nomura, R. Oba, T. Ogasawara, K. Oii, T. Orchard, M. Padian, K. Reif, W.-E. Reisz, R. R. Reitner, J. Revets, S. A. Reyment, R. A. Sasaki, T. Shigeta, Y. Suzuki, M. Takayanagi, Y. Takeda, M. Tanai, T. Tanimura, Y. Thomas, R.D.K Ting, S.-Y. Tomida, Y. Ubukata, T. Uemura, K. Ueno, T. Ujiié, H. Utting, J. Yamamoto, M. Yun, C. Weidrich, O. ms ae # vt Bs i ee) | : Tes SAG EAN ie So SN ee eS ae SYSTEMATIC INDEX (vol. 3, no. 1-vol. 4, no. 4: 1999-2000) 307 The 53 papers published in volumes 3-4 of Paleontological Research are listed under major systematic divisions of fossils. Entries in each category are arranged in alphabetical order of authorship, with two or more papers by the same author (s) in chronological order of publication. The volume number, part number (in parentheses), page numbers are given for each paper. PALEOZOOLOGY Protoctista vol.(no.) Hasegawa, Takashi: Planktonic foraminifera and biochronology of the Cenomanian-Turonian (Cretaceous) Sequence inithe:Oyuban area; Hokkaido; Japan... sn ee RENE RER tee eee Kitazato, Hiroshi, Masashi Tsuchiya and Kenji Takahara: Recognition of breeding populations in foraminifera: ansexampleusingithe'gemüstGlabratellake er. ee en seele = eee noce ete Kurihara, Toshiyuki and Katsuo Sashida: Early Silurian (Llandoverian) radiolarians from the Ise area of the Hida Gaienn, Beltiacentrall Japanese een een ee re leiser er Matsumaru, Kuniteru; A new Foraminifera from the upper Middle Eocene of the Ebro Basin, Spain ...... Mohiuddin, Mia Mohammad, Yujiro Ogawa and Kuniteru Matsunaru: Late Oligocene larger foraminifera from the Komahashi-Daini Seamount, Kyushu-Palau Ridge and their tectonic significance ............ Nomura, Ritsuo and Yokichi Takayanagi: Foraminal structures of some Japanese species of the genera Ammonia and Pararotalia, family Rotaliidae (Foraminifera) .................................. Nomura, Ritsuo and Yokichi Takayanagi: The suprageneric classification of the foraminiferal genus Murrayinella and a new species from Japan ............ ccc cee cece cece e ce eteeressenees Sugiyama, Kazuhiro: Replacement names for Permian stauraxon radiolarians .......................... Warraich, Muhammad Yousaf, Kenshiro Ogasawara and Hiroshi Nishi: Late Paleocene to early Eocene planktic foraminiferal biostratigraphy of the Dungan Formation, Sulaiman Range, Central Pakistan Porifera Matsuoka, Keiji and Yoshiki Masuda: A new potamolepid freshwater sponge (Demospongiae) from the Miocene: Nakamura Formation; centralJapan 56... cer 6 o-cveiel epareieisiers cre oye seen Cnidaria Kim, Jeong-Yul, Hyonyong Lee and Chang-Hi Cheong: Occurrence of Carbnoniferous corals from the Geumcheon!Eormation!of/Danyanglarea, Korea... een a RL eat Mollusca Amano, Kazutaka, Konstantin A. Lutaenko and Takashi Matsubara: Taxonomy and distribution of Macoma (Rexithaerus) (Bivalvia: Tellinidae) in the northwestern Pacific .................................. Amano, Kazutaka and Yoshinori Hikida: Evolutionary history of the Cenozoic bivalve genus Kaneharaia (Veneridae) ER stevens Te te Nate one ne ae 2 te atop RAR a NN a Das, Shiladri S., Subhendu Bardhan and Tapes C. Lahiri: The Late Bathonian gastropod fauna of Kutch, wWestemilndias"ainemassemblage SEE ee ee es nr ous te ats CT A Re ae Honda, Yutaka: A new species of Ancistrolepis (Gastropoda: Buccinidae) from the Iwaki Formation (lower Oligocene) ‘of the: Jobanicoali field} northern; Japan... .. u... nennen nenne seen ests Jana, Sudipta K., Subhendu Bardhan and Subrata K. Sardar: Kheraiceras Spath (Ammonoidea) - new forms and records from the Middle Jurassic sequence of the Indian subcontinent ...................... Janz, Horst: Hilgendorfs planorbid tree — the first introduction of Darwin’s Theory of Transmutation into palaeon too Var Coding CBAC oD CH MU Re ee le ee el et Kafanov, Alexander |., Konstantin B. Barinov and Louie Marincovich, Jr.: Papyridea harrimani Dall, 1904 (Bivalvia, Cardiidae) as a marker for upper Eocene and lower Oligocene strata of the North Pacific Kano, Yasunori and Tomoki Kase: Pisulinella miocenica, a new genus and species of Miocene Neritiliidae (Gastropoda: Neritopsina) from Eniwetok Atoll, Marshall Islands ................................ 4(2) 3(1) page 173-192 1-15 147-162 259-267 191-204 17-31 171-181 227-228 275-301 131-137 49-56 95-105 249-258 268-286 89-94 205-225 287-293 141-150 69-74 308 Kano, Yasunori and Tomoki Kase: Taxonomic revision of Pisulina (Gastropoda: Neritopsina) from submarine caves)inithe tropical) Indo-Pacific: =. 7. =... er ee erseleters eier > ce ere Ce CCI 4(2) Kurihara, Yukito: Middle Miocene deep-water molluscs from the Arakawa Formation in the Iwadono Hills area SaitamaPrefecturencentral Japan: 222 eee ee core ccm ce CR Ce 3(4) Matsumoto, Taturo and Akitoshi Inoma: The first record of Mesoturrilites (Ammonoidea) from Hokkaido (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXIll) .................... 3(1) Matsumoto, Tatsuro, Akitoshi Inoma and Yoshitaro Kawashita: The turrilitid ammonoid Mariella from Hokkaido-Part1 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXV) ...... 3(2) Matsumoto, Tatsuro and Yoshitaro Kawashita: The turrilitid ammonoid Mariella from Hokkaido-Part 2 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXVI) .................... 3(3) Matsumoto, Tatsuro and Toshio Kijima: The turrilitid ammonoid Mariella from Hokkaido-Part 3 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXVII) .............................. 4(1) Matsumoto, Tatsuro and Takemi Takahashi: Further notes on the turrilitid ammonites from Hokkaido-Part 1 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXIX) .................... 4(4) Nakazawa, Keiji: Permian bivalves from West Spitsbergen, Svalbard Islands, Norway .................. 3(1) Niko, Shuji, Yoshitaka Kakuwa, Daisuke Watanabe and Ryo Matsumoto: Early Silurian actinocerid and orthocerid cephalopods from the Kerman area, East-Central lran .............................. 3(1) Niko, Shuji and Tamio Nishida: A new pseudorthoceratid cephalopod from the Kazanian (middle Late Permian),of,Japan essen desserte Meetic Ce ce en se eee rote 4(1) Niko, Shuji, Tamio Nishida and Keiji Nakazawa: Orthoconic cephalopods from the Lower Permian Atahoc Ronmation: invB aston LE 2e me io topspeas co. otasa a iasaseny ouckscsuetstore sorseoyoa laze d Stereo soteueee Mic ST erro Tene 4(2) Niko, Shuji: New cephalopod material from the Bashkivian (Middle Carboniferous) of the Ichinotani Formation; Central Sapa as... «ya enecsi215) 5 evens auege tater stone unions tn eee renee 4(4) Takenaka, Naoko: Relation of growth rings to reproductive cycle in Cryptopecten vesiculosus, a dimorphic pectinidibiValVer reve crave oterevsileyey orator ie [axe oneguveeyana Sopsuor GE Ore ance efor eke Irre TT Cee 3(1) Tojo, Bunji and Fujio Masuda: Tidal growth patterns and growth curves of the Miocene potamidid gastropod Vicarya yokoyamdi .............. TRE D do 3(3) Yun, Cheol-Soo: Three Ordovician nautiloids from Jigunsan Formation of Korea ........................ 3(2) Yun, Cheol-Soo: Ordovician cephalopods from the Maggol Formation of Korea ........................ 3(3) Zakharov,Yuri D. and Yasunari Shigeta: Gyronautilus, a new genus of Triassic Nautilida from South Primerye;.Rüssia:..“.usse ea een dueseeniao nement ess Ces re ee ee CU 4(4) Arthropoda Karasawa, Hiroaki and Hiroshi Hayakawa: Additions to Cretaceous decaopod crustaceans from Hokkaido, Japan-Part 1. Nephropidae, Micheleidae adn Galatheidae...................................... 4(2) Karasawa, Hiroaki: Discovery of Early Cretaceous (Barremian) decapod Crustacea from the Arida Formation of:Wakayama: Prefecture; Japan... “0. MR NE eue ee decor sec eek 4(4) Karasawa, Hiroaki and Yasuhiro Fudouji: Palaeogene decapod Crustacea from the Kishima and Okinoshima Groups, KYUSHU, Japan... nent est Suess oi cie sometimes Ree I 4(4) Taylor, Rod S., Frederick R. Schram and Shen Yan-Bin: A new crayfish family (Decapoda: Astacida) from the Upper Jurassic of China, with a reinterpretation of other Chinese crayfish taxa .................. 3(2) Brachiopoda Tazawa, Jun-ichi: Boreal-type brachiopod Yakovlevia from the Middle Permian of Japan ................ 3(2) Conodonta Koike, Toshio: Apparatus of a Triassic conodont species Cratognathodus multihamatus (Huckriede) ...... 3(4) Vertebrata Ikegami, Naoki, Alexander W. A. Kellner and Yukimitsu Tomida: The presence of an azhdarchid pterosaur in the: Cretaceous: Of JAPAN .... c.ceseaiecsslasereceraveveaneerasesdre sores dose de secure CU oe ECE 4(3) Monsch, Kenneth A.: A new fossil bonito (Sardini, Teleostei) from the Eocene of England and the Caucasus, and evolution of tail region characters of its Recent relatives .................................. 4(1) 107-129 225-233 36-40 106-120 162-172 33-38 261-273 1-17 41-48 53-55 83-88 255-260 57-64 193-201 65-80 202-221 231-234 139-145 235-238 239-253 121-136 88-94 234-248 165-170 75-80 Setoguchi, Takeshi, Takehisa Tsubamoto, Hajime Hanamura and Kiichiro Hachiya: An early Late Cretaceous mammal from Japan, with reconsideration of the evolution of tribosphenic molars ................ Tsubamoto, Takehisa, Patricia A. Holroyd, Masanaru Takai, Nobuo Shigehara, Aye Ko Aung, Tin Thein, Aung Naing Soe and Soe Thura Tun: Upper premolar dentitions of Deperetella birmanica (Mammalia: Perissodactyla: Deperetellidae) from the Eocene Pondaung Formation, Myanmar ................ PALEOBOTANY Ohana, Tamiko, Tatsuaki Kimura and Shya Chitaley: Keraocarpon gen. nov., magnolialean fruits from the Üppen&retaceoustot Hokkaido Japan RER M me ere eeecmeesccer Pole, Mike: Dicotyledonous leaf macrofossils from the latest Albian-earliest Cenomanian of the Eromanga Basin Queesland AUS NA PR ee eee oi as nie te tease ee Ve Saiki, Ken’ichi: A new cheirolepidiaceous conifer from the Lower Cretaceous (Albian) of Hokkaido, Japan Takahashi, Masamichi, Peter R. Crane and Hisao Ando: Esgueiria futabensis sp. nov.; a new angiosperm flower from the Upper Cretaceous (lower Coniacian) of northeastern Honshu, Japan .............. Yang, Wei-Ping and Jun-Ichi Tazawa: Early Carboniferous miospores from the southern Kitakami Mountains, northeastJapam ces TEE era storeys RS ee nee Watkins, Rodney: Upper Paleozoic biostromes in island-arc carbonates of the eastern Klamath terrane, ENTER Rasa DE STE NA sata DEI LC OB DAR TERRESTRIAL ORGANIC MATTER Hasegawa, Takeshi and Takayuki Hatsugai: Carbon-isotope stratigraphy and its chronostratigraphic signifi- cance for the Cretaceous Yezo Group, Kotanbetsu area, Hokkaido, Japan ...................... 309 3(1) 18-28 4(3) 183-189 3(4) 294-302 4(1) 39-52 3(1) 29-35 3(2) 81-87 4(1) 57-67 310 INDEX OF GENERA AND SPECIES Genera and species described in volumes 3-4 of Paleontological Research are listed in alphabetical order. number, part number (in parentheses), page numbers, and figure numbers are given for each taxon. are in bold type. A vol. (no.), page, fig (s) Acanthopecten licharewi.................... 3(1), 5, fig. 4 Adanatoceras ichinotaniense........ 4(4), 259, fig. 2.2-2.6 AmmonlajaBOnlCarscersisieseivauersnsnesieieneen.eherenetete 4(1), 25, fig. 7 AIMMONASD ANS Cube ee ce ose 4(1), 23, figs. 2, 4, 6, 7 Ammonia sp. cf. A. parkinsoniana .......... 4(1), 25, fig. 7 AIMIMONA TODIGA sss; CHUMGES. DSRKERILKS-RERUSN ELAOTTER FAN. KRI-BROHLA | AT) A 142001 5 H 9A OK) T3. O&3151E#l& (2002 1 AFHHETE) LUENSBAFEFEDSOH ER LUS 0 & LH. ©2002 E& - GS (20024 6 A PHBA PE) (cS RED OBAHEH LA Zi à D & LH. ObEMBA TIS, \AMCHHMENZI-FPY¥avT7FRPVYa-bIA-REEHLTHVET. FEDS SRZSUTEHENNITENTLEIDT, SHEKBHEOAIUTBRE TEN DER FSU. BIER VV RV OU AROHLAZS ABHOR LAU PRERRABEEKYD FSW. e-mail P77» 7ATORLASI, JHAIEL TZUNGTBHERA,. 7240-0067 HET RE 7 RRKEER79-2 BER VAZARAMN SS BARE TEL 045-339-3349 (ii) FAX 045-339-3264 (HE) E-mail majima@ edhs.ynu.ac.jp FIM KE— (TBR) BHO, THD PacOTSRSE CHAE FAW. 7250-0031 /I\EMTTAF#EH499 FEAR) MLA AD EB > HIER VIRE TEL 0465-21-1515 FAX 0465-23-8846 E-mail taru @pat-net.ne.jp fll (TSS) ABORT IBS SRA, SÉOSADAE, MMAR SHARAMS HE 5UIBUSAD SOSH BATONTUETS, HEOEHNZARFEILDEN TE, AVERY TARA LH RIGA OR He = IE LIN TH BA ES AmABARKRASH FAA HKNA SH REA VAC RROD Sa-Y7TAN-TEGEBREDE (7 1 % x XI) ORB SHARDS HAKRAREER) 1 & 2, FE 4a ae AS he GE SS 200047 12H 27H 9 mil 7113-8622 HO AEAS-16-9 2000 # 12 A 30 H FE fr HAFAASEKBKeL VI -B Sm 03-58 14-5801 EEE me - kh + MEERE Rte MH. ROR: ee KEE Al fll & FARMS OARA EH À 2,500F 7176-0012 BRMRBEKSEI201301 CS RE 9) 99 Er 4 ISSN 1342-8144 Paleontological Research FAB, BAZ Paleontological Research | Vol. 4, No. 4 December 30, 2000 CONTENTS Yuri D. Zakharov and Yasunari Shigeta: Gyronautilus, a new genus of Triassic Nautilida from South Primorye, Russia -+ +++ +++: 022s sees seer eee eee eee eee eee eee e es 231 Hiroaki Karasawa: Discovery of Early Cretaceous (Barremian) decapod Crustacea from the Arida Formation of Wakayama Prefecture, Japan -----:-:-----+................................... 235 Hiroaki Karasawa and Yasuhiro Fudouji: Palaeogene decapod Crustacea from the Kishima and Okinoshima Groups, Kyushu, Japan :---------:::::.....................................0... 239 Shuji Niko: New cephalopod material from the Bashkirian (Middle Carboniferous) of the Ichinotani Formation, Central Japan ----------------............................eeeeesesssee 255 Tatsuro Matsumoto and Takemi Takahashi: Further notes on the turriliid ammonites from Hokkaido-Part 1 (Studies of the Cretaceous ammonites from Hokkaido and Sakhalin-LXXXIX) :--:: 261 Muhammad Yousaf Warraich, Kenshiro Ogasawara and Hiroshi Nishi: Late Paleocene to early Eocene planktic foraminiferal biostratigraphy of the Dungan Formation, Sulaiman Range, central Pakistan sons ss ee et eC CC CS Cer à à 0 na 001313 23 err ele Ce CC ee ale eleleiiene 275 PROCEEDINGS wee min nie we nn cle cece ee ces ss ne solo ee wie wie meine ein © © se ses solos /el= a 0a aie 2 Pete ete e eteletete serete 303 SYSTEMATIC INDEX nn sms ee CC) 307 INDEX OF GENERA AND SPECIES Se erie er On orn Uo cm DT OO OS 310 à Le if | b a iH HECKMAN BINDERY, INC. 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