Bulletin of the Mizunami Fossil Museum, no. 45 (March 15, 2019), p. 27–32, 1 fi g., 1 appendix. © 2019, Mizunami Fossil Museum

Two new species of Planoprosopon (Decapoda: Brachyura: Longodromitidae) from the Torinosu Group (Upper Jurassic–Lower Cretaceous), Shikoku, Japan

Hiroaki Karasawa* and Takayoshi Hirota**

*Mizunami Fossil Museum, Yamanouchi, Akeyo, Mizunami, Gifu 509-6132, Japan **Hei 78, Sakawa-cho, Kochi 789-1203, Japan

Abstract

Two new species of Longodromitidae, Planoprosopon ogawaense and Planoprosopon sarumaru, are described, based upon examination of the previously known and new specimens of crabs from the Torinosu Group (Upper Jurassic–Lower Cretaceous), Shikoku, Japan. Both species together with goniodromitids from the Torinosu Group (Karasawa and Kato, 2007) and a longodromitid from the Somanakamura Group (Kato et al., 2010) represent the oldest records of Brachyura known from the circum- Pacific realm.

Key words: Decapoda, Brachyura, Dromiacea, Longodromitidae, Torinosu Group, Late Jurassic–Early Cretaceous, Japan

Introduction Shiraishi et al. (2005). More recently, Kakizaki et al. (2012) suggested, using strontium isotopic stratigraphy Karasawa and Kato (2007) described three new species in age, that the Torinosu Group was 151.1 Ma (latest of goniodromitids, Goniodromites hirotai, Goniodromites Kimmeridgian) to 140.3 Ma (latest Berriasian). Kobayashi sakawense, and Pithonoton iyonofutanajima, from the and Wernli (2013) provided the detailed information on Upper Jurassic Torinosu Group of Shikoku, Japan (Fig. the geological age of the Torinosu Group. 1.4–1.6). At that time, they only figured an unnamed species of Nodoprosopon Beurlen, 1928, from the same Institutional abbreviations locality. Subsequently, the species was moved to the longodromitid genus Planoprosopon Schweitzer, MFM: Mizunami Fossil Museum, Yamanouchi, Feldmann, and Lazăr, 2007 (Schweitzer and Feldmann, Akeyo, Mizunami, Gifu, Japan 2009b). SGM: Sakawa Geology Museum, Sakawa-cho, The purpose of the present study is to describe a Kochi, Japan new species of Planoprosopon based upon examination of previously known specimens collected from shale of Systematics the Yatsuji Formation (Kano and Jiju, 1995) of the Torinosu Group exposed at Ogawa (Karasawa and Kato, Section Dromiacea de Haan, 1833 2007), Sakawa-cho, Kochi Prefecture (33°29′18″N; Superfamily Homolodromioidea Alcock, 1900 133°14′18″E). Another new species of Planoprosopon is Family Longodromitidae Schweitzer and Feldmann, 2009a described herein from shale of the Yatsuji Formation of the Torinosu Group distributed in Yoshidayashiki, Genus Planoprosopon Schweitzer, Feldmann, and Sakawa-cho, Kochi Prefecture (33°29′26″N; 133°17′37″E). Lazăr, 2007 Although index fossils have not yet been recorded from Type species: Prosopon heydeni von Meyer, 1857, by the crab-bearing localities, Karasawa and Kato (2007) original designation. noted that the age of the Yatsuji Formation is middle Included species: Planoprosopon aequus (von Meyer, Tithonian based upon the strontium isotopic data of 1857); P. conspicuus Schweitzer, Lazăr, Feldmann,

最終_研究報告-45_本文.indd 27 2019/03/08 9:10:26 28

Stoica, and Franţescu, 2017; P. cornutus (Wehner, 1988); orbital margin, axially concave, rimmed. Dorsal surface P. dumosus (Wehner, 1988); P. heydeni; P. hystricosus densely granulated; regions more or less defined. Schweitzer and Feldmann, 2009b; P. kashimaensis Kato, Protogastric regions weakly inflated. Mesogastric region Takahashi, and Taira, 2010; P. major (Hée, 1924); P. widened posteriorly, with long anterior process ogawaense, new species; P. quadratum Schweigert extending to base of rostrum. Hepatic regions weakly and Koppka, 2011; P. rathamingus Schweitzer and inflated. Cervical groove continuous, deep, sinuous; Feldmann, 2009b; P. sarumaru, new species; P. lateral elements nearly straight, slightly directed schweigerti Schweitzer and Feldmann, 2009c. obliquely toward metagastric region; axial element moderately concave forward. Branchiocardiac groove Planoprosopon ogawaense, new species deepest laterally, nearly straight, directed obliquely (Fig. 1.1a–1.2) posteriorly, weakening axially. Postcervical groove Nodoprosopon sp.; Karasawa and Kato, 2007, p. 65, deep, connected laterally with branchiocardiac fig. 1a–1c. groove, composed of two elements on each side of axis Planoprosopon sp.; Schweitzer and Feldmann, arched posteriorly and joining with branchiocardiac 2009b, p. 10. groove. Metagastric region much wider than long, Etymology: The trivial name is derived from gently convex, weakly bilobed axially, separated from “Ogawa”, the village name in a modern history age. epibranchial regions by subtle groove. Urogastric Diagnosis: Small-sized Planoprosopon; carapace region short, narrow, depressed. Epibranchial regions subpentagonal, longer than wide, widest at about well inflated. Meso- and metabranchial regions outer orbital angle, weakly vaulted transversely and confluent, gently convex. Cardiac region wider than longitudinally; fronto-orbital width as long as maximum long, pentagonal, weakly inflated. Intestinal region carapace width; rostrum protruded anteriorly, deeply narrow, depressed. sulcate axially, with broad, V-shaped anterior margin; Ventral aspects and appendages unknown. upper orbital margin gently concave with small, broadly Remarks: The new species is most similar to triangular inner orbital spine; outer orbital spine Planoprosopon hystricosus and P. rathamingus from acutely triangular, directed anterolaterally; lateral the Tithonian Ernstbunn Limestone of Austria margins sinuous, diverged posterior to metabranchial (Schweitzer and Feldmann, 2009b) by having a area, with deep cervical and branchiocardiac incisions; relatively short carapace with well inflated epibranchial posterior margin wide, axially concave, rimmed; dorsal regions. However, the new species has the densely surface densely granulated; cervical groove deep, granulated carapace and lacks tubercles on the gastric sinuous, slightly directed obliquely toward axial region; and hepatic regions. Additionally, within the new branchiocardiac groove deepest laterally, nearly species lateral margins lack hepatic spines, which both straight, directed obliquely posteriorly; postcervical P. hystricosus and P. rathamingus possess. Schweigert groove deep, connected laterally with branchiocardiac and Koppka (2011) suggested that P. quadratum groove; epibranchial regions well inflated. Schweigert and Koppka, 2011, from the Middle Jurassic Description: Small-sized Planoprosopon. Carapace of Germany bore some resemblance to the present new subpentagonal, longer than wide, maximum width species (=“Nodoprosopon sp.” as in Schweigert and including rostrum about 90 percent maximum length, Koppka, 2011); a much longer hepatic region widest at about outer orbital angle, weakly vaulted distinguished it from P. quadratum. Planoprosopon transversely and longitudinally. Fronto-orbital width ogawaense has densely granular ornamentations of the about as long as maximum carapace width. Rostrum carapace. protruded anteriorly, slightly wider than long at base, Material examined: SGM1300 (holotype) and SGM1302 deeply sulcate axially; anterior margin broad, V-shaped; (paratype); shale of the Yatsuji Formation of the Torinosu lateral margins flared. Orbit wide, shallow, directed Group (Upper Jurassic–Lower Cretaceous) exposed at forward. Upper orbital margin gently concave, directed Ogawa (Locality of Karasawa and Kato, 2007), Sakawa- obliquely posteriorly toward lateral margin, with cho, Kochi Prefecture (33°29′18″N; 133°14′18″E). small, broadly triangular inner orbital spine directed anterolaterally; outer orbital spine well developed, Planoprosopon sarumaru, new species acutely triangular, directed anterolaterally. Lateral (Fig. 1.3a–1.3e) margins sinuous, diverged posterior to metabranchial Etymology: The specific name is derived from “Den area, with deep cervical and branchiocardiac incisions. sarumarudayū no haka”, a historical site of Sakawa- Posterior margin wide, slightly narrower than fronto- cho near the type locality. Therefore, the name is an

最終_研究報告-45_本文.indd 28 2019/03/08 9:10:26 29

Fig. 1. Crabs from the Torinosu Group (Upper Jurassic–Lower Cretaceous) in Sakawa-cho, Shikoku, Japan. 1a–1e, 2. Planoprosopon ogawaense, new species. 1a–1e, holotype (SGM1300), carapace. 1a, 1b, internal mold, dorsal view; 1c, internal mold, oblique-frontal view; 1d, 1e, external mold. 2, paratype (SGM1302), external mold of carapace. 3a–3e. Planoprosopon sarumaru, new species. Holotype (SGM1303), carapace. 3a, 3b, internal mold, dorsal view; 3c, internal mold, oblique-frontal view; 3d, 3e, external mold. 4. Goniodromites hirotai Karasawa and Kato, 2007, MFM247020, dorsal view of carapace. 5. Goniodromites sakawense Karasawa and Kato, 2007, MFM247021, dorsal view of carapace. 6. Pithonoton iyonofutanajima Karasawa and Kato, 2007, MFM247022, dorsal view of carapace. Scale bars = 2 mm. 1b, 1e, 3b, 3e, 4, 5, and 6 are whitening images coated with ammonium chloride sublimate.

最終_研究報告-45_本文.indd 29 2019/03/08 9:10:26 30

arbitral combination of letters. and oblique groove extending from posterolateral corner of Diagnosis: Moderate-sized Planoprosopon; carapace metagastric region. Meso- and metabranchial regions subrectangular, much longer than wide, widest at confluent, gently convex. Cardiac region inverted about posterior fourth, weakly vaulted longitudinally, triangular, about as long as wide, weakly inflated. nearly flattened transversely; fronto-orbital margin Intestinal region short, narrow, depressed. wide with broadly triangular outer orbital angle; Ventral aspects and appendages unknown. lateral margins sinuous, slightly diverged posteriorly, Remarks: Planoprosopon sarumaru possesses carapace with deep cervical, postcervical, and branchiocardiac characters most like those of P. conspicuus from the incisions; posterior margin concave, rimmed, wide, Topalu Member (?upper Oxfordian–lower Kimmeridgian) with broadly triangular axial incision; dorsal surface of Romania (Schweitzer et al., 2017), but differs in that the densely covered with small spines; regions well outer orbital angle is broadly triangular, the cardiac region defined; protogastric regions with protuberance lacks a posterior tubercle, and the posterior margin bears posteriorly; hepatic regions with small protuberance; a broadly triangular axial incision. Additionally, the cervical groove continuous, deep, moderately concave intestinal region in the new species is much shorter than forward, directed obliquely toward axial region; that in P. conspicuus. branchiocardiac and postcervical grooves deep; Material examined: SGM13003 (holotype); shale of the epibranchial regions flattened, composed of three Yatsuji Formation of the Torinosu Group (Upper regions; intestinal region short. Jurassic–Lower Cretaceous) exposed at Yoshidayashiki, Description: Moderate-sized Planoprosopon. Sakawa-cho, Kochi Prefecture (33°29′26″N; 133°17′37″E). Carapace subrectangular, longer than wide, maximum width excluding rostrum about 80 percent maximum Acknowledgment length, widest at about posterior fourth, weakly vaulted longitudinally, nearly flattened transversely. Rostrum We thank R. M. Feldmann (Kent State University, broken. Fronto-orbital width about 85 percent maximum Ohio) for careful review and valuable comments of carapace width. Upper orbital margin wide, sinuous, our manuscript. directed obliquely posteriorly toward lateral margin; outer orbital angle broadly triangular, directed laterally. References Lateral margins sinuous, slightly diverged posteriorly, with deep cervical, postcervical, and branchiocardiac Alcock, A. 1900. Materials for a carcinological fauna of incisions; margins behind branchiocardiac incision India, 5: The Brachyura Primigenia or Dromiacea. gently convex; posterolateral angle widely rimmed. Journal of the Asiatic Society of Bengal 68: 123– Posterior margin concave, rimmed, wide, about 85 169. percent maximum carapace width, with broadly Beurlen, K. 1928. Die fossilen Dromiaceen und ihre triangular axial incision. Dorsal surface densely Stammesgeschichte. Paläontologische Zeitschrift covered with small spines; regions well defined. 10: 144–183. Protogastric regions weakly inflated with protuberance Haan, W. de. 1833–1850. Crustacea. In: Siebold, P. F. posteriorly. Mesogastric region widened posteriorly; von, Fauna Japonica sive Descriptio Animalium, anterior process long, well raised, narrowing posteriorly. Quae in Itinere per Japoniam, Jussu et Auspiciis Hepatic regions bearing small protuberance, separated Superiorum, qui Summum in India Batava from protogastric regions by weak depression. Cervical Imperium Tenent, Suscepto, Annis 1823–1830 groove continuous, deep, moderately concave forward, Collegit, Noitis, Observationibus et Adumbrationibus directed obliquely toward axial region. Branchiocardiac Illustravit. Leiden, Lugduni-Batavorum: i–xvii, groove deep, nearly straight, directed obliquely posteriorly, i–xxxi, ix–xvi, 1–243, plates A–J, L–Q, 1–55. weakening axially. Postcervical groove deep, composed of Hée, A. 1924. Catalogue critique des Crustacés two elements on each side of axis arched posteriorly and jurassiques du Calvados et de l‘Orne. Bulletin de connected with branchiocardiac groove; lateral element la Societé Linéene de Normandie 6: 126–157. nearly parallel to branchiocardiac groove. Metagastric Kakizaki, Y., T. Ishikawa, K. Nagaishi, M. Tanimizu, region much wider than mesogastric region, gently convex T. Hasegawa, T., and A. Kano. 2012. Strontium longitudinally, weakly bilobed axially, separated laterally isotope ages of the Torinosu-type limestones from epibranchial regions by arcuate groove. Urogastric (latest Jurassic to earliest Cretaceous, Japan): region depressed, only developed as groove. Epibranchial Implication for biocalcification event in regions flattened, divided into three by postcervical groove northwestern Palaeo-Pacific. Journal of Asian

最終_研究報告-45_本文.indd 30 2019/03/08 9:10:27 31

Earth Sciences 46: 140–149. species of Longodromitidae Schweitzer and Kano, A., and K. Jiju. 1995. The Upper Jurassic– Feldmann, 2009, from the Ernstbrunn Formation, Lower Cretaceous carbonate–terrigenous Late Jurassic (Tithonian), Austria. Annalen des succession and the development of a carbonate Naturhistorischen Museums in Wien, Serie A 111: mound in western Shikoku, Japan. Sedimentary 207–224. Geology 99: 165–178. Schweitzer, C. E., and R. M. Feldmann. 2009c. Revision Karasawa, H., and Kato, H. 2007. New prosopid of Gabriella Collins et al., 2006 (Decapoda: crabs (Crustacea, Decapoda, Brachyura) from the Brachyura: Homolodromioidea: Tanidromitidae) Upper Jurassic Torinosu Group, Shikoku, Japan. with new Jurassic species. Neues Jahrbuch für Memorie della Società italiana di Scienze Geologie und Paläontologie, Abhandlungen 252: naturali e del Museo civico di Storia naturale in 1–16. Milano 35: 62–65. Schweitzer, C. E., R. M. Feldmann, and I. Lazăr. Kato, H., T. Takahashi, and M. Taira. 2010. Late 2007. Decapods from Jurassic (Oxfordian) sponge Jurassic decapod crustaceans from northeast reefs of Dobrogea, Romania and reconsideration Japan. Palaeontology 53: 761–770. of Nodoprosopon Beurlen, 1928. Neues Jahrbuch Kobayashi, F., and R. Wernli. 2013. Latest Jurassic für Geologie und Paläontologie, Abhandlungen to earlier Early Cretaceous foraminifers from the 244: 99–114. Torinosu-type limestone blocks in Southwest Schweitzer, C. E., I. Lazăr, R. M. Feldmann, M. Stoica, Japan: Constraints on chrolonogic calibration of and O. D. Fra侉 escu. 2017. Decapoda (Anomura; the Torinosu-type limestones. The Journal of the Brachyura) from the Late Jurassic of Dobrogea, Geological Society of Japan 119: 25–38. Romania. Neues Jahrbuch für Geologie und Meyer, H. von. 1857. Briefliche Mitteilungen. Neues Paläontologie, Abhandlungen 286: 207–228. Jahrbuch für Mineralogie, Geognosie, Geologie Shiraishi, S., Y. Hayasaka, Y. Takahashi, M. Tanimizu, und Petrefaktenkunde 1857: 556. T. Ishikawa, J. Matsuoka, M. Murayama, and A. Schweigert, G., and J. Koppka, J. 2011. Decapods Kano. 2005. Strontium isotopic age of the Torinosu (Crustacea: Brachyura) from the Jurassic of Limestone in Niyodo Village, Kochi Prefecture, SW Germany and Lithuania, with descriptions of Japan. The Journal of the Geological Society of new species of Planoprosopon and Tanidromites. Japan 111: 610–623. Neues Jahrbuch für Geologie und Paläontologie, Wehner, G. 1988. Über die Prosoponiden (Crustacea, Abhandlungen 260: 221–235. Decapoda) des Jura. Dissertation zur Erlangung des Schweitzer, C. E., and R. M. Feldmann. 2009a. Doktorgrades der Fakultät für Geowissenschaften Revision of the Prosopinae sensu Glaessner, 1969 der Ludwig-Maximilians-Universität zu München. (Crustacea: Decapoda: Brachyura) including four München: 1–154. new families, four new genera, and five new species. Annalen des Naturhistorischen Museums in Wien, Manuscript accepted on September 15, 2018 Serie A 110 [for 2008]: 55–121. Schweitzer, C. E., and R. M. Feldmann. 2009b. New

最終_研究報告-45_本文.indd 31 2019/03/08 9:10:27 32

Appendix 和文概要

四国の鳥巣層群（上部ジュラ系－下部白亜系）産 Planoprosopon 属（十脚目：短尾下目） の 2 新種

柄沢 宏明・廣田 隆吉

高知県佐川町に分布する鳥巣層群（上部ジュラ系－下部白亜系）から産したナガカイカムリ科（新称） Longodromitidae に所属するヒラナガカイカムリ属（新称）Planoprosopon の 2 新種を記載した．オガワヒラナガカイ カムリ（新称）Planoprosopon ogawaense は，甲は小型，頸溝及び鰓心溝が深く，良く膨れた前鰓域を持つ．一方，サ ルマルヒラナガカイカムリ（新称）Planoprosopon sarumaru は，甲は中型，甲背面は平たく，前鰓域が三分され，極 端に短い肝域を持つ．ヒラナガカイカムリ属は，ジュラ紀中期～ジュラ紀後期の西部テチス地域から化石種が良く知ら れ，環太平洋域では鳥巣層群の他，福島県の上部ジュラ系相馬中村層群（Kato et al., 2010）から化石記録が知られる のみである．

最終_研究報告-45_本文.indd 32 2019/03/08 9:10:27