Molluscs from Hydrothermal Vents and Cold Seeps in Japan: A ...

128T. Sasaki, T. Okutani & K. FujikuraAmano (2003).6) Neogastropoda: Neogastropods from vents and seeps are represented by only threefamilies (Buccinidae, Cancellariidae and Turridae). While the number of recorded species ofNeogastropoda (11 Species: Table 1) is not very small, the number of collected specimens of eachis extremely limited in all neogastropod species. This suggests that the population density of thesepredatory gastropods is generally low compared to that of other gastropods and bivalves. Somespecies (e.g. Eosipho desbruyeresi nipponensis) are endemic to vents or seeps, whereas others (e.g.Buccinum soyomaruae) are obviously temporary invaders from ambient environments into seepsites.7) Heterobranchia: Heterobranchs (‘Heterostropha,’ opisthobranchs and pulmonates) arenearly absent from in vents and seeps worldwide, except for lower heterobranchs such asLurifax, Xylodiscula and Hyalogyrina (Warén & Bouchet, 2001; Sasaki & Okutani, 2005). In thenorthwest Pacific, only a pyramidellid has been recorded (Okutani & Fujiwara, 2002). Shelledcephalaspideans (e.g., Cylichnidae), which are typical gastropods in deep-sea soft bottoms, havenever been collected in seeps. No pulmonates live in deep-sea environments.AcknowledgementsWe thank Dr. Anders Warén (Swedish Museum of Natural History), Dr. Philippe Bouchet (MuséumNational d’Histoire Naturelle, Paris), Prof. Kazushige Tanabe (University of Tokyo) and Dr. KazunoriHasegawa (National Science Museum, Tokyo) for their substantial improvement of the manuscript. Weare also indebted to Dr. Shigeaki Kojima (Ocean Research Institute, University of Tokyo) for suggestionson Calyptogena molecular phylogeny, and to Dr. Kazutaka Amano (Joetsu University of Education) Dr.Takami Nobuhara (Shizuoka University) and Prof. Ryuichi Majima (Yokohama National University)for relevant information in paleontology. Dr. Hiroshi Saito (National Science Museum, Tokyo) kindlypermitted and helped the first author to take photographs of holotypes in NSMT illustrated here.ReferencesAmano, K. 2003. Predatory gastropod drill holes in upper Miocene cold seep bivalves, Hokkaido, Japan.Veliger 46: 90-96.Amano, K. & Kanno, S. 2005. Calyptogena (Bivalvia: Vesicomyidae) from Neogene strata in the JoetsuDistrict, Niigata Prefecture, central Japan. Veliger 47: 202-212.Beck, L. A. 1992. Two new neritacean limpets (Gastropoda: Prosobranchia: Neritacea: Phenacolepadidae)from active hydrothermal vents at Hydrothermal Field 1 “Wienerwald” in the Manus Back ArcBasin (Bismarck Sea, Papua New Guinea). Annalen des Naturhistorisches Museum, Wien 93B:259-275.Bernard, F. R. 1972. The genus Thyasira in western Canada (Bivalvia: Lucinacea). Malacologia 11:365-389.Boss, K. J. & Turner, R. D. 1980. The giant white clam from the Galapagos Rift, Calyptogena magnificaspecies novum. Malacologia 20: 161-194.Bouchet, P. & Rocroi, J.-P. 2005. Classification and nomenclator of gastropod families. Malacologia 47:1-397.Coan, E. V., Scott, P. V. & Bernard, F. R. 2000. Bivalve Seashells of Western North America. 764 pp.Santa Barbara Museum of Natural History.Cosel, R. v. 2002. A new species of bathymodioline mussel (Mollusca, Bivalvia, Mytilidae) fromMauritania (West Africa), with comments on the genus Bathymodiolus Kenk & Wilson, 1985.Zoosystema 24: 259-271.Cosel, R. v. & Salas, C. 2001. Vesicomyidae (Mollusca: Bivalvia) of the genera Vesicomya,Waisiuconcha, Isorropodon and Callogonia in the eastern Atlantic and the Mediterranean. Sarsia 86:333-366.Dall, W. H. 1891. On some new or interesting West American shells obtained from dredgings of the U. S.fish commission steamer “Albatross” in 1888. Proceedings of the United States National Museum14: 173-191, pl. 3.