New and Known Vesicomyid Bivalves Recently Collected from the Western and Central Nankai Trough off Shikoku and Honshu, by Deep Sea Research Systems of Japan Marine Science and Technology Center

Abstract

Two species of bivalve of the genus Vesicomya were collected by the submersible Shinkai 6500 and the ROV Kaiko from chemosynthetic environments in upper abyssal depths in the western and central sectors of the Nankai Trough, extending from off Shikoku to off western Honshu, Japan. They are Vesicomya crenulomarginata n. sp. and large specimens of V. kaikoae Okutani, Fujikura & Kojima, 2000. Besides five known species of Calyptogena collected, another new species of the same genus Calyptogena (Archivesica) magnocultellus n. sp. was found and is described here. Ontogenic and individual variabilities in C. (Ectenagena) nautilei are discussed.