2 NEW BRANCHIATE SCALE-WORMS (POLYNOIDAE, POLYCHAETA) FROM THE HYDROTHERMAL VENT OF THE OKINAWA TROUGH AND THE VOLCANIC SEAMOUNT OFF CHICHIJIMA ISLAND

Two new polynoid polychaete species are described from the Kaikata Seamount, a volcanic front of Izu-Ogasawara Island-Arc system, and the Izena Hole, a hydrothermal vent in the Okinawa Trough. Branchipolynoe pettiboneae, found living commensally in the mantle cavities of deep-sea mussels, is close to B. seepensis in having large elytra and branchiae beginning on segment 3, however the new species differs from the latter in having the subbiramous parapodia with digitiform notopodia instead of the biramous parapodia with conical notopodia. Opisthotrochopodus japonicus differs from other congeners in having the ventral cirri and lacking the modified neuropodial organs on posterior parapodia.