Record of a Rare Ophidiid Fish, Barathrites iris (Actinopterygii: Teleostei: Ophidiiformes), from off Southern Japan

抄録

Two specimens of a rare ophidiid fish, Barathrites iris Zugmayer, 1911, were collected from the abyssal Pacific Ocean, off Kagoshima Prefecture, southern Japan. They agree with the diagnosis of Barathrites in having two pelvic-fin rays, five to six long gill rakers on the anterior gill arch, and a small head (33.5-33.8% of pre-anal-fin length) and eye (1.6-1.8% standard length, SL). Additionally, they can be separated from B. parri Nybelin, 1957, the only other known species of the genus, by their lack of basibranchial tooth patches, smaller eye (10.7-12.3% head length), and shorter pre-dorsal-fin region (17.1-18.9% SL). Previously B. iris was said to differ from B. parri in the number of branchiostegal rays (six versus seven, respectively), but one of the present specimens of B. iris (413mm SL) has seven branchiostegal rays on the left side and six on the right. Earlier workers have suggested the occurrence of Barathrites in the Pacific Ocean, but no documented records from this ocean appear to exist. This study confirms the occurrence of Barathrites and its type species B. iris in the Pacific Ocean.