A new species of amphinomid polychaete, Branchamphinome kohtsukai sp. nov., is described from Japanese waters, 29-211 m in depth. The species is distinguishable from other congeners by the following features: i) branchiae with four-six filaments in midbody segments; ii) two pairs of eyes not coalescent; iii) the ventral side of the first four chaetigers broadly pigmented. This is the first record of Branchamphinome from the North Pacific Ocean. We provide a phylogenetic tree based on the sequences of four genes (COI, 16S, 18S, 28S) and discuss amphinomids' relationships.
Keywords: Amphinomida; Japan; Polychaeta; deep sea; polychaetes; taxonomy.