A new species of snailfish of the genus (Liparidae) from the western North Pacific, with a redescription of the poorly known species .

A new snailfish, , is described on the basis of 18 specimens collected off the Pacific coast of Tohoku District, northern Japan at depths of 422-890 m. The new species is distinguished from 28 species of described from the North Pacific by the following combination of characters: mouth oblique; uppermost pectoral-fin base below horizontal through posterior margin of maxillary; 60-63 vertebrae, 54-58 dorsal-fin rays, 50 or 51 anal-fin rays, six principal caudal-fin rays, and 17-20 pectoral-fin rays. A maximum likelihood tree based on 106 COI gene sequences (492 bp) of recovered a monophyletic group comprising , , and . is similar to in having an oblique mouth, but it has four caudal-fin rays (vs six rays) and the uppermost pectoral-fin base above a horizontal through the maxillary posterior margin. differs from in having a horizontal mouth, 12-14 pectoral-fin rays, and lacking pyloric caeca (present in ). is most similar to the eastern North Pacific in having an oblique mouth and the uppermost pectoral-fin base below a horizontal through the posterior margin of the maxillary. However, differs from in having six caudal-fin rays (vs five rays) and greater preanal length (29.9-35.3% SL vs 26.7-28.5% SL). A poorly known species, , previously known from only two specimens collected from Tosa Bay, southern Japan, is redescribed based on the holotype and seven newly collected specimens. It is also similar to the new species but has 27-30 pectoral-fin rays and a shorter pectoral-fin lower lobe (13.8-15.9% SL in vs 16.7-23.4% SL in ).