Hoplostethus roseus, a new roughy fish from the western Pacific based on morphology and DNA barcoding (family Trachichthyidae).

A new species of the roughy fish genus Hoplostethus is described from 11 types and a non-type specimen collected from Taiwanese waters. It can be distinguished from its congeners by a combination of characters: pectoral-fin rays 14-17 (modally 15-16); pyloric caeca 65-84; total gill rakers 19-20; predorsal scales 18-22; oral cavity, branchial chamber, top and underside of tongue, and peritoneum uniformly black; distal margin of membrane between dorsal-fin spines black; caudal fin without a black margin; caudal-fin base brownish. Comparisons of the new species with similar species are provided. DNA barcoding supports the monophyly of the new species, which appears to be closely related to Hoplostethus japonicus [average cytochrome c oxidase subunit I Kimura-2-parameter (COI K2P) distance of 4.1%].