Abstract
A new species of the whalefish genus Cetomimus is described based on eight female specimens from the Japanese seas, eastern Australia and the South Atlantic. The females of the new species, Cetomimus papilio sp. nov ., can be distinguished from its congeners by the presence of tent‐like lateral‐line flaps that are wider than the lateral‐line canal, lateral‐line pores 11–14, internal cavernous tissue surrounding the anus and the urogenital papilla, forming pseudocloaca, body depth 26.8%–32.4% SL and head length 36.2%–42.0% SL. Reassessments of the literature records of the genus and species are provided, along with a revised diagnosis for the females in the genus and an identification key to the nominal species of Cetomimus.