Revision of the bathyal fish genus Pseudonus (Teleostei, Bythitidae); P. squamiceps a senior synonym of P. platycephalus, new to Australian waters

The viviparous, bathyal fish genus Pseudonus (Teleostei, Bythitidae, Bythitinae) is known from the Indo-Pacific Ocean. Three species have been described, all based on 1-2 specimens: P. acutus Garman, 1899 from the tropical East Pacific, P. platycephalus (Smith & Radcliffe, 1913) from the Indo-Australian area and P. squamiceps (Lloyd, 1907) from the Gulf of Aden. An additional 18 specimens have become available to justify this revision. The result has established the conspecificity of P. squamiceps and P. platycephalus with P. squamiceps the senior synomym of the two. The major differences between P. acutus and P. squamiceps are that the former has more dorsal (101-119 vs 95-102) and anal (74-85 vs 64-71) fin rays, more vertebrae (61-63 vs 55-58) and lacking pelvic fin rays (vs one of 15 specimens lacks pelvic fin rays). This is the first record of P. squamiceps from Australian waters.