Redescription of a rare bothid, Asterorhombus bleekeri (Macleay), and description of a new species of Asterorhombus from northwestern Australia (Teleostei: Pleuronectiformes)

A rare Australian bothid flounder, Asterorhombus bleekeri (Macleay), is redescribed from the holotype and ten additional specimens from the east coast of Qeensland Gulf of Carpentaria and Rowly Shoal (Western Australia). The species is transferred from Arnoglossus Bleeker to Asterorhombus Tanaka because of the lack of obvious sexual dimorphism in the interorbital width and pectoral fin length, the lack of rostral and orbital spines, the yellow-white blind side body coloration, and the deeply cleft parhypural and hypural plates. The definition of Asterorhombus was emended as follows: the first dorsal fin ray continuous with or separated from remaining fin rays and gill rakers slender or stubby, with or without serrations. Asterorhombus osculus sp. nov., formerly briefly described in the literature as unidentified species of Engyprosopon, was described from eight specimens from the northwestern coast of Australia. The new species is most similar to A. bleekeri in lacking sexual dimorphism, and having the caudal skeleton with deep clefts, two or three rows of teeth on the upper jaw and a pair of conspicuous black spots on the caudal fin, in addition to a similar general appearance, but is distinguished from the latter by shorter gill rakers, a very small mouth and feebly ctenoid scales on the ocular side. Both species clearly differed from A. intermedius and A. fijiensis in having two (or three) rows of teeth on the upper jaws, slender gill rakers without serrations, first dorsal fin ray continuous with the other fin rays, and a pair of conspicuous black spots on the caudal fin.