Asterorhombus Tanaka 1915

Asterorhombus Tanaka, 1915

Asterorhombus Tanaka, 1915:567. Type species: Asterorhombus stellifer Tanaka, 1905.

Diagnostic features. Body ovate. Tip of isthmus below posterior margin of lower eye. No orbital and rostral spines. Front margin of head same in both sexes. Interorbital space narrowly concave, width same in both sexes or slightly wider in males than in females and juveniles.

Mouth rather large in size, upper-jaw length on ocular side 9.6–12.9% SL. Maxilla extending to anterior margin of lower eye. Teeth on both jaws uniserial. Gill rakers short and palmate. Scales ctenoid on ocular side, cycloid on blind side; 46–67 scales in lateral line. Lateral line on ocular side curved above pectoral fin; lateral line absent on blind side.

Dorsal-fin origin on blind side in front of upper margin of lower eye, first ray elongate, separated from remaining rays. Anal-fin origin below anterior base of pectoral fin on ocular-side. Pectoral fin not elongate, without sexual dimorphism. Pelvic fin on ocular side originating at tip of isthmus, fourth or fifth ray opposite to first ray on blind side. Caudal skeleton with four plates including parhypural and three hypurals, all plates with deep clefts.

Remarks. Asterorhombus is closely related to Engyprosopon in having a concave interorbital space and all four plates of the caudal skeleton with deep clefts, but it differs from the latter in having palmate gill rakers and an elongate first dorsal-fin ray.