Engyprosopon Günther, 1862

Amaoka, Kunio & Ho, Hsuan-Ching, 2018, Review of the genus Engyprosopon Günther, 1862 (Pleuronectiformes: Bothidae) from waters off Taiwan, with descriptions of two new species, Zootaxa 4413 (3), pp. 449-481 : 450

Genus Engyprosopon Günther, 1862

Engyprosopon Günther, 1862:431 (type species: Rhombus mogkii Bleeker, 1854 ).

Scaeops Jordan & Starks, 1904:627 (type species: Rhombus grandisquama Temminck & Schlegel, 1846 ).

Diagnosis. Body shallow to deeply ovate. Anterior tip of isthmus ventral to middle of lower eye. A strong, or feeble (rarely absent) rostral spine in males; rostral spine feeble or absent in females and juveniles of both sexes. Anterior margin of head steeper in mature males than in females and juveniles, or rarely with the same profile in both sexes. Interorbital space wide to narrow, concave (to almost ridge-like), becoming wider with growth, and wider in males than in females and juveniles. Mouth usually moderate or sometime large in size, upper jaw length on ocular side 2.0– 3.6 in HL. Teeth on upper jaw uniserial or biserial; teeth uniserial on lower jaw.

Scales ctenoid on ocular side with row of feeble ctenii along apical margin; scales cycloid on blind side; 36–61 scales in lateral line. Lateral line on ocular side curved above pectoral fin, absent on blind side. Dorsal-fin origin on blind side anterior to dorsal margin of lower eye. Anal-fin origin below anterior base of ocular-side pectoral fin. Pelvic fin on ocular side originating at tip of isthmus, that on blind side equal to third to fifth fin ray on ocular side. Anus on blind side, just anterior to origin of anal fin; urogenital pore on ocular side, opposite to vent. Caudal skeleton of four plates including a parhypural and three hypurals, all with deep clefts from their distal margins to near their bases.

Remarks. Engyprosopon shares many characters with Asterorhombus including the cleft parhypural and three hypurals. Members of Engyprosopon have been distinguished from specimens of the latter genus by having sexual differences in interorbital width, length of the ocular-side pectoral fin, presence of a rostral spine, and sometimes an orbital spine and orbital flap, and by differences in body coloration on the blind side ( Amaoka et al., 1993). However, Hensley (2005) found that sexes of Asterorhombus filifer differ in interorbital width. In this paper, no sexual differences in the interorbital width and the coloration on the blind side were found for Engyprosopon mogkii or E. parvipectorale sp. nov. Based on these results, these two genera cannot be definitely separated by presence or absence of these sexual characters. Therefore, Engyprosopon can be clearly distinguished from Asterorhombus only in lacking a lure on the first dorsal-fin ray and in lacking palmate gill rakers, both features that characterize species of Asterorhombus .