Engyprosopon longipelvis Amaoka, 1969

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 : 468-470

Engyprosopon longipelvis Amaoka, 1969

Figure 12 , Table 2

Engyprosopon longipelvis Amaoka, 1969: 93 (type locality: Mimase , Kochi Prefecture, Japan).

Material examined: NMMB-P26187 , 3 males, 46.0– 58.1 mm SL, Ke-tzu-liao, Kaohsiung, southwestern Taiwan, 5 Apr. 2017.

Diagnosis. Gill rakers slender with spines; 37–40 scales in lateral line; ocular-side pelvic-fin rays in males elongate, and its fin membrane with many black spots.

Description. Dorsal-fin rays 78–82, anal-fin rays 59–60, ocular-side pectoral-fin rays 11–12, blind-side pectoral-fin rays 9–10, caudal-fin rays 3 + 11–12 + 2–3, ocular-side pelvic-fin rays 6, blind-side pelvic-fin rays 6, scales in lateral line 37–40, gill rakers 0 + 7, vertebrae 10 + 24.

In SL: HL 3.62–3.90, body depth 1.93–2.11. In HL: snout 4.03–4.55, upper eye diameter 3.34–3.71, lower eye diameter 3.53–4.70, interorbital width 3.63–5.08 in males, ocular-side upper jaw 2.52–2.70, blind-side upper jaw 2.57–2.65, ocular-side lower jaw 1.88–2.04, blind-side lower jaw 1.86-1.95, caudal peduncle depth 2.23–2.35, ocular-side pectoral fin 1.41–1.51 in males, blind-side pectoral fin 2.13–2.43, ocular-side pelvic fin 1.66–1.82, blind-side pelvic fin 2.07–2.66, base of ocular-side pelvic fin 2.26–3.20, base of blind-side pelvic fin 6.05–6.21, longest dorsal fin ray 1.84–2.20, longest anal fin ray 1.88–2.05, middle caudal fin ray 1.26-1.27.

Body elliptical, deepest at middle of body, its depth about 1/2 of SL; dorsal and ventral contours similar, except head region with gradual posterior taper. Caudal peduncle less than 1/4 of body depth. Head rather large, its length more than 1/4 of SL, upper profile somewhat steeply arched with shallow notch anterior to interorbital area; steep in mature males (not so in females and juveniles in comparative specimens). Snout obtuse, much shorter than eye diameter. A short, obtuse rostral spine on snout in males (spine absent in females). Eyes large; eye diameter much less than upper jaw length; lower eye slightly in advance of upper eye. Interorbital region wide, concave, becoming wider with growth (wider in males than in females and juveniles).

Mouth large, oblique, maxilla extending to vertical through anterior 1/2 of lower eye; anterior tips of both jaws almost on same line when mouth closed. Teeth on upper jaw biserial, those in outer series larger, more widely spaced and sparse compared with those in inner series, and enlarged anteriorly; lower jaw teeth uniserial, conical, all almost same size, and close-set. Gill rakers on first arch slender, distal part of inner margin with some small teeth; no gill rakers on upper limb. Ocular-side scales large, ctenoid with short ctenii, very deciduous; snout and both jaws naked; cycloid scales on blind side.

Dorsal-fin origin on blind side ventral to concavity on dorsal margin, no elongate rays. Anal fin origin below pectoral fin base. Ocular-side pectoral fin very short, much shorter than head length. Ocular-side pelvic-fin origin at tip of isthmus; ocular-side fourth or fifth ray opposite to first ray of blind-side fin; ocular-side pelvic-fin rays elongate in males (longest one much longer than ocular-side pectoral fin in mature males). Tip of isthmus near vertical line through middle of lower eye. Caudal-fin rays branched, expect for three upper- and two or three lowermost rays.

Coloration in alcohol. Ground color on ocular side uniformly light brown, without distinct dark spots; blind side of body more or less dark in males (uniformly yellowish white in females). Dorsal and anal fins with irregularly scattered dark spots; pectoral and caudal fins without distinctly dark blotches or spots; ocular-side pelvic-fin membrane with many distinct black spots in males.

Sexual dimorphism. This species shows sexual dimorphism in presence or absence of the rostral spine, interorbital width, curve of anterior dorsal profile of head, length and coloration of ocular-side pelvic fin, and in coloration of the blind side of the body.

Distribution. Western Pacific Ocean off Taiwan and southern Japan. Bathymetric range about 30– 100 m.

Remarks. Engyprosopon longipelvis is closely related to E. mozambiquense and E. parvipectorale in having serrate gill rakers, and is easily separated from them in having 37–42 scales in the lateral line (46–52 in the latter species), by its wider interorbital width ( Table 2), elongate pelvic-fin rays on the ocular side in males, ocular-side pelvic-fin membrane with many black spots, and by the uniformly dark brown caudal fin.

This is the first record of E. longipelvis from the waters off Taiwan, and also from beyond the waters off Japan.

Figures

FIGURE 12. Engyprosopon longipelvis Amaoka, 1969.NMMB-P26187, male, 52.5 mm SL. A. ocular side, B. blind side.