Engyprosopon multisquama Amaoka, 1963

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 : 456-459

Engyprosopon multisquama Amaoka, 1963

Figures 4–5 ; Table 1

Engyprosopon multisquama Amaoka, 1963:111 , fig. 3 (type locality: Susaki, Kochi Prefecture, Japan). Amaoka, 1969:146, fig. 47; Shen, 1983:20, fig. 26; Shen, 1993:569, pl. 19-9; Shao et al., 2008:264; Shen & Wu, 2012:751, 2 figs.

Material examined. NMMB-P8852 , male, 89.5 mm SL, Penghu, Taiwan, 30 Aug. 2005 ; NMMB-P8859 , male, 87.5 mm SL, Penghu, Taiwan, 27 Oct. 2005 ; NMMB-P14467 , 2 females, 73.1–75.3 mm SL, Chie-din , Kaohsiung, Taiwan, 1 Nov. 2001 . NMMB-P22258 , 2 males, 82.0–97.0 mm SL, Ke-tzu-liao, Kaohsiung, Taiwan, 11 Mar. 2015 ; NMMB-P22245 , 1 females, 91.7 mm SL, Ke-tzu-liao, Kaohsiung, Taiwan, 11 Feb. 2015 ; NMMB-P22770 , 3 males, 83.3–92.3 mm SL, Chie-din , Kaohsiung, Taiwan, 50 m, 1 Nov. 2015 .

Diagnosis. Caudal fin with a pair of black blotches, arranged between the second and fourth fin rays from the uppermost and lowermost fin rays in this fin; ocular-side pectoral fin with greatly elongate filament, longer in males than females; gill rakers not serrate.

Description. Dorsal-fin rays 89–98, anal-fin rays 68–75, ocular-side pectoral-fin rays10–12, blind-side pectoral-fin rays 9–10, caudal-fin rays 3 + 11 + 3, ocular-side pelvic-fin rays 6, blind-side pelvic-fin rays 6, scales 45–50 in lateral line, gill rakers 0 + 6, vertebrae 10 + 25–26.

In SL: HL 3.75–4.36, body depth 1.83–2.03. In HL: snout 4.67–5.25, upper eye diameter 3.27–3.92, lower eye diameter 3.26–3.87, interorbital width 3.75–5.66 in males, 6.99–8.76 in females, ocular-side upper jaw 2.94–3.18, blind-side upper jaw 2.90–3.18, ocular-side lower jaw 2.11–2.38, blind-side lower jaw 1.96–2.13, caudal peduncle depth 1.82–2.22, ocular-side pectoral fin 0.48–0.72 in males, 0.95–1.11 in females, blind-side pectoral fin 1.70– 1.94, ocular-side pelvic fin 1.75–2.33, blind-side pelvic fin 2.01–2.85, base of ocular-side pelvic fin 2.16–2.59, base of blind-side pelvic fin 5.08–7.86, longest dorsal fin ray 1.73–2.28, longest anal fin ray 1.71–2.07, middle caudal fin ray 1.01–1.16.

Body rather narrowly ovate, deepest about at middle of body, body depth usually less than 1/2 of SL; dorsal and ventral contours of body almost symmetrical. Caudal peduncle about 1/4 of body depth. Head small, its length about 1/4 of SL; upper profile with distinct concavity anterodorsal to upper margin of lower eye, profile steep in mature males, not so in females and juveniles. Snout short, much shorter than eye diameter. Ocular-side rostral spine on snout tip in males, absent or feeble in females and juveniles. Eyes small, eye diameter distinctly less than upper jaw length; lower eye slightly in advance of upper eye. No orbital spine in either sex. Interorbital space moderately concave, distinct sexual and ontogenetic differences in its width; interorbital width greater in males than in females. Ocular-side nostrils anterior to upper margin of lower eye; anterior nostril tubular with wide flap; posterior nostril a short tube; blind-side nostrils very small and similar to those on ocular side, closely set below origin of dorsal fin.

Mouth small, oblique; maxilla extending ventroposteriorly slightly beyond vertical through anterior margin of lower eye; anterior tips of both jaws about on same vertical line, when mouth closed; small knob on mandibular symphysis. Teeth in upper jaw biserial, those in outer series larger and more widely spaced than those in inner series; some teeth anteriorly canine-like; lower jaw teeth uniserial, conical, almost same size as upper inner teeth. Gill rakers on first arch moderately slender, sharp at tip, inside edge not serrate; no gill rakers on upper limb. Ocular-side scales ctenoid with short ctenii, large and deciduous; tips of both jaws and tip of ocular side of snout naked; scales cycloid on blind side of body.

Dorsal and anal fins without elongate rays. Ocular-side pectoral fin with elongate filamentous rays in both sexes; rays in males longer than those in females; blind-side pectoral fin not elongate; same length in both sexes. Ocular-side pelvic-fin origin at tip of isthmus, fifth ray of ocular-side fin opposite to first ray of blind-side fin; anterior margin of first ray of ocular-side pelvic fin with skin flap. Tip of isthmus near vertical line through middle of lower eye. Caudal-fin rays branched except for three upper- and three lowermost rays. Tip of pelvic bone not distinctly extruded.

Coloration in alcohol. Ocular side of body uniformly light yellowish green without any distinct markings; caudal fin with pair of large black blotches arranged between second to fourth fin rays from upper- and lowermost fin rays, respectively; all fins with irregularly-scattered, small black spots; blind side of body dark, except for part of head in males; blind side of body uniformly yellowish white in females.

Sexual dimorphism. This species shows sexual dimorphism in slope of the anterior margin of the head, in interorbital width, presence or absence of a rostral spine, length of the ocular-side pectoral fin, and in coloration on the blind side of the body.

Distribution. Western Pacific Ocean off Taiwan and southern Japan; also found in mouth of Mekong River, Vietnam (KA, pers. data). Commonly collected at depths less than 100 m off Taiwan.

Remarks. This species has frequently been confused with E. grandisquama in having a pair of black blotches on the caudal fin. However, E. multisquama differs from the latter in having larger black blotches on the caudal fin, a more elongate body, a more elongate ocular-side pectoral fin, greater number of scales in the lateral line, and by its higher meristic values.

Figures

FIGURE 4. Engyprosopon multisquama Amaoka, 1963. Ocular side, NMMB-P8852, male, 89.5 mm SL. B. NMMB-P14467, female, 75.3 mm SL.

FIGURE 5. Engyprosopon multisquama Amaoka, 1963.Blind side, same specimens as those in Figure 4.