Engyprosopon macrolepis ( Regan, 1908 )

Su, Yo, Ho, Hsuan-Ching & Amaoka, Kunio, 2024, New record of Engyprosopon macrolepis (Regan, 1908) from Taiwan (Pleuronectiformes: Bothidae), Zootaxa 5474 (1), pp. 50-58 : 51-54

Engyprosopon macrolepis ( Regan, 1908)

English name: Largescale dwarf flounder

Chinese name: 大ṕḇạḛ

Figs 1–3 . Tables. 1 & 2

Scaeops macrolepis Regan, 1908:233 (original description; type locality: Cargados Carajos Shoals, Indian Ocean, depth 20–30 fathoms [36.6–54.9 m]).

Engyprosopon macrolepis : Norman 1934:214 (new combination). Norman 1939:100 (Gulf of Aden). Fowler 1956:168 (Red Sea). Hensley in Smith & Heemstra 1986: 858. Hensley & Randall 1990:674 (redescription). Amaoka et al. 1993:398 ( New Caledonia). Hensley & Amaoka 2001:3831 (Western Central Pacific). Amaoka in Randall & Lim 2000:645 (South China Sea). Randall 2005:615 (South Pacific Ocean). Katayama et al. 2012:173 (new record from Japan). Yoshigou & Yoshino 2015:5 (Ryukyu Islands). Amaoka 2016:99 ( Japan). Hensley & Amaoka 2022:337 (Western Indian Ocean).

Specimens examined. NMMB-P 39332 , 2 specimens, 1 male, 45.0 mm SL, and 1 female, 39.3 mm SL, 14 Jun. 2023 . NMMB-P 40031 , 1 male, 55.4 mm SL, 13 Jul. 2021 . NMMB-P 40032 , 1 male, 53.1 mm SL, Jul. 2021 . All collected from Chi-kan, Peng-hu Islands, western Taiwan, ca. 23°39’58.2”N 119°36’25.9”E, coll. H.-C. Ho.

Description of Taiwanese specimens. Meristic and morphometric data are provided in Tables 1 & 2 . Dorsal-fin rays 75–79.Anal-fin rays 55–60. Caudal-fin rays 3+11+3. Ocular-side pectoral-fin rays 11–12; blind-side pectoral-fin rays 9. Ocular-side pelvic-fin rays 6; blind-side pelvic-fin rays 6. Gill rakers 0+6–8=6–8. Lateral-line scales 40–48, not including 1–2 scales on caudal fin. Vertebrae 10+24=34 (n=2).

Body ovate, greatest depth 1.8–2.2 in SL; its dorsal and ventral profiles convex and nearly symmetric. Head length 3.6–3.9 in SL; anterior profile of head steep, and with slight concavity above snout, in front of interorbital space. Snout length 4.0– 4.6 in HL, distinctly shorter than both eyes. Rostral spine present in male. Eyes sinistral, upper-eye and lower-eye diameter 3.1–3.4 and 3.0– 3.3 in HL, respectively; anterior margin of upper eye slightly posterior to vertical through anterior margin of lower eye. Orbital spines present on both eyes in male. Ocular flap present in male, situated at posterodorsal and posteroventral corner of upper and lower eye, respectively. Interorbital space separated by concavity, its width 2.6–3.6 (male) or 12.0 (female) in HL. Two nostrils on ocular side: anterior nostril forming tube and short flap, situated on snout; posterior nostril forming pore, situated in front of lower eye; nostrils on blind side present, minute, both situated just below dorsal-fin origin.

Mouth oblique and large; upper-jaw length on ocular side 2.7–2.9 in HL; its anterior tip slightly in advance of lower-jaw tip when closed; its posterior tip reaching point at one-third of lower eye. Upper-jaw teeth uniserial on both ocular and blind sides, slightly and gradually larger anteriorly. Lower-jaw teeth uniserial on both ocular and blind side jaws.

Gill rakers present on outer-three arches; those on first arch laterally compressed; all rakers smooth, not serrated on inner sides; those on second arch about same size as those on first arch; those on third arch shorter than first and second arches; upper limb of all four arches without rakers. Scales on ocular side deciduous, with very short ctenii; scales absent on snout and both ocular-side jaws; scales on blind side cycloid and deciduous.

Dorsal-fin origin before midline of interorbital space, above ocular-side anterior nostril; anterior rays not elongated; longest ray (ca. 40 th –45 th ray) at point slightly posterior to vertical through middle of body. Anal-fin origin at vertical through base of pectoral-fin origin on ocular side; its shape subsymmetrical to that of dorsal fin. Pectoral fin on ocular side filamentous, longer in male than in females, its length 0.6–0.8 and 1.1 in HL, respectively; pectoral fin on blind side short, length 2.0– 2.2 in HL. Origin of pelvic fin on ocular side at tip of isthmus; origin of pelvic fin on blind side opposite to middle of fourth and fifth rays on ocular side. Tip of isthmus slightly before vertical through middle of lower eye. Caudal fin rounded, length 1.0– 1.2 in HL. All rays simple except middle 11 caudal-fin rays branched.

Figures

FIGURE 1. Fresh specimen of Engyprosopon macrolepis (Regan, 1908). A. Ocular side. B. Blind side. C. Close-up image of cheek region on blind side. A, B. NMMB-P 39332, male, 45.0 mm SL. C. NMMB-P 40031, 55.4 mm SL.

FIGURE 2. Preserved specimens of Engyprosopon macrolepis (Regan, 1908), NMMB-P 39332, showing ocular (A, C) and blind sides (B, D). A, B. Male, 45.0 mm SL. C, D. Female, 39.3 mm SL.

FIGURE 3. Close-up image of Engyprosopon macrolepis (Regan, 1908), NMMB-P 39332, male, 45.0 mm SL, preserved. A. Ocular side of head. B. Cheek region on blind side, with black melanophores indicated with arrow. Figures not to scale.