Engyprosopon mozambiquense Hensley, 2003

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 : 470-473

Engyprosopon mozambiquense Hensley, 2003

Figures 13–15 , 19 ; Table 2, 4

Arnoglossus annulatus (not of Weber, 1913): Norman, 1927: 19.

Engyprosopon cocosensis (not of Bleeker, 1855): Norman, 1927: 24; Norman, 1934: 204, fig. 151; Hensley & Amaoka, 2001: 3830.

Bothus (Arnoglossus) cocosensis: Weber & de Beaufort, 1929: 428 .

Engyprosopon sp.: Hensley, 1986: 858.

Engyprosopon mozambiquensis Hensley, 2003: 834 (type locality: Porto Amelia , Mozambique, 13°00'S, 40°35'E).

Material examined. NMMB-P22218 , 11 males, 49.8–67.0 mm SL, 3 females, 47.3–48.1 mm SL, Ke-tzu-liao, Kaohsiung, southwestern Taiwan, 10 Apr. 2015 .

Diagnosis. Gill rakers with spines; large maxilla (2.21–2.43 in HL) extending to vertical through anterior 1/3 to 1/2 of lower eye; interorbital width narrow in both sexes, that of males wider than width found in females and juveniles; ocular-side pectoral fin filamentous, greatly elongate in males; ocular-side pectoral fin with two dark cross bands; ventral margin of ocular-side lower jaw with 3 distinct black spots, the posteriormost especially distinct.

Description. Dorsal-fin rays 79–84, anal-fin rays 57–64, ocular-side pectoral-fin rays 10–12, blind-side pectoral-fin rays 8–9, caudal-fin rays 3 + 11 + 3, ocular-side pelvic-fin rays 6, blind-side pelvic-fin rays 6, scales in lateral line 46–52, gill rakers 0 + 6–7, vertebrae 10+24–25.

In SL: HL 3.45–3.83, body depth 1.92–2.21. In HL: snout 4.07–4.68, upper eye diameter 2.96–3.50, lower eye diameter 2.94–3.55, interorbital width 7.70–14.4 in males, 27.4–27.6 in females, ocular-side upper jaw 2.21–2.43, blind-side upper jaw 2.17–2.40, ocular-side lower jaw 1.68–1.90, blind-side lower jaw 1.68–1.87, caudal peduncle depth 2.15–2.75, ocular-side pectoral fin 0.58–0.88 in males, 1.23–1.38 in females, blind-side pectoral fin 1.75– 2.14, ocular-side pelvic fin 1.90–2.98, blind-side pelvic fin 1.90–2.91, base of ocular-side pelvic fin 2.19–2.87, base of blind-side pelvic fin 5.84–9.13, longest dorsal fin ray 1.69–2.29, longest anal fin ray 1.94–2.23, middle caudal fin ray 1.12–1.38.

Body ovate, deepest at middle of body, its depth about 1/2 of SL; dorsal and ventral contours gently arching with gradual posterior taper. Caudal peduncle less than 1/4 of body depth. Head large, its length more than 1/4 of SL, upper profile gently arched with shallow notch anterior to interorbital area; upper profile steep in mature males, not so in females and juveniles. Snout round, much shorter than eye diameter. A short, obtuse rostral spine on snout in males; spine absent in females. Eyes small; eye diameter much less than upper jaw length; anterior margins of both eyes on about same vertical line. Interorbital region very narrow, concave, becoming wider with growth, and wider in males than in females and juveniles ( Fig. 19A ).

Mouth large, oblique, maxilla extending to vertical through anterior 1/3 to 1/2 of lower eye; anterior tips of both jaws almost on same line when mouth closed. Teeth on upper jaw uniserial, some anterior teeth somewhat larger and stronger; lower jaw teeth uniserial, almost all of same size, similar in size to anterior upper teeth. Gill rakers on first arch flattened and slender ( Fig. 15 ), distal part of inner margin with some small teeth; no gill rakers on upper limb. Ocular-side scales large, ctenoid with short ctenii, highly 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 greatly elongated into filament in males, second ray longest, much longer than head length; ocular-side pectoral fin shorter than head length in females ( Fig. 19B ). Ocular-side pelvic-fin origin at tip of isthmus; ocular-side fourth or fifth ray opposite to first ray of blind-side fin. Tip of isthmus near vertical line through middle of lower eye. Caudal-fin rays branched, expect for three upper- and three lowermost rays.

Coloration in alcohol. Ground color on ocular side uniformly light brown, scattered with numerous, small, indistinct dark dots on body: two distinct dark spots on lower jaw, anterior one on symphysial portion of lower jaw, posterior one near posterior end of jaw; dark band from middle of lower eye, crossing upper jaw and extending to lower jaw; blind side of body more or less dark in males, uniformly yellowish white in females. Dorsal and anal fins with a series of dark spots; caudal fin with irregularly scattered dark spots; ocular-side pectoral fin with two dark cross bands, lower band wider than upper.

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

Distribution. Widespread in the Indo-West Pacific Ocean: Taiwan, Philippine Islands, Indian Ocean ( Mozambique, northern Madagascar, India, Burma, Nicobar Islands and Cocos Islands), and Coral Sea (KA, pers. data). Bathymetric range 8–90 m ( Hensley, 2003).

Remarks. The present species, described by Hensley (2003), was previously misidentified as E. cocosensis by Norman (1927, 1934) and Hensley & Amaoka (2001). Hensley (2003) found that the holotype of E. cocosensis has palmate gill rakers and a lure on the first dorsal-fin ray, these are unique characters to members of the genus Asterorhombus .

Engyprosopon mozambiquense belongs to a species group in Engyprosopon with serrate gill rakers. It is easily discriminated from congeners of the group in having the combination of some dark spots on the caudal fin, 3 black spots on the ventral margin of the ocular-side lower jaw, two dark cross bands on the ocular-side pectoral fin, a large mouth (length of ocular-side maxilla about 2.2–2.4 in HL), and narrower interorbital width compared with respective features of other species (when compared between same sexes and same sizes). This species is widely distributed in the Indian Ocean, Coral Sea, and the Philippine Islands. This is the first record of E. mozambiquense from the waters of Taiwan, and is also the northernmost record for this species.

Figures

FIGURE 13. Engyprosopon mozambiqense Hensley, 2003. Ocular side, A. NMMB-P22218, male, 58.8 mm SL. B. NMMB- P22218, female, 47.6 mm SL.

FIGURE 14. Engyprosopon mozambiquense Hensley, 2003. Blind side, same specimens as those in Figure 12.

FIGURE 15. Engyprosopon mozambiquense Hensley, 2003. Gill rakers on first arch from NMMB-P22218.

FIGURE 19. Relationship between SL and interorbital width (A), and ocular-side pectoral fin length (B) in Engyprosopon mozambiquense (trangles) and Engyprosopon parvipectorale sp. nov. (circles).