Engyprosopon parvipectorale, Amaoka & Ho, 2018

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 : 474-479

publication ID	https://doi.org/ 10.11646/zootaxa.4413.3.2
publication LSID	lsid:zoobank.org:pub:4CBD6FA5-1E36-4857-8992-2DCBA902EE13
DOI	https://doi.org/10.5281/zenodo.5967724
persistent identifier	https://treatment.plazi.org/id/B25B3C79-FFAB-FF82-30E1-F9C1FB1D987D
treatment provided by	Plazi
scientific name	Engyprosopon parvipectorale
status	sp. nov.

Treatment

Engyprosopon parvipectorale sp. nov.

Figures 16–19 View FIGURE 16 View FIGURE 17 View FIGURE 18 View FIGURE 19 ; Tables 2, 4

Holotype. NMMB-P 22220, male, 67.8 mm SL, Ke-tzu-liao, Kaohsiung, southwestern Taiwan, northern South China Sea, bottom trawl, ca. 30–100 m, 10 Apr. 2015.

Paratypes. NMMB-P25747 and 25748, 2 females, 61.9–64.6 mm SL, collected with the holotype; NMMB- P24736, male, 63.3 mm SL, Dong Gang , Kaohsiung, bottom trawl, 29 Sep. 2016; NMMB-P26188 , 1 male and 1 female, 58.7 mm SL and 55.6 mm SL, Ke-tzu-liao, Kaohsiung, bottom trawl, 6 Apr. 2017.

Diagnosis. A species of Engyprosopon characterized by the combination of serrate gill rakers, large head (3.1– 3.4 in SL); extremely narrow or almost ridge-like interorbital in both sexes; ocular-side pectoral fin distinctly short, 1.4–1.6 times in HL in both sexes; and no rostral or orbital spines in either sex ( Fig. 18A View FIGURE 18 ).

Description. Data for the holotype are followed by those for the paratypes in parentheses.

Dorsal-fin rays 80 (78–84), anal-fin rays 58 (60–61), ocular-side pectoral-fin rays 12 (10–14), blind-side pectoral-fin rays 9 (8–10); caudal-fin rays 3 + 11 + 3 (2–3 + 11–12 + 3); ocular-side pelvic-fin rays 6 (6), blind-side pelvic-fin rays 6 (6), scales in lateral line 51 (49–52), gill rakers 0 + 7 (0 + 6–8), vertebrae 10 + 25 (10 + 24–10 + 25).

In SL: HL 3.34 (3.12–3.44), body depth 2.01 (1.91–2.01). In HL: snout 4.28 (3.98–4.83), upper eye diameter 4.31 (3.75–4.31), lower eye diameter 4.11 (3.93–4.38), interorbital width 33.8 (27.5–67.7), ocular-side upper jaw 2.19 (2.02–2.26), blind-side upper jaw 2.17 (1.98–2.21), ocular-side lower jaw 1.74 (1.62–1.75), blind-side lower jaw1.71(1.51–1.68), caudal peduncle depth 2.30 (2.30–2.48), ocular-side pectoral fin 1.53 (1.40–1.62), blind-side pectoral fin 2.16 (2.07–2.48), ocular-side pelvic fin 2.33 (2.09–2.80), blind-side pelvic fin 2.39 (2.46–2.81), base of ocular-side pelvic fin 2.71 (2.58–2.85), base of blind-side pelvic fin 8.46 (7.50–9.71), longest dorsal fin ray 2.26 (2.06–2.39), longest anal fin ray 2.27 (1.94–2.33), middle caudal fin ray 1.34 (1.30–1.45).

Body moderately ovate, deepest about at anterior 1/3 of body; body depth about 1/2 of SL; dorsal and ventral contours nearly symmetrical, with gradual posterior taper. Caudal peduncle slightly greater than, or about equal to 1/4 of body depth. Head large, its length greater than 1/4 of SL; upper profile with small concavity anterior to middle of upper eye. Snout short, about equal to eye diameter. No rostral spine in males or females. Eyes small; eye diameter more than one-half of maxilla length; lower eye slightly in advance of upper eye. No orbital spine in either sex. Interorbital space very narrow, concave or almost ridge-like, no distinct differences in interorbital width between sexes ( Fig. 19A View FIGURE 19 ). Ocular-side nostrils anterior to interorbital region; anterior nostril a short tube with small round flap posteriorly, posterior nostril without flap; blind-side nostrils rudimental or absent, closely set below origin of dorsal fin.

Mouth large, oblique; maxilla extending to below middle of lower eye; anterior tip of upper jaw beyond tip of lower jaw when mouth closed. Teeth on upper jaw uniserial, rather strong, anterior 4–6 enlarged, canine-like; lower jaw teeth uniserial, canine anteriorly, strong conical laterally, stronger than upper lateral teeth; anterior teeth on upper jaws extruded beyond tip of lower jaws ( Fig. 18A View FIGURE 18 ). Gill rakers on first arch short and flattened, inner margin of each raker with 2–5 stout spines, no gill rakers on upper limb ( Fig. 18B View FIGURE 18 ). Ocular-side scales ctenoid with short ctenii, moderate and deciduous; tips of both jaws and ocular side of snout naked; scales cycloid on blind side.

Dorsal-fin origin on blind side below concavity in dorsal margin, no elongate rays. Anal-fin origin below pectoral-fin base. Ocular-side pectoral fin short, about 1.40–1.62 times in head length in both sexes; length of ocular-side pectoral fin less than about 2 times that of blind-side fin. Ocular-side pelvic-fin origin at tip of isthmus, fifth ray of ocular-side fin opposite to first ray of blind-side fin. Tip of isthmus near vertical line through middle of lower eye. Caudal-fin rays branched, except for three upper- and three lowermost rays.

Coloration in alcohol. Body light brown with many dark spots on lateral line; ventral half of lower jaw black in males and with 3 black spots in females; area of upper gill opening in region just below pectoral-fin base dark; posterior 1/3 of dorsal and anal fins with numerous black spots, and also with 3 or 4 spots on posterior part of these fin bases; ocular-side pectoral fin with dark band crossing at middle and distal 1/4 of fin; caudal fin with many small black spots; a pair of spots in middle slightly more distinct compared with others. Blind side of body yellowish-white in males and females.

Sexual dimorphism. This species shows no clear sexual dimorphism in interorbital width, rostral spine development or coloration on the blind side of the body.

Distribution. Known from the types collected from Ke-tzu-liao, Kaohsiung, southwestern Taiwan, at depths around 30– 100 m.

Remarks. This species well resembles E. mozambiquense in appearance and meristic features, but can be separated from the latter by its larger head (3.12–3.44 in SL vs 3.45–3.83), smaller eyes (upper eye 3.75–4.31 in HL vs 2.96–3.50, lower eye 3.93– 4.38 vs 2.94–3.55), narrower interorbital width (27.5–67.7 in HL in both sexes vs 7.70–14.4 in males, 27.4–27.6 in females), longer blind-side upper jaw (1.98–2.21 in HL vs 2.17–2.40), and shorter ocular-side pectoral fin (1.40–1.62 in HL in both sexes vs 0.58–0.88 in males, 1.23–1.38 in females) ( Table 4, Fig. 19B View FIGURE 19 ). In addition, E. parvipectorale differs from E. mozambiquense in having some strong canine-like teeth anteriorly in both jaws (vs. no canine-like teeth), no sexual dimorphism in interorbital width (vs. width in males wider than that of females) and by its yellowish-white coloration on the blind side of the body in both sexes (vs. dark color in males). The extremely narrow, almost ridge-like, interorbital space and lack of sexual dimorphism, distinctly distinguishes this species from most of the known species of Engyprosopon .

Among congeners, E. mogkii lacks sexual differences in coloration of the blind side of the body, and also does not exhibit sexually dimorphic differences in interorbital width. However, it is apparent that this species, as well as E. mogkii , belongs to Engyprosopon , because both have a branched caudal skeleton and both lack a dorsal-fin lure and palmate gill rakers that characterize species of the genus Asterorhombus ( Hensley, 2005) .