Kamoharaia megastoma ( Kamohara, 1936 )

Amaoka, Kunio & Ho, Hsuan-Ching, 2019, The lefteye flounder family Bothidae (Order Pleuronectiformes) of Taiwan, Zootaxa 4702 (1), pp. 155-215 : 193

Kamoharaia megastoma ( Kamohara, 1936)

Widemouthed flounder; öpľ

Figures 7 B–C; Table 10

Chascanopsetta megastoma Kamohara, 1936:308 (Ttype locality: Kochi Prefecture, Japan). Chen & Weng, 1965:61. Kamoharaia megastoma: Kuronuma, 1940:36 ; Shen, 1983:34; Shen in Shen et al., 1993:570; Ho et al., 2009:11; Shen & Wu,

2012:752.

Specimens examined. NMMB-P17856 (1, 186.6), Nan-fang-ao, 13 Oct. 2012 ; NMMB-P21088 (1, 109), Donggang, 30 Mar. 2014 ; NMMB-P22267 (1, 164.2), Dong-gang, 7 Nov. 2013 ; NMMB-P25330 (1, 95.0), Dong-gang, 26 May 2013 ; NMMB-P29037 (1, 95.4), Ke-tzu-liao, 18 Mar. 2018 . More specimens deposited in NMMB-P.

Diagnostic features. D 109–112; A 84–88; P 12; C 3–5+7–11–5=17; LLs 126–132; GR 0–3+7–8; vert. 13+39– 40=52–53.

Body elliptical, strongly compressed; greatest depth near tip of pectoral fin (34.1–38.3% SL). Caudal peduncle narrow, its depth 5.1–5.7% SL. Head small, its length 17.1–20.1% SL; upper profile of head deeply concave anterior of interorbital area, and more or less convex in front of upper eye. Snout much shorter than eye diameter. Eyes small, about 1/3 of upper jaw, separated by narrow flat ridge.

Mouth very large, upper-jaw length about 14.5–19.2% SL; maxilla extending well beyond posterior margin of lower eye; tip of upper jaw protruding beyond tip of snout by half eye diameter. Teeth on upper jaw uniserial, 3 or 4 pairs of larger teeth anteriorly, narrow tooth band on posterior half; lower jaw teeth uniserial, anteriorly 3 pairs of large inward curved canine teeth, posterior teeth becoming smaller. Tip of vomer projecting into mouth cavity. Gill rakers short and slender without serration on lower limb, rudimentary on upper limb.

Scales on both sides very small, cycloid. First ray of dorsal fin elongate, its length 2.5–2.8 in HL. Pectoral fin on ocular side about half of that on blind side. Caudal fin slender and round, with 3–5 unbranched rays dorsally and ventrally.

Coloration. Ocular side of body uniformly brownish with many irregular dark blotches; median fins and pectoral fin on ocular side dark except for basal portion. Blind side of body yellowish white.

Size. Reaching 187 mm SL in Taiwan; up to 220 mm SL elsewhere ( Hensley & Amaoka, 2001).

Distribution. Northeastern and southwestern Taiwan; widespread in the Indo-Australian archipelago to southern Japan ( Amaoka, 2016).

Remarks. This species resembles Chascanopsetta lugubris in having an extremely large mouth, but can be easily distinguished in having the tip of the maxilla strongly extending beyond the tip of the snout, in having 3 pairs of canine teeth on the tip of the lower jaw and in the tip of the vomer projecting into the mouth cavity. In juveniles of 100–120 mm SL, both jaws are not particularly protruding ( Amaoka, 2016).

Figures

FIGURE 7. A. Japonolaeops dentatus, NMMB-P 23281, 130 mm SL. B–C. Kamoharaia megastoma, NMMB-P 17856, 186.6 mm SL(B) and NMMB-P21088, juvenile, 105 mm SL (C). D–E. Laeops kitaharae, NMMB-P21087, female, 130.8 mm SL (D) and NMMB-P22276, male, 150 mm SL (E).