Pethia gelius (Hamilton, 1822)

(Images 1 C&D, 4)

Cyprinus gelius Hamilton, 1822: 320.

Material examined: Neotype: ZSI / SRC, F.8735 (here designated), 30.9 mm SL, river Torsa at Totapara in Jalpaiguri, West Bengal, A. Rao, 10 Dec 2011; MKC 395, 1, 29.8 mm SL, Ponds in Nadia District, West Bengal, A. Rao, 10 December 2011. ZSI / SRC, F.8736, 4, 24.1 – 38.7 mm SL, Chembarampakkam lake, Tamil Nadu, J. D. M. Knight, 15 Aug 2010.

Diagnosis. Pethia gelius is distinguished from all other species of Pethia by the combination of the following characters: lateral line incomplete, with 3–4 pored scales; 21–22 + 1 scales in lateral series, ½4/1/2½ scales in transverse line on body; predorsal scales 8; last unbranched dorsal-fin ray thick, straight, serrated, with 20–25 serrae on posterior margin; barbels absent; a broad black band around the caudal peduncle covering scales 19–21 in the longitudinal series. Three diffuse black blotches on the body, first behind opercle, second below dorsal-fin origin, third above anal-fin origin. Black spot at base and origins of dorsal, anal and pelvic fins.

Description. See Table 1 for morphometric data, and Figs. 1 C,D and 4 for general appearance. Body deep, its depth greater than head length, laterally compressed, its dorsal profile slightly curved, indented at nape. Ventral profile deeply convex, gently rising up to caudal peduncle. Dorsal fin with 3 simple and 8½ branched rays, its height 55.4– 69.3% body depth. Last unbranched dorsal-fin ray thick, straight, serrated, with 20 – 25 serrae on posterior margin. Pelvic fin rounded, with 1 unbranched and 8 branched rays. Anal fin with 3 simple and 5½ branched rays, its ventral margin slightly concave. Pectoral fin rounded with 1 simple and 14 (4) – 15 (2) branched rays. Caudal fin deeply forked, its lobes equal, with 9+8 principal rays.

Head small, about one fourth of standard length, its dorsal profile slightly curved. Eyes large, placed forward, their diameter almost half head length. Mouth subterminal, angle of gape reaching behind the proximal margin of eye. Snout pointed, devoid of tubercles. Nostrils closer to eye than to snout tip. Snout length less than eye diameter. Caudal peduncle deep, its length almost equal to its depth. Lateral line incomplete, with 3 (3) or 4 (1) pored scales on body, 21 (2) or 22 (4) + 1 scales in lateral series. Predorsal scales 8; scales in transverse line on body ½4/1/2½. Circumpeduncular scales 8.

Coloration. In life (see Fig. 1 C&D), body pale yellow, abdomen white; a black band around caudal peduncle, covering scales 19–21 of longitudinal series. Three diffuse black blotches on body, first behind the opercle, second below dorsal-fin origin, third above anal-fin origin. Black spot at base and root of dorsal, anal and pelvic fins. Iris golden. Dorsal, pelvic and anal fin bright yellow; other fins hyaline. Specimens in presrvative white, with scattered melanophores along dorsum. Fins hyaline with melanophores scattered along base. All body pigmentation faded, with black band around caudal peduncle reduced to a few closely placed melanophores (Fig. 4).