Pethia canius (Hamilton, 1822)

Marcus Knight, J. D., 2013, Pethia aurea (Teleostei: Cyprinidae), a new species of barb from West Bengal, India, with redescription of P. gelius and P. canius, Zootaxa 3700 (1), pp. 173-184 : 176-177

Pethia canius (Hamilton, 1822)

( Figures 1 B, 3)

Cyprinus canius Hamilton, 1822: 320 .

Material examined: Neotype: ZSI / SRC, F.8732 (here designated), 30.1 mm SL, Pond in Cooch Behar District, West Bengal, Nikhil Sood, 18 May 2013. Other material: ZSI / SRC, F.8733, 2, 27.9 – 29.1 mm SL, same data as neotype. ZSI / SRC, F.8734, 1, 25.6 mm SL, Pond in Srirampur, Nadia District, West Bengal, A. Rao, 30 May 2013.

Diagnosis. Pethia canius is distinguished from all other species of Pethia by the combination of the following characters: lateral line incomplete, with 3–4 pored scales; 20–21+1 scales in the lateral series, ½4/1/2 scales in transverse line on body; predorsal scales 8; last unbranched dorsal-fin ray strong, curved, serrated, with 24 – 27 large, curved serrae on posterior margin; barbels absent; a broad black band around caudal peduncle covering scales 17–19 of longitudinal series. Three diffuse black blotches on body, first behind opercle, second below dorsal-fin origin, third above anal-fin origin. Black spots at base and root of dorsal, anal and pelvic fins.

Description. See Table 1 for morphometric data, and Figs. 1 B and 3 for general appearance. Body deep, its depth more than head length, laterally compressed, dorsal profile slightly curved, ventral profile deeply convex, gently rising up to caudal peduncle. Dorsal fin with 3 simple and 8½ branched rays, its height 83.5–117% body depth. Last unbranched dorsal-fin ray strong, curved, serrated, with 24–27 large curved, hook like 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 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 ascending, straight. Eye large, placed forward, diameter less than half of head length. Mouth subterminal, angle of gape reaching behind vertical from anterior margin of eye. Snout pointed, devoid of tubercles. Nostrils closer to eye than snout tip. Snout length equal to eye diameter. Caudal peduncle deep, its length 1½ times its depth. Lateral line incomplete, with 3 (3) or 4 (1) pored scales on body, 20(3) or 21(1) + 1 scales in lateral series. Predorsal scales 8; scales in transverse line on body ½4/1/2. Circumpeduncular scales 8.

Coloration. In life (see Fig. 1 B), body reddish, abdomen white; a black band around caudal peduncle, covering scales 17–19 in lateral series. Three diffused black blotches on body, first behind opercle, second below dorsal-fin origin, third above anal-fin origin. Black spots at base and root of dorsal, anal and pelvic fins. Iris golden, dorsal fin and caudal fin bright red; anal fin yellowish orange, other fins hyaline. Specimens in preservative 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 spaced melanophores ( Fig. 3 ).

Remarks. Hamilton (1822) evidently based his descriptions on the notes he made from fresh specimens, and the drawings executed by Haludar, his Bengali artist (Hora, 1931). In any event, despite extensive searches no types of Hamilton’s fishes have been discovered in the two centuries that have elapsed since their collection, and they must therefore be presumed lost. Pethia canius has been considered a synonym of P. gelius by all authors since Day (1978). The two species also have the same type locality: Northeastern Bengal. Given their overlapping type localities and superficial similarity, it is important that their taxonomic status be clarified and stabilized by the designation of neotypes. Accordingly I here designate the 30.1 mm SL specimen ZSI / SRC F.8732 as neotype of Cyprinus canius Hamilton, 1822 , and the 30.9 mm SL specimen ZSI / SRC F.8735 as neotype of Cyprinus gelius Hamilton, 1822 . Cooch Behar District, the collection locality of the former, is in the northeastern region of Bengal, as is Jalpaiguri, the collection locality of C. gelius .

Figures

FIGURE 3. Pethia canius, neotype, ZSI / SRC, F. 8732, 30.1 mm SL, pond in Cooch Behar District, West Bengal.

FIGURE 1. A, Pethia aurea, holotype, prior to fixation, ZSI / SRC, F. 8730, 23.6 mm SL, Ponds in South 24 – Parganas district, West Bengal; B, P. canius, neotype, prior to fixation, ZSI / SRC, F. 8732, 30.1 mm SL, Ponds in Cooch Behar district, West Bengal; C, P. gelius, neotype, prior to fixation, ZSI / SRC, F. 8735, 30.9 mm SL, river Torsa at Totapara in Jalpaiguri, West Bengal; D, P. gelius, ZSI / SRC, F. 8736, 29.8 mm SL, Chembarampakkam lake, Tamil Nadu.