Barilius ardens, sp. nov.

(Figs. 1, 2)

Barilius canarensis Day, 1878: 592, pl. 149, fig. 1 (not Jerdon, 1849).

Holotype. ZSI/SRC, F.8812, 82.1 mm SL, 13°20’02”N, 74°54’46”E, Swarna River, Karnataka, India, A. Rai.

Paratypes. ZSI/SRC, F.8813, 2 ex., 83.5–85.5 mm SL, 13°20’02”N, 74°54’46”E, Swarna River, Karnataka, India, A. Rai. MKC 385, 3 ex., 63.4–87.2 mm SL. 13°20’02”N, 74°54’46”E, Swarna River, Karnataka, India, A. Rai.

Diagnosis. Barilius ardens is distinguished from B. canarensis and B. malabaricus by its colour pattern, consisting of a row of 7–9 large, vertically-elongate, bluish-green blotches 4–6 scales high and 2–3 scales wide along the length of the body, of which in large adults the first three blotches are fragmented into a smaller row of blotches (vs. single or double rows of spots along the length of the body, the first row with 9–13 round or oval bluish-green spots 1–2 scales high and 1–2 scales wide and the second row, if present, with 3–4 smaller spots reaching up to the anal fin origin: see Figs. 1, 4, 6). Moreover, B. ardens can be distinguished from both B. canarensis and B. malabaricus by its fifth ceratobranchial, which has 5+4+3 (vs. 5+4+2) teeth (see Fig. 3). It can further be distinguished from B. canarensis by possessing 16–18 (vs.14–15) predorsal scales, and having the dorsal and anal fins margined with bright orange (vs. broadly margined with white). In addition, B. ardens can be distinguished from B. malabaricus by having 10½ (vs. 11½) branched dorsal-fin rays and 13½ (vs. 14½–15½) branched anal-fin rays. The new species can be distinguished from B. bakeri by its unique colour pattern, consisting of a row of 7–9 large, vertically-elongate bluish-green blotches 4–6 scales high and 2–3 scales wide along the length of the body, of which in large adults the first three blotches are broken up into a smaller row of intercalate blotches (vs. only a single row of spots along the length of the body); its fifth ceratobranchial with 5+4+3 (vs. 5+4+2, Fig. 3 C) teeth; and the dorsal and anal fins margined with bright orange (vs. white: see Figs. 1, 9).

Description. See Tables 1 and 2 for morphometric and meristic characters, and Figures 1 and 2 for general appearance. Body deep, its depth about one-third SL, laterally compressed, its dorsal profile slightly curved, ventral profile deeply convex. Caudal peduncle deep, its depth almost equal to its length. Head small, length about one-fourth SL, depth more than three-fourths length, dorsal profile almost straight, slightly raised at nape. Eyes large, placed forward, diameter about one-third HL. Mouth oblique, angle of gape almost reaching vertical from posterior margin of orbit. Two pairs of minute barbels (rostral and maxillary). Nostrils closer to eye than to snout tip. Lower jaw slightly longer than upper jaw. Dentary and snout covered by large tubercles in males, small, fine tubercles in females. Snout length about one-third HL.

B. ardens B canarensis. B. malabaricus B. bakeri Dorsal fin with 3 simple and 10½ (6) branched rays, its posterior margin slightly concave, origin anterior to anal fin origin. Pelvic fin short, not reaching anal fin origin, with 1 simple and 8 (6) branched rays. Anal fin with 3 simple and 13½ (6) branched rays, ventral margin deeply concave, with a sharp curve among the first few branched rays. Pectoral fin with 1 simple and 10 (4)–11 (2) branched rays. Caudal fin deeply forked, lobes subequal, lower lobe slightly longer, with 1+9+8+1 principal rays. Lateral line complete, slightly curved, with 36 (2) or 37 (4) + 1 (6) pored scales. Predorsal scales 16 (4), 17 (1) or 18 (1); scales in transverse line on body½8/1/2½ (5)–3 (1) between dorsal fin origin and pelvic-fin base; 3 (6) scales between lateral line and anal-fin base. Gill rakers, slender, well-defined with 3 (4), 4 (2) + 8 (5), 10 (1) rakers in first fill arch. Fifth ceratobranchial with 5+4+3 teeth (Fig. 3 A).

Coloration. In life (see Fig. 1 A), body bright greenish gold with 7–9 large, bluish-green, vertically-elongate blotches 4–6 scales high, 2–3 scales wide along its length, of which in large adults the first three blotches are broken up into a smaller row of intercalate blotches. Dorsal fin and anal fin bases black, fin margins lined with orange. In mature males lower jaw, opercles and breast region, and pectoral and pelvic fins become bright orange. Females and juveniles generally a little less brightly coloured than males, their dorsal and anal fins edged orange (see Fig. 1 b,c). Caudal fin black, lobe-tips and medial rays white.

Preserved specimens (Fig. 2) lose the bright colours: greyish brown, darker on dorsal side, progressively lighter towards abdomen, which is white. Vertically-elongate blotches on body dark grey. Fins opaque; dorsal, anal and caudal with black bases.

Etymology. The species name is a Latin adjective meaning burning, an allusion to the flame-like colours in mature males.

Distribution. Barilius ardens is presently known from the Sita–Swarna River system in the Western Ghats of Karnataka, India.