Laubuka trevori, Marcus Knight, J. D., 2015

Laubuka trevori , sp. nov.

( Figs. 1 View FIGURE 1 A, 2)

Chela laubuca (not Hamilton 1822) from Kabini River (?): Shaji & Easa 2003: 19, fig. 28, image on left.

Holotype. ZSI/SRC F. 8903, 35.5 mm SL, 12 ° 20 ' 11 "N, 75 ° 38 '03"E, streams in Yemmemadu, Coorg, Karnataka, India; Deepak Sathyanarayan, 17.iv. 2015.

Paratypes. MKC 428, 30.4–31.3 mm SL, 3; (30.4, 30.9 mm SL, cleared and stained), same collection information as the holotype.

Diagnosis. Laubuka trevori is distinguished from its Indian congeners as follows. From L. laubuca by possessing 7 ½ branched dorsal-fin rays (vs. 8 ½); 15 ½– 16 ½ branched anal-fin rays (vs. 18 ½– 20 ½); 8–9 branched pectoral-fin rays (vs. 11–12); 1 ½ scales between lateral line and pelvic-fin origin (vs. 2 ½); a lesser preanal length (61.1–62.3 % SL, vs. 64.4–69.1 % SL); a longer (13.9–15.2 % SL, vs. 11.9–13.1 % SL) and slenderer caudal peduncle (6.4–7.3 % SL, vs. 9.3–10.6 % SL); a lesser body depth (18.8–20.1 % SL, vs. 27.4–32.6 % SL) and a shorter dorsalfin base (10.0– 11.1 % SL, vs. 13.2–16.9 % SL). Moreover, L. trevori , when compared to L. laubuca , has the articular surface of the supraorbital with the lateral ethmoid straight (vs. with a deep concavity) ( Fig. 3 -1 View FIGURE 3 , 22); third suborbital slender, with its anterior end much narrower than its posterior end (vs. third suborbital broad, with both ends almost the same width) ( Fig. 3 -2 View FIGURE 3 , 23); maxilla slender, with its ventral margin straight (vs. ventral margin curved) ( Fig. 3 -3 View FIGURE 3 , 24); dentary with the coronoid process blunt (vs. posteriorly pointed), its inferior border slightly convex (vs. straight) ( Fig. 3 -4 View FIGURE 3 View FIGURE 4 , 25); posterior margin of fifth ceratobranchial smooth (vs. with a sharp process) ( Fig. 3 -5 View FIGURE 3 View FIGURE 4 View FIGURE 5 , 26); postero-dorsal margin of opercle slightly concave (vs. straight) ( Fig. 3 -6 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 , 27); caudal skeleton with the sixth hypural greatly reduced, its length less than half that of the fifth (vs. length of sixth hypural more than half that of fifth) ( Fig. 3 -7 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 , 28). In addition, L. trevori is distinguished from L. laubuca by the presence of two longitudinal stripes: a golden and a bluish green stripe on the body, running from behind the opercle to the base of the caudal fin, the latter broken and less distinct in the anterior half of the body (vs. blue and golden blotches along the sides of the body) ( Fig. 1 View FIGURE 1 A, D, F). Preserved specimens of L. trevori can be distinguished from L. laubuca by the presence of a prominent black stripe one scale high, running from behind opercle to the base of the caudal fin, less distinct on anterior half of body (vs. indistinct brown blotches along the sides of the body).

Laubuka trevori is distinguished from L. fasciata by a greater prepelvic length (42.0– 44.4 % SL, vs. 37.4– 40.1 % SL); a lesser preanal length (61.1–62.3 % SL, vs. 63.8–67.2 % SL); a lesser caudal-peduncle depth (6.4–7.3 % SL, vs. 8.7–9.5 % SL); a lesser dorsal-fin height (16.3–19.4 % SL, vs. 20.1–21.3 % SL); a lesser pelvic-fin length (10.1–16.3 % SL, vs. 31.2–35.3 % SL) and a lesser pectoral-fin length (26.4–28.7 % SL, vs. 33.4–34.1 % SL). Moreover, L. trevori , when compared with L. fasciata , has the articular surface of the supraorbital with the lateral ethmoid straight (vs. concave) ( Fig. 3 -1 View FIGURE 3 , 15); third suborbital slender, with its anterior end much narrower than its posterior end (vs. third suborbital broad with both its ends almost the same width) ( Fig. 3 -2 View FIGURE 3 , 16); maxilla slender, with its ventral margin straight (vs. ventral margin slightly curved) ( Fig. 3 -3 View FIGURE 3 , 17); dentary with its coronoid process blunt (vs. angular) ( Fig. 3 -4 View FIGURE 3 View FIGURE 4 , 18); posterior margin of the fifth ceratobranchial smooth (vs. with a sharp process) ( Fig. 3 -5 View FIGURE 3 View FIGURE 4 View FIGURE 5 , 19); postero-dorsal margin of the opercle slightly concave (vs. deeply concave) antero-dorsal margin straight (vs. slightly convex) ( Fig. 3 -6 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 , 20); caudal skeleton with the sixth hypural greatly reduced, its length less than half that of fifth hypural (vs. length of sixth hypural more than half that of fifth hypural) ( Fig. 3 -7 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 , 21). In addition, L. trevori can be distinguished from L. fasciata by the presence of two longitudinal stripes: a golden and a bluish-green stripe on the body, running from behind the opercle to the base of the caudal fin, the latter broken and less distinct in the anterior half of the body (vs. a clear bluish-black stripe two scales high proceeding from behind the eye up to the caudal-fin base) ( Fig. 1 View FIGURE 1 A, C). The coloration of preserved specimens of both L. trevori and L. fasciata superficially resemble each other, but the black stripe in L. trevori is narrower (one scale high) compared to that of L. fasciata (two scales high) and also less distinct on the anterior half of body (vs. distinct from behind the opercle to the base of the caudal fin).

Laubuka trevori is distinguished from its Sri Lankan congeners by possessing 1 ½ scales between lateral line and pelvic-fin origin (vs. 2 ½– 3 ½); 8–9 branched pectoral-fin rays (vs. 10–11); 7 ½ branched dorsal-fin rays (vs. 8 ½– 9 ½ in L. lankensis , L. insularis and L. varuna ); 15 ½– 16 ½ branched anal-fin rays (vs. 17 ½– 18 ½ in L. insularis and L. ruhuna ); 31–32 + 1–2 lateral-line pored scales (vs. 34–36 + 1–2 scales in L. lankensis and L. insularis ); a lesser body depth, of 18.8–20.1 % SL (vs. 27.2–30.3 % SL in L. lankensis , 26.0– 28.8 % SL in L. insularis , 32.8– 34.6 % SL in L. ruhuna and 27.9–32.4 % SL in L. varuna ); a lesser caudal-peduncle depth, of 6.4–7.3 % SL (vs. 8.8– 10.3 % SL in L. lankensis , 9.1–10.1 % SL in L. insularis , 9.6–10.9 % SL in L. ruhuna and 9.1–10.4 % SL in L. varuna ); a lesser head depth, of 11.8–12.9 % SL (vs. 13.1–14.4 % SL in L. lankensis , 13.8–15.4 % SL in L. ruhuna and 13.8–14.7 % SL in L. varuna ); a lesser pectoral-fin length, of 26.4–28.7 % SL (vs. 33.1–36.2 % SL in L. insularis , 34.4–37.1 % SL in L. ruhuna and 33.6–39.8 % SL in L. varuna ); and a lesser pelvic-fin length, of 10.1– 16.3 % SL (vs. 20.5–25.2 % SL in L. lankensis , 27.9–31.9 % SL in L. insularis , 18.3–24.4 % SL in L. ruhuna and 18.9–26.2 % SL in L. varuna ). Preserved specimens of Laubuka trevori can be distinguished from all Sri Lankan Laubuka by the presence of a prominent black stripe one scale high, running from behind the opercle to the base of the caudal fin, less distinct on anterior half of body (vs. a fine longitudinal line from shoulder spot to caudal-fin base in L. lankensis , diffused patches on the side of the body in L. insularis , and a vague stripe more prominent in the posterior half of the body in L. ruhuna and L. varuna ).

Laubuka trevori is distinguished from both Southeast Asian species of Laubuka by possessing 7 ½ branched dorsal-fin rays (vs. 8 ½– 10 ½); 1 ½ scales between the lateral line and pelvic-fin origin (vs. 2 ½– 4 ½); and a lesser body depth of 18.8–20.1 % SL (vs. 28.6 –33.0% SL in L. siamensis and 36.4–40.7 % SL in L. caeruleostigmata ). The new species is further distinguished from L. siamensis by a slimmer caudal peduncle (6.4–7.3 % SL, vs. 9.2– 10.9 % SL); and a lesser pelvic-fin length, of 10.1–16.3 % SL (vs. 20.8–36.6 % SL). In addition, preserved specimens of L. trevori can be distinguished from L. caeruleostigmata by the presence of a prominent black stripe one scale high, running from behind the opercle to the base of the caudal fin, less distinct on anterior half of body (vs. a series of four or five short bars on the anterior half of the body).

Description. See Table 1 View TABLE 1 for morphometric characters and meristics, and Figures 1 View FIGURE 1 A and 2 for general appearance. Body slender, its depth about one-fifth standard length, laterally compressed, its dorsal profile slightly curved, ventral profile convex, keeled from origin of pelvic fin to anus. Dorsal fin with 2 simple and 7 ½ branched rays, its posterior margin slightly concave, its origin above base of fifth branched anal-fin ray. Pelvic fin with 1 unbranched and 5 branched rays, unbranched ray not extending beyond anus. Anal fin with 3 simple and 15 ½(3) or 16 ½(1) branched rays, its ventral margin deeply concave, with a sharp curve among the first few branched rays. Pectoral fin with 1 simple and 8 (2) or 9 (2) branched rays. Caudal fin deeply forked, its lobes subequal, with 1 + 9 + 8 + 1 principal rays.

Anal-fin rays iii, 16 ½ iii, 15 ½– 16 ½ iii, 18 ½ iii, 17 ½– 18 ½ iii, 18 ½– 20 ½ iii, 14 ½– 15 ½ Caudal-fin principal rays 1 + 9 + 8 + 1 1 + 9 + 8 + 1 1 + 9 + 8 + 1 1 + 9 + 8 + 1 1 + 9 + 8 + 1 1 + 9 + 8 + 1 Predorsal scales 18 17–18 17 17–18 16–17 18

Head small, its dorsal profile almost straight, a slight indentation at nape. Eyes large, placed forward, their diameter greater than snout length. Mouth oblique, angle of gape slightly below level of lower margin of eye. Lower jaw devoid of tubercles, with 5 pores medially on dentary. Nostrils dorsally oriented, closer to eye than snout tip. Caudal peduncle slender, its length almost twice its depth.

Lateral line complete, with 31 + 1 (1), 31 + 2 (2), 32 + 1 (1) pored scales. Predorsal scales 17 (2) or 18 (2); Scales in transverse line on body ½ 6 / 1 / 1 ½.

Pre-caudal vertebrae 14, caudal vertebrae 21. Ventral profile of supraorbital curved, its articular surface with lateral ethmoid almost straight ( Fig. 3 - 1 View FIGURE 3 ); third suborbital slender, its dorsal profile concave, its posterior end much broader than anterior end ( Fig. 3 - 2 View FIGURE 3 ); maxilla slender, slightly curved, its ventral margin straight ( Fig. 3 - 3 View FIGURE 3 ); dentary with coronoid process blunt, its inferior border slightly convex, its superior border with a prominent depression ( Fig. 3-4 View FIGURE 3 View FIGURE 4 ); fifth ceratobranchial curved, its posterior margin smooth, with 5 + 4 + 2 distally curved teeth ( Fig. 3-5 View FIGURE 3 View FIGURE 4 View FIGURE 5 ); postero-dorsal margin of opercle slightly concave, its postero-ventral margin straight ( Fig. 3-6 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 ); caudal skeleton with first neural spine simple, sixth hypural greatly reduced, its length less than half of fifth ( Fig. 3-7 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 ).

Coloration. In life, body greenish gold with two longitudinal stripes: a golden and a bluish-green stripe on body, proceeding from behind opercle to base of caudal fin, the latter broken and less distinct on anterior half of body. A faint bluish humeral spot, and a bluish spot at base of caudal fin, both of which appear to be a part of bluish-green stripe. Sclera silver, fins hyaline, tinged with pale yellow ( Fig. 1 View FIGURE 1 A). Preserved specimens overall grayish white; longitudinal golden stripe faded, bluish-green stripe turning black, becoming less distinct on anterior half of body. All fins pale yellow, with melanophores scattered along base ( Fig. 2 View FIGURE 2 ).

Etymology. The species is named after Trevor Menezes (21.07.1957 – 10.12.2010), for his enthusiasm and support to aquarium-fish hobbyists in exploring the Cauvery and Tunga River systems; he died during one such expedition. The species name is formed as a noun in the masculine genitive singular.

Distribution. Laubuka trevori is at present known from the Cauvery River system at Coorg (Kodagu) in Karnataka, but probably occurs throughout a wider range in the Cauvery River and its tributaries.