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

Marcus Knight, J. D., 2015, Description of two new species of Laubuka (Teleostei: Cyprinidae) from River Cauvery, southern Iandia, Zootaxa 4000 (5), pp. 518-530 : 519-524

Laubuka trevori , sp. nov.

( Figs. 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 7½ branched dorsal-fin rays (vs. 8½); 15½–16½ branched anal-fin rays (vs. 18½–20½); 8–9 branched pectoral-fin rays (vs. 11–12); 1½ scales between lateral line and pelvic-fin origin (vs. 2½); 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 , 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 , 23); maxilla slender, with its ventral margin straight (vs. ventral margin curved) ( Fig. 3-3 , 24); dentary with the coronoid process blunt (vs. posteriorly pointed), its inferior border slightly convex (vs. straight) ( Fig. 3-4 , 25); posterior margin of fifth ceratobranchial smooth (vs. with a sharp process) ( Fig. 3-5 , 26); postero-dorsal margin of opercle slightly concave (vs. straight) ( Fig. 3-6 , 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 , 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 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 , 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 , 16); maxilla slender, with its ventral margin straight (vs. ventral margin slightly curved) ( Fig. 3-3 , 17); dentary with its coronoid process blunt (vs. angular) ( Fig. 3-4 , 18); posterior margin of the fifth ceratobranchial smooth (vs. with a sharp process) ( Fig. 3-5 , 19); postero-dorsal margin of the opercle slightly concave (vs. deeply concave) antero-dorsal margin straight (vs. slightly convex) ( Fig. 3-6 , 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 , 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 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 1½ scales between lateral line and pelvic-fin origin (vs. 2½–3½); 8–9 branched pectoral-fin rays (vs. 10–11); 7½ branched dorsal-fin rays (vs. 8½–9½ in L. lankensis , L. insularis and L. varuna );15½–16½ branched anal-fin rays (vs. 17½–18½ 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 7½ branched dorsal-fin rays (vs. 8½–10½); 1½ scales between the lateral line and pelvic-fin origin (vs. 2½–4½); 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 for morphometric characters and meristics, and Figures 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 7½ 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 15½(3) or 16½(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, 16½ iii, 15½–16½ iii, 18½ iii, 17½–18½ iii, 18½–20½ iii,14½–15½ 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 ½6/1/1½.

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

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 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 ).

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.

Figures

FIGURE 1. Coloration in life of Laubuka species: A, L. trevori (paratype), MKC 428, 31.3 mm SL, Yemmemadu, Coorg (Kodagu), Karnataka, India; B, L. latens (paratype), ZSI / SRC, F. 8905, 31.8 mm SL, Cauvery River, Gandehosahalli, Karnataka, India; C, L. fasciata, ZSI / SRC F 8647, 42.1 mm SL; Chalakudy River, Cochin, Kerala, India; D, L. laubuca, MKC 412, 48.1 mm SL, Pond in Cooch Behar District, West Bengal, India; E, Neochela dadyburjori, ZSI / SRC F. 8648, 24.7 mm, Nagercoil, Tamil Nadu; F, L. laubuca, ZSI / SRC F 8646, 43.8 mm SL, Chembarampakkam lake, Chennai, Tamil Nadu, India.

FIGURE 2. Laubuka trevori, holotype, ZSI / SRC, F. 8903, 35.5 mm SL, Cauvery River, Yemmemadu, Coorg (Kodagu), Karnataka, India.

FIGURE 3. Left side view of bones: first row— Laubuka trevori, MKC 428; second row— L. latens, MKC 414; third row— L. fasciata, MKC 27; fourth row— L. laubuca, MKC 412. 1, 8, 15, 22 — supraorbital; 2, 9, 16, 23 — third suborbital; 3, 10, 17, 24 — maxilla; 4, 11, 18, 25 — dentary; 5, 12, 19, 26 — fifth ceratobranchial; 6, 13, 20, 27 — opercle; 7, 14, 21, 28 — caudal skeleton.

Tables

TABLE 1. Morphometric and meristic data of Laubuka trevori (ZSI / SRC F. 8903, MKC 428), L. latens (ZSI / SRC F. 8904, F. 8905, MKC 414), L. laubuca (ZSI / SRC F. 8646, MKC 153, MKC 229, MKC 412) and L. fasciata (ZSI / SRC F. 8647, MKC 27). Range includes data of holotype.

L. trevori	L. latens	L. laubuca	L. fasciata
Morphometrics Holotype Range	Holotype Range	Range	Range
Standard length [in mm] 35.5 30.4–35.5	34.7 28.1–41.3	36.3–52.1	42.1–51.2
In percent SL Head length 24.2 23.6–24.6 Head depth 12.1 11.8–12.9	21.7 21.7–25.9 13.6 13.2–16.6	22.4–25.3 12.0–14.9	23.8–26.1 11.1–13.8
Predorsal length 61.6 61.6–66.4 Preanal length 61.9 61.1–62.3 Prepelvic length 43.3 42.0–44.4	68.6 65.4–70.5 65.2 64.0–66.5 41.1 41.1–42.9	63.6–69.2 64.4–69.1 44.8–48.8	64.6–69.0 63.8–67.2 37.4–40.1
Caudal-peduncle length 15.2 13.9–15.2 Caudal-peduncle depth 6.4 6.4–7.3 Body depth 18.8 18.8–20.1	15.0 14.9–16.5 8.6 7.8–8.8 23.7 22.9–25.9	11.9–13.1 9.3–10.6 27.4–32.6	14.1–16.0 8.7–9.5 19.2–25.5
Dorsal-fin height 16.3 16.3–19.4 Length of dorsal fin base 10.9 10.0–11.1 Anal-fin depth 18.3 18.3–20.1	17.1 17.1–19.1 10.4 10.4–12.1 22.6 21.0–23.7	16.3–19.6 13.2–16.9 17.9–23.1	20.1–21.3 10.0–13.1 23.7–25.8
Length of anal fin base 20.5 20.5–22.0 Pectoral-fin length 26.4 26.4–28.7 Pelvic-fin length 10.1 10.1–16.3	28.6 24.6–30.1 33.3 33.2–36.2 23.7 23.2–26.9	24.0–29.5 32.0–37.1 15.9–20.5	21.8–22.8 33.4–34.1 31.2–35.3
Dorsal-hypural distance 36.3 30.7–36.3	34.4 32.7–35.5	32.1–37.0	32.3–35.3
In percent HL Snout length 27 25–27	26 23–26	16–26	28–30
Eye diameter 33 33–36 Interorbital width 38 38–39 Internarial width 22 17–22	40 35–40 38 37–47 26 25–34	25–35 40–48 20–33	39–40 41–44 27–29
Meristic data Lateral-line scales 32+1 31–32 +1–2 Scales in transverse line ½6/1/1½ ½6/1/1½ on body Dorsal fin rays ii, 7½ ii, 7½	33+1 32–33+1–2 ½6/1/2½ ½6/1/2½ ii,7½ ii,7½	31–33+1–2 ½6/1/2½ ii,8½	32–33 +1 ½6/1/1½ ii,7½
Pelvic-fin rays i,5 i,5 Pectoral-fin rays i, 8 i, 8–9	i,5 i,5 i, 12 i, 11–12	i,5 i, 11–12	i,5 i, 9