Laubuka parafasciata, Vanlalhlimpuia, Denis & Singh, Mahender, 2017

Vanlalhlimpuia, Denis & Singh, Mahender, 2017, Laubuka parafasciata, a new cyprinid fish species (Teleostei: Cyprinidae) from Mizoram northeastern India, Zootaxa 4244 (2), pp. 269-276 : 270-272

Laubuka parafasciata , new species

( Fig. 1 )

Holotype. ZSI FF 6032, 43.2 mm SL; India: Mizoram: Siaha District: Sala River, a tributary of Kaladan River , in the vicinity of Lungpuk , 22°04'38"N 92°54'57" E; Lalramliana et al., 14 November 2012.

Paratypes. ZSI FF 6033, 2, 32.1–48.3 mm SL; PUCMF 16007, 9, 35.0– 55.9 mm SL; PUCMF 16008, 2, 40.5–44.4 mm SL; (cleared & stained); same collection data as holotype.

Diagnosis. Laubuka parafasciata is distinguished from all of its congeners in having more precaudal vertebrae (16 vs. 14) and having the premaxillae not in contact (vs. in contact) at the symphysis. It is further distinguished, with the exception of L. fasciata , in having a broad, dark-brown midlateral stripe from the posterior rim of the orbit to the middle of the caudal-fin base. It is distinguished from L. fasciata in having a short pelvic fin, not reaching the anal-fin origin (vs. pelvic fin elongated, reaching beyond anal-fin origin), more branched dorsal-fin rays (8½ vs. 7½), more scales (2½ vs. 1½) between lateral line and pelvic-fin origin and more branched anal-fin rays (16½–19½ vs. 14½–15½). It is further distinguished from all other congeners by the combination of the following characters: premaxillae not in contact at symphysis, 16 precaudal vertebrae, minute tubercles scattered on the lower jaw, 28–33 lateral-line scales, 16–18 predorsal scales, 8½ branched dorsal-fin rays, 2½ scales between lateral line and pelvicfin origin, and 16½–19½ branched anal-fin rays.

Description. Morphometric data are presented in Table 1. Body elongate, compressed. Dorsal profile slightly convex, rising evenly from tip of snout to dorsal-fin origin, slightly concave between dorsal-fin origin and caudalfin origin. Ventral profile convex, keeled from vertical through posteriormost point of pectoral-fin base to anal-fin origin. Anus located just anterior to anal-fin origin.

Head small, compressed, its dorsal profile almost straight, a slight indentation at nape, sub-acute in lateral view; depth much greater than width. Nostrils closer to orbit than to snout tip, dorsolaterally oriented. Barbels absent. Eye positioned laterally, visible in both dorsal and ventral view. Mouth oblique, angle of gape slightly anterior to vertical through anterior rim of orbit. Lower jaw with minute scattered tubercles, 4 pores over dentary.

Dorsal fin with its origin closer to caudal-fin base than snout tip and posterior to vertical through anal-fin origin, with 2 simple and 8½ (14) branched rays. Pectoral fin long, with 1 simple and 9 (1), 10 (1), 11 (9) or 12 (3) branched rays, adpressed fin reaching midway between pelvic-fin origin and anal-fin origin. An axillary pectoral lobe present. Pelvic fin with 1 simple and 5 (1) or 6 (13) rays. An axillary pelvic scale present, extending about one-third length of first branched pelvic-fin ray. Anal fin with 3 simple and 16½ (1), 17½ (4), 18½ (8) or 19½ (1) branched rays. Caudal fin forked, its lobes subequal, with 9 + 7 (5) or 9 + 8 (9) branched rays. Caudal peduncle 1–1½ times longer than deep.

Lateral line complete, prominent, with 28 (2), 29 (2), 30 (4), 31 (4) or 32 (2) scales on body plus 2 scales on caudal-fin base; ½6/1/2½ scales in transverse line from dorsal-fin origin to pelvic-fin origin. Predorsal scales 16 (2), 17 (7) or 18 (5); prepelvic and preanal region scaled; circumpeduncular scales 12 (14).

Premaxillae broad at their medial articular surface, not in contact at symphysis ( Fig. 3 A). Maxilla slender, slightly curved, distal portion long ( Fig. 3 B). Supraorbital lateral margin curved, its posterior margin blunt, its articular surface with lateral ethmoid concave ( Fig. 3 C). Third suborbital largest, deep, partly overlapping preoperculum, its ventral profile rounded, dorsal profile slightly concave ( Fig. 3 D). Operculum with postero-dorsal margin slightly concave, its postero-ventral margin straight ( Fig. 3 E). Fifth ceratobranchial curved, its posterior margin smooth, with 5+4+2 distally curved teeth ( Fig. 3 F). Dentary with coronoid process blunt, inferior border straight or slightly convex, superior border with prominent depression ( Fig. 3 G). Vertebrae (pre-caudal +caudal): 16+18 = 34 (2).

Coloration. In 70% alcohol: Body brownish, lighter ventrally. A broad, dark-brown midlateral stripe (about one scale high), proceeding from posterior rim of orbit to middle of caudal-fin base. The midlateral stripe of three paratypes (45.6, 41.4, 37.8 mm SL) faded, leaving indistinct blotch like markings along the stripe. A black humeral spot behind operculum. Sclera whitish. All fins hyaline, with scattered melanophores.

Etymology. The species is named for its similarity to Laubuka fasciata in having a broad, dark brown midlateral stripe on the body.

Distribution. The species is presently known only from the Sala River, a tributary of the Kaladan River, Mizoram, north-eastern India.

Figures

FIGURE 1. Laubuka parafasciata, holotype, ZSI FF 6032, 43.2 mm SL; lateral view.

FIGURE 3. Left side view (except supraorbital and premaxillae which are in dorsal view) of bones, paratype, PUCMF 16008, 44.4 mm SL; A) premaxillae; B) maxilla; C) supraorbital; D) third suborbital (IO 3); E) operculum; F) fifth ceratobranchial; G) dentary. Scale bars = 1 mm.