A new fish species of genus Garra (Teleostei: Cyprinidae) from Nagaland, India

A species of the genus Garra is described from the Langlung River, Brahmaputra basin, Nagaland, India. The new species is distinguished from its congeners in having weakly-developed unilobed proboscis, a distinct transverse lobe with 8–12 small sized unicuspid acanthoid tubercles, 30–32 lateral line scales, and 13–15 circumpeduncular scales.


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The members of the labeonine genus Garra Hamilton, 1822 are elongated fish that live in torrential rivers and streams. They are widely distributed from Sub-Saharan Africa to Borneo through the Arabian Peninsula, southern Asia, and southern China (Zhang & Chen 2002). The species of Garra are diagnosed by the presence of a labial fold forming a gular disc that displays variations in the snout (Kottelat 2020). Nebeshwar & Vishwanath (2017) divided the genus found in southern and southeastern Asia into five groups based on snout morphology: smooth, transverse lobe, proboscis, rostral flap, and the rostral lobe.
The Langlung River, also known as Atu Ghoki (meaningstone River) is an important tributary of Dhansiri River in Nagaland. It originates near New Jalukie, Peren District and flows through Zutovi Village, Dimapur, and joins with Dhansiri River and finally confluences into the Brahmaputra. The river forms an ideal habitat for Garra. There are no prior reports of ichthyological explorations of this river.
A field survey in the Langlung River, a tributary of Brahmaputra drainage in Nagaland, India included the collection of seven undescribed Garra with a weaklydeveloped proboscis and a transverse lobe on the snout. The present paper deals with the formal description of this species as Garra langlungensis sp. nov.

Material and Methods
Samples were fixed in 10% formaldehyde and then kept in 70% ethanol. All measurements were made using digital callipers, point to point on the left side of the specimen closest to 0.1mm. Counts, measurements and terminology follow Nebeshwar & Vishwanath (2013). Gular disc terminology follows (Kottelat 2020). Dorsal and anal fin rays follow Kottelat (2001). Lateral line scales were counted from the anterior-most scale in contact with the shoulder girdle to the posterior-most scale on the caudal J TT fin. Fin rays and number of scales were counted using Huvitz stereo zoom microscope. Numbers in parentheses following meristic data indicate the number of specimens with that count. Head length and measurements of body are expressed in percentage of standard length (%SL); pelvic-anal distance in the percentage of ventanal distance; subunits of the head in the percentage of head length (%HL); caudal peduncle depth in the percent of caudal peduncle length. Examined specimens are deposited in the Zoological Survey of India (ZSI), Kolkata.

Diagnosis
Garra langlungensis sp. nov., a member of the snout with proboscis species group, can be distinguished from other members of this group in having the following combination of characters: weakly-developed unilobed proboscis, a distinct transverse lobe with 8-12 small sized unicuspid acanthoid tubercles, 8-9 pre-dorsal scales, 30-32 lateral line scales and 13-15 circumpeduncular scales. Vent closed to the anal-fin origin than pelvic-fin origin.

Description
Table 1 depicts morphometric and meristic data. Body elongate, laterally compressed, more towards the caudal peduncle. Dorsal head profile rising gently over the snout, slightly convex, more or less continuous with dorsal body profile to dorsal-fin origin, then gently sloping towards caudal peduncle. Ventral profile from head to chest straight and profile from chest to anal-fin origin more or less convex. Head moderately large, depressed with slightly convex inter-orbital area; height less than length; width greater than height. Eyes dorso-laterally located, closer to posterior margin of opercle than to snout tip.
Snout rounded, with a distinct transverse lobe covered with 8-12 small-sized unicuspid acanthoid tubercles, demarcated posteriorly by a narrow moderately deep transverse groove. Proboscis weakly developed, unilobed with small tubercles on its margin (Image 2). Barbels two pairs; rostral barbel anteroventrally located, shorter than eye diameter; maxillary barbel at the corner of the mouth, shorter than rostral barbel. Rostral cap well-developed, its distal margin highly fimbriate, papillate ventral surface moderately wide; separated from upper jaw by deep groove and laterally continuous with the lower lip. Upper jaw entirely covered by the rostral cap. Disc elliptical, shorter than wide and narrower than head width through roots of maxillary barbel; labellum of lower lip distinct; torus well developed with papillae, not covered by the rostral cap; toral groove between the posterior torus and pulvinus deep; papillae on inner half of the whole length of labrum larger and coarsely arranged; anterior marginal surface of pulvinus with coarsely arranged fleshy papillae; posterior most margin of labrum extending vertical to eye.
Dorsal fin with two simple and 8½ branched rays; distal margin concave; origin nearer to snout tip than to caudal-fin base, inserted anterior to vertical through pelvic-fin origin. Pectoral fin with 1 simple and 11 (4) or 12 (3) branched rays, reaching beyond midway to pelvicfin origin; margin subacuminate. Pelvic fin with 1 simple and 7½ branched rays; second branched ray longest, reaching beyond midway to anal-fin origin, surpassing anus; origin closer to anal-fin origin than to pectoral-fin origin. Anal fin with 2 simple and 5½ branched rays; first branched ray longest, not reaching base of caudal fin; distal posterior margin slightly concave, origin closer to caudal-fin base than to pelvic-fin origin. Vent closer to the anal-fin origin than to pelvic-fin origin. Caudal fin forked with 10+9 principal caudal rays; upper lobe slightly longer; tip of lobes pointed.
Lateral line complete, scales along lateral line 28 (3), 29 (2) or 30 (2) + 2 (7) on caudal-fin base. Transverse scale rows above lateral line scale 3½ (7); between lateral line and pelvic-fin origin 3 (7); between the lateral line to analfin origin 3½ (7). Circumpeduncular scales 13 (3), 14 (2) or 15 (2). Pre-dorsal scales 8 (4) or 9 (3); scales regularly arranged. Chest and belly with well-developed scales. One long axillary scale at the base of the pelvic fin, its tip reaching the posterior end of pelvic-fin origin. Dorsal-fin base scales 7 of which last three to four connected to the base of the dorsal fin. Anal-fin base scales 4 of which last three to four connected to the base of the anal fin. Scales between the vent and anal-fin origin 2 (3) or 3 (4).
Coloration: In fresh specimens, head and body greenish-brown dorsally and laterally. Mouth, chest and abdomen white. Dorsal, pectoral, pelvic, anal and caudal fins orange yellowish, fin rays moderately spotted. In preservative, head, dorsal and lateral side dark grey. Mouth, chest and abdomen yellowish white. A black spot at upper angle of gill opening. Dorsal, pectoral, and J TT pelvic fins with thin melanophores. Anal and caudal fins greyish-yellow. Six narrow black stripes on lateral side more prominent towards caudal peduncle. Median rays and tips of upper and lower lobe of caudal fin dark brown.
Etymology: Named after its type locality, Langlung River.