Garra clavirostris, Roni, Narengbam, Sarbojit, Thaosen & Vishwanath, Waikhom, 2017

Roni, Narengbam, Sarbojit, Thaosen & Vishwanath, Waikhom, 2017, Garra clavirostris, a new cyprinid fish (Teleostei: Cyprinidae: Labeoninae) from the Brahmaputra drainage, India, Zootaxa 4244 (3), pp. 367-376 : 368-372

Garra clavirostris , new species

( Fig. 1 )

Holotype: MUMF 22004, 117.5 mm SL, male; India: Assam: Dima Hasao District: Dilaima River at Boro Chenam Village below the confluence of Dilaima and Dihandi (Brahmaputra drainage); 25°18′03" N, 92°52′05" E, 401 m above sea level, Sarbojit et al, 19 April 2015.

Paratypes: MUMF 22001–22003, 3 specimens, 87.7–127.46 mm SL, MUMF 22005–22013, 9 specimens, 54.28–77.74 mm SL; India: Assam: Dima Hasao District: Diyung River (Brahmaputra drainage); 25°48′22" N, 92°57′26" E, 87 m above sea level, Roni et al, 16 March 2016. MUMF 22002, 110.4 mm SL, dissected for osteology.

Diagnosis. Garra clavirostris is distinguished from its congeners in the Brahmaputra and the Chindwin drainages in having the following combination of characters: a transverse lobe bearing 17–25 small- to large-sized multicuspid tubercles; a prominent club-shaped unilobed proboscis prominently protruding forward and overhanging the depressed rostral surface, with a row of 5–9 medium- to large-sized uni- to multi-cuspid tubercles on its anterior margin; the antero-ventral marginal aspect of the proboscis with 5–6 medium-sized uni- to multicuspid tubercles, distinctly differentiated from the depressed rostral surface by a distinct transverse groove; 8½ or 9½ branched dorsal-fin rays; 5½ branched anal-fin rays; 33–34 lateral-line scales; a black spot at the upper angle of gill opening; and 4–5 narrow black stripes laterally, more distinct towards the caudal peduncle.

Description. General body shape as shown in Fig. 1 . Morphometric and meristic data for the holotype and 12 paratypes are listed in Table 1 . Body elongate, compressed laterally, more compressed towards caudal penducle. Dorsal head profile rising gently over snout, slightly more convex than dorsal body profile to dorsal-fin origin. Ventral profile more or less straight to anal-fin origin. Head large, depressed, with moderately convex interorbital region, head depth less than head width and head length. Snout rounded, its transverse lobe covered with 17–25 medium to large multicuspid tubercles, each demarcated posteriorly by a shallow transverse groove ( Fig. 2 a,b,c). Proboscis prominent, protruding forward up to transverse groove, with 5–9 medium to large uni- to multi-cuspid tubercles on anterior margin, 5–6 uni- to multi-cuspid tubercles on anteroventral marginal aspect, differentiated from depressed rostral surface by a distinct transverse groove; anterior region of proboscis bulging, club-shaped, overhanging depressed rostral surface ( Fig. 3 ). Depressed rostral surface slightly convex, sub-lachrymal groove shallow, connected to rostral-cap groove. Eyes dorsolaterally located, closer to posterior margin of opercle than to snout tip ( Fig. 3 ).

Barbels in two pairs; rostral barbels anterolaterally located, shorter than eye diameter; maxillary barbels at the corner of mouth, much shorter than rostral barbels. Upper jaw entirely covered by well-developed rostral cap which has a highly fimbriate posterior margin, about one-sixth of its length at distal margin smooth ( Fig. 4a ). Papillae on rostral cap with finger-like unculi projecting in different directions ( Fig. 4 b). Mental disc oval; papillae on anteromedian fold irregularly arranged; unculi on papillae blunt, projecting to one side ( Fig. 4 c). Anterior marginal region of central callous pad with small, elongated, sparsely-arranged papillae; papillae of whole length of lateroposterior flap large, coarsely arranged; posteriormost margin of lateroposterior flap extending slightly beyond vertical through posterior margin of eye.

Dorsal fin with three simple and 8½–9½ branched rays, last simple ray slightly shorter than head length; distal margin markedly concave; origin closer to snout tip than to caudal-fin base; first branched ray longest, tip of last branched ray not extending beyond vertical through anal-fin origin. Pectoral fin with one simple and 14–15 branched rays; its length less than head length; margin subacuminate; fifth branched ray longest, not extending to base of pelvic fin. Pelvic fin with one simple and 7–8 branched rays, not surpassing vent when adpressed; second branched ray longest, not extending to base of anal-fin origin; origin closer to anal-fin origin than to pectoral-fin origin, inserted below third or fourth branched dorsal-fin ray; distal margin slightly convex. Anal fin short, with three simple and 5½ branched rays; first branched ray longest. Anus situated posteriorly (distance between anus and anal-fin origin 18–25% of that between pelvic-fin origin and anal-fin origin). Caudal fin forked; tips of lobes pointed; lobes equal; 10+9 principal rays.

Lateral line complete, with 33–34 scales. Transverse scale rows above lateral line 4½–5½; between lateral line and pelvic fin origin 3½. Predorsal scales 9–10; scales regularly arranged; chest and belly scaled, scales partially embedded in skin. Preanal scales 3–4. Scales on dorsal-fin base 6–7. Scales on anal fin base 4–5.

Total vertebrae 32 (1), consisting of 21 abdominal + 11 caudal vertebrae; predorsal vertebrae 9 (1).

Colour. In formalin: head, dorsum and side dark brown to dark grey. Mouth, chest and abdomen yellowish white. Dorsal fin more distinct dark-grey hue than anal, pelvic and pectoral fins. In some specimens, lower lobe of caudal fin darker than upper lobe. Four or five narrow black stripes laterally, more distinct towards caudal peduncle; yellowish white ventrally at origin of pectoral and pelvic fins. A black spot on first scale of lateral line, covering about one-third height of scale anteriorly.

Distribution. Garra clavirostris is presently known only from the type locality Dilaima River (Brahmaputra drainage), Boro Chenam Village, below the confluence of the Dilaima and Dihandi, and also from the Diyung River (Brahmaputra drainage) of Dima Hasao district, Assam, India ( Fig. 5 ). It inhabits medium- to fast-flowing clearwater hill streams with a gravelly substrate covered in lush green algal growth ( Fig. 6 ).

Etymology. The species-name is derived from the Latin ‘clava’(club), an allusion to the shape of the proboscis; and ‘rostrum’(snout). A noun in apposition.

Discussion. The characteristics of the snout and the size and distribution patterns of the tubercles on the proboscis are of taxonomic significance in distinguishing species of the genus Garra ( Nebeshwar & Vishwanath 2013) . Garra clavirostris has a prominent proboscis and is therefore compared only with the congeners in the river drainages of northeast India having a proboscis on the snout. Garra clavirostris is easily distinguished from other proboscis-bearing congeners, viz., G. arunachalensis , G. birostris , G. cornigera , G. elongata , G. gotyla , G. kalpangi , G. litanensis , G. nasuta , G. quadratirostris and G. trilobata as follows. From G. arunachalensis (Brahmaputra drainage) in having the depressed rostral surface slightly convex (vs. flat), 33¯34 (vs. 35) lateral-line scales, presence (vs. absence) of anterolateral lobe of the lower lip, and absence (vs. presence) of minute tubercles and pores on the depressed rostral surface; from G. birostris (Brahmaputra drainage) in having a club-shaped unilobed (vs. bilobed) proboscis, disc of the lower lip oval (vs. elliptical) and sublachrymal groove connected (vs. not connected) to rostral-cap groove; from G. gotyla (Brahamaputra drainage) in having the forward protrusion of the proboscis reaching (vs. not reaching) the transverse groove and a slightly (vs. highly) convex depressed rostral surface; from G. quadratirostris (Brahmaputra drainage) in having 33¯34 (vs. 37) lateral-line scales, 3–4 (vs. 5–6) preanal scales and slightly convex (vs. creased and convex) depressed rostral surface; from G. kalpangi (Brahamaputra drainage) in having a well-developed (vs. weakly developed) proboscis, 4½–5½ (vs. 3½) transverse scale rows above the lateral line and 14–16 (vs. 10–12) branched pectoral-fin rays; from G. elongata (Chindwin drainage) in having prominent (vs. weakly developed) proboscis, 33–34 (vs. 39–40) lateral-line scales, the absence (vs. presence) of a transverse black bar on the dorsal fin and the absence (vs. presence) of a longitudinal black band on the middle of the caudal fin; from G. litanensis (Chindwin drainage) in having 33–34 (vs. 32) lateral-line scales and the absence (vs. presence) of black spots along the base of the dorsal fin; from G. cornigera (Chindwin drainage) in having a unilobed (vs. bilobed) proboscis, the presence (vs. absence) of a black spot at the upper angle of the gill opening, slightly convex (vs. flat) depressed rostral surface and 4½–5½ (vs. 3½) transverse scale rows above the lateral line; and from G. trilobata (Chindwin drainage) in having an unilobed (vs. trilobed) proboscis, the presence (vs. absence) of an anterolateral lobe of the lower lip and in having 33–34 (vs. 31–32) lateral-line scales.

M’Clelland (1838) described G. nasuta from a single specimen from the Khasi hills and provides insufficient information for its diagnosis, except for its characteristic presence of a pit between the nares. The new species, however, is distinct from G. nasuta in the absence of a pit between the nares.

Garra clavirostris can be distinguished from the two recently-described species occurring in Bhutan, G. bimaculacauda and G. parastenorhynchus , in the absence (vs. presence) of two distinct black spots on the caudal fin, one each on the tips of the dorsal and ventral lobes). In fact these ‘spots’ (see Fig 3 , page 118, of Thoni et al 2016) may be better described as elongated dark brown pigmentation on two or three principal rays. The new species also differs from G. parastenorhynchus in having a more pronounced (vs. less pronounced) club-shaped proboscis, the club overhanging the depressed rostral surface (vs. not overhanging); in the absence (vs. presence) of a conspicuous dark spot at the caudal-fin base, the absence (vs presence) of a series of 8 ̶9 dark-brown spots at the base of dorsal fin (as in Thoni et al, 2016, Fig. 9 and R.J. Thoni, pers. comm) and also in the tuberculation pattern on the snout. Garra clavirostris also possesses a greater number of multicuspid tubercles on the proboscis, transverse lobe and lateral surface of the snout. The ‘rostral lobe’ referred to by Thoni et al (2016) is in fact the transverse lobe ( Zhang & Kottelat, 2006; Nebeshwar & Vishwanath, 2013).

Figures

FIGURE 1. Garra clavirostris, sp. nov., holotype, MUMF 22004, 117.5 mm SL, male; a. lateral, b. dorsal and c. ventral views. India: Assam: Dima Hasao District: Dilaima River at Boro Chenam Village.

FIGURE 2. Snout of Garra clavirostris, a. morphology of snout showing transverse lobe, proboscis, depressed rostral surface and lateral surfaces of holotype; b. transverse lobe showing tubercles (MUMF 22001, paratype, 87.7 mm SL); c. one tubercle in b enlarged.

FIGURE 3. Lateral view of snout of Garra clavirostris, holotype, showing shape of proboscis and the position of eye.

FIGURE 4. a. Oromandibular structure of Garra clavirostris, holotype; magnified images of b. rostral cap and c. lateroposterior flap (MUMF 22001, paratype, 87.7 mm SL).

FIGURE 5. Map showing the type locality of Garra clavirostris, sp. nov.; Holotype (•) and Paratype (̊).

FIGURE 6. Diyung River, type locality and habitat of Garra clavirostris.

Tables

TABLE 1. Morphometric and meristic data of holotype and twelve paratypes of Garra clavirostris.

	Holotype MUMF	Paratypes Range	Mean	S.D
Standard length (mm)	117.5	46.4–127.46
In % of standard length
Body depth	20.8	19.4–24.0	21.3	1.4
Head length	24.8	23.1–27.1	25.9	1.2
Head depth at nape	8.4	8.0–14.1	11.4	2.1
Head depth at eye	9.7	9.7–18.2	14.2	2.5
Body width at anal-fin origin	14.7	7.9–16.0	11.7	2.6
Body width at dorsal-fin origin	19.1	14.3–21.1	17.7	1.8
Caudal peduncle length	11.5	10.1–14.6	12.5	1.3
Caudal peduncle depth	11.4	2.2–11.5	5.9	3.8
Dorsal-fin base length	12.0	12.0–19.0	16.8	2.0
Dorsal-fin length	22.7	20.9–27.0	24.2	1.9
Pectoral-fin length	21.1	19.6–24.8	21.9	1.4
Pelvic-fin length	17.4	17.4–22.7	19.8	1.3
Anal-fin base length	8.0	6.1–8.5	7.7	0.8
Anal-fin length	17.0	11.0–19.4	17.6	2.2
Predorsal length	44.4	44.4–50.4	47.8	1.7
Prepectoral length	23.2	21.9–25.3	23.9	1.1
Prepelvic length	52.0	50.5–55.8	52.1	1.5
Preanal length	79.0	76.6–81.5	78.4	1.7
Pelvic anal distance	25.9	24.9–30.9	27.1	1.7
Snout length	14.6	13.6–16.5	15.1	0.8
Eye diameter	3.4	3.4–5.6	4.3	0.5
In % of pelvic-anal di s tance
Distance from anus to anal fin	20.0	18.6–25.1	22.7	2.5
In % of head length
Snout length	58.9	52.0–64.4	58.4	2.8
Eye diameter	14.0	14.0–21.4	16.9	1.8
Disc width	41.4	40.9–61.5	52.1	7.5
Disc length	55.1	50.9–65.7	54.7	4.4
Central callous pad width	22.2	21.9–34.3	29.1	4.6
Central callous pad length	31.1	20.8–35.2	26.0	4.9
Meristic counts
Dorsal- fin	iii/9½	iii/8½–9½
Pectoral- fin	i/15	i/14–15
Pelvic- fin	i/8	i/7–8
Anal- fin	iii/5½	iii/5½
Lateral line scales	34	33–34
Predorsal scales	10	9–10
Preanal scales	4	3–4
Dorsal fin base scales	7	6–7
Anal fin base scales	4	4–5