Garra parastenorhynchus, Thoni, R. J., Gurung, D. B. & Mayden, R. L., 2016

Thoni, R. J., Gurung, D. B. & Mayden, R. L., 2016, A review of the genus Garra Hamilton 1822 of Bhutan, including the descriptions of two new species and three additional records (Cypriniformes: Cyprinidae), Zootaxa 4169 (1), pp. 115-132 : 125-128

Garra parastenorhynchus sp. nov.

( Figs. 9 & 10 )

Holotype. NBC 15580, 57.0 mm SL; Bhutan: Samdrup Jongkhar Dzongkhag: Dungsamchhu at Samdrup Jongkhar Town, D.B. Gurung & R.J. Thoni, October 18, 2013.

Paratype. 5 Specimens, CNR 15582, CNR 15590, CNR 13060-13062. 46.2–57.3 mm SL; same data as holotype.

Non-type material: 1 Specimen, CNR 13063; Bhutan: Samdrup Jongkhar Dzongkhag: Martangchhu, R.J. Thoni & D.B. Gurung, October 19, 2013.

Diagnosis. Garra parastenorhynchus is distinguished from its congeners by the following combination of characters: a large, overhanging, club-shaped proboscis, 31–32 lateral-line scale rows, 16 circumpeduncular-scale rows, 10–11 predorsal-scale rows, head length 28.5–30.7% SL, head depth 56.9–59.8 % HL, and orbit 17.8–18.4 % HL.

Description. Morphometric and meristic counts are provided in Tables 3 and 4, respectively. The lateral, dorsal, and ventral view of a preserved specimen can be seen in Figure 9 . The lateral view of a live specimen can be seen in Figure 10 . Body elongate. Tip of snout upturned and rough with large multi-cuspid tubercles along a welldeveloped rostral lobe. Head with large tuberculate proboscis; club-shaped, being restricted at its base when viewed both dorsally and laterally. Proboscis maintaining same angle as nape, not projecting upwards. Dorsal profile from occiput to dorsal-fin origin with moderate convex rise. From dorsal-fin origin to caudal peduncle, declining with slight concave curvature. Ventral surface from snout to vent, flat. Vent to caudal peduncle rising with concave curvature.

Head somewhat pointed; rostral lobe semicircular from ventral aspect. Head length about 2/7 of standard length; depth roughly same as width. Orbit nearly 1/5 of head length. Mouth with large mental disc; slightly wider than long. Disc length roughly 3/8 of head length; width 1/2 head length. Anterolateral lobe separate from posterolateral flap. Rostral cap short, not fully covering upper jaw. Two pairs of barbels; maxillary barbels 4/5 the length and thickness of rostral barbels.

Dorsal-fin origin located roughly halfway between tip of snout and caudal base. First branched ray the longest; roughly 1/4 of SL. Margin of fin concave. Dorsal-fin base roughly 1/6 of SL; fin rays ii,8. Anal fin nearly 1/5 of standard length; rays i,5. Paired fins inserted horizontally. Pectoral fin roughly 1/4 of standard length; rays i,13(1) i,14(5). Pelvic fin roughly 1/5 of standard length; fin rays ii,7. Caudal fin forked; lobes roughly equal in length; principal rays 2; branched rays 17.

Coloration. Live specimens captured during this study were pale brown to olive green in base color. Many scales along lateral line, and one scale row below lateral line, pink in color. Operculum and first lateral-line scale posterior to upper operculum form iridescent blue spot. Ventral surface, including mouth, lips and isthmus white. Both pairs of barbels pale brown to white.

When preserved in alcohol, the overall pigmentation patterns of specimens same as in life, with the exception that the iridescent blue spot is absent and overall color appears to be more grey than brown. Barbels without color. A conspicuous dark spot at the caudal base is present.

Etymology. The species epithet parastenorhynchus is in reference to its similarity to Garra stenorhynchus .

Distribution. Presently known from the Dungsamchhu and Martangchhu rivers in southeastern Bhutan.

Remarks. The status of G. stenorhynchus has been debated for more than a century. Jerdon (1849) described it as a unique species based on the following description: “[acute muzzle] ending in a blunt, rounded projection studded with large and prominent mucous pores; 4 longish cirri; head is to the whole body as 1 is to 4 1/2 height is 4 times in the length; 34 scales along the body in 7 rows; D. 10, A.9, &c. About 10 inches long. Colors as in above (referring to G. mclellandi )” which was described as “…dusky green above, golden on sides and greenish white beneath; caudal fin green in the center, reddish above and below; other fins yellow, edged with red; cheeks golden…”. Hora (1921) recognized G. stenorhynchus as a valid species. He also described a new species, G. montisalsi Hora 1921 , based on one specimen, which bears similar features to G. stenorhynchus . His diagnosis between the two is that the snout from below is trenchant and distinctly semi-circular in G. montisalsi versus evenly rounded and convex. Menon (1964) synonymized both G. montisalsi and G. stenorhynchus with G. g o t y l a with little justification. It has seemingly remained in this state due to lack of further investigation. Nebeshwar & Vishwanath (2013) briefly discussed this unsupported decision and make note of it in their redescription and diagnosis of G. gotyla . After much consideration and comparison between specimens collected in Bhutan, and the descriptions of G. stenorhynchus and G. montisalsi , we conclude that the species from Bhutan is unique and that G. stenorhynchus and G. montisalsi are both valid species. As there is much fidelity to the characters of individuals sharing the G. stenorhynchus morphology, there is little evidence convincing the authors that it is a synonym of G. gotyla , particularly following the redescription of G. gotyla by Nebeshwar & Vishwanath (2013), and is herein treated as a separate, independent lineage.

Garra parastenorhynchus was found at three localities, but vouchers were only collected at two, the Dungsamchhu River in the border town of Samdrup Jongkhar and Martangchhu stream in southeastern Bhutan. It is likely that this species occurs in Northeast India, as this locality was only 2 km upstream from the Indian state of Assam. They were found in small numbers, occurring in riffles over cobblestone substrate. They were never found in areas of high gradient, and were in one of the few areas of the country that is more plain-like than mountainous. Along with this species, we also encountered, Devario , Neolissochilus , Glyptothorax , Anguilla bengalensis, Balitora brucei, Chagunius chagunio, Bangano dero , Barilius bendelisis , and Raiamas bola .

Figures

FIGURE 9. Garra parastenorhynchus. Holotype. NBC 15580, 57.0 mm SL; Bhutan: Samdrup Jongkhar Dzongkhag: Dungsamchhu at Samdrup Jongkhar Town, D. B. Gurung & R. J. Thoni, October 18, 2013.

FIGURE 10. Live specimen Garra parastenorhynchus. Holotype. NBC 15580, 57.0 mm SL; Bhutan: Samdrup Jongkhar Dzongkhag: Dungsamchhu at Samdrup Jongkhar Town, D. B. Gurung & R. J. Thoni, October 18, 2013.

Tables

TABLE 3. Morphometric measurements for Garra parastenorhynchus.

Morphometrics	Min	Max	Mean	SD
Standard length	46.2	57.4	51.1	4.6
% Standard Length
Body depth	20.2	22.0	20.7	0.8
Head length	28.5	30.7	29.6	0.9
Body width	15.2	16.5	15.6	0.6
Caudal peduncle width	4.6	5.4	4.9	0.4
Caudal peduncle length	14.8	16.6	15.5	0.8
Caudal peduncle depth	11.9	12.7	12.2	0.4
1st dorsal ray length	25.3	27.7	26.3	1.1
Dorsal-fin length	28.1	31.4	29.7	1.3
Dorsal-fin base length	16.1	17.3	16.6	0.6
Pectoral-fin length	22.6	25.0	23.9	1.0
Pelvic-fin length	20.7	21.7	21.2	0.4
Anal-fin length	19.3	20.0	19.8	0.3
Upper caudal-fin lobe length	30.4	31.8	31.1	0.6
Lower caudal-fin lobe length	31.8	33.2	32.3	0.7
Median caudal-fin rays length	16.7	19.2	17.9	1.0
Preanal length	77.9	82.1	79.8	1.9
Prevent length	70.1	74.2	72.7	1.9
Preventral length	53.8	56.0	55.2	1.0
Predorsal length	47.7	51.4	49.3	1.8
Occiput-dorsal length	23.1	24.4	23.8	0.6
Prepectoral length	24.9	29.7	26.8	2.1
Ventral-anal length	23.4	26.9	25.1	1.6
% Ventral-anal
Vent-anal length	22.5	31.1	26.3	4.0
% Heal length
Head depth	56.9	59.8	58.2	1.4
Head depth at eye	46.2	51.3	48.9	2.5
Head width at opercle	57.4	62.9	61.3	2.6
Snout length	44.6	51.2	47.6	2.7
Orbit	17.8	18.4	18.2	0.3
Interorbital width	34.7	39.5	37.8	2.1
Disc length	32.6	37.2	35.0	2.1
Disc width	46.0	52.3	50.2	3.0
Callous pad length	15.7	21.1	18.8	2.5
Callous pad width	24.4	27.4	25.8	1.3
Rostral barbel length	11.7	16.0	13.9	1.9
Maxillary barbel length	8.7	14.3	10.4	2.6