Garra bimaculacauda Thoni, Gurung & Mayden, 2016, sp. nov.
Creators: name: Thoni, R. J.
name: Gurung, D. B.
name: Mayden, R. L.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Cypriniformes
Cyprinidae
Garra
Garra bimaculacauda

description: Garra bimaculacauda, sp. nov.
(Figs. 3 & 4)
Holotype. NBC 15184, 66.2 mm SL; Bhutan: Zhemgang Dzongkhag: Marangdud: Dangmechhu River, 27 o 11.513 N 0 91 o 36.059 E; R.J. Thoni & D.B. Gurung, September 28, 2013.
Paratype. CNR 15185, 63.7 mm SL; same data as holotype.
Non-type material. CAS 239485, 103.4 mm SL; Bhutan: Trashigang Dzongkhag: Dangmechhu River above confluence with Sherichhu, T. R. Roberts, October 7, 1995.
Diagnosis. Garra bimaculacauda sp. nov. is distinguished from its congeners by the following combination of characters: two distinct black spots on the caudal fin, one on the tip of the dorsal lobe and the other on the tip of the ventral lobe, weak proboscis forming a tuberculate ridge, 32–34 lateral-line scale rows, 12 circumpeduncular-scale rows, 11–12 predorsal-scale rows, six scales from dorsal origin to lateral line, three anal scales, and the absence of a dark lateral band along the length of the body.
Description. Morphometric and meristic counts are provided in Tables 1 and 2, respectively. The lateral, dorsal, and ventral view of a preserved specimen can be seen in Figure 3. The lateral view of a live specimen can be seen in Figure 4. Body elongate. Tip of snout upturned and rough with small tubercles along rostral lobe. Snout to nape interrupted by rostral lobe, transverse groove, and proboscis. Rostral lobe reduced, not prominent or deeply incised. Proboscis not overhanging; roughly 90 degrees in angle to surface of head. From proboscis to occiput, slightly convex. Dorsal profile from occiput to dorsal-fin origin with slight rise. From dorsal-fin origin to caudalfin base, slightly declining with slight concave curvature. Ventral surface from snout to pectoral-fin insertion flat. In line with distal edge of shortest pectoral-fin ray, belly drops slightly until pelvic-fin insertion. From pelvic fins to vent, flat. Vent to caudal-fin base rising with concave curvature.
Head blunt; depth roughly 5/6 of width. Head length about 1/4 of standard length. Orbit nearly 1/5 of head length. Mouth with large mental disc; slightly wider than long. Disc length slightly less than 1/2 of head length; width slightly more than 1/2 head length. Anterior edge of callus pad with slight fold and covered in sparse papillae. Anterolateral lobe fused with posterolateral flap. Rostral cap short, not completely covering upper jaw. Two pairs of barbels; maxillary barbels roughly one half the length and thickness of rostral barbels.
Head ornate with small tubercles occurring in three locations. Rostral lobe with one to two rows of small tubercles. Lateral lobe of snout with one single row of small tubercles running posteriorly from tip of lobe to anterior base on nares. Proboscis with three tubercles on its anterior terminus; two large tubercles laterally and one small tubercle between them. One singular row of small tubercles running posteriorly from laterally-located large tubercle on proboscis to posteromedial base of naris.
Dorsal-fin origin located roughly halfway between tip of snout and caudal base. First branched ray the longest; nearly as long as HL; margin of fin concave. Dorsal-fin base roughly 2/3 head length; fin rays ii,8. Anal fin nearly 1/5 of standard length; rays i,5. Paired fins inserted horizontally. Pectoral fin roughly 1/5 of standard length; rays i,14. 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 silvery grey to olive green. Individuals displaying different color morphs, likely due to sexual dimorphism. Males with olive green base. Sparse scales one to two scale rows above and below lateral line with pale pink color. Females with grey base color; scales on dorsum with dark margin, making dorsal half of body darker grey than ventral half. Several scales above lateral line anterior to dorsal fin have an iridescent blue coloration at the base of the scale. The first scale posterior to upper operculum has the brightest iridescent blue spot on the body. Ventral surface, including mouth, lips and isthmus white. Both pairs of barbels red.
When preserved in alcohol, the overall pigmentation patterns of specimens same as when if life, with the exception that the iridescent blue spots are absent and overall color appears to be more grey and brown. Barbels without color. A conspicuous dark spot at the caudal base is present.
Etymology. The species epithet bimaculacauda is in reference to the two spots on the caudal fin.
Distribution. Presently known from the Dangmechhu drainage in central and eastern Bhutan from near Panbang Village to the confluence of the Sherichhu River (Fig. 5).
Remarks. Upon examining a small lot of Bhutanese fishes collected in 1995 by T. R. Roberts, a single specimen from the Dangmechhu River was found having the same caudal-fin spots, body pigmentation, and tuberculation, as well as a large mental disc, and papillose region on the anterior edge of the callous pad. Meristic values were within range of the two previous specimens as were most mensural data, with some exceptions, most likely due to allometric differences associated with its much larger size. Data from this specimen were taken and added to the analysis.
Interestingly, a species with similar caudal-fin pigmentation was encountered at the Aquarium Glaser in Frankfurt, Germany. When enquired of their collection locality, it was said to have collected in West Bengal, most likely in the Buxa Tiger Reserve, which shares a border with Chhukha, a southern district of Bhutan (Personal communication with Frank Schäfer). This location, though close to Bhutan, is four river drainages west of the locality of G. bimaculacauda. No fishes bearing these pigmentation patterns were collected in the river drainages between the two localities. The species from West Bengal did not have the same head morphology as that of G. bimaculacauda as two mature individuals, similar in size to those collected in Bhutan had large, protruding proboscises, which were not present in G. bimaculacauda. This species deserves further investigation.
Garra orientalis Nichols 1925, from China and Vietnam, has caudal-fin markings similar to those described above. However, it also has a medial stripe on the caudal fin and head ornamentation, tubercle arrangement, and morphometric dimensions differ greatly.
Garra bimaculacauda was only encountered in one location by the authors, at the confluence of the Marangdudchhu stream and the Dangmechhu River, in the Zhemgang Dzongkhag. Both specimens were found in shallow riffles over cobble substrate. Other species collected at this locality include: Barilius vagra, Garra annandalei, Bangana dero, Pseudecheneis sulcata, and Tor putitora.
description: Published as part of 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), pp. 115-132 in Zootaxa 4169 (1) on pages 118-122, DOI: 10.11646/zootaxa.4169.1.5, http://zenodo.org/record/265168