Garra yajiangensis, Gong & Freyhof & Wang & Liu & Liu & Lin & Jiang & Liu, 2018

Gong, Zheng, Freyhof, Jörg, Wang, Jian, Liu, Meng, Liu, Fei, Lin, Pengcheng, Jiang, Yueliang & Liu, Huanzhang, 2018, Two new species of Garra (Cypriniformes: Cyprinidae) from the lower Yarlung Tsangpo River drainage in southeastern Tibet, China, Zootaxa 4532 (3), pp. 367-384 : 375-378

Garra yajiangensis , new species

( Figs. 5–6 )

Holotype. IHB 20161577 , 165.0 mm SL; China: Tibet Autonomous Region: Motuo County: lower Yarlung Tsangpo River , 29°19'22"N, 95°18'13"E, 708 m above sea level; collected by Zheng Gong, Jian Wang, & Huaming Hu, October 2016.

Paratypes. IHB 20161578–20161592 , 15 specimens, 125.8–175.1 mm SL; same data as holotype .

Diagnosis. Garra yajiangensis , a member of the proboscis species group, is distinguished from the other members of this group by the following combination of characters: a quadrate and slightly bilobed proboscis covered with 2–7 middle-sized unicuspid tubercles, including two large-sized tubercles on the anterior margin of each lobe; some small unicuspid tubercles on the transverse lobe and the lateral surface of snout; anus situated substantially closer to the anal-fin origin than to the pelvic-fin origin (distance from anus to anal fin 19–24% of pelvic-anal distance); 34–36 lateral-line scales; 12 circumpeduncular scales; and morphometric features: body depth 17.4–19.5% SL, caudal-peduncle length 15.7–19.2% SL, snout length 43–49% HL, eye diameter 13–18% HL, and disc length 49–58% HL.

Description. Morphometric data of 16 type specimens in Table 4. Body elongate; cylindrical anteriorly, laterally compressed posteriorly. Head moderately large; head length greater than width, head width greater than depth; interorbital region slightly convex. Snout rounded with transverse lobe covered with some small unicuspid tubercles, demarcated posteriorly by deep transverse groove; some small unicuspid tubercles on lateral surface. Proboscis quadrate, moderately prominent, and slightly bilobed, each lobe slightly protruding; anterodorsal region of proboscis covered with 2–7 middle-sized unicuspid tubercles, including two large-sized tubercles on anterior margin of each lobe; tubercles more conspicuous in larger individuals. Eyes moderately large, situated dorsolaterally behind middle of head.

Barbels in two pairs; rostral barbels situated antero-laterally, shorter than eye diameter; maxillary barbels shorter than rostral barbels. Rostral cap with crenulated margin and numerous tiny papillae, separated from upper jaw by deep groove, posteriorly continuous with lower lip on each side. Edge of upper and lower jaws covered with thin horny sheath. Mental adhesive disc large, elliptical; disc length shorter than width, slightly longer than half head length; anteromedian fold densely covered by tiny papillae, separated from lower jaw by deep groove, posteriorly bordered by shallow notch from central callous-pad; lateral and posterior margins free; lateroposterior flap with densely arranged tiny papillae.

Dorsal fin with 3 simple and 8½ branched rays; distal margin slightly concave; first branched ray longest, almost equal to head length; origin closer to snout tip than to caudal-fin base. Pectoral fin with 1 simple and 13 (10), or 14 (6*) branched rays; length shorter than head length; distal tip not reaching pelvic-fin origin, reaching vertically to dorsal-fin origin. Pelvic fin with 1 simple and 8 branched rays; length shorter than head length, equal to pectoral-fin length; distal tip reaching beyond anus; origin closer to caudal-fin base than to snout tip. Anal fin with 3 simple and 5½ branched rays; distal tip reaching base of caudal fin; origin closer to caudal-fin base than to pelvic-fin origin. Caudal fin forked; lower lobe slightly longer.

Lateral line complete and horizontal; with 32 (3), 33 (10), or 34 (3*) scales plus 2 scales on the caudal-fin base. Transverse scale rows above lateral line 4 (8) or 4½ (8*), between lateral line and pelvic-fin origin 2½ (3*) or 3 (13). Circumpeduncular scales 12. Predorsal scales 9 (7*), 10 (8), or 11 (1); smaller than flank scales. Chest and belly scaled; scales on chest smaller than on belly. One long axillary scale at base of pelvic fin. Anus situated very closer to anal-fin origin than to pelvic-fin origin (see Fig. 5 , distance from anus to anal fin 19–24% of pelvic-anal distance), separated from anal-fin origin by 3 scale rows.

Coloration. In preserved specimens, head, dorsum, and side of head pale brown or gray. Mouth, chest, and belly faint yellow or light brown. Dorsal, pectoral, pelvic, and anal fins gray or grayish white; pectoral fin darker than other fins. A gray submarginal band on distal half of dorsal fin. Lower lobe and distal margin of upper lobe of caudal fin dark gray.

Distribution. Known only from the lower Yarlung Tsangpo River drainage in Motuo County, southeastern Tibet ( Fig. 3 ).

Ecology. This new species was primarily caught in the mainstem of the Yarlung Tsangpo (occasionally found in the tributaries), where it inhabits swift-flowing waters with numerous rocks ( Fig. 7 ). The spawning period occurs from March to May when water temperature ranges from 12–17°C according to macroscopic visual examination of the gonads. The eggs are yellow and demersal. Examinations of intestinal contents show that this species mainly feeds on periphytic algae.

Etymology. Named after its type locality, Yajiang (the Chinese abbreviation of the Yarlung Tsangpo River). An adjective.

Molecular phylogenetic analysis. After alignment, 1137 bps of Cyt b gene sequences belonging to 86 individuals of 40 species of Garra and two species of Labeo were used for analysis. Of all 1137 bps, 182 were variable sites and 151 were parsimony informative sites. Based on the K2P model, paired genetic divergences between these two new species and their congeners are given in Table 5. The genetic divergences between G. motuoensis and its sampled congeners known from the Brahmaputra and the adjacent river drainages ranged from 2.6% (vs. G. cf. gotyla A) to 19.8% (vs. G. poecilura ); between G. yajiangensis and its congeners ranged from 6.3% (vs. G. cf. gotyla B) to 16.1% (vs. G. poecilura ).

Phylogenetic trees from two inference methods (BI and ML) showed identical topologies for the most part, although some shallow nodes varied. Only the Bayesian Inference tree is shown, with node support values displayed from the two inference methods ( Fig. 8 ). Topology of the phylogenetic tree indicated that all sampled individuals of G. motuoensis grouped into a monophyletic clade with high probabilities (0.99/100), which was sister to G. cf. gotyla A. Similarly , all sampled individuals of G. yajiangensis clustered into a monophyletic clade with high probabilities (1/99), which was the closest to G. cf. gotyla B. Both G. motuoensis and G. yajiangensis were independent from their sister taxon with high probabilities (1/100 and 0.9/66, respectively).

Figures

FIGURE 3. Map showing the sampling sites of Garra motuoensis (▲) and Garra yajiangensis (?).

FIGURE 5. Garra yajiangensis, holotype, IHB 20161577, 165.0 mm SL; China: Tibet: lower Yarlung Tsangpo River.

FIGURE 6. Garra yajiangensis, holotype, IHB 20161577, 165.0 mm SL; China: Tibet: lower Yarlung Tsangpo River; dorsal and ventral views of head.

FIGURE 7. Habitat of Garra yajiangensis in the lower Yarlung Tsangpo River.

FIGURE 8. Phylogenetic relationships of G. motuoensis, G. yajiangensis, and 38 Garra species using Bayesian Inference of Cyt b sequences. Numbers on nodes before and after slash (/) represent posterior probabilities in BI tree and bootstrap values in ML tree, respectively (above 0.5/50 are shown). Garra motuoensis and G. yajiangensis are labeled with black rectangles.