Gymnocypris pengquensis, Tang, Yong-Tao, Feng, Chen-Guang, Wanghe, Kun-Yuan, Li, Guo-Gang & Zhao, Kai, 2016

Tang, Yong-Tao, Feng, Chen-Guang, Wanghe, Kun-Yuan, Li, Guo-Gang & Zhao, Kai, 2016, Taxonomic status of a population of Gymoncypris waddelli Regan, 1905 (Cypriniformes: Schizothoracinae) distributed in Pengqu River, Tibet, China, Zootaxa 4126 (1), pp. 123-137 : 132-134

Gymnocypris pengquensis , sp. nov.

( Figs.7 , 8 )

Holotype. NWIPB 1161025, 167 mm SL, Pengqu River, Zhaguo Town, Nielamu County, Tibet Autonomous Region, China (28°36'0.30"N, 86°55'11.43"E), 30 June 2011, collected by Kai Zhao, Guogang Li and Yongtao Tang.

Paratypes. NWIPB 1161012–24, 1161026–34, collected with the holotype. 101–186 mm SL. 22 examined specimens.

Diagnosis. G. pengquensis is cleary distinguished from congeners by the combination of the following characters: mouth subinferior, nearly straight oral fissure, arched; inner side of lower jaw without a horny layer; dorsal-fin origin nearly at midway of the body length. Commencement of ventral fin under the 4–5th branched ray of dorsal fin; last unbranched dorsal-fin ray weak; dorsal fin spines 8–15, minutely serrated; gill rakers on first arch: ONG = 9–14, ING = 13–21.

Description. D iv, 8; P i, 15–19; V i, 8–9; A iii, 5; vertebrae: 4+47.

Counts and proportional measurements are given in Table 2 . Body elongate, somewhat compressed. Greatest depth at origin of dorsal fin, dorsal profile arched, ventral profile less curved. Anal opening near origin of anal fin. Caudal forked. Head somewhat large, conical. Snout obtuse; No barbels; anterior border of the mouth below level of lower margin of eye. Eyes moderate, round. Nostrils nearer to eye than to tip of snout. Mouth subinferior, nearly straight oral fissure, inner side of lower jaw without horny layer. Ventral view of margin of lower jaw horseshoeshaped; lip of lower jaw underdeveloped, thin; lower lip divided into two lateral lobes, postlabial groove discontinued ( Fig. 8 a). Body entirely naked, except 2–3 rows of scales above the pectoral axil and a sheath consisting of 20–24 enlarged scales at the base of anal fin behind ventral fin. Dorsal origin nearly at midpoint of body length. Commencement of ventral fin under 4 or 5th branched ray of dorsal; last unbranched dorsal-fin ray weak; dorsal-fin spines with 8–15 small, almost indiscernible serrations. Lateral line complete, running along middle of flank and caudal peduncle. Gill rakers small, short, thick; those on outside somewhat sparse set; those on inside slightly close set ( Fig. 8 b,c). Pharyngeal teeth in 2 row 3,4/4,3, rod-like, hooked at tip; first tooth in main row small, second tooth in main row well developed ( Fig. 8 d). Air bladder composed of 2 chambers, posterior one is 2.2 times longer than anterior one ( Fig. 8 e). Digestive canal short: intestine exhibits three rostro-caudad loops before descending to anus ( Fig. 8 f). Total length of intestinal tract about 1.3 times SL.

Color pattern. Preserved specimens in alcohol back-gray, abdomen yellowish, whole body with large or small black spots; dorsal and caudal fin also with black spots.

Ecology. Gymnocypris pengquensis inhabits cold highland streams with a substrate of sand or sand-mud at altitudes 4000 m above sea level ( Fig. 9 ). It is an omnivores fish, feeding on juvenile fishes, plant fragments, periphytic algae (e.g. diatoms growing on solid substrate, such as stones), benthic invertebrates and organic debris. Mud and sand were found in the gut, suggesting a benthic foraging style.

Distribution. Gymnocypris pengquensis is known only from the Pengqu River and its tributaries, Nielamu County and Dingri County, Tibet Autonomous Region, China ( Fig. 1 ).

Etymology. The species name ‘pengquensis’ is a combination of Pengqu (where the type series was collected) and the geographic Latin suffix (- ensis).

Figures

FIGURE 1. Sampling locations for Gymnocypris waddelli (red square: Pengqu River population; blue square: Lake Yamzhog Yumco population; gray area indicates approximate inferred distribution of G. waddelli).

FIGURE 7. Gymnocypris pengquensis sp. nov., holotype, NWIPB 1161025, 138 mm SL. Color pattern of specimen preserved in 95 % alcohol (right side; image laterally inverted).

FIGURE 8. Gymnocypris pengquensis, paratype, NWIPB 1161026, 172 mm SL. (a) Ventral view of head; (b) Lateral view of outside of first gill arch from right side; (c) Lateral view of inside of first gill arch from right side; (d) Dorsomedial view of left side pharyngeal tooth plate; (e) Ventral view of air bladder; (f) Ventral view of the coiling type of intestine.

FIGURE 9. Type locality of Gymnocypris pengquensis, Pengqu River, Zhaguo Town, Nielamu County, Tibet Autonomous Region, China. Photographed by Yongtao Tang.