Triplophysa sanduensis, Chen & Peng, 2019

Chen, Shi-Jing & Peng, Zuo-Gang, 2019, Triplophysa sanduensis, a new loach species of nemacheilid (Teleostei: Cypriniformes) from South China, Zootaxa 4560 (2), pp. 375-384 : 376-378

Triplophysa sanduensis sp. nov.

( Figs. 1 and 2 ; Table 2)

Holotype. SWU 2017061305, male, 67.9 mm SL; an outlet of a small karst cave in Dengguang Village , Zhonghe Town, Sandu County, Guizhou Province, China (25°49′45.81″ N, 107°50′37.63″ E); collected by J.- H. Lan, May 2017.

Paratypes. SWU2017061301–2017061304, 45.2–71.5 mm SL, location data same as holotype ; CLJH 2017061306 , male, 78.8 mm SL, location data same as holotype .

Diagnosis. Triplophysa sanduensis can be distinguished from its congeners by the following combination of characters: branched dorsal-fin rays 8–9; branched pectoral-fin rays 8–9; branched pelvic-fin rays 5; branched anal-fin rays 5; vertebrae 4+37; snout length 45.5–50.1% of HL; postdorsal length 39.0–42.8% of SL; CPD/CPL range from 56.4% to 71.9%; the posterior chamber of the gas bladder degenerated; body elongated, covered by scattered scales; eyes present and normal in size, not reduced or absent; lateral line complete.

Description. Morphometric data presented in Table 2. Body elongated, anterior trunk subcylindrical, posterior portion laterally compressed. Caudal peduncle laterally compressed, its depth greater than 1/2 its length. Head depressed, width slightly greater than depth ( Fig. 2A ). Snout moderately blunt, snout length greater than postorbital head length. Eyes present and normal in size (eye diameter 11.9–15.4% HL). Anterior and posterior nostrils adjacently located, the latter larger than the former; anterior nostril in short tube, tip elongated to form barbel. Mouth inferior, arched; mouth corner situated below anterior nostril. Lips thin, slightly furrowed; upper lip with slight median incision; lower lip with well-marked V-shaped median incision ( Fig. 2B ). Upper jaw covered by upper lip; lower jaw scoop-shaped, uncovered medially by lower lip. Three pairs of barbels; inner rostral barbels extend to mouth corners, outer rostral barbels extend to anterior margin of eyes; maxillary barbels extend to posterior margins of eyes.

D II, 8–9; P I, 8–9; A I, 5; V I, 5; C 17–18. Thirteen inner gill rakers of first arch (1 specimen). Vertebrae: 4+37 (2 specimens).

Dorsal fin emarginate, situated slightly anterior to midpoint between snout tip and caudal-fin base; its origin anterior to pelvic-fin origin. Tips of depressed pelvic fins not reaching to anus. Pectoral fins moderately long, reaching beyond 1/2 the distance between pectoral-fin origin and pelvic-fin origin when adpressed, tips of depressed pectoral fins not reaching to pelvic-fin origin. Anal fin distally truncate or slightly concave. Anus close to anal-fin origin. Caudal fin forked, upper lobe slightly longer than lower lobe, distal tips of lobes slightly blunt.

Body covered with scattered scales. Cephalic lateral-line system developed. Lateral line complete, ending at caudal-fin base. Intestine short, bending in zigzag pattern posterior to stomach, stomach U-shaped. The posterior chamber of the gas bladder degenerated.

Coloration. In formalin-fixed specimens, body yellowish-brown dorsally becoming gradually lighter toward ventral side; yellowish-gray ventrally. All fins transparent and slightly gray with scattered black pigments; two dark brown bars on caudal fin and dorsal fin. Body covered with abundant irregular brown blotches dorsally and laterally. Dark spots densely present on top of head. Five specimens examined have 5–6 obvious dark brown blotches along dorsal midline. Brown basal bar on caudal-fin base.

Sexual dimorphism. Two of six specimens male. Males with area of slender pad of tubercles between snout and eye on each side of head; branched pectoral-fin rays become stiff and thick.

Distribution. The specimens were collected from an outlet of a small karst cave in Dengguang Village, Zhonghe Town, Sandu County, Guizhou Province, China; the water is interconnected with the upper reaches of the Duliujiang River system in the Pearl River drainage. Triplophysa sanduensis was found cohabiting with a cyprinid fish Sinocyclocheilus longibarbatus Wang & Chen , which is a typical cave-dwelling species. Currently, Triplophysa sanduensis is found only in caves.

Etymology. The specific epithet is derived from the name of Sandu County and Latin suffix ensis meaning originating in. The name refers to the name of the type locality.

Figures

FIGURE 1. Triplophysa sanduensis preserved in formalin (paratype, 78.8 mm standard length, CLJH 2017061306). (A) Lateral view; (B) Ventral view; (C) Dorsal view.

FIGURE 2. Triplophysa sanduensis preserved in formalin (holotype, 67.9 mm standard length, SWU 2017061305). (A) Dorsal view of the head; (B) Ventral view of the head.