Triplophysa lixianensis, He, Chunlin, Song, Zhaobin & Zhang, E, 2008

He, Chunlin, Song, Zhaobin & Zhang, E, 2008, Triplophysa lixianensis, a new nemacheiline loach species (Pisces: Balitoridae) from the upper Yangtze River drainage in Sichuan Province, South China, Zootaxa 1739, pp. 41-52 : 42-47

Triplophysa lixianensis sp. nov.

( Figures 1–3 )

Holotype: SCUM 20070717008, male, 142.3 mm SL; Zagunao River, a tributary on the western bank of the Min Jiang of the upper Yangtze River drainage, at Jiujiapeng village (102°52” E, 31°33” N; 2450 m above the sea level), Lixian County, Aba Prefecture, Sichuan Province, South China; collected by Chun-lin He and Jianghong Ran on July 17, 2007.

Paratypes: SCUM 20070717001–2, SCUM 20070717004–7, male, 6 specimens, 126.6–149.5 mm SL; 20070717003, female, 1 specimen, 109.2 mm SL; IHB 20070717009, male, 1 specimen, 127.4 mm SL; other data same as holotype. IHB 20060715001–4, female, 4 specimens, 109.2–140.2 mm SL; collected on July 15, 2006; other data same as holotype.

Diagnosis. Triplophysa lixianensis can be easily separated from all other congeners by having a unique combination of the following characters: posterior chamber of gas bladder greatly reduced or absent, caudal peduncle columnar with a roughly round cross-section at its beginning, anterior margin of lower jaw entirely exposed or uncovered by lower lip, intestine short, forming a zigzag loop below stomach, dorsal-fin origin closer to caudal-fin base than to snout tip, pelvic fin inserted anterior to dorsal-fin origin, snout length 50.6– 57.5 % of HL, eye diameter 12.3–15.4 % of HL, caudal peduncle length 25.1–27.1 % of SL, 5 branched rays of anal fin, lower lip greatly furrowed with two thick lateral lobes and body smooth or scaleless.

Description. Morphometric and meristic data are summarized in Table 1. Body elongate, smooth or scaleless. Predorsal trunk stout, columnar, with greatest width nearly equal to body depth and greatest depth slightly anterior to dorsal-fin origin. Postventral trunk tapering sharply towards base of caudal fin. Caudal peduncle slender, columnar, with a roughtly round cross-section at its beginning or posterior end of anal-fin base; least depth at origin of anterior-most procurrent caudal-fin ray. Dorsal profile of head and predorsal body concave; dorsal-fin base and postdorsal profile almost straight and oblique. Ventral profile of head straight; rounded from chest to pelvic-fin insertion; from there to anal-fin origin slightly concave; anal-fin base and postanal profile straight. Lateral line complete, straight, extending somewhat above middle of flank anterior to posterior end of anal-fin base and along middle of caudal peduncle.

Head depressed when laterally viewed, wider than deep and roughly triangular when dorsally viewed. Snout prominent and obtuse, longer than postorbital length of head, with a slightly convex interobtial space. Eye small, close to dorsal profile of head, and situated in posterior half of head. Nostrils closer to anterior margin of eye than to tip of snout; anterior and posterior nostrils closely spaced; anterior one pierced at extremity of a short tube and posterior one slightly larger than anterior ones.

Mouth inferior; opening arched with its gape approximately twice as wide as long. Lips thick; upper lip without a median incision, finely and regularly furrowed and slightly plicated; lower lip with a well-marked median incision and a few well-marked irregular furrows on each side. Upper jaw unexposed or covered by upper lip and lower jaw scoop-shaped, with its anterior margin entirely exposed or uncovered by lower lip ( Fig. 2 a). Three pairs of barbels; inner rostral pair extending to corner of mouth and outer rostral pair reaching slightly beyond a vertical through anterior nostril or not; maxillary pair reaching a vertical of posterior margin of eye.

T. lixianensis

Holotype Paratypes (n=12)

Min Max Mean SD

SL (mm) 142.3 109.2 149.5

% SL

Fin flexible, D. iii, 7–8; P. i, 9–10; V. i, 7; A. ii, 5; C. 7–8+8 = 15–16 branched rays. Dorsal fin with a slightly concave distal margin; origin nearer to caudal-fin base than to tip of snout; posterior end of dorsal-fin base opposite to or immediately anterior to vent; tips of depressed last branched dorsal-fin rays extending slightly beyond a vertical of anal-fin origin. Pectoral fin inserted immediately anterior to a vertical through posteriormost point of opercle, reaching beyond halfway to pelvic-fin insertion. Pelvic fin inserted midway between tip of snout and caudal-fin base, or immediately anterior to dorsal-fin origin; surpassing vent and extending to anal-fin origin when depressed. Anal fin with a truncate distal margin; tip of depressed rays extending halfway to caudal-fin base; origin closer to pelvic-fin insertion than to caudal-fin base. Caudal fin emarginated or concave, upper lobe slightly longer than lower one, longest branched ray of upper lobe 4/3 times as long as median ray.

Gas bladder bipartite; anterior chamber fully enclosed in dumbbell-like bony capsule and posterior chamber greatly reduced or absent. Intestine short, forming a zigzag loop reaching anteriorly one-third of ‘U’- shaped stomach, 1.4 times as long as SL ( Fig. 3 ).

Coloration. In formalin-stored specimens, ground color of back and upper half of flank above lateral line brown, lower half of flank below lateral line grayish with some irregular blackish blotches, and abdomen white. In some specimens, especially males, no bars present on predorsal body, but 3–4 irregularly transverse bars on postdorsal back. Sometimes, no bars present on back of females. Dorsal and caudal fin shaded-gray with black spots; pectoral and pelvic fins with a hyaline distal margin; each of outside rays with a dusky basal portion on its dorsum; anal fin with a hyaline distal margin, outside rays dusky.

Sexual dimorphism. Males have 5–6 broadened and widened outer branched pectoral-fin rays covered with setaceous aggregations of tubercles. The same setaceous aggregations are present on the sides of the head in the pre- and suborbital areas, where they form two fields on each side, divided by infraorbital sensory canal. The upper field is an elongated ellipsoid laid obliquely from the upper posterior margin of the mouth to the anterior margin of the eye. The lower field is narrow in the anterior portion, but significantly broadening distally ( Fig. 1 a). In females, no setaceous aggregations of tubercles are present on the head and pectoral-fin rays ( Fig. 1 b).

Distribution. Known only from the Zagunao River, a tributary flowing to the Min Jiang of the upper Habitat. Triplophysa lixianensis was collected from the Zagunao River, a tributary to the Min Jiang of the upper Yangtze River drainage. The water was approximately 1.2 m depth in July, its bottom rocky with gravels and cobbles. The species found synotypical with this new species are: a river loach Oreias dabryi Sauvage and a cyprinid species Gymnocypris potanini Herzenstein. They may forage together.

Etymology. The specific epithet is named after the Chinese name ‘Lixian’, where the type specimens have been collected.

Figures

FIGURE 1. Lateral view of Triplophysa lixianensis. (a) SCUM 20070717008, male, holotype, 142.3 mm SL; (b) IHB 2006071503, female, paratype, 116.8 mm SL.

FIGURE 2. Ventral view of mouth part: (a) Triplophysa lixianensis, IHB 20060715003, female, paratype, 116.8 mm SL, scale = 5 mm; and (b) Triplophysa aliensis, IHB 761445, female, 66.8 mm SL, scale = 3 mm. ib = inner rostral barbel; ob = outer rostral barbel; mb = maxillary barbel; lj = lower jaw; ul = upper lip; ll = lower lip.

FIGURE 3. Ventral view of alimentary tract of Triplophysa lixianensis IHB 2006071501, female, paratype, 140.2 mm SL.