Vanmanenia intermedia Fang, 1935

Deng, Shu-Qing, 2020, Vanmanenia intermedia Fang, 1935, a valid hill-stream species of loach (Teleostei Gastromyzontidae) from the middle Yangtze River basin, Southwest China, Zootaxa 4819 (1), pp. 109-127 : 117-122

Vanmanenia intermedia Fang, 1935

( Fig. 2 and Fig. 3b )

Praeformosania intermedia Fang, 1935: 75 (Duyun City, Guizhou Province, in mountain streams running into Lake Dongting )

Vanmanenia pingchowensis: Wu et al., 1989: 6 (Qingshui-Jiang at Duyun and Kaili cities, a river discharging into Yuan-Jiang, Guizhou Province); Ran, 2001: 5 (Qingshui-Jiang at Duyun City, a river draining into Yuan-Jiang, Guizhou Province); Dai & Chen, 2007: 684 ( Qingshui-Jiang of Yuan-Jiang at Duyun and Kaili cities, Guizhou Province)

Material examined. South China: Guizhou Province: IHB 2017121981–1985 , 5 specimens, 84.2–93.8 mm SL, Jian-Jiang, a tributary of Qingshui-Jiang flowing into Yuan-Jiang of Lake Dongting system connected to middle Yangtze River, at Duyun City ; IHB 2017121987–1989 , 3 specimen, 51.9–70.0 mm SL, Pingzhou-He, a mountain stream of upper Hongshui-He of Xi-Jiang, at Pingtang County ; IHB 2017121976–1979 , 4 specimens, 50.3–74.4 mm SL, Qingshui-Jiang at Kaili City. All specimens were caught by S.Q. Deng and W.H. Shao in December 2017 .

Diagnosis. Vanmanenia intermedia resembles V. caldwelli , V. stenosoma and V. maculata in having three triangular-shaped rostral lobules whose apical parts, in the papilla-like form, are connected with the rostral lobules, but not modified into secondary rostral barbels ( Table 3). It is distinguished from V. caldwelli in having no longitudinal black stripe extending from the snout tip to the caudal-fin base along the lateral line on the flank (vs. present), a longer (vs. shorter) snout [length 52.6–64.5 (mean 58.8) vs. 40.0–49.2 (mean 44.1) % of HL and a more backwards-placed anus [the vent to anal distance 34.7–46.1 (mean 41.2) vs. 60–70.3 (mean 68.5) % of the pelvic to anal distance]; and from V. stenosoma in having a slender (vs. stout) caudal peduncle [depth 9.1–11.3 (mean 10.3) vs. 11.3–13.5 (mean 12.9) % of SL], a longer (vs. shorter) anal-fin base (length 7.5–9.5 vs. 5.1–6.4 % of SL) and a more forwards-positioned anus [the vent to anal distance 34.7–46.1 (mean 41.2) vs. 29.8–37.1 (mean 34.3) % of the pelvic to anal distance]; and from V. maculata in the presence of a longer (vs. shorter) snout [length 52.6–64.5 (mean 58.8) vs. 42.6–56.8 (mean 50.9) % of HL; see Fig. 4a ), a longer (vs. shorter) anal-fin base (length 7.5–9.5 vs. 5.2–7.2% of SL; see Fig. 4b ), smaller (vs. larger) eyes [diameter 15.5–22.2 (mean 18.0) vs. 20.3–29.3 (mean 23.7) % of HL, see Fig. 4c ], and a narrower (vs. wider) internasal space [width 24.1–30.0 (mean 27.1) vs. 28.5–44.6 (mean 37.1)% of HW, see Fig. 4d and Fig. 5 ]. It is further distinct from V. maculata in having a smaller gill opening with its upper extremity closer to the level of the lower margin of the orbit (vs. larger, reaching the level of the middle of the orbit).

Description. Morphometric measurements and meristic counts for specimens examined are given in Table 2. See Fig. 2 .a–c for lateral, dorsal and ventral views of body, and Fig. 3b for its mouthpart structures.

Body elongate, anteriorly depressed before dorsal-fin origin and posteriorly compressed laterally, with greatest depth at dorsal-fin origin and least caudal-peduncle depth closer to caudal-fin base than to posterior end of anal-fin base. Dorsal profile of head and predorsal body slightly convex; from dorsal-fin origin to origin of dorsal procurrent rays of caudal fin slightly concave. Ventral profile of head straight and oblique; nearly straight and flattened or slightly convex from pectoral-fin insertion to anal-fin origin; from anal-fin origin to ventral caudal-fin origin concave.

Head moderately large and depressed, slightly longer than wide, and wider than high. Snout broadly rounded in dorsal view and bluntly pointed in lateral view, slightly longer than postorbital head. Eyes small, situated dorsolaterally in posterior half of head with slightly flat and broad interorbital space. Anterior and posterior nostrils set separately, and short flap on anterior nostril. Mouth small, inferior and arched. Deep groove present between rostral fold and upper lip. Lips fleshy and thick; upper lip pendulous, covered with inconspicuous small papillae, and connected with lower lip around corners of mouth by papillated flap; lower lip with four large papillae, two median ones more anteriorly positioned and usually bigger than lateral two; postlabial groove short and restricted only to corner of mouth on chin. Upper and lower jaws bearing thick, flexible horny sheaths on cutting margins. Rostral fold divided into three triangular lobules, median one slightly wider than two lateral ones. Two pairs of rostral barbels; outer pair larger than inner pair. Pair of maxillary barbels rooted at corners of mouth. Gill opening small; its upper extremity in same level of horizontal line passing lower margin of orbit and its lower extremity extending to ventral surface of head. Scales minute, cycloid; no scales on head, breast and anterior one-third between pectoral- and pelvic-fin insertion.

Dorsal fin with 3 simple and 7 (1) or 8 (11) branched rays, nearly as long as head; origin anterior to pelvic-fin insertion, particularly when viewed dorsally, opposite to vertical through base of second branched ray; slightly closer to caudal-fin base than to snout tip or equidistant to both; distal margin slightly concave. Paired fins horizontally extended. Pectoral fin with 1 simple and 13 (4), 14 (4) or 15 (4) branched rays, much longer than head; inserted slightly behind lower extremity of gill-opening; tip of adpressed fin not reaching pelvic-fin insertion. Pelvic fin with 1 simple and 8 (12) branched rays, inserted slightly closer to caudal-fin base than to snout tip; tip of adpressed fin surpassing anus, but far from anal-fin origin; distal margin convex; axillary lobe present at pelvic-fin base. Anal fin with 2 simple and 5(12) branched rays, last one split to base; origin closer to caudal-fin base than to pelvic-fin insertion; distal margin convex. Anus positioned closer to anal-fin origin than to posterior end of pelvic-fin base. Anal fin extending posterior to origin of ventral caudal-fin procurrent rays. Caudal fin shallowly emarginated with lower lobe slightly longer.

Coloration. In fresh specimens, head and body yellowish dorsally and laterally, grayish on ventral surface. In formalin-stored specimens, top of head with numerous, small, irregular, light brown bars or blotches; yellowish on cheek and side of snout. Body with four predorsal, one subdorsal and four postdorsal black saddles. Predorsal ones wider than interspaces; last saddle anterior to dorsal-fin origin, prominent and extending down to pelvic-fin base in small individuals. In large individuals, predorsal saddles inconspicuous, more or less discontinuous with blotches on flank. Subdorsal and postdorsal saddles slightly narrower than interspaces in small individuals, but subdorsal saddle split in large ones. Blotches on flank of predorsal body fused together. Above lateral line, a number of irregular brown blotches on flank of postdorsal body connected to postdorsal saddles in small individuals, but more or less disconnected from predorsal and saddles in large ones. Brown blotches present below lateral line, varying in size and shape. Dorsal fin with 3 black bands across rays, anal fin with 2 black bands. Pectoral fin with 4 irregular faint black bands across rays, pelvic fin with 2 black bands. Caudal fin with 4 or 5 black bands.

Distribution and habitat. Vanmanenia intermedia is so far present in the Qingshui-Jiang of the upper Yuan- Jiang flowing into Lake Dongting in the middle Yangtze River basin at Duyun and Kaili cities, and the upper Hongshui-He flowing into the Xi-Jiang of the Pearl River basin in Pingtang County, Guizhou Province, southern China ( Fig. 6 ). Topotypic specimens utilized in this study were collected from a tributary emptying into the Jian-Jiang, a mountain stream with pebbly and sandy mixed substrate. Juveniles prefer slowly-running water. The sympatric species included: Acrossocheilus parallens , Zacco platypus , Onychostoma barbatum , Rhinogobius cliffordpopei , Misgurnus anguillicaudatus and Channa asiatica .

Figures

FIGURE 2. Vanmanenia intermedia, IHB2017121983, 91.3 mm SL, Yuan-Jiang of the middle Yangtze River basin, at Duyun City, Guizhou Province, China. Lateral (a), dorsal (b) and ventral (c) views of body. Scale bar = 1 cm.

FIGURE 3. Mouthpart soft-tissue structures of four species of Vanmanenia: (a) V. striata, IHB 83403, 86.1 mm SL,Yong-Jiang, a coastal river in Zhejiang Province, China; (b) V. intermedia, IHB2017121983, 91.3mm SL, Yuan-Jiang of the middle Yangtze River basin, at Duyun City, Guizhou Province, China (c) V. pingchowensis: IHB2017122224, 91.3 mm SL, Xi-Jiang of Pearl River basin at Pingtang County, Guizhou Province, China; (d) V. xinyiensis, IHB 77VII074, 96.3 mm SL, Pearl River basin at Xinyi County. lj: lower jaw; mb: maxillary barbel; rb: rostral barbel; rf: rostral fold; srb: secondary rostral barbel; uj: upper jaw; ul: upper lip; ll: lower lip.

FIGURE 4. Relation between snout length and standard length (a), between anal-fin base length and standard length (b), between eye diameter and standard length and (c), and between internasal width and head width (d) for V. intermedia (△) and V. maculata (■).

FIGURE 5. Internasal width (IW) and head width (HW) of two species of Vanmanenia: (a) V. intermedia, IHB2017121983, 91.3mm SL,Yuan-Jiang of the middle Yangtze River basin, at Duyun City, Guizhou Province, China; (b) V. maculata, IHB2006064914, 64.1mm SL,Qing-Jiang of the middle Yangtze River basin, at Jianshi County, Hubei Province, China.

FIGURE 6. Map showing collection localities of nine species of Vanmanenia involved in molecular biology studies. The names of rivers and lakes are italicized and two provincial capitals (Wuhan and Guiyang) highlighted.