Vanmanenia duci sp. nov.

Figs 3, 4, Table 1

Type locality.

Vietnam, Cao Bang Province, Nguyen Binh District, Bang Giang River basin, 20 ° 34 ′ 731 ″ N, 105 ° 55 ′ 407 ″ E.

Holotype.

HNUE-F 00293, 47.6 mm SL, Vietnam, Cao Bang Province, Nguyen Binh District, Bang Giang River basin, 20 ° 34 ′ 731 ′′ N, 105 ° 55 ′ 407 ′′ E, ca. 760 m above sea level, 24 May 2020, coll. H. D. Tran, V. S. Ngo, and H. V. Pham; electro-fishing, medium speed current stream with stone and gravel bottom, both the sides fringed by plants.

Paratypes

(n = 15). HNUE-F 00294 -296, 3 ex., 33.0– 50.1 mm SL, data same as for holotype. HNUE-F 00297 -298, 2 ex., 35.8–39.4 mm SL, same locality as for holotype, 8 May 2021, coll. H. D. Tran, V. S. Ngo, H. Q. Nguyen, N. T. Nguyen, and A. N. T. Do. HNUE-F 00299 -303, 5 ex., 32.4–52.1 mm SL, Vietnam, Cao Bang Province, Nguyen Binh District, Gam River, 22 ° 35 ′ 197 ″ N, 105 ° 51 ′ 903 ″ E, 1005 m above sea, 21 May 2020, coll. H. D. Tran, V. S. Ngo, and H. V. Pham; electro-fishing and hand net, fast speed current stream with large stone and sandy bottom, both the sides fringed by plants. HNUE-F 00304 -305, 2 ex., 48.3–54.0 mm SL, same locality as for HNUE-F 00299, 7 May 2021, coll. H. D. Tran, V. S. Ngo, H. Q. Nguyen, N. T. Nguyen, and A. N. T. Do. HNUE-F 00306, 1 ex., 41.3 mm SL, 8 May 2021, other data same as for HNUE-F 00303. HNUE-F 00307 -308, 2 ex., 39.1–40.3 mm SL, Vietnam: Cao Bang Province, Nguyen Binh District, Bang Giang River basin, 22 ° 39 ′ 289 ″ N, 105 ° 55 ′ 339 ″ E, 500 m above sea, 22 May 2020, coll. H. D. Tran, V. S. Ngo, and H. V. Pham; electro-fishing and hand net, fast speed current stream with gravel bottom.

Diagnosis.

Vanmanenia duci sp. nov. can be distinguished from congeners by following combination of characters: pectoral fin rays: I, 15; pelvic fin rays: I, 8; lateral line scales: 77–83; anus farther posterior insertion of pelvic fin than to anal fin origin, caudal peduncle depth approximately as caudal peduncle length (8.2 % – 8.5 %), distance from pelvic fin to pectoral fin (39.1 %) larger than distance from pelvic fin to anal fin (29.8 %). It has a broad midlateral black stripe running from behind head to caudal-peduncle base. Black dotted stripe stretching from base of pectoral fin to posterior end of anal fin. Lower lip with three large papillae; median wider than two lateral ones. Rostral fold divided into three triangular lobules of same size. Distinct black dot at base of pelvic and pectoral fins, and fleshy black protrusion in pelvic fin base.

Description.

Meristic and morphometric data for type specimens are presented in Table 1. View of body and its mouth structures are shown in Figs 3, 4, 5 A. Body elongate, anteriorly depressed before dorsal-fin origin and posteriorly compressed laterally. Body width almost as wide as body depth. Dorsal profile of head and predorsal body slightly curved, and flat ventral profile. Moderate gill opening extending to ventral surface for short distance in front of pectoral fin base (Fig. 3).

Values of Mean, SD, and Range do not include the holotype.

Head depressed, slightly longer than wide, and wider than deep. Snout broadly rounded in dorsal view and bluntly pointed in lateral view. Small eyes situated dorsolaterally in posterior half of head, with interorbital space bigger than eye diameter. Nostrils large, closer to eyes than to snout. Small fleshy papillae above top of head and edges of the eyes. Mouth inferior, medium-sized and curved, with muzzle grooves and muzzle folds in front. Snout groove wide and shallow, extending to corner of mouth (Fig. 3). Lips fleshy; upper lip covered with conspicuous papillae, and shallow groove present with rostral fold and, disconnected from lower lip at corners of mouth; lower lip with three large papillae, slightly tips curved, one median bigger than lateral two ones. Rostral fold divided into three triangular lobules same size, and two pairs of lobulated papillae between the folds, with inner side mastoid. Two pairs of rostral barbels, outer pair larger than inner pair, and about 1 / 2 of eye diameter (Fig. 5 A). Body covered by small scales, present except on anterior pectoral fin to pelvic fin base, and on ventral surface in front of and between bases of pectoral fins. Lateral line complete and straight. No spine on dorsal fin, with 3 simple and 7 branched rays. Its origin anterior to pelvic fin origin, closer to caudal fin base than to tip of snout, and distal margin slightly straight. Two simple and 5 branched rays on anal fin, and its origin nearer to anus than to caudal fin base. One simple and 15 branched rays on pectoral fin, much longer than head length. Its base slightly behind lower extremity of eye, tip of adpressed fin not reaching pelvic-fin insertion. One simple and 8 branched rays on pelvic fin. Its origin closer to caudal fin base than to snout tip and tip of adpressed fin touching or exceeding anus, but far from anal fin origin. Anus positioned closer to anal fin origin than to base of pelvic fin. Caudal fin slightly concave, with lower lobe slightly longer than upper lobe.

Coloration (freshly collected).

Body yellowish-brown; belly a pale ivory color (Figs 3, 4). Head with small, irregular, black bars and blotches on cheeks and snout. Dorsum with eight or nine black blotches and irregular small blotches. Round black protrusions on pectoral and pelvic fin bases. One brown-black band across rays on dorsal fin, and two in caudal fin. Pectoral and pelvic fins pale yellow. Midlateral black stripe from behind head to caudal fin base. A brown-black dotted stripe along from pectoral-fin base to posterior insertion of the anal fin; caudal fin base with a black spot of eye size (Fig. 4).

Coloration (preserved).

Specimens fixed in formalin solution with yellowish body and head; belly yellow. Black bars present on behind of head to caudal fin base. Black dotted stripes from posterior end of pectoral fin to anal fin. These fins pale whitish, with black bands across rays of dorsal and caudal fins (Fig. 3).

Distribution.

Vanmanenia duci sp. nov. is known only from three localities in the Phia Oac-Phia Den National Park, Cao Bang Province, northern Vietnam (Fig. 2). Other species of Vanmanenia are distributed in different localities of the Red River and Bang Giang River.

Habitat and ecology.

Figure 6 shows the three known localities of Vanmanenia duci sp. nov. The holotype was found in a narrow forests stream with medium speed current and gravel bottom (Fig. 6 A). Co-occurring fish species included Parazacco sp. (Duong et al. 2022); Liniparhomaloptera cf. qiongzhongensis Zheng et Chen, 1980; Schistura sp.; Carassius auratus (Linnaeus, 1758); Discogobio sp., Rhinogobius duospilus (Herre, 1935) (see Nguyen et al. 2024). Several paratypes were found in a fast speed current forest stream with large stones and sand as bottom (Fig. 6 B). This sampling site is next to the road, where a new bridge is under construction. There were several other fish species, including Schistura sp. (see Nguyen et al. 2024) and Chimarrichthys nami (Tran, Nguyen, Dang, Nguyen et Nguyen, 2023). At the third sampling site (Fig. 6 C), accompanying fish species included Beaufortia pingi (Fang, 1930); Schistura spp.; Barbodes semifasciolatus (Günther, 1868); Discogobio microstoma (Mai, 1978); Onychostoma gerlachi (Peters, 1881); Discogobio spp.; Hemibarbus cf. umbrifer (Lin, 1931); and Gambusia affinis (Baird et Girard, 1853) (see Nguyen et al. 2024).

Etymology.

The specific name is in honor of Vietnamese ichthyologist, Prof. Nguyen Huu Duc, who had spent his whole life studying freshwater fishes in Vietnam.