Oreonectes zhangi Zhong, Yang & Chen, 2024

Zhong, Jia-Hong, Yang, Jian, Mo, Hao-Lin & Chen, Wei-Cai, 2024, Description of a new species of the genus Oreonectes (Teleostei, Cypriniformes, Nemacheilidae) from Guangxi, China, Zoosystematics and Evolution 100 (4), pp. 1259-1267 : 1259-1267

Oreonectes zhangi Zhong, Yang & Chen sp. nov.

Figs 4 , 5 , 6 , 7 , 8 , 10 , Tables 3 , 4

Materials.

Holotype. • NNNU 2023100203 (Fig. 4 ); 71.1 mm TL, 63.1 mm SL; collected by Jia-Hong Zhong on 2 October 2023; in Mt. Hanshan , Xinye County, Yulin City, Guangxi, China; (22.7364 ° N, 110.0605 ° E; elevation 199 m; Fig. 1 ) . Paratypes. • 14 specimens; NNU 2023100201 –202, 2023100204–215; were collected by Jia-Hong Zhong from the same locality and at the same time as the holotype .

Etymology.

The species was named in honor of the three Zhang brothers, who assisted local residents in locating water during an ancient drought. Following their passing, they were revered as rain deities by the community ( Li 2014). We suggest the common Chinese name “ 张氏岭鳅 ” (Zhang Shi Ling Qiu).

Comments.

Oreonectes zhangi sp. nov. is classified within the genus Oreonectes based on molecular phylogenetic analyses and genus-specific characteristics, including narrowly separated anterior and posterior nostrils, elongated barbel-like anterior nostrils longer than the depth of the nostril tube (Fig. 5 ), having an epural in the caudal skeleton (Fig. 7 ), and a rounded caudal fin with 7 branched dorsal-fin rays. ( Du et al. 2023; Ito 2024)

Diagnosis.

Comparative data between Oreonectes zhangi sp. nov. and all seven known species within the genus Oreonectes are provided in Table 3 . Oreonectes zhangi sp. nov. can be distinguished from O. guilinensis , O. luochengensis , O. guananensis , O. andongensis , and O. polystigmus by the reduced posterior chamber of air-bladder (vs. developed), from O. platycephalus by six branched plevic-fin rays (vs. 7), seven branched dorsal-fin rays (vs. 6), from O. damingshanensis by six branched pelvic-fin rays (vs. 7), the tip of the male pelvic fin not reaching the anus (vs. exceeding) (Fig. 8 ), vertebrae 4 + 32 (vs. 4 + 34), head depth at nape (59.6–68.1 % HL vs. 46.7–54.6 %), body depth at dorsal-fin origin (14.0–16.1 % SL vs. 11.1–13.3 %).

Description.

Morphometric data are given in Tables 3 , 4 . Body elongated and cylindrical, with insignificant depth decreasing from dorsal-fin origin to caudal-fin base. Head short, head length 18.6–20.2 % of standard length, slightly depressed and flattened, width greater than depth (head width / head depth = 1.1–1.5), head depth 59.6–68.1 % of head length. Snout round, oblique, and flat, length 38.2–48.8 % of head length (HL). Mouth inferior, curved, upper, and lower lips have shallow wrinkles and small spinous processes; lower lip with V-shaped median notch (Fig. 6 ). Three pairs of barbels, long: inner rostral barbel 35.4–44.1 % of HL, extending backward, not reaching anterior margin of eye; outer rostral barbel 49.0–67.6 % of HL, extending backward beyond posterior margin of eye. Maxillary barbel 38.4–52.2 % of HL, tip not reaching posterior margin of gill cover. Anterior and posterior nostrils are separated by a short distance, 16.8 % – 36.8 % of eye diameter. Anterior nostril tube short, with elongated, short barbel-like tip. Eyes normal, diameter 11.9–17.1 % of HL. Gill opening small; gill rakers not developed; nine inner gill rakers on first gill arch (n = 2).

Dorsal-fin rays iii, 7, pectoral-fin rays i, 8–9, pelvic-fin rays i, 6, anal-fin rays iii, 5, branched caudal fin rays 15–16. Dorsal fin short, length 16.7 % – 21.1 % of SL, distal margin round, origin posterior to pelvic-fin insertion, situated slightly posterior to two-thirds distance between snout tip and caudal-fin base. Pectoral fin short, length 15.9 % – 18.9 % of SL. Pelvic fin length 16.1–17.7 % of SL; tips of pelvic fin not reaching anus; distance between tips of pelvic fin and anus 0.7 times eye diameter. Anal fin short, length 15.1 % – 19.5 %, origin short distance from anus. Caudal fin rounded, length 13.3 % – 19.9 % of SL, length greater than depth (caudal peduncle length / caudal peduncle depth = 1.1–1.7). vertebrae 4 + 32 (n = 4), having an epural in the caudal skeleton (Fig. 7 ).

Body completely covered by scales, except head; lateral line incomplete, with 7–13 pores, last one not reaching above tip of pectoral fin; cephalic lateral-line system, with 8 supraorbital pores, 4 + 9–10 infraorbital pores, three supratemporal canal pores, and 5–8 preoperculo-mandibular canal pores.

U-shaped stomach with straight intestines (Fig. 9 ). Anterior chamber covered by dumbbell-shaped bony capsule, and posterior chamber reduced, reaching the vertical of the pectoral-fin base (Fig. 10 ).

Coloration.

The body is mainly light yellowish brown in color, with dark brown extending from the front of the eyes to the outer rostral barbel. The base of the caudal fin is black, with each fin showing a light yellow hue. When preserved in 10 % formalin, the body color fades to a dark brown shade (Fig. 4 B ).

Sexual dimorphism.

Males have an oval genital papilla located immediately posterior to the anus (Fig. 8 B ), which is unclear in females (Fig. 4 C ).

Distribution, habitat, and populations.

Based on field investigations, the species is abundant and commonly found in the streams of Mt. Hanshan in Xingye County, Yulin City, and Guangxi, China (Fig. 11 ). During the day, the species typically seeks shelter in stone crevices and substrates, emerging at night to feed. Exposure to intense light can cause their body color to change from light yellow to dark brown or black. Their diet consists of sediment and tadpoles, including those of Quasipaa spinosa. Interestingly, many pregnant females were collected, even in December. The stream habitats also harbored other species, such as Schistura fasciolatus , Liniparhomaloptera disparis , and Rhinogobius similis .

Figures

Figure 1. Distributions of Oreonectes species.

Figure 4. Dorsal, lateral, ventral, and living views of Oreonectes zhangi sp. nov. NNNU 2023100203, holotype, 71.1 mm TL, 63.1 mm SL.

Figure 5. Oreonectes zhangi sp. nov., dorsal view of head., NNNU 2023100203, holotype, 63.1 mm SL.

Figure 6. Oreonectes zhangi sp. nov., NNNU 2023100203, holotype, 71.1 mm TL, 63.1 mm SL. The ventral view of the mouth (A) and close-ups of the upper (B) and lower (C) lips are shown; the black arrow indicates the position of the small spinous processes.

Figure 7. The caudal fin skeleton of Oreonectes zhangi sp. nov., NNNU 2023100202, paratype, 64.2 mm SL, pc 1, first preural centrum; pc 2, second preural centrum; h, hypural; hs, haemal spine and arch; ph, parhypural; pls, pleurostylar.

Figure 8. Gonadal structure of O. damingshanensis (A), NNNU 2024052007, 56 mm SL, and O. zhangi sp. nov. (B), NNNU 2023100215, paratype, 43.2 mm SL; the black arrow refers to the position of the anus.

Figure 9. Oreonectes zhangi sp. nov., NNNU 2023100202, paratype, 64.18 mm SL; digestive tract.

Figure 10. Air-bladder of Oreonectes zhangi sp. nov.: a, anterior chamber; b, tube connecting anterior and posterior chambers of the air-bladder; c, posterior chamber.

Figure 11. Habitat of Oreonectes zhangi sp. nov.