Beaufortia viridis Chen & Tang, 2024

Chen, Jing-Chen, Li, Jia-Jia, Tang, Wen-Qiao, Pu, Xin-Rui & Lei, Hao-Tian, 2024, Taxonomic resolution of the hillstream suck-loach Beaufortia pingi species group (Cypriniformes, Gastromyzontidae) and two new species from Southwest China – Beaufortia granulopinna and Beaufortia viridis, Zoosystematics and Evolution 100 (3), pp. 941-963 : 941-963

Beaufortia viridis Chen & Tang sp. nov.

Figs 10 , 11 , 12

Beaufortia pingi : Yue (1981): 170–172, Lingyun County, Guangxi, admixed within B. pingi . Zheng (1989): 257 –258, Lingyun County, Guangxi, admixed within B. pingi .

Beaufortia pingi : Chen (1990): 85–87, Xiyang River, Guangnan County, Yunnan.

Beaufortia zebroidus : Chen and Tang (2000): 504–505, Tian′e County, Guangxi. Chen (2013): 292, Xiyang River, Yunnan.

Type material.

Holotype. SHOU 20240103101 , 48.42 mm total length (TL), 38.03 mm standard length (SL), adult (Fig. 10 ). Collected by Jing-Chen Chen and Qian-Yu Liang on 27 December 2023, from Wuming River , a stream tributary to the You River of the Pearl River basin, at Wuming District, Nanning City, Guangxi Province, China (24 ° 20.34 ' N, 106 ° 21.624 ' E; c. 160 m a. s. l.) (Fig. 13 ).

Paratypes. 15 specimens from the same locality as holotype, SHOU 20240103102-116, 18.82–46.64 mm SL, were collected by Qian-Yu Liang and Jing-Chen Chen on 27 December 2023; eight specimens from Lingyun County, Baise City, Guangxi Province, China, SHOU 20240126101-108, 50–59.85 mm SL, were collected by Qian-Yu Liang and Jing-Chen Chen on 24 January 2024; five specimens from Guangnan County, Wenshan Zhuang, and Miao Autonomous Prefecture, Yunnan Province, China, SHOU 20240109101-105, 36.23–54.20 mm SL, were collected by Lao Xing on 28 December 2023.

Additional materials.

Seven specimens from Guangnan County, Wenshan Zhuang, and Miao Autonomous Prefecture, Yunnan Province, China, SHOU 20240112101-107, 39.97–48.64 mm SL, were collected by Lin Yang and Lao Xing from December 2022 to February 2023.

Diagnosis.

B. viridis sp. nov. shares the typical characteristics with members of the B. pingi species group, with distinct vertical stripes on lateral body and a pinnate-type lower lip (vs. lacking prominent vertical stripes and having a dicot-type lower lip in other congeneric species apart from this group) (see Figs 6 C , 7 , Table 2 ). B. viridis sp. nov. can be clearly distinguished from B. granulopinna , B. pingi , and B. zebroida by consistent vertical stripes with uniform length, width, and inter-spacing at all growth stages (stripes on mid-section lateral body occasionally shorten in individuals from the Xiayang and Tuoniang Rivers in Yunnan) (vs. a certain proportion (54.76 %) of adults exhibit blurred or vanished vertical stripes on mid-section lateral body in B. granulopinna ; stripe length and width uneven, with a high proportion (94.00 %) of adults showing blurred or vanished mid-section vertical stripes in B. pingi ; stripe length and width uneven, typically narrower than inter-spacing, sometimes reduced to dots in B. zebroida ). B. viridis sp. nov. can be further distinguished from B. granulopinna sp. nov. by the lack of prominent tubercles on the branched rays of the pectoral fins (vs. well-developed tubercles on anterior 6–9 rays of the pectoral fins present). Moreover, B. viridis sp. nov. differs from B. zebroida by body dark cyan to green in dorsal profile (vs. brown yellow to golden).

Description.

Dorsal iii- 7, anal ii- 4, pectoral i- 19–23 (21.08 ± 1.02), pelvic i- 14.5–19 (17.11 ± 1.01). Lateral-line canal pores and scales: 65–83 (73.47 ± 4.21) (see Table 2 ).

Morphometric measurements for the specimens examined are given in Table 3 . See Fig. 10 for lateral, dorsal, and ventral views of the body.

Head-thorax cylindrical, dorsal slightly humped medially, flattened ventrally, body compressed from pelvic fins to caudal peduncle. Head broad, blunt, length slightly less than width, more than depth, nuptial tubercles well-developed on lower half of head in mature individuals, snout rounded, length about half of head length. Mouth inferior, narrow, width about one-fifth head width, horseshoe-shaped, angle about 94 ° from midpoint to ends. Upper lip smooth, without distinct papillae; lower lip pinnate-type, slightly concave medially with multilobed sides; jaw edges slightly protrude. Shallow groove between upper lip and snout, extending to mouth corners. Lateral grooves shallow or indistinct. Two pairs of rostral barbels present, with outer pair slightly longer, space between rostral barbels with leaf-like folds, edges of which rounded and poor developed. One pair of maxillary barbels, length about equal to outer rostral barbels. Nostrils with tubular nasal flaps, distance between nostrils equals one-third head width. Eyes supralateral, medium-sized, eye diameter about one-quarter head length, interorbital space flat, width about half head width. Gill opening small, about equal to eye diameter, originated about vertically above the second to third branched pectoral fin ray, limited to dorsal side of head. Scales small, diameter smaller than pupil, dorsal surface of head, base of paired fins, and ventral area before pelvic fin bases nude. Lateral line complete, at midlateral.

Dorsal fin base about equal to pre-pectoral length, starting around midpoint from snout to caudal fin base, adpressed extending to about midway between dorsal fin origin and caudal fin base. Anal fin base length about half of that of dorsal fin base, adpressed extending to slightly beyond caudal fin base. Paired fins extending outwards, forming disc-like structure with body. Pectoral fin base slightly longer than head length, starting at the posterior one-third point of head, pectoral fin length about twice to head length, tip of which reaching pelvic fin base midpoint, pectoral disc width about 1.5 times head width at pectoral origin, tubercles on rays absent. Pelvic fin shorter than pectoral, with well-developed fleshy flap at dorsal base, last 1–3 branched rays partially connected by fin membrane forming pelvic disc, connected part about two-thirds ray length, remaining parts separated, forming notch in middle rear edge, exposing anus. Pelvic disc width about equal to length. Anus at or near posterior edge of pelvic disc, distance to which less than to anal fin origin. Caudal fin length about equal to pelvic fin, slanted end, lower lobe slightly longer.

Coloration in preservation.

Preserved specimen from sub-adult to adult stage, body dark green to grey, white ventrally. Head with black spots or vermiculation dorsally, 2–5 larger black blotches along mid-dorsal body anterior to dorsal fin. Sides with 9–15 thick dark vertical stripes, with uniform length, width, and inter-spacing, easily recognizable at all ages. Paired fin with pale-white or hyaline margin, inner edges with continuous or dotted black arc. Dorsal fin hyaline with black stripes, one black spot present on the root before the second branched ray.

Coloration in live.

In life, sides of body dark cyan to green. After maturity, black stripes and spots on body turn metallic green, inter-spacing and hyaline fin membranes pale yellow.

Juvenile morphology.

Pelvic fins completely separated, body dark green in dorsal profile, few wider vertical dark stripes on sides, 2–3 vertical black stripes on caudal fin, other fins hyaline or with inconspicuous black lines (see Fig. 11 ).

Sexual dimorphism.

In fully mature individuals, males generally slightly larger than females, with well-developed tubercles (see Fig. 8 A, B ).

Geographic variation.

From east to west, vertical stripes generally tend to become thinner. Specimens from type locality, inter-spacings narrower than dark stripes, sometimes appearing fissure-like (see Fig. 10 ). In contrast, Lingyun County populations typically exhibit broader and taller bodies, shorter and thicker caudal peduncles, longer snouts, and wider inter-spacings (see Fig. 12 A , Table 4 ). In populations from the Xiyang River and Tuoniang River, vertical stripes vary greatly, sometimes becoming finer, inter-spacings wider than stripes, few individuals with shorter stripes before caudal peduncle (see Fig. 12 B ).

Individual variation.

Two specimens, SHOU 20240109101 and SHOU 20240112102, from Tuoniang River, Guangnan County, Yunnan, vertical stripes notably shortened. One specimen, SHOU 20240109701, from Chengbi River, Lingyun County, Guangxi, possesses completely separated pelvic fins.

Ethology.

Inhabits shallow streams with rapid currents and smooth pebble substrates that adhere to crevices between stones. Feeds on algae and small invertebrates and consumes mucus from fresh fish carcasses. Exhibits territorial behavior.

Distribution.

Found exclusively in small tributaries from the Tuoniang River, Xiyang River, Leli River, and Wuming River to the You River basin, the upper reaches of the Pearl River system, central Guangxi, and eastern Yunnan, China (see Fig. 9 ).

Etymology.

Species epithet “ viridis, ” from Latin, meaning “ green, ” describes bright green coloration over dorsal body after sexual maturity, in nominative masculine. We propose the Chinese common specific name “ 绿斑爬岩鳅. ”

Figures

Figure 6. Pinnate-type lower lip of the Beaufortia pingi species group, elongated, with the lower lip on both sides being multilobed, typically comprising more than three lobes, with deep divisions; the extremities of the lower lip extend to the corners of the mouth, with several wart-like protrusions present on the extended parts. The red line outlines the left side of the lower lip contour; the red arrow indicates the position of the ventral head sensory canal-pores located anterior to the origin of the pectoral fins. А. B. pingi, from the type locality; B. B. zebroida, from Napo County, Guangxi Province; C. B. viridis, from the type locality; D. B. granulopinna, from the type locality.

Figure 7. Dicot-type lower lip of species outside the Beaufortia pingi group, shorter, with the sides of the lower lip being smooth or featuring 1–2 shallow notches; the ends of the lower lip do not extend to the corners of the mouth, or the extension is poor-developed and lacks protrusions. The red line outlines the left side of the lower lip contour; the red arrow indicates the position of the ventral head sensory canal-pores, with the second pair of canal-pores located posterior to the origin of the pectoral fins in all species except B. liui. А. B. leveretti, from the type locality; B. B. kweichowensis, from Congjiang County, Guizhou Province, downstream near the type locality; C. B. cyclica, holotype; D. B. intermedia, paratype; E. B. polylepis, syntype; F. B. huangguoshuensis, syntype; G. B. szechuanensis, from Neijiang City, Sichuan Province; H. B. niulanensis, from the type locality; I. B. liui, syntype. (C-F and I were photographed by Yi-Yang Xu, Institute of Hydrobiology, Chinese Academy of Sciences.)

Figure 8. Sexual dimorphism within the Beaufortia pingi species group, with males exhibiting well-developed and numerous nuptial tubercles on the head compared to females. A, B. B. viridis sp. nov.; C, D. B. pingi; and E, F. B. granulopinna sp. nov.

Figure 9. Distribution map of species within the Beaufortia pingi species group. Light red: B. granulopinna sp. nov.; light green: B. viridis sp. nov.; light blue: B. pingi; light yellow: B. zebroida. Rivers are labeled with their names in Chinese: Qingshui River (清水江), Nanpan River (南盘江), Beipan River (北盘江), Hongshui River (红水河), Tuoniang (驮娘江), Xiyang River (西洋江), Leli River (乐里河), Chengbi River (澄碧河), Bo’ai River (剥隘河), Jian River (鉴河), You River (右江), Wuming River (武鸣河), Yu River (郁江), Shuikou River (水口河, known as Sông B ằng in Vietnamese), and Red River (红河).

Figure 10. Lateral (top), dorsal (middle), and ventral (bottom) views of Beaufortia viridis sp. nov., holotype, adult, SHOU 20240103101, 38.03 mm SL; from Wuming River, a stream tributary to the You River of the Pearl River basin, at Wuming District, Nanning City, Guangxi Province, China.

Figure 11. Lateral (top), dorsal (middle), and ventral (bottom) views of Beaufortia viridis sp. nov. during early juvenile and sub-adult stages. А. Early juvenile stage, SHOU 20240103623, from type locality, 12.64 mm SL, pelvic fins completely separated; B. Sub-adult stage, SHOU 20240103102, paratype, 25.81 mm SL.

Figure 12. Lateral (top), dorsal (middle), and ventral (bottom) views of different regional phenotypes of Beaufortia viridis sp. nov. А. Regional phenotype from Lingyun County, Guangxi, SHOU 20240126104, paratype, 58.71 mm SL; B. Regional phenotype from Tuoniang River, Guangnan County, Yunnan, SHOU 20240109105, paratype, 40.15 mm SL (left); SHOU 20240109103, paratype, 39.36 mm SL (right).

Figure 13. Collection site of the holotype (SHOU 20240103101) of Beaufortia viridis sp. nov., from Wuming River, a stream tributary to the You River of the Pearl River basin, Wuming District, Nanning City, Guangxi Province, China. Photographed by Jing-Chen Chen on 27 December 2023.