Paranemachilus luegvetensis Mo, Yang, Li & Du, 2024

Mo, Hao-Lin, Yang, Jian, Li, Peng & Du, Li-Na, 2024, Description of two new species of the genus Paranemachilus (Cypriniformes, Nemacheilidae) from Guangxi, China, Zoosystematics and Evolution 100 (4), pp. 1375-1385 : 1375-1385

Paranemachilus luegvetensis Mo, Yang, Li & Du sp. nov.

Figs 1 , 2 A, C , Tables 1 , 3

Materials.

Holotype. • NNNU 230611 ( NNNU: Nanning Normal University), 41.2 mm standard length. China: Guangxi, Wuming County, Chuanqian Village , 23 ° 13 ' 25.08 " N, 108 ° 26 ' 18.50 " E, collected by H. L. Mo and J. H. Zhong in June 2023.

Paratypes. • NNNU 230603 –230610, 8 ex., 26.1–33.4 mm standard length; same data as for holotype .

Etymology.

The name luegvetensis originates from the Zhuang language of the Luoyue Ancient Kingdom, pronounced LOKWET. This kingdom, believed to be located in what is now the Wuming District of Nanning City, Guangxi, China, where the type specimens were collected, is considered the cradle of this ancient civilization. The Luoyue Ancient Kingdom was known for its rich cultural contributions, including rice cultivation, cotton textiles, cliff paintings, witchcraft, Longmu rituals, and jade carving. These cultural elements profoundly influenced not only Chinese and Southeast Asian civilizations but also had significant global impacts. We propose the common Chinese name “ 骆越异条鳅 ” (Luo Yue Yi Tiao Qiu).

Diagnosis.

Comparative data between Paranemachilus luegvetensis sp. nov. and all five known species within the genus Paranemachilus are provided in Table 3 . Paranemachilus luegvetensis sp. nov. differs from all other congeneric species of Paranemachilus by cheeks scaled (vs. scaleless in P. chongzuo , P. pingguoensis , and P. zhengbaoshani ), 11–12 branched pectoral fin rays (vs. 10 in P. chongzuo ), 4–5 preoperculomandibular canal pores (vs. zero in P. chongzuo , 11–12 in P. pingguoensis and P. zhengbaoshani , 10 in P. genilepis , and 10–11 in P. jinxiensis ), body depth 13.5 % – 16.8 % of standard length (vs. greater than 18 % in P. jinxiensis and P. pingguoensis ), and preanus length 68.3 % – 73.9 % of standard length (vs. greater than 75.3 % in P. chongzuo , P. genilepis , P. jinxiensis , P. pingguoensis , and P. zhengbaoshani ).

Description.

The morphometric data of the type specimen of Paranemachilus luegvetensis sp. nov. are given in Table 1 . Body short, slightly bulging at back. From snout to dorsal-fin origin, body depth increases to maximum, 13.5 % – 16.8 % of standard length, head slightly depressed, flattened, maximum head width greater than deepest head depth, 44.7 % – 56.5 % of head length, snout length 24.5–32.1 % of lateral head length, shorter than postorbital length. Mouth inferior, snout obtuse, lips developed and smooth, median of lower lip with V-shaped notch. Anterior and posterior nostrils adjacent; anterior nostrils tube-like, barbel-like elongation of anterior nostrils shorter than half the depth of nostril tube. Cheeks scaled, no reduction in eye size, eye diameter 19.3 % – 25.3 % of head length. Three pairs of barbels: inner rostral barbel extending to posterior margin of eye, outer rostral barbel reaching or exceeding posterior margin of anterior opercular, above posterior operculum, and maxillary barbel above posterior margin of posterior operculum. Dorsal fin with three unbranched and 8–9 branched rays; distal margin cut; origin closer to caudal-fin base than to tip of snout. Pectoral fin with one unbranched and 11–12 branched rays; pectoral fin length 45.7 % – 61.4 % of pelvic-fin insertion; pelvic fin with one unbranched and 6–7 branched rays, inserted below first or second unbranched dorsal-fin ray; tip of pelvic fin far from anus. Anal fin with three unbranched and 5–6 branched rays with truncate distal margins; origin halfway between pelvic-fin insertion and caudal-fin base. Caudal fin with 17–18 branched rays; caudal fin forked, upper and lower lobes equivalent.

Cephalic lateral-line canals developed, with 7 + 18–19 infraorbital canal pores, 15–17 supraorbital canal pores at base of anterior nostrils, 2–4 supratemporal canal pores, and 4–5 preoperculomandibular canal pores. Lateral line incomplete, with 2–6 lateral line pores present before midpoint of pectoral fin, 15–16 inner gill rakers on first gill arch (two specimens).

Stomach “ U ” - shaped, intestines slightly to back of stomach, curved. Two air-bladder chambers: anterior chamber encased in bony capsule, posterior chamber filling body cavity, and anterior and posterior chambers connected by short, thin, and curved tubes (Fig. 2 ).

Coloration.

Photograph of Paranemachilus luegvetensis sp. nov. alive is provided in Fig. 1 D . Sides of head and trunk brownish yellow; abaxial surface dark brown; ventral and lateral surfaces of head untextured. Obscure brown longitudinal stripe extending along lateral line to base of caudal fin. Body sides light yellow, except along lateral line; no spots on entire body at capture. Post-feeding, some individuals developed small black spots on side and back above lateral line, with darkened longitudinal stripes on side of body, though basic body color remained unchanged. No spots on fin, fin membrane hyaline. Specimens preserved in 10 % formalin appear grayish-white.

Distribution and habitat.

The species is known only from a karst cave (23 ° 13 ' 25.0813 " N, 108 ° 26 ' 18.4973 " E) near Nonghu Tun, Chuanqian Village, Wuming District, Nanning City (Fig. 3 ). The cave entrance has been artificially enlarged, with the underground river serving as an important source of drinking water and irrigation for local residents. Paranemachilus luegvetensis sp. nov. inhabits this silt-based underground river, co-occurring with Caridina sp. and Silurus sp. The underground river was not swollen at the time of collection, so the specimens were obtained deep within the cave.

Remarks.

All collected individuals were initially extremely thin and weak. The holotype, raised in the same tank as other cavefish species for 91 days in an artificial environment. It was fed once every two days and sacrificed on day 91, with prepared specimens showing obvious fat accumulation on its back and sides. The species often migrates from the cave to feed in flooded mountain swales and farmlands during the rainy season, a behavior frequently observed by working locals. In the dry season, the water temperature of the pool is 18–20 ° C, and in the rainy season, the temperature of the pool formed outside the outflow of the river can reach 26 ° C. Despite its water habitats being contaminated with fertilizers and pesticides, Paranemachilus luegvetensis sp. nov. appears to have adapted to these environmental conditions.

Figures

Figure 1. The dorsal (A), lateral (B), and ventral (C) views of Paranemachilus luegvetensis sp. nov. NNNU 230611, holotype, 41.2 mm standard length. D. Living photo of Paranemachilus luegvetensis sp. nov., NNNU 230611, holotype. Scale bar: 1 cm

Figure 2. Swim bladder, stomach, and intestine of Paranemachilus luegvetensis sp. nov. (A, C) and Paranemachilus liui sp. nov. (B, D).

Figure 3. Pool or a cave from which Paranemachilus luegvetensis sp. nov. type species was collected in Nonghu Tun, Chuanqian Village, Wuming District, Nanning City. Left (15 October 2023), right (10 June 2023).