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

Figs 2 B, D , 4 , Tables 1 , 3

Materials.

Holotype. • NNNU 230710006 , 51.4 mm standard length, China: Guangxi, Liuzhou County, Youshan Village , 24 ° 15 ' 03.9813 " N, 109 ° 25 ' 42.8397 " E, collected by H. L. Mo and J. J. Zhou in July 2023.

Paratypes. • NNNU 230710001 –008, 47.59–61.63 mm standard length; same data as for holotype .

Etymology.

The new species is named in honor of Zongyuan Liu, a distinguished official, literary author, and thinker. During his tenure in Liuzhou, Liu significantly promoted the economic and cultural landscape of the region, thereby elevating the quality of life for its residents and earning him deep admiration and respect from the local community. We propose the common Chinese name “ 柳氏异条鳅 ” (Liu Shi Yi Tiao Qiu).

Diagnosis.

Comparative data among Paranemachilus liui sp. nov. and all five known species within the genus Paranemachilus are provided in Table 3 . Paranemachilus liui sp. nov. can be distinguished from all other congeneric species of the genus Paranemachilus by cheeks scaled (vs. scaleless in P. chongzuo , P. pingguoensis , and P. zhengbaoshani ), 11–13 branched pectoral fin rays (vs. 10 in P. chongzuo ), 7–9 preoperculomandibular canal pores (vs. zero in P. chongzuo , 11–12 in P. pingguoensis and P. zhengbaoshani ), preanus length 67.4 % – 74.3 % of standard length (vs. greater than 75.3 % in P. chongzuo , P. genilepis , P. jinxiensis , P. pingguoensis , and P. zhengbaoshani ), snout length 21.4 % – 28.7 % of lateral head length (vs. greater than 30.0 % in P. chongzuo , P. genilepis , P. jinxiensis , P. pingguoensis , and P. zhengbaoshani ), and 11–15 supraorbital canal pores at base of anterior nostrils (vs. 3 in P. chongzuo , 9 in P. jinxiensis , and 9–10 in P. zhengbaoshani and P. pingguoensis ).

Description.

The morphometric data of the type specimen of Paranemachilus liui sp. nov. are given in Table 1 . Body elongated, large in size. Maximum body depth occurs before insertion of dorsal fin, body depth 18.7 % – 23.2 % of standard length, head slightly depressed, flattened, maximum head width greater than deepest head depth, head width 49.9 % – 63.7 % head length, snout length 21.4 % – 28.7 % of lateral head length, shorter than postorbital length. Anterior and posterior nostrils adjacent; anterior nostrils tube-like; tip of anterior nostrils with distinct triangular elongation, shorter than half of tube depth. Cheeks scaled, no reduction in eye size, eye diameter 17.3 % – 21.9 % of head length. Mouth inferior, snout obtuse, lips developed and smooth; in most specimens, median of lower lip with V-shaped notch; missing in specimens such as NNNU 230710006 (holotype). Three pairs of barbels: inner rostral extending to posterior margin of posterior opercular, outer rostral, and maxillary barbel reaching or exceeding posterior margin of head. Dorsal fin with three unbranched and eight branched rays; distal margin straight; origin closer to caudal-fin base than to tip of snout. Pectoral fin with one unbranched and 11–13 branched rays; pectoral fin length 49.5 % – 51.8 % 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 five branched rays with truncate distal margins; origin closer to pelvic-fin insertion than to caudal-fin base. Caudal fin with 17 branched rays; caudal fin forked, upper and lower lobes equivalent.

Body completely covered by tiny scales. Cephalic lateral-line canals developed, with 4–6 + 13 – 15 infraorbital canal pores, 11–15 supraorbital canal pores at base of anterior nostrils, four supratemporal canal pores, and 7–9 preoperculomandibular canal pores. Lateral line incomplete, with 8–14 lateral line pores present before tip of pectoral fin, 14–16 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 liui sp. nov. specimen in life is provided in Fig. 4 D . Dorsal surface dark brown, head and trunk of body yellowish brown, head untextured. Obscure brown longitudinal stripe extending along lateral line to base of caudal fin. Whole body untextured at capture. Post-feeding, some samples developed small black spots on dorsal surface. Fin rays faint yellow, fin membrane hyaline.

Distribution and habitat.

Specimens of Paranemachilus liui sp. nov. were collected from several caves around Youshan Village, Yifeng District, Liuzhou City, Guangxi Province, China. The type specimen was collected from an underground river in Keyuan Cave (Fig. 5 ), which sustains a long, narrow, perennially water-filled pool. Near the cave entrance, some water sections are exposed to sunlight, with an average water temperature ranging from 20 to 23 ° C. In the same location, we also collected Yunnanilus bailianensis , Typhlocaridina semityphlata , and an unidentified catfish species. Notably, the vicinity of Keyuan Cave is heavily utilized for farmlands and duck farms, resulting in a significant population from fertilizers and feed in the water where the specimens were found. Despite this, Paranemachilus liui sp. nov. appears to have adapted to these environmental conditions.

Phylogenetic analysis.

The BI phylogenetic tree (Fig. 6 ) revealed that the Paranemachilus species formed a monophyletic group, sister to the genus Troglonectes . Paranemachilus luegvetensis sp. nov. and Paranemachilus liui sp. nov. formed a well-supported monophyletic group (bootstrap support = 98 and Bayesian posterior probability = 1) with other Paranemachilus species, including the type species P. genilepis . All samples from Wumin District, Nanning City, Guangxi Zhuang Autonomous Region clustered together in a sister clade to ( P. genilepis + Paranemachilus liui sp. nov.). All samples from Yüfeng District, Liuzhou City, and Guangxi Zhuang Autonomous Region clustered together in a sister clade to P. genilepis . The tree topologies are similar to those reported in previous studies [2, 13], with highly consistent and strong support of the monophyly of the genus Paranemachilus . Analysis also indicated that the genus could be divided into two major clades, i. e., cheek-scaled group and cheek-scaleless group. The cheek-scaled group contained P. genilepis , P. jinxiensis , Paranemachilus liui sp. nov. and Paranemachilus luegvetensis sp. nov., while the cheek-scaleless group contained P. chongzuo , P. pingguoensis , and P. zhengbaoshani .

Mitochondrial differentiation.

Comparative analysis of the cytb gene revealed that the two new species could be distinguished from all known Paranemachilus species based on distinct molecular differences. The minimum p-distances were 7.92 % between Paranemachilus luegvetensis sp. nov. and Paranemachilus liui sp. nov. and 6.16 % between Paranemachilus liui sp. nov. and P. genilepis (Table 2 ).

Figures

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

Figure 4. A – C. dorsal, lateral, and ventral views of Paranemachilus liui sp. nov. NNNU 230710006, holotype, 51.39 mm standard length. D Paranemachilus liui sp. nov. NNNU 230710006, holotype, live, photo taken on 11 June 2023. Scale bar: 1 cm.

Figure 5. Pool and a cave from which type Paranemachilus luegvetensis sp. nov. was collected in Youshan Village, Yufeng District, Liuzhou County.

Figure 6. Bayesian phylogeny of cytb lineages of species within the family Nemacheilidae. Botia genus was used as an outgroup. Numbers on internode branches are Bayesian posterior probabilities.