Taxonomic revision of the cavefish genus Karstsinnectes (Cypriniformes, Nemacheilidae), with a description of a new species from Guangxi Province, China Author Ge, Jia-Yue Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, Guangxi 541004, China Author Nong, Zheng-Quan Guangxi Key Laboratory of Rare and Endangered Animal Ecology, College of Life Science, Guangxi Normal University, Guilin, Guangxi 541004, China Author Yang, Jian Administration Center of Guangxi Nonggang National Nature Reserve, Longzhou Guangxi 532400, China Author Du, Li-Na 0000-0002-2246-643X Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, Guangxi 541004, China Author Zhou, Jia-Jun 0000-0003-1038-1540 Key Laboratory of Environment Change and Resource Use, Beibu Gulf, Nanning Normal University, Nanning, Guangxi, 530001, China & Zhejiang Forest Resource Monitoring Center, Hangzhou, Zhejiang 310020, China text Zoosystematics and Evolution 2024 2024-05-27 100 2 663 673 journal article 297349 10.3897/zse.100.118061 074544ab-8f96-42ea-8290-5bbff95c91b9 0440F4DE-BECE-4B8B-9D84-88E17489226C Karstsinnectes longzhouensis Ge, Du & Zhou sp. nov. Figs 1 A, B , 4 ; Table 1 Type materials. Holotype . China (permanent whole specimen in 75 % alcohol); Guangxi , Chongzuo City , Longzhou County , Xiadong Town ; 22.4222 ° N , 106.6385 ° E , 170 m a. s. l. ; collected by Z. Q. Nong and J. J. Zhou , 29 December 2022 . Kunming Natural History Museum of Zoology, KIZ 2023000001 , 50.6 mm standard length ( SL ). Paratypes . China (permanent whole specimens in 75 % alcohol); same collection data as for holotype, collected by Z. Q. Nong and J. J. Zhou , 29 December 2022 ; KIZ 2023000002–04 , 3 ex. , 49.4–60.1 mm SL . Diagnosis. Karstsinnectes longzhouensis sp. nov. can be distinguished from all other members of Karstsinnectes based on the combination characteristics of the lateral line present, 11 or 12 branched pectoral-fin rays, and five branched pelvic-fin rays. It can be further distinguished from K. anophthalmus by caudal fin forked (vs. truncated), five branched pelvic-fin rays (vs. four), nine branched dorsal-fin rays (vs. seven), 13 or 14 branched caudal-fin rays (vs. 12); from K. acridorsalis by nine branched dorsal-fin rays (vs. eight), body depth 16.1 % – 19.4 % of SL (vs. 13.9 % – 15.5 %); from K. hyalinus by body scaleless (vs. scaled), lateral line present (vs. absent), nine branched dorsal-fin rays (vs. seven), five branched anal-fin rays (vs. four); from K. parvus by 11 or 12 branched pectoral-fin rays (vs. 10), five branched pelvic-fin rays (vs. six), and uncorrected p distance is 3.9 %. Lateral, dorsal, and ventral views of Karstsinnectes longzhouensis sp. nov. , holotype KIZ 2023000001. Scale bar: 1 cm. Description. Morphometric data of the type specimens of Karstsinnectes longzhouensis sp. nov. are given in Table 1 . Body elongated, head depressed, forehead raised, head height at nostril 60.8 % – 71.0 % of maximum head height. Body trunk compressed, with maximum body depth in middle of pectoral-fin origin and pelvic-fin origin, deepest body depth 16.1 % – 19.4 % of SL . Dorsal profile of forehead and predorsal profile convex, concave from dorsal-fin origin to anterior margin of upper caudal adipose keel. Caudal adipose keel on upper edge of caudal of peduncle slightly convex. Ventral profile of head straight, slightly convex from pectoral-fin origin to pelvic-fin origin, straight between pelvic-fin and anal-fin origin, and gradually concave from anal-fin base to anterior quarter of caudal fin due to caudal adipose keel on lower edge of caudal peduncle. Anterior and posterior nostrils adjacent, distance less than posterior nostril diameter, base of anterior nostril tube-shaped and tip not elongated to barbel-like. Eyes absent. Mouth inferior, snout rounded, upper and lower lips smooth, lower lip with V-shaped median notch. Three pairs of barbels, inner rostral barbel reaching anterior nostril, outer rostral barbel reaching posterior margin of posterior nostril, and maxillary barbel reaching anterior margin of interopercle. Two specimens with 11–12 inner gill rakers on first gill arch. Dorsal fin with three unbranched and nine branched rays, distal margin of dorsal fin straight, origin anterior to pelvic-fin origin, predorsal length 55.1 % – 57.3 % of SL . Pectoral fin with one unbranched and 10 branched rays, pectoral-fin length 72.4 % – 85.9 % of distance between pectoral-fin origin and pelvic-fin origin. One unbranched and five branched pelvic-fin rays, tip of pelvic fin reaching, but not exceeding anus. Anus abutting anal-fin base. Caudal fin forked, with 13 or 14 branched caudal-fin rays. High caudal adipose keels on upper and lower edges of caudal peduncle, height at most of upper adipose keel less than 1 / 2 caudal peduncle depth. Caudal peduncle length 151.2 % – 212.9 % of its depth (containing adipose keels). Lateral line and head sensory pores absent. Body scaleless. Coloration. Dorsal and trunk of body yellowish, abdomen gray and translucent, stomach and intestine visible from outside. Without color pattern. Fin membrane hyaline. Distribution and habitat. Karstsinnectes longzhouensis sp. nov. inhabits karst caves located in the Guangxi Qinglongshan provincial natural reserve, specifically in Xiadong Town, Longzhou County, Chongzuo City, Guangxi , China ( 22.4222 ° N , 106.6385 ° E , 171 m a. s. l.). The species was observed in a subterranean pool accessed through an oval cave entrance and a narrow passage. The pool water depth exceeded 1 m and was characterized by a substratum of mud and cobblestones. Etymology. The specific name “ longzhouensis ” is derived from the Chinese name of the type locality in Longzhou County. Therefore, the Chinese and English common names for this new species are “ 龙州中华喀鳅 ” and “ Longzhou Chinese Karst Loach, ” respectively. Remarks. On 29 December 2022 , Z. Q. Nong collected type specimens within a karst cave. By May 2023 , the cave showed significant signs of drying. In another cave located 300 m away, J. J. Zhou collected a deteriorated specimen. Decreased precipitation and the removal of domestic water from the cave appear to have negatively influenced the viability of cavefish during the dry season.