Triplophysa baishuijiangensis Shi, Chen, Yang & X. - A. Wang, 2025

Triplophysa baishuijiangensis Shi, Chen, Yang & X. - A. Wang sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , Table 2 View Table 2

Type material.

Holotype. • KIZ 2025000165 View Materials (Fig. 2 View Figure 2 ), 75.64 mm total length, 61.5 mm standard length ( SL), collected by Min Shi, Long Zhu, Yuan-Chao Chen, Jian-Fu Wei on May 17, 2023, at Xiaoganxi Village , Niujie town, Yiliang County, Yunnan Province, China, an outlet of a subterranean river belonging to the Baishui River system, Jingsha River drainage ( 27.82093589 ° N, 104.47385841 ° E; ca 628 m. a. s. l.; Fig. 5 View Figure 5 ) GoogleMaps . Paratypes. • KIZ 2025000175 View Materials , collected on March 11, 2023; KIZ 2025000166–174 View Materials ( 9 specimens) collected on May 17. 31.7–64.7 mm SL, other collection information same as holotype GoogleMaps .

Diagnosis.

The diagnostic characters for cave-dwelling species of Triplophysa are provided in Suppl. material 2. Triplophysa baishuijiangensis sp. nov. is distinguished from its congeners by the following combination of characters:

Vestigial eyes (vs absent or normal in T. nanpanjiangensis Zhu & Cao, 1988 , T. huapingensis , T. sanduensis Chen & Peng, 2019 , T. rongduensis Mao, Zhao, Yu, Xiao & Zhou, 2023 , T. panzhouensis Yu, Luo, Lan, Xiao & Zhou, 2023 , T. anlongensis , T. baotianensis Li, Liu & Li, 2018 , T. xiangshuiqingensis Li, 2004 , T. zhenfengensis Wang & Li, 2001 , T. nandanensis , T. tianxingensis Yang, Li & Chen, 2016 , T. guizhouensis , T. nasobarbatula Wang & Li, 2001 , T. longliensis , T. fengshanensis , T. posterodorsalus (Li, Ran & Chen, 2006) , T. qini , T. qiubeiensis Li & Yang, 2008 , T. shilinensis , T. xuanweiensis , T. erythraea , T. anshuiensis , T. xiangxiensis , T. gejiuensis , T. flavicorpus Yang, Chen & Lan, 2004 , T. yunnanensis Yang, 1990 , and other epigean congeners);

Skin pigment absent (vs reduced or covers the whole body in T. luochengensis , T. qingzhenensis , T. macrocephala , T. wudangensis , T. longipectoralis , T. xichouensis , T. ziyunensis Wu, Luo, Xiao & Zhou, 2024 , T. yaluwang Lan, Liu, Zhou & Zhou, 2024 , and T. wenshanensis Jiang, Cao, Song, Yi & Yang, 2025 );

Tip of pelvic fin reaching anus (vs not reaching anus in T. tianlinensis , T. aluensis Li & Zhu, 2000 , and T. tianeensis );

Lateral line complete (vs incomplete in T. langpingensis Yang, 2013 );

Posterior chamber of air bladder developed (vs reduced in T. yangi Jiang, Cao, Song, Yi & Yang, 2025 );

Dorsal fin iii, 7 (vs iv, 9 in T. cehengensis Luo, Mao, Zhao, Xiao & Zhou, 2023 , and iii, 9 in T. rosa ).

Description.

Detailed morphometric data of Triplophysa baishuijiangensis sp. nov. specimens are summarized in Table 2 View Table 2 and Suppl. material 4. Dorsal fin iii, 7; pectoral fin i, 9–10; pelvic fin i, 6; anal fin ii, 5; 15–16 branched rays in the caudal fin; vertebrae: 4 + 34.

Body elongated, anteriorly cylindrical, posteriorly compressed laterally behind dorsal-fin origin. Maximum body depth at tip of adpressed pectoral fins (corresponding to the swollen position of posterior swim bladder chamber). Snout slightly pointed. Eyes vestigial, reduced to black pigment spots.

Three pairs of barbels: outer rostral barbel longest, extending beyond posterior nostril; maxillary barbel shorter, extending past the eye spot; inner rostral barbel shortest, extending to the corner of mouth. Mouth inferior, arched, lower lip folded with medial V-shaped notch. Anterior and posterior nostrils closely connected, anterior nostril enclosed within a nasal valve that extends into a barbel-like tip, posterior nostril larger and without nasal valve.

Posterior edge of dorsal fin straight, distance from dorsal fin base to snout tip greater than to caudal fin base, dorsal fin starts before pelvic fins. Pectoral fins developed, arc-shaped, tips reaching or exceeding midpoint between dorsal and pectoral fin bases. Pelvic fins arc-shaped, slightly behind dorsal fin, extending to anus. Posterior edge of anal fin straight, separated from anus by a short distance. Caudal fin shallowly concave, upper lobe slightly longer than lower. Faint adipose crests on both dorsal and ventral sides of caudal peduncle, dorsal crest larger than ventral.

Two chambers of swim bladder, anterior chambers dumbbell-shaped and encased in bony capsule, posterior chamber developed, oval, and free within the abdominal cavity (Fig. 2 G, H View Figure 2 ). Gill rakers not developed, nine gill rakers on first gill arch. Intestine short, length 52.0 % of SL, bends downward behind the stomach and gradually narrows, stomach is U-shaped and enlarged.

Coloration.

Entire body lacks pigment and scaleless, lateral line complete. Live specimens semi-transparent, flesh-colored, internal organs vaguely visible ventrally. Fin rays white, fin membranes transparent (Fig. 4 B View Figure 4 ). After fixation, body turns white, abdomen pale yellow. Eye spot color intensity varies, with some nearly invisible.

Sexual dimorphism.

All examined specimens lack thickened pads and furcella on the head and pectoral fins. However, males and females show significant differences in head shape. Male heads narrow sharply at the eye position, then taper gradually, resembling a “ bell shape ” with a blunt snout. Female heads taper gradually, resembling a “ triangle ” with a pointed snout (Fig. 3 A, B View Figure 3 ). Consistent with the sexual dimorphism characteristics of T. daqiaoensis , described by Hou et al. (2010).

Distribution and habitat.

So far, the new species has only been found at the outlet of an underground river in Xiaoganxi Village, Yiliang County, Zhaotong City, Yunnan Province. Water of outlet is clear year-round (Fig. 4 A View Figure 4 ). The new species is active and feeds near the outlet, rarely far from the outlet, responding to light but is insensitive to vibrations, and moves slowly and is easy to capture.

Etymology.

The specific epithet baishuijiangensis is in reference to the type locality of the new species: the core area of Baishuijiang National Aquatic Germplasm Resources Reserve for Endemic Fish. We propose the common English name “ Baishuijiang high-plateau loach ” and the Chinese name “ Bái Shuǐ Jiāng Gāo Yuán Qiū (白水江高原鳅) ”.