Triplophysa yangi Jiang, Cao, Song, Yi & Yang, 2025

Cao, Jianhan, Song, Shuang, Yi, Wenjing, Xiang, Hongmei, Yang, Hongfu, Li, Jie & Jiang, Wansheng, 2025, Two new cavefish species of Triplophosa (Cypriniformes: Nemacheilidae) from the karst subterranean rivers of Yunnan, China, Zoological Journal of the Linnean Society 204 (1) : -

Triplophysa yangi Jiang, Cao, Song, Yi & Yang sp. nov.

( Figs 1–3; Tables 1 and 2)

ZooBank registration: urn:lsid:zoobank.org:act:70DECDOE- A286-460F-B2F5-B061DFE79F6E

Holotope: JWS2023676, 97.5 mm SL; China: Yunnan Province, Qujing Prefecture, Shizong Country, Wulong Town , a subterranean tributary of the Nanpanjiang River drainage; caught on 5 January 2024 by Hongfu Yang and local people; specimen intact and undissected .

Paratopes: JWS2023018–2023026 (9), 43.0– 86.1 mm SL; caught on 8 January 2023 by Hongfu Yang and local people; JWS2023037–2023043 (7), 44.1–80.0 mm SL; caught on 24 March 2023 by Hongfu Yang and local people; all collected at the same type locality as the holotype but at different times; tissues of the pectoral fin (right side) of some specimens were taken for DNA sequencing .

Diagnosis: Triplophosa oangi can be distinguished from all other congeners by having bilaterally expanded anterior swim bladder chambers protruding from the enlarged bony capsule, distending the lateral body wall, and becoming externally visible (vs. swim bladder chambers lack such expansion and protrusion). It also differs from all other congeners except Triplophosa xiangxiensis (Yang, Yuan & Liao, 1986) , Triplophosa rosa Chen & Yang, 2005 , and Triplophosa longipectoralis Zheng, Du, Chen & Yang, 2009 by having highly developed pectoral and pelvic fins with filamentous extensions (vs. fins without such developed and filamentous extensions). It can also be distinguished from Triplophosa gejiuensis (Chu & Chen, 1979) , Triplophosa shilinensis Chen & Yang, 1992 , Triplophosa qiubeiensis Li & Yang, 2008 , and Triplophosa xuanweiensis Lu, Li, Mao & Zhao 2022 in having reduced but still discernible eye dots (vs. completely eyeless). It can also be distinguished from Triplophosa aluensis Li & Zhu, 2000 , Triplophosa nanpanjiangensis (Zhu & Cao, 1988) , Triplophosa xiangshuingensis Li, 2004 , Triplophosa xichouensis Liu, Pan, Yang & Chen 2017 , Triplophosa baotianensis Li, Li, Liu & Li, 2018 , Triplophosa zhenfengensis Wang & Li, 2001 , Triplophosa rongduensis Mao, Zhao, Yu, Xiao & Zhou 2023 , and Triplophosa anlongensis Song, Luo, Lan, Zhao, Xiao & Zhou 2023 by having pectoral fin tip reaching (vs. not reaching) the pelvic fin origin, and from T. baotianensis , T. nanpanjiangensis , T. zhenfengensis , T. rongduensis , and T. anlongensis by having the pelvic-fin tip reaching (vs. not reaching) the anus. In addition, T. oangi can be distinguished from Triplophosa ounnanensis Yang, 1990 and T. zhenfengensis by the absence of scales (vs. presence of scales) and from T. anlongensis by the posterior chamber of the swim bladder reduced (vs. developed).

Description: Body elongated; anterior part subcylindrical, posterior portion laterally compressed; deepest body depth anterior to dorsal-fin origin. Dorsal profile nearly sloping from snout to dorsal-fin insertion, straight from posterior dorsal-fin origin to caudal-fin base. Ventral profile slightly convex from snout tip to pelvic-fin origin, slightly concave from pelvic-fin origin to caudal-fin base. Bilaterally anterior chambers of swim bladder expanded, protruding from the bony capsule, distending the lateral body wall and externally visible, more pronounced in large individuals.

Head moderately depressed; head length 23.3%–31.1% of SL; head width slightly greater than head depth. Snout slightly blunt; snout length 40.9%–52.3% of HL. Mouth inferior, curved; mouth corner anterior to vertical through anterior nostril. Upper and lower jaws arched. Lip thick, with shallow furrows; upper and lower lips complete, connected at mouth corner. Lower lip with median interruption, V-shaped median incision. Anterior and posterior nostrils adjacent; anterior nostril in short tube with tip elongated into short barbel, not reaching anterior eye margin. Eye present as small black dot, discernible; eye diameter 2.0%–5.3% of HL; interorbital width 30.0%–40.2% of HL. Tree pairs of barbels: inner rostral barbel shortest, 11.3%–23.9% of HL, not reaching mouth corner; outer rostral barbel moderate, 22.8%–35.2% of HL; maxillary barbel longest, 23.3%–37.1% of HL, extending to posterior edge of eye.

Dorsal-fin origin nearly at mid-point between snout tip and caudal-fin base, close to vertical through pelvic fin origin; distal margin truncate; length 15.4%–24.0% of SL. Pectoral fin highly developed with filamentous extensions of exterior branched ray, more pronounced in large individuals; reaching beyond anus; length 16.0%–37.5% of SL. Pelvic fin well developed with filamentous extension of exterior branched ray, more pronounced in large individuals; origin closer to anal-fin origin than pectoral-fin origin; reaching beyond anal-fin origin; length 12.6%–25.6% of SL. Anal fin long, origin nearly at mid-point between pelvic-fin origin and caudal-fin base; distal margin truncated; length 10%–17.2% of SL. Caudal fin emarginate; lobes of equal length, distal tips pointed; caudal peduncle length 14.9%–21.5% of SL, depth 6.7%–10.0% of SL.

Lateral line complete. Vertebrae: 4 + 34 (6), 4 + 35 (2). No sexual dimorphism observed. Anterior swim bladder chambers expanded and protruded beyond the bilateral sacs of the bony capsule; posterior swim bladder chamber greatly reduced, not extending beyond the posterior margin of the bony capsule, invisible in situ of anatomical view. Te skeletal 3D reconstruction based on one specimen of T. oangi is analysed with T. wenshanensis in a subsequent section. Other morphometric characters of T.oangi are listed in Table 2.

Coloration: In live specimen, body generally white to flesh pink, semi-translucent, without skin pigment, all fins hyaline ( Fig. 1).

In 10% formalin-preserved specimens, body white to yellowish, all fins partly transparent ( Fig. 2).

Distribution and habitat: Te new species was collected from a subterranean river ( Fig. 3) in Wulong Township, Shizong County, Qujing Prefecture, Yunnan Province, China. Tis river is a tributary to the Nanpanjiang River basin and is situated tens of metres below the cave entrance. Te river flows slowly and experiences seasonal fluctuations, ranging from dry periods to rainy seasons, but it never dries completely. During the dry season, the river channel is generally shallow, although it includes several deep pools (> 5 m). Te region surrounding the cave is rich in similar subterranean rivers, suggesting the potential presence of additional populations. Within this cave, T. oangi was found in association with Sinococlocheilus rhinocerous Li & Tao, 1994, Sinococlocheilus malacopterus Chu & Cui, 1985, Sinocrossocheilus tridentis (Cui & Chu, 1986) , and Discogobio sp. Etomologo: Te specific epithet of the new species, oangi , is named afer Dr Junxing Yang, in recognition of his outstanding contributions to the research and conservation of cavefish diversity in China. Consequently, the Chinese name for the new species is ‘Yáng Shì Máng Gāo Yuán Qīu (杨氏盲高原鳅)’.

Triplophysa wenshanensis Jiang, Cao, Song, Yi & Yang sp. nov.

( Figs 4–6; Tables 1 and 2)

ZooBank registration: urn:lsid:zoobank.org:act:56949D47-1DDF-4AB8-834B-E08F6CB383E6

Holotope: JWS2023003; 113.2 mm SL; China: Yunnan Province, Wenshan Prefecture, Dehou Town, a subterranean tributary of the Panlonghe River drainage; caught on 11 January 2023 by Hongfu Yang and local people; tissues of the pectoral and pelvic fin (right side) of this specimen were taken for DNA sequencing. Paratopes: JWS2023002, JWS2023004–005 (3); 85.5– 117.5 mm SL; caught with the holotype; tissues of the pectoral fin and pelvic fin (right side) of all specimens were taken for DNA sequencing; the abdominal surface of one individual (JWS2023002) was incised to examine the swim bladder and other internal organs .

Diagnosis: Triplophosa wenshanensis can be distinguished from all other congeners except Triplophosa tianxingensis Yang, Li & Chen 2016 by having a nearly cone-shaped head (vs. subcylindrically shaped head), and it can be distinguished from T. tianxingensis by having light brown to flesh pink body colour with faint brown blotches (vs. light yellow body colour with numerous star-like brown blotches). It can be distinguished further from T. gejiuensis , T. shilinensis , T. qiubeiensis , and T. xuanweiensis in having reduced but still discernible eye dots (vs. completely eyeless). It can be distinguished further from T. gejiuensis , T. qiubeiensis , T. shilinensis , T. xichouensis , and T. xuanweiensis by having the pelvic-fin tip not reaching (vs. reaching) the anus. It can also be distinguished from T. aluensis , T. gejiuensis , T. nanpanjiangensis , T. tianxingensis , and T. xichouensis by having a concave (vs. truncate) distal margin of the dorsal fin. It can also be distinguished from T. ounnanensis by absence of scales (vs. presence of scales) and from T. qiubeiensis by having a barbel-like tip (vs. no barbel-like tip) of the anterior nostril and more vertebrae (4 + 38~39 vs. 4 + 35).

Description: Body elongated, cylindrical anteriorly, laterally compressed posteriorly; deepest body depth anterior to dorsal-fin origin. Dorsal profile slightly convex from snout to dorsal-fin insertion, straight from dorsal-fin origin to caudal-fin base. Ventral profile slightly convex from snout to pelvic-fin origin, slightly concave from pelvic-fin origin to caudal-fin base.

Head slightly elongated, nearly cone shaped, profile triangular; head length 20.9%–23.4% of SL; head depth> head width (head depth/head width = 1.4). Snout long, 41.1%– 43.6% of HL. Mouth inferior, curved; mouth corner anterior to vertical through anterior nostril. Upper and lower jaws arched. Lips thick, smooth; connected at mouth corner; lower lip with median interruption, V-shaped incision. Anterior and posterior nostrils adjacent; anterior nostril in short tube, tip elongated into short barbel, not reaching anterior eye margin. Eye present as black dot, eye diameter 5.1%–6.4% of HL; interorbital width 17.3%–20.6% of HL. Tree pairs of barbels: inner rostral barbel shortest, 14.9%–23.5% of HL, reaching mouth corner; outer rostral barbel longest, 34.6%–53.7% of HL, extending to posterior edge of eye; maxillary barbel moderate, 20.4%–29.1% of HL.

Dorsal-fin origin at nearly mid-point between snout tip and caudal-fin base, close to vertical through pelvic fin origin; distal margin concave; length 17.6%–19.9% of SL. Pectoral fin normal; length 14.4%–16.7% of SL, not reaching pelvic fin origin. Pelvic fin short; length 8.2%–14.7% of SL, not reaching anus. Anal fin short; origin nearly at mid-point between pelvic-fin origin and caudal-fin base; distal margin truncated; length 14.0%–15.2% of SL. Caudal fin emarginate; lobes of equal length, distal tips blunted; caudal peduncle length 5.6%–18.0% of SL, depth 5.6%–8.3% of SL.

Lateral line complete. Vertebrae: 4 + 38 (1), 4 + 39 (2). No sexual dimorphism observed. Anterior swim bladder chambers normally developed, wrapped in the bony capsule; posterior swim bladder chamber well developed, visible in situ of anatomical view, oval in shape and elongated, connected to anterior chamber by a long and slender tube. Te skeletal 3D reconstruction based on one specimen of T. wenshanensis is analysed with T. oangi in a later section. Other morphometric characters of T. wenshanensis are listed in Table 2.

Coloration: In live specimens, body light brown, tinged with flesh pink, skin pigment prominent, especially on dorsal view; all fins hyaline ( Fig. 4). Pigmentation intensifies in light. In 10% formalin-preserved specimens, body yellowish with faint brown blotches, especially on dorsal view; all fins faint yellow and translucent ( Fig. 5).

Distribution and habitat: Tis new species was collected from a subterranean river ( Fig. 6), a tributary to the Panlonghe River basin, located in Dehou Township, Wenshan Prefecture, Yunnan Province, China. Te subterranean river features an accessible exit that extends> 100 m upwards until it encounters an impassable blockage. Te cave contains well-formed stalactites, and local residents occasionally enter the cave. Within this cave, T. wenshanensis coexists with Sinococlocheilus wenshanensis Li, Yang, Li & Chen 2017 , Homatula wenshanensis Li, Yang, Li & Liu, 2017 , and Discogobio sp.

Etomologo: Te specific epithet of the new species, wenshanensis , is derived from the type locality, Wenshan Prefecture, in Yunnan Province. Te Chinese name for this new species is ‘Wén Shān Gāo Yuán Qīu’ (文山高原鳅) .

Remarks: Te precise GPS locations of the two new cavefish species are not provided in this study to ensure the conservation of their small populations. Tis information is available from the corresponding author upon reasonable request.

Skeletal analysis based on 3D reconstruction

Te bony capsule of the swim bladder of both T. oangi ( Fig. 7) and T. wenshanensis ( Fig. 8) exhibits typical Nemacheilidae characteristics. It was formed through ossifications developing from the second (v2) and the fourth (v4) vertebrae. Te lateral process of the v2 divided into a dorsal arm and a ventral arm, which expanded caudally and connected to the dorsal rib of the v4 (or outer arm of the os suspensorium, as per Conway 2011) and the ventral rib of the v4 (or inner arm of the os suspensorium, as per Conway 2011), respectively. Te dorsal rib of the v4 extended laterally and projected downwards along the anterior and posterior distal edges, fusing with the expanded ventral rib. In both species, the dorsal and ventral rib fused completely at the caudal end, leaving only a small opening at the midline, which serves as the connecting passage between the anterior and posterior chambers of the swim bladder. Te bony capsule presented no lateral walls, and its lateral openings were divided into an anterior and a posterior opening, with the anterior projection of the dorsal rib of the v4 serving as the boundary. Te anterior opening was significantly smaller than the posterior opening. Te ventral rib of the v4 incompletely divided the bony capsule into bilateral sacs along the midsagital plane, accommodating the lef and right anterior chambers of the swim bladder. Te remaining section, referred to as the communication zone, connected the two chambers.

A notable size difference was evident between the bony swim bladder capsule of T. oangi and T. wenshanensis , with T. oangi exhibiting a more enlarged or dilated capsule subtype. Te capsule length in T. wenshanensis extended to ~4% of the body length, reaching between the fourth and fifh vertebrae. In contrast, the bony capsule of T. oangi was ~11% of the body length, extending beyond the sixth vertebra. Compared with T. wenshanensis , T. oangi showed a pronounced reduction in the size of the anterior lateral opening, which appears as a slit, whereas its posterior lateral opening was significantly enlarged. Te capsule wall of T. wenshanensis was thick and uniform, with short and robust lateral process 1, and with a well-defined communication zone between the right and lef lateral sacs. Conversely, the bony capsule of T. oangi was thin, with high levels of fenestration, especially at the communication zone and the contacting sites with the nearby fifh and sixth vertebrae. Te lateral process 1 of T. oangi was longer and thinner than that of T. wenshanensis . Measurements of the vertebral centrum length revealed distinct paterns: in T. wenshanensis , the order was c1 <c2–3 <c5 <c4, whereas in T. oangi , the order was c1 <c5 <c2–3 ≤ c4, indicating a significantly increased length of the fused c2–3 vertebrae in T. oangi .

Molecular results

Phylogenetic analysis was conducted using a concatenated dataset of CYTB and COI gene sequences from 34 species, including the two new species described in this study ( Table 3). Te phylogenetic trees reconstructed using both ML and BI methods showed highly consistent topologies ( Fig. 9), with strong support values for most branches. Both T. oangi and T. wenshanensis were placed within the hypogean group of Triplophosa , but they were not in the same subclade. Triplophosa oangi was found to be a sister group to a lineage comprising five other species, with relationships as follows: (( T. baotianensis , T. nanpanjiangensis ), (( T. zhenfengensis , T. rongduensis ), T. anlongensis )). In contrast, T. wenshanensis was placed as a sister group to T. qiubeiensis , forming a separate subclade with this species.

Pairwise genetic distances under the Kimura two-parameter model were calculated between the two new species and other hypogean Triplophosa congeners ( Table 4). Te genetic distances between T. oangi and its cave-dwelling congeners ranged from 7.2% (vs. T. zhenfengensis ) to 17.0% (vs. T. qiubeiensis ). For T. wenshanensis , genetic distances to its cave-dwelling congeners ranged from 12.8% (vs. T. qiubeiensis ) to 19.9% (vs. T. cehengensis Luo, Mao, Zhao, Xiao & Zhou 2023 ). Te genetic distance between the two new species, T.oangi and T. wenshanensis , was 19.2%.