Research Article |
Corresponding author: Zuogang Peng ( pzg@swu.edu.cn ) Academic editor: Sven Kullander
© 2021 Shijing Chen, Bakhtiyor Sheraliev, Lu Shu, Zuogang Peng.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Chen S, Sheraliev B, Shu L, Peng Z (2021) Triplophysa wulongensis, a new species of cave-dwelling loach (Teleostei, Nemacheilidae) from Chongqing, Southwest China. ZooKeys 1026: 179-192. https://doi.org/10.3897/zookeys.1026.61570
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We describe a new species of cave-dwelling loach, Triplophysa wulongensis sp. nov., based on specimens collected in a subterranean pool in a cave in Wulong County, Chongqing, Southwest China. The pool is connected to the Wujiang River drainage. Triplophysa wulongensis differs from its congeners by the following combination of characters: eyes present, caudal fin with 18 branched rays; posterior chamber of the air bladder degenerate; stomach U-shaped; intestine without bends or loops immediately posterior to stomach; body smooth and scaleless, and lateral line complete. The mitochondrial cytochrome b sequence differs from those of other published sequences of species of Triplophysa by 14.9–24.9% in K2P distance. Phylogenetic analysis based on cytochrome b gene sequences recovered T. wulongensis as sister taxon to all other cave-dwelling species of Triplophysa.
Cavefish, cytb sequence, freshwater fish, ichthyology, phylogeny
The genus Triplophysa Rendahl, 1933, currently comprises approximately 160 valid species, most of which are known from Qinghai-Tibet Plateau and to a lesser extent from Central Asia (
To date, 33 cave-dwelling species of Triplophysa have been described from the karst areas of southern China where karst caves and subterranean streams are dominant geological features (
Characters variable across cave-dwelling species of Triplophysa from China.
No | Species | Eyes | Scales | Lateral line | Posterior chamber of air bladder | Dorsal | Anal | Pectoral | Pelvic | Caudal | Tip of pelvic fin reaching anus | Anterior nostril barbel-like |
---|---|---|---|---|---|---|---|---|---|---|---|---|
fin rays | fin rays | fin rays | fin rays | fin rays | ||||||||
1. | T. aluensis | Reduced | Absent | Complete | Degenerated | iii, 7 | iii, 5 | i, 9 | i, 6 | 13 | No | Yes |
2. | T. anshuiensis | Absent | Absent | Complete | Developed | iv, 7–8 | ii, 6 | i, 10 | i, 6 | 14 | Yes | Yes |
3. | T. baotianensis | Normal | Absent | Complete | Degenerate | iii, 6–7 | ii, 4–5 | i, 9 | i, 5 | 11–13 | No | Yes |
4. | T. erythraea | Absent | Absent | Complete | Developed | ii, 8 | i, 6 | ii, 10 | ii, 5 | 17 | Yes | No |
5. | T. fengshanensis | Absent | Absent | Complete | – | ii, 8 | ii, 6 | i, 8–10 | i, 6–7 | 16 | No | Yes |
6. | T. flavicorpus | Normal | Present | Complete | Degenerated | iii, 10 | iii, 6–7 | i, 11 | i, 6–7 | 16 | Yes | No |
7. | T. gejiuensis | Absent | Absent | Complete | Developed | iii, 7–8 | iii, 4–6 | i, 10 | i, 5 | 14–15 | Yes | Yes |
8. | T. guizhouensis | Normal | Present | Complete | Developed | iii, 8 | iii, 6 | i, 8–9 | i, 6 | 14 | No | Yes |
9. | T. huanjiangensis | Absent | Absent | Absent | Developed | iii, 8–9 | iii, 6–7 | i, 10–14 | i, 6–7 | 13–14 | No | Yes |
10. | T. huapingensis | Normal | Present | Complete | Degenerated | iii, 8–9 | iii, 5 | i, 9–10 | i, 5–6 | 16 | No | No |
11. | T. langpingensis | Reduced | Absent | Incomplete | – | iii, 7–8 | iii, 5–6 | i, 10–11 | i, 6 | 14 | Yes | Yes |
12. | T. lingyunensis | Reduced | Present | Incomplete | Degenerated | iii, 7–8 | iii, 5 | i, 8–9 | i, 5–6 | 16 | No | Yes |
13. | T. longipectoralis | Normal | Present | Complete | Degenerated | iii, 8 | iii, 5–6 | i, 9–10 | i, 6 | 14–15 | Yes | Yes |
14. | T. longliensis | Normal | Absent | Complete | Developed | iii, 8 | iii, 5 | i, 10 | i, 6 | 15–16 | Yes | Yes |
15. | T. luochengensis | Reduced | Present | Complete | Degenerated | iii, 8 | ii, 6 | i, 10 | i, 6 | 16–17 | No | Yes |
16. | T. macrocephala | Reduced | Absent | Complete | Degenerated | iii, 7–9 | iii, 5–6 | i, 9–11 | i, 6 | 15–17 | Yes | Yes |
17. | T. maolanensis | Absent | Absent | Complete | – | iii, 8 | ii, 5 | i, 11 | i, 6 | 14 | Yes | No |
18. | T. nandanensis | Normal | Present | Complete | Degenerated | iv, 8 | iv, 5 | i, 9–10 | i, 6 | 14–16 | No | Yes |
19. | T. nanpanjiangensis | Normal | Absent | Complete | Degenerated | iii, 7–8 | ii, 5 | i, 9–10 | i, 6 | 16 | No | Yes |
20. | T. nasobarbatula | Normal | Present | Complete | Degenerated | iii, 8 | iii, 5 | i, 9 | i, 6 | 15 | Yes | Yes |
21. | T. posterodorsalus | Absent | Absent | Complete | – | iii, 6 | ii, 4 | i, 13 | i, 5 | 15 | No | Yes |
22. | T. qiubeiensis | Absent | Absent | Complete | Degenerated | iii, 7 | iii, 5 | i, 7–9 | i, 5 | 14–15 | Yes | No |
23. | T. rosa | Absent | Absent | Complete | – | iii, 9 | iii, 6 | i, 12 | i, 7 | 14 | Yes | Yes |
24. | T. sanduensis | Normal | Present | Complete | Degenerated | ii, 8–9 | i, 5 | i, 8–9 | i, 5 | 17–18 | No | Yes |
25. | T. shilinensis | Absent | Absent | Complete | Degenerated | iii, 7 | iii, 5 | i, 8–10 | i, 6 | 14 | No | Yes |
26. | T. tianeensis | Reduced | Absent | Complete | Degenerated | iii, 6–7 | iii, 5 | i, 8–9 | i, 5–6 | 15–16 | No | Yes |
27. | T. tianlinensis | Reduced | Absent | Complete | Degenerated | iii, 7 | iii, 5–6 | i, 10 | i, 6 | 15–16 | Yes | Yes |
28. | T. tianxingensis | Normal | Absent | Complete | Developed | iii, 8 | ii, 5 | i, 9 | i, 5 | 16 | No | No |
29. | T. wulongensis sp. nov. | Normal | Absent | Complete | Degenerated | ii, 8–9 | i, 5–6 | i, 8–9 | i, 5–7 | 18 | No | Yes |
30. | T. xiangshuingensis | Normal | Absent | Complete | Degenerated | iii, 6 | iii, 5 | i, 9 | i, 6 | 14 | No | Yes |
31. | T. xiangxiensis | Absent | Absent | Complete | Developed | iii, 8 | iii, 6 | i, 11 | i, 6 | 16 | Yes | Yes |
32. | T. xichouensis | Reduced | Absent | Complete | Developed | iii, 8 | ii, 6 | i, 9–10 | i, 5–6 | 16 | Yes | Yes |
33. | T. yunnanensis | Normal | Present | Complete | Degenerated | iii, 7 | iii, 5 | i, 9–10 | i, 7 | 15–16 | No | Yes |
34. | T. zhenfengensis | Normal | Present | Complete | Degenerated | iii, 7 | iii, 5 | i, 9 | i, 5–7 | 14–15 | No | Yes |
We collected nine loach specimens from a subterranean pool in a cave located in Wulong County, Chongqing, Southwest China. Morphological and molecular analyses justified the recognition of this sample as representing a new species of Triplophysa, described below.
After anesthesia, the specimens were fixed in 10% formalin and stored in 70% ethanol. Measurements were made with digital calipers and rounded off to the nearest 0.1 mm. All measurements were made point to point, and whenever possible, measurements and counts were recorded on the left side of the body following the methods described by
Data on Triplophysa aluensis Li & Zhu, 2000, T. gejiuensis (Chu & Chen, 1979), T. nanpanjiangensis (Zhu & Cao, 1988), T. qiubeiensis Li & Yang, 2008, T. shilinensis Chen & Yang, 1992, T. tianxingensis Yang, Li & Chen, 2016, T. xiangshuingensis Li, 2004 and T. yunnanensis Yang, 1990 are from
Genomic DNA was extracted from ethanol-preserved fin tissue using a DNeasy Blood and Tissue Kit (QIAGEN, Shanghai, China). The primers used for PCR amplification of the mitochondrial cytochrome b (cytb) gene are described by
We sequenced partial cytb gene of T. longliensis, T. nandanensis Lan, Yang & Chen, 1995, T. sanduensis Chen & Peng, 2019, T. tianeensis Chen, Cui & Yang, 2004, and T. wulongensis and retrieved the cytb gene sequences for other species of Triplophysa from GenBank (Table
The species used in this study with their GenBank accession number for the mitochondrial cytb gene sequences.
Species | GenBank accession number | Species | GenBank accession number |
---|---|---|---|
Barbatula nuda | KF574248 | Triplophysa minxianensis | KT213596 |
Barbatula toni | AB242162 | Triplophysa nandanensis | MW582824 |
Triplophysa anterodorsalis | KJ739868 | Triplophysa rosa | JF268621 |
Triplophysa bleekeri | JQ686729 | Triplophysa sanduensis | MW582822 |
Triplophysa brevicauda | KT213588 | Triplophysa siluroides | KT213603 |
Triplophysa chondrostoma | KT213589 | Triplophysa tianeensis | MW582826 |
Triplophysa erythraea | MG967615 | Triplophysa tibetana | KT224364 |
Triplophysa huapingensis | MG697589 | Triplophysa wulongensis | MW582823 |
Triplophysa lewangensis | KU987438 | Triplophysa xiangxiensis | KT751089 |
Triplophysa longliensis | MW582825 | Triplophysa xichangensis | KT224366 |
Triplophysa markehenensis | KT213594 | Triplophysa zhenfengensis | MK610360 |
Triplophysa microps | KT213595 |
Holotype. SWU2019051309, male, 64.0 mm SL. P.R. China: Chongqing City; Wulong County: subterranean pool in Furong Cave (29°24'1.09"N, 107°54'11.60"E); collected by Ni Liu, May 2019.
Paratypes. SWU2019051301–2019051308, 8 ex., 49.0–67.2 mm SL; collected with the holotype.
Triplophysa wulongensis can be distinguished from its congeners by the following combination of characters: eyes present (vs absent in T. anshuiensis, T. erythraea, T. huanjiangensis Yang, Wu & Lan, 2011, T. rosa Chen & Yang, 2005, T. xiangxiensis and T. posterodorsalus); anterior nostril barbel-like (vs anterior nostril not elongate to barbel-like in T. erythraea, T. flavicorpus, T. huapingensis Zheng, Yang & Chen, 2012 and T. tianxingensis): caudal fin with 18 branched rays (vs 14–16 in T. guizhouensis, T. lingyunensis (Liao, Wang & Luo, 1997), T. nandanensis, T. shilinensis and T. zhenfengensis Wang & Li, 2001), vertebrae 4+38–39 (vs 36–37 in T. nasobarbatula Wang & Li, 2001 and T. sanduensis; 42–43 in T. siluroides); predorsal length 50.4–54.2% of standard length (vs 46.1–48.0% in T. sanduensis); posterior chamber of gas bladder degenerate (vs developed in T. anshuiensis, T. tianxingensis and T. xichouensis); body smooth and scaleless (vs body covered by scales in T. longipectoralis Zheng, Du, Chen & Yang, 2009 and T. yunnanensis); lateral line complete (vs incomplete in T. huanjiangensis); and pelvic-fin tip not reaching to anus (vs reaching to anus in T. gejiuensis, T. macrocephala Yang, Wu & Yang, 2012, T. rosa and T. qiubeiensis).
Morphometric data of the type specimens of T. wulongensis are presented in Table
Morphometric data of type specimens of Triplophysa wulongensis sp. nov. SD = standard deviation.
Morphometric characters | Holotype | Paratypes (SWU2019051301–08) | |||
---|---|---|---|---|---|
SWU2019051309 | Min | Max | Mean | SD | |
SL (mm) | 64 | 49 | 67.2 | 55.7 | |
% SL | |||||
Lateral head length (HL) | 22.9 | 20.4 | 23.5 | 22.6 | 1 |
Body depth | 13.3 | 9.3 | 13.6 | 12.1 | 1.3 |
Predorsal length | 54.2 | 50.4 | 53.3 | 51.9 | 0.9 |
Postdorsal length | 40.7 | 34 | 39.4 | 36.7 | 1.4 |
Prepelvic length | 49.6 | 48.3 | 50.9 | 49.7 | 0.9 |
Preanal length | 76 | 71.5 | 77.7 | 73.4 | 1.8 |
Preanus length | 70 | 67.4 | 70.2 | 69 | 1 |
Dorsal-fin height | 15.9 | 15 | 19.8 | 16.5 | 1.5 |
Dorsal-fin base length | 12 | 10.7 | 13.4 | 12.4 | 0.9 |
Anal-fin height | 14.1 | 12.4 | 16.5 | 14.5 | 1.3 |
Anal-fin base length | 6.6 | 6.6 | 8.2 | 7.4 | 0.6 |
Pelvic-fin length | 12.4 | 12.5 | 14.5 | 13.2 | 0.6 |
Pectoral-fin length | 16.6 | 15.6 | 18.4 | 17.6 | 1 |
Caudal-fin length | 17.8 | 15.9 | 20.8 | 18.1 | 1.3 |
Caudal-peduncle length (CPL) | 20.8 | 14.2 | 18.4 | 16.6 | 1.2 |
Caudal-peduncle depth (CPD) | 9.4 | 7.6 | 9.4 | 8.5 | 0.7 |
Pectoral-pelvic distance | 26.8 | 24.6 | 28.6 | 26.6 | 1.1 |
Pelvic-anal distance | 26.4 | 21.6 | 26.9 | 23.7 | 1.4 |
Vent-anal fin origin distance | 6.2 | 4 | 7.2 | 5.8 | 1 |
%HL | |||||
Head depth | 53.8 | 45.3 | 54.2 | 50.6 | 2.9 |
Head width | 62.2 | 55.7 | 65.8 | 62.4 | 3.5 |
Snout length | 39 | 38.9 | 45 | 41.9 | 1.9 |
Eye diameter | 11.1 | 12.2 | 19.1 | 17 | 2.1 |
Interorbital width | 38.7 | 38.5 | 43.1 | 41.3 | 1.5 |
Postorbital head length | 45 | 37.9 | 46.8 | 43.8 | 2.8 |
Maxillary barbel length | 21.8 | 27.2 | 35.9 | 29.8 | 3.2 |
Inner rostral barbel length | 16.5 | 20.1 | 23.4 | 21.6 | 1.2 |
Outer rostral barbel length | 21.4 | 25.9 | 41.5 | 32.4 | 4.5 |
CPD/CPL | 45.3 | 44.3 | 57.4 | 51.2 | 4.5 |
Body elongated, slightly compressed anteriorly and more strongly compressed posteriorly. Deepest point of body in front of dorsal fin origin, body depth 9.3–13.6% of SL. Caudal peduncle depth/caudal peduncle length range from 44.3% to 57.4%. Head depressed, width greater than depth (62.4% vs 50.6% of HL). Snout moderately blunt and snout length almost equal to postorbital length, approximately 38.9–45.0% of HL. Anterior and posterior nostrils adjacently located; anterior nostril in short tube, each with tip elongated to form a short barbel. Tip of nostril appendage not reaching the anterior margin of eyes. Eyes present, diameter 11.1–19.1% of HL. Mouth inferior, arched; mouth corner situated below anterior nostril. Lips thin; lower lip with well-marked, V-shaped, median notch (Fig.
Dorsal fin emarginate, origin posterior to pelvic fin insertion, situated slightly posterior to midpoint between snout tip and caudal fin base; first branched ray longest; dorsal fin height shorter than lateral head length; tip of dorsal fin reaching vertical of anus. Pectoral fin moderately developed, 56.6–72.9% of distance between pectoral fin and pelvic-fin origins. Pelvic-fin origin situated almost at midpoint between pectoral-fin origin and anal-fin origin, tip of pelvic fin not reaching to anus. Anal-fin origin situated almost at midpoint between pelvic-fin origin and caudal-fin base, distal margin of anal fin truncate; posterior tip of anal fin reaching approximately half distance between anal-fin origin and caudal-fin base. Vent-anal fin-origin distance 4.0–7.2% of SL. Caudal fin emarginate.
Body smooth and scaleless. Cephalic lateral line system developed. Lateral line complete, ending at caudal-fin base. Intestine without bends or loops immediately posterior to stomach; stomach U-shaped. Posterior chamber of gas bladder degenerate.
In formalin-fixed specimens, body yellowish dorsally, gradually lighter toward ventral side. Fins semitransparent. Body dorsally and laterally covered with irregular, brown blotches; 6–8 distinct dark brown blotches along dorsal midline.
Sexual dimorphism was not detected. This may reflect that the sampling time was outside the breeding season of this species.
The specific name, wulongensis, refers to the type locality in Wulong County, where the type specimens were collected; it is an adjective with alternative endings -is and -e.
In previous studies, the cave dwelling species of Triplophysa were nested in a basal position to congeners in phylogenetic reconstructions (
The presence or absence of the secondary sexual characteristics is important for the generic diagnosis of loaches (
The majority of the cave-dwelling species of Triplophysa were described from karst caves and subterranean streams in the Pearl river basin and the upper Yangtze river basin, with an additional two species (T. erythraea and T. xiangxiensis) reported from the Yuanjiang river drainage (a tributary of the middle Yangtze River) and a single species (T. rosa) described from the Wujiang river drainage (
The rate of discovery of new cave-dwelling species of Triplophysa has increased in recent years (
1 | Eyes normal | 2 |
– | Eyes reduced or absent | 16 |
2 | Scales absent | 3 |
– | Body covered by scales | 8 |
3 | Tip of pelvic fin reaching anus, outer gill rakers on first gill arch absent | T. longliensis |
– | Tip of pelvic fin not reaching anus; outer gill rakers on first gill arch present | 4 |
4 | Posterior chamber of air bladder developed; anterior nostril not elongate to barbel-like | T. tianxingensis |
– | Posterior chamber of air bladder degenerated; anterior nostril elongate to barbel-like | 5 |
5 | Dorsal-fin origin closer to caudal-fin base than to snout tip | T. wulongensis sp. nov. |
– | Dorsal-fin origin closer to snout tip than to caudal-fin base | 6 |
6 | Dorsal-fin origin opposite vertical line trough pelvic-fin origin | T. nanpanjiangensis |
– | Dorsal-fin origin anterior to vertical line trough pelvic fin origin | 7 |
7 | Caudal fin deep forked with 11–13 branched fin rays | T. baotianensis |
– | Caudal fin slightly forked with 14 branched fin rays | T. xiangshuingensis |
8 | Processus dentiformis present in upper jaw | T. zhenfengensis |
– | Processus dentiformis absent in upper jaw | 9 |
9 | Posterior chamber of air bladder developed | T. guizhouensis |
– | Posterior chamber of air bladder degenerated | 10 |
10 | Tip of depressed pelvic fin exceeding anus | 11 |
– | Tip of depressed pelvic fin not reaching anus | 13 |
11 | Anterior nostril not elongate to barbel-like; branched dorsal-fin rays 10 | T. flavicorpus |
– | Anterior nostril elongate to barbel-like; branched dorsal-fin rays 8 | 12 |
12 | Tip of pectoral fin extending beyond pelvic-fin origin | T. longipectoralis |
– | Tip of pectoral fin not reaching pelvic-fin origin | T. nasobarbatula |
13 | Branched dorsal-fin rays 7, branched anal-fin rays 7 | T. yunnanensis |
– | Branched dorsal-fin rays 8, branched anal-fin rays 5–6 | 14 |
14 | Dorsal-fin origin opposite vertical line trough pelvic-fin origin | T. nandanensis |
– | Dorsal fin origin anterior to vertical line trough pelvic fin origin | 15 |
15 | Anterior nostril not elongate to barbel-like; branched caudal-fin rays 16 | T. huapingensis |
– | Anterior nostril elongate to barbel-like; branched dorsal-fin rays 17–18 | T. sanduensis |
16 | Eyes reduced | 17 |
– | Eyes absent | 24 |
17 | Body covered with scales | 18 |
– | Scales absent, body smooth | 19 |
18 | Lateral line complete, branched anal-fin rays 6 | T. luochengensis |
– | Lateral line incomplete, branched anal-fin rays 5 | T. lingyunensis |
19 | Lateral line incomplete; adipose keels present on upper or lower side of caudal peduncle | T. langpingensis |
– | Lateral line complete; adipose keels absent from caudal peduncle | 20 |
20 | Posterior chamber of air bladder developed | T. xichouensis |
– | Posterior chamber of air bladder degenerated | 21 |
21 | Tip of pelvic fin reaching anus | 22 |
– | Tip of pelvic fin not reaching to anus | 23 |
22 | Tip of pectoral fin reaching to midway between pectoral-fin origin and pelvic-fin origin; Spots absent from body | T. tianlinensis |
– | Tip of pectoral fin reaching a vertical through dorsal-fin origin; spots present on body | T. macrocephala |
23 | Dorsal-fin origin posterior to or at to vertical line trough pelvic-fin origin; branched caudal-fin rays 13 | T. aluensis |
– | Dorsal-fin origin anterior to vertical line trough pelvic-fin origin; branched caudal-fin rays 15–16 | T. tianeensis |
24 | Lateral line absent | T. huanjiangensis |
– | Lateral line complete | 25 |
25 | Tip of pelvic-fin not reaching to anus | 26 |
– | Tip of pelvic fin reaching to anus | 28 |
26 | Adipose keels present on upper or lower side of caudal peduncle | T. posterodorsalus |
– | Adipose keels absent from caudal peduncle | 27 |
27 | Branched dorsal-fin rays 8; branched caudal-fin rays 16 | T. fengshanensis |
– | Branched dorsal-fin rays 7; branched caudal-fin rays 14 | T. shilinensis |
28 | Anterior nostril not elongate to barbel-like | 29 |
– | Anterior nostril elongate to barbel-like | 31 |
29 | Lips developed, papillary process absent, branched caudal-fin rays 17 | T. erythraea |
– | Lips developed, papillary process present, branched caudal-fin rays 14–15 | 30 |
30 | Branched dorsal fin rays 8; branched pectoral-fin rays 11 | T. maolanensis |
– | Branched dorsal-fin rays 7; branched pectoral-fin rays 7–9 | T. qiubeiensis |
31 | Distal margin of dorsal fin truncate; branched dorsal-fin rays 7–8; branched pectoral-fin rays 9–11; branched pelvic-fin rays 6 | 32 |
– | Distal margin of dorsal-fin concave; branched dorsal-fin rays 9; branched pectoral-fin rays 12; branched pelvic-fin rays 7 | T. rosa |
32 | Snout blunt; tip of pectoral fin not reaching vertical level of dorsal fin origin; tip of caudal-fin lobes pointed; branched caudal-fin rays 14–15 | 33 |
– | Snout rectangle-like; tip of pectoral fin reaching a vertical through dorsal-fin origin; tip of caudal-fin lobe sharp; branched caudal-fin rays 16 | T. xiangxiensis |
33 | Cephalic lateral-line canals with 5 supraorbital and 7 preoperculo-mandibular pores | T. gejiuensis |
– | Cephalic lateral-line canals with 8 supraorbital and 12–13 preoperculo-mandibular pores | T. anshuiensis |
We are indebted to Ms Ni Liu for her help with the specimen collections. This work was supported by grant from the National Natural Science Foundation of China (31872204).
Table S1
Data type: Specimen list
Explanation note: Material examined of Triplophysa species from China.