Triplophysa yaluwang Lan, Liu, Zhou & Zhou, 2024

Lan, Chang-Ting, Wu, Li, Luo, Tao, Liu, Ye-Wei, Zhou, Jia-Jun, Yu, Jing, Zhao, Xin-Rui, Xiao, Ning & Zhou, Jiang, 2024, Two new hypogean species of the genus Triplophysa (Osteichthyes, Cypriniformes, Nemacheilidae) from Guizhou Province, Southwest China, with underestimated diversity, ZooKeys 1214, pp. 237-264 : 237-264

Triplophysa yaluwang Lan, Liu, Zhou & Zhou sp. nov.

Figs 6 , 7 , Table 5 , Suppl. material 1

Type material.

Holotype. GZNU 20240118001 (Fig. 6 ), 87.6 mm total length (TL), 73.9 mm standard length (SL), collected by Jia-Jun Zhou on 18 January 2024, in Xinzhai Village , Maoying Town, Ziyun County, Guizhou Province, China (25.89908752 ° N, 106.07921141 ° E, 1276 m a. s. l.; Fig. 1 ).

Paratypes. Four specimens from the same locality as the holotype: GZNU 20240118002–118005, 54.1–83.9 mm SL, collected by Jia-Jun Zhou and Ye-Wei Liu on 27 September 2023.

Diagnosis.

Triplophysa yaluwang sp. nov. is distinguished from other hypogean species of the genus Triplophysa by the following characteristics in combination: (1) body naked, scaleless, with irregular pale dark brownish brown markings, except ventral; (2) eyes reduced, diameter 4.6–6.1 % of head length; (3) pelvic-fin tip reaching anus; (4) tip of pectoral fin not reaching to pelvic fin origin; (5) anterior and posterior nostrils closely set, with the anterior nostril elongated to a barbel-like tip; (6) tip of outrostral barbel extending backward, not reaching to anterior margin of eye; (7) lateral line complete; (8) posterior chamber of air bladder degenerated; and (9) dorsal-fin rays iii- 7, pectoral-fin rays i- 9, pelvic-fin rays i- 5, anal-fin rays i- 5, and 14 branched caudal-fin rays.

Description.

Morphological data of Triplophysa yaluwang sp. nov. specimens are provided in Table 5 and Suppl. material 1. Body elongated and cylindrical, posterior portion gradually compressed from dorsal fin to caudal-fin base, with deepest body depth anterior to dorsal-fin origin, deepest body depth 12–16 % of SL. Dorsal profile slightly convex from snout to dorsal-fin insertion, then straight from posterior portion of dorsal-fin origin to caudal-fin base. Ventral profile flat. Head short, length 26–27 % of SL, slightly depressed and flattened, width slightly greater than depth (HW / HD = 1.1–1.3). Snout slightly pointed, and snout length 43–52 % of HL. Mouth inferior and curved, mouth corner situated below anterior nostril, upper and lower lips smooth, lower lip with V-shaped median notch. Three pairs of barbels are present: inner rostral barbel long, length 16–27 % of HL, backward extending to corner of mouth; out rostral barbel long, length 39–44 % of HL, backward extending to beyond anterior margin of eyes. Maxillary barbel not extending to posterior margin of operculum, length 22–36 % of HL. Anterior and posterior nostrils closely set, length 0.44–0.82 mm. Anterior nostril tube long, with an elongated short barbel-like tip, tip of posterior nostril extending backwards not reaching to anterior margin of eye. Eyes reduced, with diameter 5–6 % of HL. Gill opening small, gill rakers not developed, nine inner gill rakers on first gill arch (n = 1).

Dorsal-fin rays iii- 7, pectoral-fin rays i- 9, pelvic-fin rays i- 5–6, anal-fin rays i- 5, 14 branched caudal-fin rays. Dorsal fin short, length 19–22 % of SL, distal margin emarginated, origin anterior to pelvic-fin insertion and situated slightly posterior to the midpoint between snout tip and caudal-fin base, first branched ray longest, shorter than head length, tip of dorsal fin vertical to anus. Pectoral fin moderately developed, length 19–25 % of SL, tip of pectoral fin extending backward almost to the midpoint between origin of pectoral and pelvic fin origins, not reaching to pelvic fin origin. Pelvic fin length 16–17 % of SL, vertically aligned with second branched ray of dorsal fin, tips of pelvic fin reaching to anus. Anal fin length 16–18 % of SL, distal margin truncated, origin close to anus, tips of anal fin not reaching caudal-fin base, distance between tips of anal fin and anus 2.2 × the eye diameter. Caudal fin forked, upper lobe slightly longer than lower lobe, tips pointed, caudal peduncle length ~ 12 mm, caudal peduncle depth ~ 4.8 mm, with weak adipose crests along both dorsal and ventral sides. Total vertebrae: 40 (n = 1).

Cephalic lateral line system developed. Lateral line complete, exceeding tip of pectoral fin and reaching base of caudal fin. Two chambers of air bladder, anterior chamber dumbbell-shaped and membranous, open on both sides, slightly closed posteriorly; posterior chamber degenerated, slightly filling the body cavity, connected with anterior chamber by a long, slender tube.

Coloration.

In cave water, living fish were semi-translucent with a pale pink body with irregular dark brownish brown patches on the Entire body (Fig. 7 ). After fixation in 10 % formalin, the body color was white, and the dark brown color lightened (Fig. 6 ).

Variations.

Among the five specimens collected, GZNU 20240118002–118004 are essentially identical to the holotype in fin characteristics and body coloration. GZNU 20240118005 differs from the holotype by the absence of body pigmentation and the absence of the eye (Fig. 7 ).

Secondary sex characteristics.

Secondary sex characteristics were not observed in the specimens of Triplophysa yaluwang sp. nov.

Comparisons.

Detailed morphological comparative data of Triplophysa yaluwang sp. nov. with Triplophysa ziyunensis sp. nov. and the 39 hypogean species of Triplophysa are given in Table 2 . Triplophysa yaluwang sp. nov. is genetically close to T. guizhouensis , T. longliensis , and T. sanduensis , but it can be distinguished in combination with morphological characteristics.

Triplophysa yaluwang sp. nov. can be distinguished from Triplophysa ziyunensis sp. nov. by having dorsal fin distal margin being emarginated (vs truncated), total vertebrae 40 (vs 39), seven branched dorsal fin rays (vs 8), nine branched pectoral fin rays (vs 10), and 14 branched caudal fin rays (vs 16).

Triplophysa yaluwang sp. nov. is distinguished from T. longliensis by having eyes reduced, small diameter 4.6–6.1 % of HL (vs normal, diameter 9.5–11.5 % of HL), interorbital width, 24.3–26.0 % of HL (vs 31.4–37.5 of HL), total vertebrae 40 (vs 42), degenerated posterior chamber of air bladder (vs developed), seven branched dorsal-fin rays (vs 8), nine branched pectoral-fin rays (vs 10), and 14 branched caudal-fin rays (vs 15–16).

Triplophysa yaluwang sp. nov. is distinguished from T. sanduensis by having eyes reduced, small diameter 4.6–6.1 % of HL (vs normal, diameter 11.9–15.4 % of HL), interorbital width, 24.3–26.0 % of HL (vs 31.2–40.2 of HL), total vertebrae 40 (vs 41), dorsal-fin rays, iii, 7 (vs ii, 8–9), three unbranched anal-fin rays (vs 1), 14 branched caudal-fin rays (vs 17–18), and tip of pelvic fin reaching anus (vs not reaching anus).

Triplophysa yaluwang sp. nov. differs from T. guizhouensis by having eyes reduced, diameter 4.6–6.1 % of HL (vs normal, diameter 9.4–12.1 % of HL), dorsal fin distal margin being emarginated (vs truncated), body scaleless (vs body covered by sparse scales), degenerated posterior chamber of air bladder (vs developed), seven branched dorsal fin rays (vs 8), five branched anal-fin rays (vs 6), and tip of pelvic fin reaching anus (vs not reaching anus).

Ecology and distribution.

The new species Triplophysa yaluwang sp. nov. was found in one cave far from the village of Xinzhai Village, Maoying Town, Ziyun County, Guizhou Province, China (Fig. 1 ), in a water system where the underground river is a tributary of the Hongshui River. The cave habitat is a vertical shaft with an entrance located halfway up the mountainside. The underground river is approximately 150 m deep from the entrance, and the accessible portion is around 200 m long, 3 m wide, and 1–2 m deep. In this cave, the new species is sympatric with Sinocyclocheilus multipunctatus and some unnamed spiders.

Remarks.

The new species, Triplophysa yaluwang sp. nov., inhabits the underground rivers of the type locality. Eyes are present and reduced, and with irregular dark brownish brown patches on the head and body. Therefore, this species can be considered as a stygophile fish within the hypogean group of the genus Triplophysa .

Etymology.

The specific epithet yaluwang comes from King Yalu, a hero to the Miao people of Ziyun County, Guizhou Province, China, where the type locality is found. He was the 18 th generation leader of the Miao ancestors in western China and led the Miao people through many trials and tribulations. He eventually carved out a suitable land for his people to live in near the type locality. His deeds have been preserved in the form of a song, which has been organized into the first full-length heroic epic of the Hmong, King Yalu. We propose the common English name “ King Yalu high-plateau loach ” and the Chinese name “ Yà Lǔ Wáng Gāo Yuán Qīu (亚鲁王高原鳅) ”.

Figures

Figure 1. Sample collection localities and distributions of the two new species and 39 hypogean species of the genus Triplophysa in southern China. The base maps are from the Standard Map Service website (http://bzdt.ch.mnr.gov.cn/index.html).

Figure 6. Morphological characteristics of holotype GZNU 20240118001 of Triplophysa yaluwang sp. nov. in preservative (10 % formalin) A dorsal view B ventral view C lateral view D dorsal view of head E lateral view of head, and F ventral view of head.

Figure 7. Ecological photographs of Triplophysa yaluwang sp. nov. and closely related species in life A Triplophysa yaluwang sp. nov. (paratype, GZNU 20240118002) B Triplophysa yaluwang sp. nov. (paratype, GZNU 20240118005), and C T. guizhouensis.