Balitora dehouensis Lei, Pu & Yang, 2025

Balitora dehouensis Lei, Pu & Yang, 2025 sp. nov.

Holotype.

PXR 20241123001 , 61.1 mm SL; outlet of Lengfeng Cave, Dehou River, a tributary of the Lujiang River in Tieze Village , Dehou Town, Wenshan Zhuang and Miao Autonomous Prefecture, Yunnan Province, China (23.515678°N, 103.845043°E). Collected by Xin-Rui Pu, 24.XI.2024. GoogleMaps

Paratypes.

PXR 20241123002 -005 (4), 44.5–29.0 mm SL; other data same as holotype GoogleMaps . YHF 20230925001 -012 (12), 58.4– 28.6 mm SL; Subterranean stretch of Dehou River, a tributary of the Lujiang River in Lengfeng Cave , Tieze Village, Dehou Town, Wenshan Zhuang and Miao Autonomous Prefecture, Yunnan Province, China. Collected by Hong-Fu Yang, 25. X. 2023 .

Diagnosis.

A medium-sized balitorid with separated pelvic fins and two simple pelvic fin rays. Paired fins with no dark markings. Arched mouth with both jaws covered by a horny sheath; rostral flap divided into three lobes, separated by long rostral barbels; both lips with one row of indistinct papillae; two pairs of prominent maxillary barbels at corners of mouth, both longer than eye diameter. Oblique caudal-fin base, upper end significantly longer than lower end (Figs 8 View Figure 8 , 9 View Figure 9 ). The upper lobe of caudal fin longer than lower.

Description.

Morphological comparison of B. dehouensis with two other known troglobitic members of Balitora as well as their only congener possessing two pairs of long maxillary barbels, Namely B. anlongensis , B. longibarbata and B. ludongensis are demonstrated in Table 2 View Table 2 . See Fig. 3 View Figure 3 for a general profile of body. Body elongated, rounded laterally and flattened ventrally, posterior portion gradually compressed from dorsal fin to caudal-fin base, With the highest point of body at dorsal-fin origin. Body covered in small scales, lateral-line scales 74–78. Each scale with a prominent longitudinal keel along center. Lateral-line scales with two additional smaller keels along posterior edge, above and below principal longitudinal keel.

Head blunt and depressed, dorsum of head densely covered with tiny tubercles. Head length greater than head width and head width much greater than head depth. Eyes small, 2.31–1.05 % SL; situated dorsally, slightly posterior to the midpoint of head, not visible from ventral view. Interorbital space wide and flat.

Mouth small, arched shaped, inferior, relatively shallow preoral groove present between rostral cap and upper lip, extending across corners of mouth. Rostral cape around upper lip and divided into three lobes by rostral barbels, the median one the largest, slightly curved. Two pairs of rostral barbels, both longer than eye diameter, outer one slightly longer than the inner one. Two pairs of long maxillary barbels, both exceeding eye diameter, outer one slightly longer than the inner one, situated at corner of mouth. Upper and lower jaws covered by a horny sheath. Upper and lower lips with a single row of large, indistinct papillae. Lower jaw with radiate ridges on surface. Two longitudinal fleshy ridges on mid-chin (Fig. 4 View Figure 4 ). Gill opening large, extending to the pectoral fin origin on the ventral surface.

Dorsal fin rays i, 8, pectoral fin rays xi, 12, pelvic fin rays ii, 8, anal fin rays i, 5, and Principal caudal fin rays 7 + 8. Dorsal fin origin slightly anterior to pelvic-fin origin and nearer to tip of snout than to caudal fin base. Pectoral fins large and horizontally placed, posterior margin rounded. Tip of the pectoral fin not reaching pelvic fin origin. Pelvic fins short, not reaching or just reaching anus, posterior margin straight. Pelvic fin origin closer to snout tip than caudal fin base and closer to anal fin origin than snout tip. Pelvic fin not reaching anus. Anus situated approximately 2 / 3 distance from posterior end of the pelvic-fin base to the anal fin origin. Anal fin short, origin close to the anus and far from the caudal fin base, tips of which not reaching caudal fin base when extended backwards. Caudal-fin base oblique, upper end significantly longer than lower end. Caudal fin deeply forked, upper lobe longer than lower lobe. Uppermost and lowermost three or four principal caudal rays without interradial membranes and tightly associated. Caudal peduncle slender, length of which 4.82–3.37 times of depth.

Coloration.

In living specimens: a comparison of live coloration of epigean and hypogean individuals of B. dehouensis is illustrated in Fig. 5 View Figure 5 .

In specimens from subterranean water bodies, body uniformly creamy yellow. Dorsum of head yellowish, covered with white tubercles. Dorsum of body with obscure dark blotches situated longitudinally in dorsal profile. Sides of body with scattered dark spots on scales. Dorsal fin rays golden, interradial membranes hyaline. pectoral and pelvic fin bases with dark blotches. Pectoral and pelvic fin rays golden, interradial membranes hyaline. Anal fin hyalin. Caudal-fin base with a rectangular dark blotch. Uppermost and lowermost caudal fin rays light brown, other rays golden. Interradial membranes hyaline. (Fig. 5 View Figure 5 ).

In specimens collected from epigean waters, dorsal and lateral sides of the body greyish brown, creamy ventrally. Dorsum of head dark grey, covered with white tubercles. Medium of body with 8 saddle shaped dark blotches situated longitudinally in the dorsal profile. Sides of body uniformly dark grey. Dorsal fin rays dark grey, interradial membranes hyaline. Pectoral and pelvic fin bases brown with dark blotches from dorsal view. Pectoral and pelvic fin rays dark grey with no markings, interradial membranes hyaline. Anal fin hyalin. Caudal-fin base with a rectangular dark blotch. Caudal fin greyish with a black bar, closer to margin of fin than to caudal-fin base. Uppermost and lowermost fin rays dark grey. Interradial membranes hyaline. (Figs 5 View Figure 5 , 6 View Figure 6 ).

In preserved specimens: coloration turned lighter in preservation, body background colour light grey to creamy white laterally and creamy-yellowish ventrally. Scales with scattered black spots Pigments on fins fainted.

Distribution and ecology.

This species is presently only known from the outlet and subterranean river of Lengfeng Cave, a stretch of Dehou River (Fig. 7 View Figure 7 ). This species inhabits torrential stretches of river with clear, well-oxygenated water as well as boulder and gravel substrate. Enlarged and flattened paired fins enable it to resist the current and adhere to the rocky surface while feeding on algae and aquatic invertebrates. During the rainy season, subterranean water levels rise, creating a riparian environment at the outlet of Lengfeng Cave ideal for B. dehouensis , making it possible to be collected outside the cave. During the dry season, subterranean water levels fall and B. dehouensis retreats into the cave. It was initially discovered by locals on 10. I. 2023. (private communication). Syntopic fish species observed at the same locality with B. dehouensis include Anabarilius transmontana ( Xenocyprididae ), Discogobio antethoracalis , Sinocyclocheilus wenshanensis ( Cyprinidae ), Homatula wenshanensis , Triplophysa wenshanensis ( Nemacheilidae ) and Paralepidocephalus yui ( Cobitidae ).

Etymology.

The specific epithet “ dehouensis ” refers to the type locality: Tieze Village, Dehou Town, Wenshan Zhuang and Miao Autonomous Prefecture, Yunnan Province, China. Regarding the bizarre caudal-fin base of B. dehouensis , we propose the common English name “ Dehou heterocercal stone loach ” and the Chinese name “ De Hou Yi Wei Pa Qiu (德厚异尾爬鳅) ”.

Remarks.

Balitora dehouensis sp. nov. distinguished it from all other Balitora spp. from an oblique caudal-fin base (vs. vertical) and upper caudal fin lobe longer than lower (vs. equals to or shorter). B. dehouensis is further differentiated from B. annamitica , B. brucei , B. burmanica , B. chipkali , B. eddsi , B. elongata , B. jalpalli , B. lancangjiangensis , B. laticauda , B. meridonalis , B. mysorensis and B. tchangi in possession of two pairs of maxillary barbels (vs. one pair); from B. kwangsiensis as well as four Vietnamese species ( B. nigrocorpa , B. haithanhi , B. vanlani and B. vanlongi ) from both pairs of maxillary barbels longer than eye diameter (vs. both pairs of maxillary barbels not longer than eye diameter). Balitora dehouensis resembled B. anlongensis , B. longibarbata and B. ludongensis morphologically. It is differentiated from B. anlongensis , B. longibarbata and B. ludongensis by a shorter snout (snout length 6.82–5.53 % SL vs. larger than 9 % SL); it is further differentiated from B. anlongensis by a higher count of lateral line scales (78–74 vs. 68–66), shorter pectoral fins (pectoral fin length 23.08–19.27 % SL vs. 25.63–23.17 % SL) and smaller mouth (mouth width 29.41–26.41 % HL vs. 43.62–34.95 % HL); from B. longibarbata by narrower body (body width 16.80–11.59 % SL vs. 22.55–16.89 % SL), shorter pectoral fins (pectoral fin length 23.08–19.27 % SL vs. 27.94–24.48 % SL) and shorter pelvic fins (pelvic fin length 21.42–15.96 % SL vs. 23.00–22.03 % SL); from B. ludongensis by higher count of lateral line scales (78–74 vs. 72–68), slender caudal peduncle (length of caudal peduncle 4.82–3.37 times of depth vs. 2.73–2.05) and shallower caudal peduncle (depth of caudal peduncle 5.80–5.18 % SL vs. 8.57–6.75 % SL).