Balitora anlongensis Luo, Chen, Zhao, Yu, Lan & Zhou, 2023

Luo, Tao, Chen, Zhi-Xia, Zhao, Xin-Rui, Yu, Jing, Lan, Chang-Ting, Zhou, Jia-Jun, Xiao, Ning & Zhou, Jiang, 2023, Balitora anlongensis, the first cavefish species of the genus Balitora (Teleostei, Balitoridae) from Guizhou Province, southwest China, ZooKeys 1185, pp. 21-42 : 21

Balitora anlongensis Luo, Chen, Zhao, Yu, Lan & Zhou sp. nov.

Figs 4 , 5 , 6

Type material.

Holotype. GZNU20230215007 (Fig. 4 ), 60.4 mm total length (TL), 47.9 mm standard length (SL), collected by Tao Luo on 15 February 2023 in Xīniú Cave (犀牛洞), NaNao Village, Xinglong Town, Anlong County, Guizhou Province, China (105.59143424E, 25.07096446N, 1450 m. a.s.l.; Figs 1 , 2 ).

Paratypes. Ten specimens from the same locality as the holotype: GZNU20230215008-215017, collected by Tao Luo, Xin-Rui Zhao, Wei-Feng Wang, Jing Yu, and Chang-Ting Lan on 15 February 2023.

Comments.

The new species is assigned to the genus Balitora based on the combination of the following diagnostic characters ( Kottelat 1988; Kottelat and Chu 1988): (1) body strongly depressed; head and abdomen ventrally flattened; (2) mouth inferior, arched, with both jaws covered by a horny sheath; (3) rostral flap divided into three lobes, both lips with one or two rows of papillae, lower lip not interrupted; (4) one or two pairs of maxillary barbels; (5) gill-openings extending on the ventral surface of head; (6) unbranched pelvic rays two, 8-10 unbranched pectoral rays and 10-12 branched pectoral rays; and (7) adhesive pads present on ventral surface of the 8-11 anterior most pectoral rays and 3-4 anterior most pelvic rays.

Diagnosis.

Balitora anlongensis sp. nov. can be distinguished from other congeners by the following combination of characters: (1) two pairs of maxillary barbels; (2) dorsal fin rays iii, 8½; (3) pectoral fin viii, 11; (4) pelvic fin rays ii, 9; (5) anal fin rays iii, 5½; (6) lateral-line scales 66-68; (7) tip of pectoral fin not reaching to the pelvic fin origin; (8) dorsal fin origin anterior to the pelvic fin origin; (9) tip of the pelvic fin reaching to the anus; (10) eyes small, eye diameter equal to outer maxillary barbel length; (11) six to seven indistinctly separated transversely oval blotches on the dorsal side; and (12) each fin transparent and unpigmented in life.

Description.

Morphological data of the 11 specimens of the Balitora anlongensis sp. nov. are provided in Table 3 . Body elongated and sub-cylindrical, posterior portion gradually compressed from dorsal fin to caudal-fin base, with deepest body depth anterior to dorsal-fin origin, deepest body depth 11-13% 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. Pelvic profile flat. Head blunt and depressed, head length (HL) 21-24% of SL and greater than head width, head width greater than depth (head width/head depth = 1.7). Snout short, oblique, and blunt, length 52-58% HL. Interorbital space wide and flat. Mouth inferior, small and curved, mouth corner situated below anterior nostril, upper and lower lips smooth and fleshy. Relatively shallow preoral groove present between rostral cap and upper lip, extending across corners of mouth. Mouth width 35-44% of head width. Rostral cap around upper lip divided into three lobes, median one largest, slightly curved. Four pairs of barbels: two pairs of rostral barbels, short, outer rostral barbel longer than inner one; two pairs of maxillary barbels, short, situated at corner of mouth: outer maxillary barbels longer than inner one. Upper and lower lips connected at corner of mouth, upper lip with 3-5 papillae in middle, and lower lip thin, with large fleshy papilla at upper and lower lip joint. Lower jaw with radiate ridges on its surface. Two longitudinal fleshy ridges on mid-chin. Anterior and posterior nostrils closely set, anterior nostril without any elongated barbel-like tip. Eyes reduced, 8-13% HL. Gill opening large, extending to origin of pectoral fin, gill rakers absent.

Dorsal fin rays iii, 8½, pectoral fin rays viii,11, pelvic fin rays ii, 9, anal fin rays iii, 5½, and 17 branched caudal fin rays. Dorsal fin long, 22-24% of SL, nearly equal to head length, distal margin truncated, origin anterior to pelvic fin insertion, situated slightly anterior to midpoint between snout tip and the caudal fin base, first branched ray longest, shorter than HL, tip of the dorsal fin extending to the vertical of the anus. Pectoral fin elongated and developed, distal margin rounded, pectoral fin length slightly greater than HL, 23-25% of SL, tip of the pectoral fin extends backward beyond 3/4 of the distance between the origin of the pectoral fin and the origin of the pelvic fin, without reaching to the pelvic fin-origin. Pelvic fin moderately developed, distal margin rounded, pectoral fin length approximately equal to HL, 23-26% of SL, vertically aligned with the third branched ray of the dorsal fin, pelvic fin origin closer to the snout tip than the caudal fin base and closer to the anal fin origin than the snout tip, tips of the pelvic fin reaching to the anus. Anus ~ 4/5 distance from posterior end of the pelvic fin base to the anal fin origin. Anal fin short, 17-19% of SL, distal margin truncated, origin close to the anus and far from the caudal fin base, spacing ~ 2.9 mm, tips of the anal fin extending backwards and not reaching caudal fin base, distance between the end of the anal fin and the anus 5.4-times the eye diameter. Caudal fin deeply forked, upper lobe equal in length to the lower one, tips pointed, caudal peduncle length 8.8 mm, caudal peduncle depth 2.9 mm, without adipose crests along both dorsal and ventral sides. Vertebrae 36: nine pre-dorsal abdominal, 19 abdominal (including four Weberian and 15 pre-dorsal ones), and 17 caudal (including three pre-anal caudal and the hypural complex) (Fig. 5 ).

Body smooth, covered with thin scales all over except for on the ventral side, head, and fins. Lateral line complete and straight, with 66-68 lateral line scales, exceeding the tip of the pectoral fin and reaching the base of the caudal fin. Two air bladder chambers, posterior chamber of the air bladder slightly developed and closed (Fig. 5 ).

Coloration.

Dwelling in the water bodies of the cave (Fig. 6 ), dorsal and lateral sides of the body grey-brown, ventral side white, slightly pinkish. Dorsal side of the head grayish-white, grayish-brown pigmented spots predominate. Dorsal side of the body with six to seven indistinctly transversely oval blotches separated by grayish-yellow gaps, and usually two blotches anterior to the dorsal fin origin, one to two blotches at the dorsal fin base, and three to four blotches posterior to the dorsal fin end. Except for discontinuous black spots on the distal end of the caudal fin, the remaining fins are transparent and unpigmented. Base of the caudal fin deeply pigmented. Lateral line of the body from the posterior to the eye to the base of the caudal fin light grayish yellow. After being moved from inside the cave to outside, the body pigmentation deepened in ~ 4 hrs. After being fixed in 10% formalin and stored (Fig. 4 ), the body pigmentation deepened and there was pigmentation on the unbranched fins of each fin.

Sexual dimorphism.

No sexual dimorphism was observed based on the present specimens of Balitora anlongensis sp. nov.

Comparisons.

Comparative data of Balitora anlongensis sp. nov. with 19 species within the genus Balitora are given in Table 4 .

Balitora anlongensis sp. nov. differs from B. annamitica , B. brucei , B. burmanica Hora, 1932, B. chipkali , B. eddsi Conway & Mayden, 2010, B. jalpalli , B. lancangjiangensis , B. laticauda , B. meridionalis , B. mysorensis , B. nantingensis Chen, Cui & Yang, 2005, B. elongata , and B. tchangi based on the presence of two maxillary barbels at each corner of the mouth (vs one maxillary barbel at each corner of the mouth). Balitora anlongensis sp. nov. can be further distinguished from B. eddsi and B. tchangi based on dorsal fin rays (iii, 8½ vs iii, 9 in B. eddsi and iii, 7 in B. tchangi ); from B. jalpalli , B. lancangjiangensis , B. laticauda , B. nantingensis , B. elongata , and B. tchangi by the tip of pelvic fin reaching to the anus (vs not reaching to the anus); from B. brucei by pectoral fin rays (viii, 11 vs ix, 11); and from B. jalpalli , B. lancangjiangensis , B. laticauda , B. elongata , and B. tchangi by the dorsal fin origin being anterior to the pelvic fin origin (vs opposite/posterior to pelvic fin origin; see Table 4 for detailed comparisons).

Balitora anlongensis sp. nov. and B. kwangsiensis , B. longibarbata , and B. ludongensis are distributed in the Pearl River and share two maxillary barbels at each corner of the mouth, but can be distinguished by the combination of serial characters. Balitora anlongensis sp. nov. can be distinguished from B. kwangsiensis by anal fin rays (iii, 5½ vs ii, 5), pelvic fin rays (ii, 9 vs ii, 8), lateral-line scales (66-68 vs 61-65), and each fin being transparent and unpigmented in life (vs each fin having black spots); from B. longibarbata by the pelvic fin rays (ii, 8 vs ii, 9-11), anal fin rays (iii, 5½ vs ii, 5), lateral-line scales (66-68 vs 74-76), the dorsal fin origin being anterior to the pelvic fin origin (vs opposite to the pelvic fin origin), and the tip of the pelvic fin reaching to the anus (vs not reaching to the anus).

Phylogeny constructed based on combined mitochondrial and nuclear genes shows that Balitora anlongensis sp. nov. is close to B. ludongensis and can be distinguished by the combination of the following morphological characters: eight unbranched pectoral fin rays (vs six to seven), anal fin rays (iii, 5½ vs ii, 5), pelvic fin rays (ii, 9 vs ii, 6-7), lateral-line scales (66-68 vs 69-74), dorsal fin origin far anterior to the pelvic fin origin (vs slightly anterior to the pelvic fin origin), body depth 13-14% of the SL (vs 15-20%), body width 12-14% of SL (vs 18-21%), head depth 38-48% of HL (vs 51-67%), head width 109-134% of body width (vs 87-107%), transversely oval blotches on dorsal side indistinctly separated (vs distinctly separated), and each fin transparent and unpigmented in life (vs each fin having black spots).

Distribution and ecology.

Balitora anlongensis sp. nov. is only known from the type locality, a vertical cave some distance from NaNao Village, Xinglong Town, Anlong County, Guizhou Province, China at an elevation of 1387 m (Figs 1 , 2 ). The type locality is located in the Nanpanjiang River, a tributary of the Pearl River. There is no surface stream outside the cave. The cave is ~ 50 m long and has a small volume of water during dry periods, but is a source of domestic water for the local population. Within this cave, Balitora anlongensis sp. nov. co-occurred with fish ( Triplophysa sp. and Misgurnus anguillicaudatus ), frog ( Odorrana sp.), red-eared slider ( Trachemys scripta ), and crab ( Diyutamon cereum ) species. Outside the cave, the arable land was farmed to produce maize, wheat, and potatoes.

Etymology.

The specific epithet " anlongensis " is in reference to the type locality of the new species: NaNao Village, Xinglong Town, Anlong County, Guizhou Province, China. We propose the common English name "Anlong stone loach" and the Chinese name “ān lóng Pá Qīu ( 安龙爬鳅)”.

Figures

Figure 1. Sampling collection location of Balitora anlongensis sp. nov. and distribution of 21 species of the genus Balitora (including B. haithanhi, B. nigrocorpa, B. vanlani, and B. vanlongi) in Asia. Species codes are provided in Table 1.

Figure 2. Distribution and hydrology of the type locality of the new species Balitora anlongensis sp. nov. (red), B. kwangsiensis (blue), B. longibarbata (purple), and B. ludongensis (red), in the Pearl River basin, Southwest China.

Figure 4. Morphological characters of holotype GZNU 20230215007 of Balitora anlongensis sp. nov. in preservative (10 % formalin) A lateral view B dorsal view C ventral view D ventral side view of head, and E dorsal side view of head. Photos from Tao Luo. Abbreviations: M, maxillary barbels; AN, anterior nostril.

Figure 5. Three-dimensionally reconstructed model of the skeleton of Balitora anlongensis sp. nov. (paratype GZNU 20230223017, standard length 44.3 mm) A dorsal view B ventral view, and C lateral view.

Figure 6. Balitora anlongensis sp. nov. in life, paratypes GZNU 20230106001 (photos A and B) and GZNU 20230215014 (photo C) A right-side view B ventral side view, and C dorsal view. Photographs A, B were shot indoors at ~ 9: 00 p. m. Photo C was taken in the cave at ~ 15: 00 noon.