Protocobitis longibarba, Qin & Liu & Zhang & Shi & Du & Zhou, 2025

Protocobitis longibarba sp. nov.

Fig. 1 View Figure 1 , Table 1 View Table 1

Type material.

Holotype. • KIZ 2024000004 View Materials , male, 44.0 mm standard length (SL), Yangcun Village , Luolou Town, Lingyun County, Baise City, Guangxi, China, from a subterranean tributary of the Hongshui River; 24.4392 ° N, 106.7409 ° E, collected by J. J. Zhou, Y. W. Liu & S. P. Zhou; 15 February 2024 GoogleMaps . Paratypes. • KIZ 2024000001–3 View Materials , female, 51.1–51.9 mm SL, KIZ 2024000005 View Materials , male, 44.0 mm SL, ZJFRF 2402010 , male, 53.5 mm SL; five specimens, collected with holotype GoogleMaps • KIZ 2024000006–7 View Materials , male, 39.5–43.1 mm SL, two specimens, Liangfeng Cave , Shima Lake, Jinya Township, Fengshan County, Hechi City, Guangxi, China; 24.5587 ° N, 106.8655 ° E; collected by Y. W. Liu; 23 May 2024 GoogleMaps .

Diagnosis.

Protocobitis longibarba can be distinguished from all other species of Protocobitis by the following combination of characteristics: whole body, except for head and abdomen, sparsely covered with minute scales (vs scaleless in P. anteroventris , scales present along midline of body in P. typhlops ; barbels elongate; 5–6 branched pectoral fin rays (vs seven in P. anteroventris , P. longicostatus , and P. polylepis ); four branched pelvic-fin rays (vs five in other Protocobitis species); caudal-peduncle height 34.9 % – 58.6 % of its length (vs 64.1 % – 65.7 % in P. polylepis , 27.9 % – 43.3 % in P. anteroventris ); head width 7.3 % – 10.3 % of SL (vs 5.4 % – 6.6 % in P. anteroventris ); head height 50.2 % – 80.6 % of lateral head length (vs 45.7 % – 49.5 % in P. longicostatus , 43.8 % – 46.8 % in P. anteroventris ).

Description.

Body elongate; maximum body width located immediately anterior to dorsal fin. Dorsal and ventral profiles almost straight except for slightly convex anus and base of fin. Snout obtuse. Head short, higher than width, roughly triangular in dorsal view. Nostrils closely set, nearer to snout tip than to the operculum, anterior nostril in short tube. Eyeless. Suborbital spine bifid, relatively thick and short, with strong mediolateral process in front of cavity of eye, length of laterocaudalis processus nearly half of mediocaudalis process, four strumae in base of mediorostralis process (Fig. 1 J, K View Figure 1 ). Mouth inferior and arched, in vertical line of nostrils. Lips thin and smooth, each side of middle of lower lip with pair of developed fleshy mental lobes (Fig. 1 G View Figure 1 ). Inner surface of mouth densely covered with numerous papillae, and outer edge of upper jaw neatly arranged with row of small nodules. Three pairs of barbels, inner rostral barbel reaching corner of mouth, outer rostral barbel reaching tip of suborbital spine, maxillary barbel extending almost to vertical line at junction of head and dorsum.

Morphometric data of the type specimen of P. longibarba are given in Table 1 View Table 1 . Dorsal fin with three unbranched and seven branched rays; pectoral fin with one unbranched and 5–6 branched rays; pelvic fin with one unbranched and four branched rays; anal fin with three unbranched and five branched rays; caudal fin with 12–13 branched rays. Dorsal-fin base short, originating at midpoint of body length, with tip of dorsal fin extending to vertical of anus origin; in male, the first branched pectoral fin ray elongated posteriorly and thicker, with a pointed tip; pelvic-fins origin closer to anal-fin origin than to pectoral-fin base, not reaching anus; anus elongated posteriorly into tube and closer to anal-fin origin; caudal fin emarginate, margins of lobes uneven.

Except for head and abdomen, whole body covered with sparse and minute scales, shallowly embedded in skin surface. Cephalic lateral-line and lateral-line pores absent. Nine to 10 inner gill rakers on first gill arch. Chest and abdominal walls thick and rich in fat. Air bladder absent, no bony bladder. Intestine straight, leading directly to anus. Ribs degenerate, each vertebra with only short and simple parapophysis (Fig. 1 I View Figure 1 ). Vertebrae (from radiograph) 4 + 42.

Coloration.

In life, body generally pale, without pigment, head and all fins transparent, outline of skull visible through skin, barbels exhibit distinct blood vessels (Fig. 1 H View Figure 1 ). Whole body after preservation in formalin pale white, without pigment.

Sexual dimorphism.

Male smaller than females, with longer pectoral fin. First branched pectoral fin ray in male thickened and elongated but without the lamina circularis, longest fin ray reaching midpoint between origin of pectoral fin and anus (Fig. 1 A – C View Figure 1 ). First branched pectoral fin ray in females as long as second branched ray (Fig. 1 D – F View Figure 1 ).

Etymology.

The specific epithet is a combination of the Latin words long - (long) and - barba (barbel), indicating its long maxillary barbel, which extends almost to the vertical line at the junction of the head and dorsal body, feminine. We suggest the common Chinese name “ Cháng Xū Yuán Huā Qiū (长须原花鳅) ” and English name “ long-barbal protocobitis ”.

Distribution and habitat.

The new species is currently known from a cave located in Yangcun Village, Luolou Town, Lingyun County, Baise City and Jinya Township, Fengshan Country, Hechi City (Fig. 2 A View Figure 2 ). In Fengshan County, this species occurs in a pool at the end of cave, which, in the dry season, has an area of approximately 100 m 2; the water surface is about 15 m from the ground. The water depth is more than 30 m, and the water is clear and unpolluted (Fig. 2 B View Figure 2 ). The pool belongs to the Poxin subterranean river system. Sympatric species include Sinocyclocheilus lingyunensis Li, Xiao & Luo, 2000 , Sinocyclocheilus microphthalmos Li, 1989 , Sinocyclocheilus anshuiensis Gan, Wu, Wei & Yang, 2013 , and Triplophysa lingyunensis Liao, Wang & Luo, 1997 . The cave in Lingyun County is approximately 300 m long, inclined downward at a 45 ° angle. The water pool located at the end of the cave is connected to the Shuiyuan Cave subterranean river system, which are, in turn, connected to a tributary of the Hongshui River. During the dry season, the water level area fluctuates from 5 to 50 m 2 (Fig. 2 C View Figure 2 ). The cave acts as a conduit for surface water, domestic waste, and mud during the rainy season (Fig. 2 D View Figure 2 ). As such, the primary substrate within the cave is mud. Protocobitis longibarba mainly feeds on algae and organic detritus and prefers to burrow into the muddy substrate. Sympatric species include S. lingyunensis , S. microphthalmos , and S. anshuiensis .

Genetic comparisons.

Four sequences totaling 1775 bp in from P. longibarba were amplified, resulting in the detection of 14 haplotypes. The haplotype matrix consisted of 1,071 invariable sites, 704 variable sites, 387 parsimony informative sites, and 43 singletons.

The ML and BI phylogenetic trees exhibited congruent topological structures ( ML tree see Fig. 4 View Figure 4 ), exhibiting high node support for the monophyly of P. longibarba ( BPP = 1; BS = 100), which was clustered with the other congeners. Protocobitis was sister to the lineage composed of species from Paramisgurnus Guichenot, 1872 , Misgurnus Lacepède, 1803 , and Cobitis Linnaeus, 1758 (Fig. 3 View Figure 3 ). In the phylogenetic tree, P. anteroventris diverged earliest, followed by P. longicostatus , while P. typhlops was identified as sister group to P. longibarba . Additionally, pairwise comparisons of the concatenated dataset of mitochondrial COI and cyt b sequences revealed that the uncorrected p - distance between species of Protocobitis ranged from 6.25 % to 16.45 %. The minimum uncorrected p - distance is between P. longibarba and P. typhlops (6.25 %), and the maximum uncorrected p - distance is between P. longibarba and P. anteroventris (16.45 %) (Table 2 View Table 2 ).