Glaridoglanis verruciloba Gong, 2025

Gong, Zheng, Wang, Huanshan, Liu, Yanchao & Li, Jianchuan, 2025, Glaridoglanis verruciloba sp. nov., a new glyptosternine catfish (Siluriformes, Sisoridae) from the Zayul River in southeastern Tibet, China, ZooKeys 1262, pp. 289-301 : 289-301

Glaridoglanis verruciloba Gong sp. nov.

Fig. 2 , Table 2

Chresonymy.

Glaridoglanis andersonii (non Day 1870): Wu et al. 1981 (Zayul River, Zayul County, China); Wu and Wu 1991 (Zayul River, Zayul County, China); Zhang et al. 1995 (Zayul River, Zayul County, China); Chu and Mo 1999 (partim, Zayul River, Zayul County, China).

Type material.

Holotype • IPBX F 202504001, 147.8 mm SL; China, Xizang Autonomous Region, Zayul County, mountain stream flowing into Sangqu River, eastern branch of upper Zayul River ; 28°35'39.31"N, 97°9'20.93"E; 1736 m a. s. l.; Zheng Gong and Yanchao Liu leg.; April 2025 . Paratypes • IPBX F 202504002 , 1, 156.6 mm SL; data as for holotype • IPBX F 202504003 – F 202504006 , 4; 106.7–149.8 mm SL; China, Xizang Autonomous Region, Zayul County, mountain stream flowing into Gongrigabu River, western branch of upper Zayul River ; 28°54'3.06"N, 96°39'54.58"E; 2016 m a. s. l.; Zheng Gong and Yanchao Liu leg.; April 2025 .

Diagnosis.

Glaridoglanis verruciloba sp. nov. can be distinguished from its two congeneric species by the following combination of characters: enlarged lower lip bearing 4–7 verruciform lobes on the central-posterior margin; anus close to the anal-fin origin; ventral surface at the base of maxillary barbels densely covered with striae; 11 branched pectoral-fin rays; 5–6 branched anal-fin rays; head relatively short ( HL 19.1–21.7 % of SL); and mandibular barbels relatively short (inner mandibular barbel length 13.9–17.7 % and outer mandibular barbel length 29.1–36.4 % of HL).

Description.

Morphometric data as in Table 2 . Head and body greatly depressed. Dorsal profile rising gently and evenly from orbital margin to dorsal-fin origin, then sloping gradually to caudal peduncle; ventral profile nearly flat to the anal-fin base, then slightly ascending to caudal peduncle. Body depth at dorsal-fin origin 11.2–13.4 % of SL, at anus 8.4–11.8 % of SL. Caudal-peduncle depth 6.9–9.7 % of SL. Head moderate in size. Snout rounded and flattened, 49.6–53.9 % of HL. Rostral cap with a shallow groove; groove margins papillate. Eye small, located dorsolaterally, subcutaneous. Nostrils paired, located closer to the snout tip than to eye, separated by the nasal barbels. Barbels in four pairs. Nasal barbels moderately long, extending beyond posterior orbital margin. Maxillary barbels slightly flattened, ventral surface at the base densely covered with striae, connected to the lower lip by a skin flap, free only at short distal end; tip pointed, almost reaching the base of first pectoral-fin ray. Inner mandibular barbels short and slightly flattened. Outer mandibular barbels lateral to inner pair, slightly flattened, not reaching the base of first pectoral-fin ray.

Mouth inferior, gape width 31.5–36.5 % of HL. Lips thick, fleshy, and papillate. Upper lip covered with tiny papillae; lower lip enlarged, with anastomosing rounded plaques, bearing 4–7 irregular verruciform lobes on the central-posterior margin. Postlabial groove interrupted. Mental region with a prominent median depression. Teeth embedded in skin, short, robust and chisel-shaped; similar in form on both jaws, but arranged in a single crescentic band on upper jaw and two well-separated triangular patches on lower jaw. Palate edentulous. Gill opening narrow, extending from the base of the first pectoral-fin ray to a position anterior and dorsal to the last pectoral-fin ray; posterior margin of the branchiostegal membrane forming a distinct boundary between cephalic and thoracic regions.

Dorsal fin without spine, with i, 5 (1) or i, 6 (5 *) rays. Adipose fin with long base; anterior extremity at approximately midway between bases of pelvic and anal fins; posterior extremity separate from upper procurrent caudal-fin rays without incision. Pectoral fin enlarged and ovoid when expanded, with i, 11 (6) rays; margin slightly concave; the first unbranched ray flattened, ventral surface with closely-arranged striae. Pelvic fin enlarged and ovoid when expanded, with i, 5 (6) rays; the first unbranched ray flattened, ventral surface with closely-arranged striae; tip not reaching anus when adpressed. Anal fin with i, 5 (1) or i, 6 (5 *) rays; posterior margin slightly concave; tip reaching approximately midway between anal-fin origin and caudal-fin base. Caudal fin nearly truncate when depressed, with i, 14, i (1) or i, 15, i (5 *) rays. Chest and abdomen densely covered with minute papillae. Anus and urogenital openings located near the anal-fin origin.

Colouration.

In life, dorsal and lateral surfaces yellow brown; ventral surface pale pink; ventral surface of the first rays of pectoral and pelvic fins faintly pink; all fins with yellowish distal margins. In 70 % ethanol, head and dorsum pale gray, ventral region dark yellow; dorsal, anal, and caudal fins yellowish gray; dorsal surfaces of pectoral and pelvic fins yellowish gray, ventral surfaces dark yellow.

Distribution and habitat.

This species is presently known only from the Zayul River (= upper Lohit River) drainage, a tributary of the Brahmaputra River, south-eastern Tibet, China. It occurs mainly in mountain streams and is less frequently found in the river mainstem (Fig. 3 ). At the type locality during sampling period, the water temperature was 4.1–7.5 ° C, the dissolved oxygen was 9.46–12.58 mg / L, and the pH was 7.86–8.32. Sympatric fishes mainly included Creteuchiloglanis kamengensis (Jayaram, 1966) and Schizothorax molesworthi Tsao, 1964 .

Etymology.

The specific epithet is derived from the Latin verruca (= wart) and lobus (= lobe), referring to the verruciform lobes on the central-posterior margin of lower lip. As Glaridoglanis is feminine (fide Kottelat 2013), the specific epithet is treated accordingly. The Chinese common name of this species is 疣叶凿齿鮡 (Yóu yè záo chǐ zhào), which literally means “wart-lobed chiseled-tooth catfish”.

Molecular phylogenetic analysis.

After alignment, 1138 bps of cyt b gene sequences were obtained from 28 species of the subfamily Glyptosterninae and two outgroup taxa for molecular phylogenetic analyses. Among these sites, 492 were variable and 463 were parsimony-informative. Within the genus Glaridoglanis , two haplotypes were detected from six individuals of G. verruciloba sp. nov., and a single haplotype was determined from six individuals of G. andersonii . Phylogenetic tree reconstructed based on the BI and ML methods yielded congruent topologies; therefore, only the ML tree was presented, with posterior probabilities from BI method and bootstrap values from ML method indicated at the nodes (Fig. 4 ). The resulting topology strongly supported the monophyly of Glaridoglanis , with each of its two species forming well-supported clade. Further, the genus Glaridoglanis , together with Parachiloglanis , was resolved as a relatively basal lineage within the glyptosternine catfishes, although this relationship was weakly supported. Pairwise genetic distance based on the K 2 P model demonstrated a 3.1 % sequence divergence between the two Glaridoglanis species, while divergences between G. verruciloba and other glyptosternine catfishes were summarized in Suppl. material 1.

Figures

Figure 2. Dorsal, lateral, and ventral views of Glaridoglanis verruciloba, holotype, IPBX F 202504001, 147.8 mm SL.

Figure 3. Type locality of Glaridoglanis verruciloba sp. nov.: a mountain stream flowing into the Sangqu River, the eastern branch of the upper Zayul River (upper left); paratype locality: a mountain stream flowing into the Gongrigabu River, the western branch of the upper Zayul River (right); the mainstem of Gongrigabu River (lower left); and a living specimen (approx. 140 mm SL) photographed in an aquarium.

Figure 4. Phylogenetic tree of 28 glyptosternine catfishes inferred from mitochondrial cytochrome b gene sequences. Numbers on nodes before and after slash (/) represent posterior probabilities of Bayesian inference method and bootstrap values of maximum-likelihood method, respectively.