Homatula shexiang Cao, Liu, Zeng & Zhang, 2025

Cao, Liang, Liu, Yi, Zeng, Zhixuan, Yi, Wenjing & Zhang, E, 2025, Two new species of the loach genus Homatula Nichols, 1925 (Pisces, Nemacheilidae) from the upper Chang-Jiang Basin in China, Zoosystematics and Evolution 101 (2), pp. 697-710 : 697-710

Homatula shexiang Cao, Liu, Zeng & Zhang sp. nov.

Figs 4 , 5

Nemachelius variegatus : Wu, 1987: 27 (Wu-Jiang).

Paracobitis variegatus : Ding, 1994: 51 (Wu-Jiang).

Holotype.

IHB 202006048998, 100.2 mm SL; China: Guizhou: Guiyang City: Xiuwen District: Maodong-He, a stream tributary to Maotiao-He, under Wugong Bridge (26°54'11"N, 106°29'22"E); collected by D. M. Guo and W. H. Shao, June 2020.

Paratypes.

IHB 202006048993 –8997, 202006048999–9002, 202006200601–0602, 11 specimens, 71.9–125.6 mm SL; other date same as holotype . IHB 202006048907 –8911, five specimens, 71.0– 132.5 mm SL; China: Guizhou: Guiyang City: Kaiyang District: Macha-He (27°7'14"N, 107°0'1"E), a stream tributary to Qingshui-He ; collected by D. M. Guo and W. H. Shao, June 2020 .

Diagnosis.

A member of the partially scaled group of Homatula defined by having a sparsely scaled or unscaled predorsal body. It differs from all other eight species of this group, except H. longidorsalis in possessing 9 (vs. 7 or 8) branched dorsal-fin rays. Homatula shexiang differs from this species in having an adipose crest along the dorsal mid-line of the caudal peduncle anteriorly terminating vertically away from the anal-fin origin (vs. above the anal-fin origin), a deep (vs. shallow) head (depth 54.0–60.8 % of its length vs. 46.46–48.65 %) and a slender (vs. stout) caudal peduncle with (depth 40.4–55.2 % vs. 57.2–61.5 % of its length).

Description.

Morphometric measurements for type specimens given in Table 2 . General appearance of holotype shown in in Fig. 4 .

Body elongated, anteriorly cylindrical and posteriorly compressed laterally, with uniform depth from behind head to caudal-fin base. Ventral profile of head straight or slightly concave; ventral profile of head and body almost straight or slightly concave from pectoral-fin insertion to anal-fin origin and slightly convex from anal-fin origin to caudal-fin base. Body partially scaled; no scales on predorsal body, but scales only present on body behind dorsal-fin origin. Lateral line complete, with 85–95 pored scales, extending along mid-lateral body to caudal-fin base. Adipose crests along dorsal and ventral mid-lines of caudal peduncle supported by rudimentary rays. Dorsal adipose crest anteriorly terminating beyond the posterior end of the anal-fin base, but away from anal-fin origin.

Head relatively long and slightly depressed, wider than deep. Snout blunt in lateral view, slightly shorter than postorbital head. Eye oval with slightly convex interorbital space, positioned dorsolaterally in upper half of head, not reaching dorsal profile when viewed laterally; diameter less than interorbital width. Anterior and posterior nostrils set closely; anterior nostril situated at end of small and oblique tube. Mouth inferior; lips slightly thick, slightly folded and smooth with small median incision in upper lip and marked median longitudinal groove on lower lip. Upper jaw with shallow processus dentiformis and lower jaw spoon-like without median notch. Two pairs of rostral barbels; inner barbels extending to rictus and outer barbels reaching rictus. Maxillary barbels rooted in corners of mouth, extending close to vertical through middle of eye, but short of posterior margin of eye. Cephalic lateralis system with 8 supraorbital, 4 + 10 infraorbital, 9 preoperculo-mandibular and 3 supratemporal pores. Gill opening large, with its upper extremity aligned with centre of orbit.

Fin rays flexible. Dorsal fin with 3 unbranched and 9 branched rays; longest ray shorter than dorsal-fin base; distal margin slightly convex. Pectoral fin with one unbranched and 9–11 branched rays, tip of depressed fin not reaching mid-way between pectoral- and pelvic-fin insertion. Pelvic fin with one unbranched and 7–8 branched rays, reaching about mid-way between pelvic-fin insertion and anus; origin of pelvic fin at vertical of 1 st or 2 nd branched dorsal fin ray. Anus positioned closer to anal-fin origin than to pelvic-fin insertion; separated from anal-fin origin by distance 1.5–2 times greater than eye diameter. Anal fin with 3 unbranched and 5 branched rays, tip of depressed fin not reaching caudal-fin base; distal margin slightly convex. Caudal fin rounded; upper and lower lobes with 9 and 8 branched rays, respectively.

Vertebrae 4 + 42–43 (n = 4), including 20–21 abdominal and 22 caudal vertebrae. Gas bladder bipartite; anterior chamber invisible, fully enclosed in capsule; posterior chamber degenerative. Intestine with a distinct transverse bend not reaching posterior end of U-shaped stomach.

Colouration.

In formalin-stored specimens (Fig. 4 ), ground colour of body yellowish. Dorsal and lateral head yellowish with vermiform brown marks; ventral head yellow, with white snout, lips and barbels. Eight or nine brown irregularly-shaped bars along dorsal mid-line of body from behind head to origin of dorsal adipose crest. Thirteen to fifteen brown vertical bars on flank; anterior nine bars usually confused with brown bars along dorsal mid-line of body and wider than interspace space; three or four brown vertical bars on caudal peduncle equal to interspace width. Ventral body surface white-yellow. Melanin pigments on branched rays to form proximal and subdistal brownish bands across dorsal fin. Pectoral, pelvic fins and anal fin translucent white-yellow. Caudal fin and adipose crest dusky, sometimes with some blackish spots. Caudal-fin base with a dark brown vertical bar. In freshly-collected specimens (Fig. 5 ), overall body colouration similar to that in formalin-stored specimens, but a little bright. Caudal fin and dorsal adipose crest reddish, particularly during spawning season.

Distribution.

To date, known only from Wu-Jiang, tributary to upper Chang-Jiang in Guiyang and Qianxi, Guizhou Province, China (Fig. 3 ).

Etymology.

The specific epithet, here used as a noun, is named after Mrs. She Xiang (奢香夫人), an outstanding female politician and the leader of the Yi nationality in Guizhou Province during the Min Dynasty. The Wugong Bridge, type locality of the new species, is one of stone bridges across the Maodong-He built by Mrs. She Xiang six hundred years ago. A corresponding common name “ 奢香荷马条鳅 ” in Chinese is proposed here for this new species.

Phylogenetic analysis and genetic distances

A total of 16 Cytb gene sequences with 1080 bp in length were amplified in this study. The molecular phylogenetic trees generated from the BI and ML analyses showed the same topologies, only the BI tree with Bayesian posterior probabilities (PP) and bootstrap support (BS) value being presented in Fig. 6 . From the tree topologies, species of Homatula in China form a monophyletic clade with a high support. The two new species, H. shexiang sp. nov. and H. xiangzhi sp. nov., formed a highly-supported lineage itself and then constituted a well-supported clade which was sister to the species H. tigris with weak support. This group consisting of the three species was recovered as the sister to a well-supported clade formed by seven other species distributed in the Chang-Jiang, Huang-He and Nanpan-Jiang drainage areas.

The genetic distances between the Homatula species are provided in Table 3 . Interspecific genetic distance between the two new species, H. shexiang and H. xiangzhi and other congeneric species ranged from 6.7 % to 12.5 % and 7.1 % to 11.5 % (Table 4 ), respectively. Interspecific genetic distance between the two new species was 3.6 % and intraspecific genetic divergence was 0.61 % and 0.06 % for H. shexiang and H. xiangzhi , respectively. The molecular phylogenetic results supported H. shexiang and H. xiangzhi to be two distinct species.

Figures

Figure 3. Distribution of the partially scaled and the scaleless group of Homatula in China.

Figure 4. Homatula shexiang sp. nov., IHB 202006048998, holotype, 100.2 mm SL; China: Guizhou: Guiyang City: Xiuwen District: Maodong-He, a stream tributary to Maotiao-He, under Wugong Bridge. Lateral (upper), dorsal (middle) and ventral (lower) view.

Figure 5. Freshly-captured individual of Homatula shexiang sp. nov. collected from China: Guizhou: Qianxi City: Wei-he.

Figure 6. Bayesian Inference tree generated from the Cytb gene from species of Homatula. Nodal numbers indicate Bayesian posterior probabilities (> 0.9) and Maximum Likelihood bootstrap values (> 70 %), respectively.