Monday 28 June 2021

Homatula guanheensis: A new species of Stone Loach from Henan Province, China

The Stone Loach genus Homatula includes a number of small, benthic Fish, which live in the drainage basins of the Yellow, Yangtze, Pearl, Lancang, Nujiang and Red rivers. They are sometimes considered to be a part of the genus Paracobitis, which is morphologically similar, but the two are generally considered separate, due to their different distributions, with Homatula known only from China, and Paracobitis found only in western Asia. Studies based on the morphology of Homatula have suggested that there is more diversity that the current number of species (19-20), but to what extent this reflects variation within species rather than the presence of undescribed species remained unclear, until scientists began to apply genetic identifications to the genus.

In a paper published in the Biodiversity Data Journal on 16 June 2021, Chuanjiang Zhou, Wenwen Ma, Xi Wang, Yongtao Tang, Xiaoling Meng, and Guoxing Nie of the Engineering Technology Research Center of Henan Province for Aquatic Animal Cultivation at Henan Normal University, describe a new species of Homatula from the Guanhe River, in the HanJiang River drainage (a tributary of the Yangtze River),  in Xixia County, Henan Province.

The new species is named Homatula guanheensis, where 'guanheensis' means 'coming from Guanhe', in reference to the Guanhe River where it was found living in cave environments. Like other Stone Loaches, the new species is an elongate, slender Fish. The known specimens range from 76.9 to 109.26 mm in length, and are cylindrical, and flattened towards the rear. The head is short and flattened, and lacks scales. The snout is short, with nostrils closer to the eye than the tip. The eyes are oval, and located towards the top of the head. The lips are thick, and cover the jaw; there are three pairs of barbels. 

Homatula guanheensis (holotype, HNU 010048, 99.6 mm SL). (A) Lateral view; (B) Dorsal view; (C) Ventral view; (D) Mouth characters; (E) Intestine form; (F) X–ray (lateral view). Zhou et al. (2021).

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