Description of a New Eyeless Cavefish Using Integrative Taxonomic Methods- (Cypriniformes, Cyprinidae), from Guizhou, China.

China's southwestern karst landscapes support remarkable cavefish diversity, especially within , the world's largest cavefish genus. Using integrative taxonomic methods, we describe sp. nov., found in a subterranean river in Guizhou Province. This species lacks horn-like cranial structures; its eyes are either reduced to a dark spot or absent. It possesses a pronounced nuchal hump and a forward-protruding, duckbill-shaped head. Morphometric analysis of 28 individuals from six species shows clear separation from related taxa. Nano-CT imaging reveals distinct vertebral and cranial features. Phylogenetic analyses of mitochondrial and genes place within group as sister to , with p-distances of 1.7% () and 0.7% (), consistent with sister-species patterns within the genus. is differentiated from by its eyeless or degenerate-eye condition and lack of bifurcated horns. It differs from , its morphologically closest species, in having degenerate or absent eyes, shorter maxillary barbels, and pelvic fins that reach the anus. The combination of morphological and molecular evidence supports its recognition as a distinct species. Accurate documentation of such endemic and narrowly distributed taxa is important for conservation and for understanding speciation in cave habitats.