Description of a New Eyeless Cavefish Species Using Integrative Taxonomic Methods— <i>Sinocyclocheilus changlensis</i> (Cypriniformes, Cyprinidae), From Guangxi, China

The extensive limestone landscapes of southwestern China form one of the world's largest karst regions, providing ideal conditions for cavefish evolution. Within this region, <i>Sinocyclocheilus</i>, the most speciose cavefish genus globally, comprises 84 species adapted to dark environments. Despite the many species, the region is still poorly explored, with new species currently being added to the total. Here, using integrative taxonomic methods involving morphological and molecular analyses, we describe <i>Sinocyclocheilus changlensis</i>, a new troglobitic species discovered in a cave in central Guangxi, China. This species is characterized by the absence of eyes, an unpigmented and complete scaled body, and a forked, horn-like structure at the dorsal posterior edge of the head. Morphologically, <i>S. changlensis</i> differs from its congeners by having pelvic-fin rays that do not reach the anus when extended, 42-46 lateral line scales, and a posterior operculum margin reaching the base of the pectoral fin at vertical. Molecular phylogenetic analyses using mitochondrial markers (<i>cytb</i> and ND4), genetic distances, and geometric morphometric analysis further confirmed <i>S. changlensis</i> as a distinct species. The description of this new species contributes to the understanding of cave-dwelling fish diversity in China and underscores the importance of further exploration of stygomorphic species across this poorly explored karstic landscape.