Discogobio angustimarginis, a new species of cyprinid fish (Pisces: Teleostei) from the Jinsha-Jiang River in Yunnan Province, southwestern China

A new species of cyprinid fish, Discogobio angustimarginis, is described from the mainstream of the Jinsha-Jiang River (upper Yangtze River basin) in Yunnan Province, Southwest China. This taxon is assigned to a specific species group within the genus Discogobio based on a suite of diagnostic morphological traits, including a large mental adhesive disc with its posterior margin extending to or beyond the vertical through the anterior margin of the eye, and a snout covered with small tubercles.

The adhesive disc of D. angustimarginis is distinguished by a flat, sparsely papillated central fleshy pad and a narrower, non-papillated posterior margin (less than one-third the length of the central pad), setting it apart from the five other species in this group. Key differentiating characters include abdominal squamation, interorbital width, mental adhesive disc size, body depth, and lateral-line scale count. Additionally, taxonomic revisions suggest D. yunnanensis may represent a cryptic species complex, with its distribution strictly limited to the Dianchi Lake system.

Phylogenetic analysis using the cytochrome b gene supports the validity of D. angustimarginis as a distinct lineage, highlighting its evolutionary significance within the genus and its ecological context in the Jinsha-Jiang River basin.