Unveiling the identity of Cockerell, 1903 (Bivalvia, Unionidae): morphology, molecular phylogenetics, and the description of a new species.

The monotypic freshwater mussel genus Cockerell, 1903 has long been enigmatic due to its rarity and morphological confusion with . In this study, we comprehensively redescribed (Heude, 1883) through a detailed analysis of shell morphology and molecular phylogenetics of recently collected specimens. Moreover, a new species, , was identified from the Fuyishui River, a tributary of the Zishui River in Shaoyang County, Shaoyang City, Hunan Province, China. Molecular phylogenetic analyses showed that and were reciprocally monophyletic and formed a clade as sister to . Our study underscores the necessity of further exploring the diversity of freshwater mussels in understudied small tributaries throughout China.