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

The monotypic freshwater mussel genus Diaurora Cockerell, 1903 has long been enigmatic due to its rarity and morphological confusion with Acuticosta. In this study, we comprehensively redescribed Diauroraaurorea (Heude, 1883) through a detailed analysis of shell morphology and molecular phylogenetics of recently collected specimens. Moreover, a new species, Diauroralaevesp. nov., 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 D.aurorea and D.laevesp. nov. were reciprocally monophyletic and formed a clade as sister to Schistodesmus. Our study underscores the necessity of further exploring the diversity of freshwater mussels in understudied small tributaries throughout China.