A new species of Cristaria Schumacher, 1817 (Bivalvia, Unionidae) from Sichuan, China

The species diversity of freshwater mussels in the upper Yangtze River has been seriously underestimated, and human-induced disturbances have severely threatened the survival of local bivalve species. In this study, we describe a new freshwater mussel species, Cristaria wangyucheni Z.-G. Chen & Y.-T. Dai, sp. nov. , from the Jialing River Basin in the upper Yangtze River, Sichuan, China, based on comparative morphology and molecular phylogeny. Phylogenetic analyses of COI and 28S rRNA gene fragments revealed that C. wangyucheni sp. nov. is a sister to the other species of Cristaria . The pairwise uncorrected COI p -distance analysis demonstrated genetic distances ranging from 10.10% (between this species and C. truncata ) to 13.17% (between this species and C. “ beirensis ”). Morphologically, C. wangyucheni sp. nov. can be distinguished from its congeners by its medium-sized shell, which ranges from an elongated triangle to an irregular rectangle. This discovery broadens our understanding of interspecific shell morphological variation within the genus Cristaria .