Mitogenomic phylogeny resolves Cuneopsis (Bivalvia: Unionidae) as polyphyletic: The description of two new genera and a new species

Freshwater mussels are known to have two types of mitochondrial DNA (mtDNA) transmitted separately through oocytes and sperms, namely, maternal (F-type) and paternal (M-type) mtDNA. The additional suite of mitochondrial genes provides a great opportunity to resolve phylogenetically problematic relationships. East Asian freshwater mussels of the genus Cuneopsis were considered a compact group of taxa having wedge-shaped shells. However, preliminary results from previous studies challenged the monophyly of Cuneopsis, and the exact phylogenetic relationships among Cuneopsis and its allied genera are yet to be determined with comprehensive species sampling. Here, we evaluated species boundaries in Cuneopsis based on COI barcoding and obtained 11 new F- and M-type mitogenomes via genome skimming to elucidate the evolutionary history of Cuneopsis. COI barcode data supported the validity of all sampled six Cuneopsis species (missing C. kiangsiensis). Our mitochondrial phylogenomic analyses confirmed that the currently recognized genus Cuneopsis sensu lato was polyphyletic, recovering three well-supported clades. Molecular dating analysis suggested Cuneopsis s.l. diversified at similar to 58.06 million years ago in the Paleogene. Hereby, we propose two new genera, that is, Arcuneopsis gen. nov. and Pseudocuneopsis gen. nov. Additionally, we report a new species, Pseudocuneopsis sichuanensis sp. nov., from Chengdu, Sichuan, China, and a newly recorded species from China, Cuneopsis demangei.