The genus Alasmidonta currently contains 12 species with 3 species presumed extinct. Six species of Alasmidonta occur in North Carolina, including the presumed extinct Alasmidonta robusta. Tissue samples from all taxa of living Alasmidonta species were included in a test of the monophyly of the genus and the relationships of the species using mitochondrial DNA sequences from cytochrome oxidase c subunit 1 (COI) and NADH dehydrogenase subunit (ND1). Alasmidonta (Prolasmidonta) heterodon and Alasmidonta (Pressodonta) viridis are significantly different from the rest of Alasmidonta and the two subgenera are elevated to generic level. Alasmidonta varicosa is split into two separate species as is A. viridis. Alasmidonta raveneliana is represented by two separate conservation units corresponding to the French Broad and Little Tennessee River drainages. Further work is needed to understand the variation in A. marginata between the upper Mississippi River basin and the Ohio River drainage populations.
