| Freshwater mussels (Order Unionoida) are one of the most endangered fauna in North America. In the western U.S., taxonomy within the genus Anodonta has been problematic, and based entirely on shell morphology. In this study, I assessed genetic variation among Anodonta currently inhabiting the Columbia River near its confluence with the Willamette River (the type locality for three of the six western U.S. Anodonta species). Two highly divergent lineages were discovered in this locality, corresponding to two distinct morphotypes (putatively A. oregonensis and A. nuttalliana). These lineages were also represented in other western U.S. drainages, and included two other currently recognized Anodonta species. The level of divergence between these lineages is suggestive of a need for genus-level taxonomic revision in western Anodonta. This research provides an important first step towards resolving taxonomic confusion in western Anodonta species, a necessity for the effective conservation, monitoring, and management of this fauna. |
