Meeting Abstract

16.1  Jan. 4  Cryptic biodiversity and phylogenetic patterns in the wide-ranging freshwater mussel genus Elliptio in southeastern North America. GANGLOFF, M. M.*; SIEFFERMAN, L. M.; HALANYCH, K. M.; Auburn University; Indiana University; Auburn University ganglmm@auburn.edu

North America possess the world�s greatest diversity of freshwater mussels (Bivalvia: Unionidae and Margaritiferidae) yet nearly 70% of its ~300 species are considered to be imperiled. Freshwater mussel conservation has been hampered by a high degree of taxonomic ambiguity resulting from few morphological characters and extreme phenotypic plasticity. For example, a recent list compiled by the American Fisheries Society recognized 36 taxa within Elliptio, making it the most species-rich unionid genus in North America. Although several Elliptio taxa are wide-ranging, >50% appear endemic to one or a very few river systems. However, due largely to taxonomic ambiguity, only 2 have received U.S. federal protection. We examined 2 mtDNA genes (CO1 and NAD1) from 20 putative Elliptio taxa from rivers on the Gulf and Atlantic slope and the Florida Peninsula. Phylogenetic analyses revealed that Elliptio, as currently recognized, is paraphyletic. The Interior (Mississippi) Basin endemic E. dilatata appears to be only distantly related to other Elliptio taxa occurring in smaller, Gulf and Atlantic slope drainages. Additionally, we found evidence of at least 2 cryptic taxa within Gulf drainage E. complanata and E. icterina. Relationships between other putative Elliptio taxa are occluded by relatively short branch lengths and poor bootstrap support for many nodes. Additional markers may be required to increase phylogenetic signal strength. Future studies will evaluate the ability of other mitochondrial genes to elucidate phylogeographic patterns and species boundaries within Elliptio lineages.