Phylogeny of the critically endangered North American spinymussels (Unionidae: Elliptio and Pleurobema)

摘要: Lateral spines are uncommon among freshwater bivalves. The North American mussel fauna includes three taxa that exhibit spines: Elliptio spinosa, steinstansana, and Pleurobema collina. All endemic to the Southeastern US, critically endangered. Currently, these species recognized in two genera a source of taxonomic confusion within unionid tribe Pleurobemini (Elliptio Pleurobema). Because mussels phenotypically plastic shell morphology, morphologically-based diagnoses problematic. I sequenced mtDNA gene fragments fragment nuclear ITS-1 locus from >70 spinymussel specimens. Bayesian phylogenetic reconstructions suggest spinymussels do not comprise monophyletic group. steinstansana is sister P. collina form clade possibly diverged its nearest ancestor late Miocene. Additionally, E. spinosa forms members core lineage mid Pliocene, >1.5 million years before multiple radiations clade. Furthermore, divergent other spinymussels, suggesting have evolved separately distinct bivalve lineages this region. These findings need revise taxonomy highly imperiled