Molecular and morphological analyses reveal cryptic crayfish invasions in the Appalachian Mountains
Abstract The crayfish genus Orconectes is widespread in North America and includes both regional endemics and several aggressively invasive species. Orconectes rusticus was recently discovered in three western North Carolina streams. We examined specimens from these localities as well as individuals from across the region using molecular and morphological analyses to verify diagnoses. We sequenced and analyzed a portion of the cytochrome c oxidase subunit (COI) gene and compared reads to GenBank reference sequences. We used mtDNA diagnoses to evaluate the utility of quantitative morphological analyses to correctly classify specimens. Comparisons with reference sequences revealed cryptic diversity among introduced populations. The population previously identified as O. rusticus in the Little Tennessee River is genetically most similar to O. juvenilis. Moreover, the putative un-described Cheoah Crayfish appears to be an introduced O. juvenilis population. Comparisons with topotypic and introduced O. juvenilis populations suggest the Little Tennessee River population originated in the lower Ohio Valley and that populations of this cryptic invader may be more widespread than previously believed. Additionally, these results demonstrate the susceptibility of reservoir fisheries to crayfish invasions. Future studies of invasive crayfish and putative new species should use molecular data to verify morphological diagnoses.