One of the goals of conservation genetics is to resolve taxonomic uncertainties, posing the question: does current taxonomy adequately reflect patterns of diversity in nature? Species and/or subspecies boundaries have been erected on scant evidence in some cases, which can have serious repercussions if the named taxon is rare and major conservation efforts are involved. The Clayton’s copper butterfly (Lycaena dorcas claytoni) was described as a subspecies of the Dorcas copper butterfly (Lycaena dorcas dorcas) in 1940. The subspecific status of Clayton’s copper is controversial because the presumed morphological differences between Clayton’s copper and Dorcas copper were not quantified as part of the original description. In addition, the original sample set for comparison was limited in terms of number of individuals and geographic scope. Despite the skepticism surrounding its subspecific status, the Clayton’s copper butterfly was listed as endangered in Maine in 1997. The objective of this research is to clarify the controversial taxonomic status of Clayton’s copper using morphological and genetic data.

Results/Conclusions

Multivariate analyses of morphological characters using both the traditional characteristics upon which the original subspecies description was based, as well as geometric characters derived from a size-free analysis of wing shape showed a continuous pattern of variation from which no individual subspecies were distinguishable. Additionally, mitochondrial and nuclear genes were sequenced for Clayton’s and Dorcas coppers, as well as other closely related species/subspecies across North America. Both sets of genetic data suggest synonymizing the subspecies of Dorcas copper, while at the same time describing subspecific and geographic differences in two congeneric species that were not elucidated by morphological analysis. Our results suggest that the taxonomy of the entire group likely needs revision to clarify those taxa that may or may not be eligible for state or federal listing.