Abstract

There is ongoing uncertainty regarding the taxonomic status of Painted Turtles (genus Chrysemys). Most recently, a phylogenetic analysis of the mitochondrial DNA control region (mtCR) resulted in the elevation of a subspecies to the species level, resulting in two species being tentatively, but not universally, accepted: Chrysemys dorsalis and C. picta, the latter encompassing the three remaining subspecies. Here, we used expanded range-wide sampling and character data from PAX-P1 nuclear intron (n = 127) and mtCR (n = 259) to further investigate taxonomic uncertainty and paleogeography of Painted Turtles. We found five mtCR characters that distinguished C. dorsalis from C. picta; no such evidence was found in PAX-P1. Chrysemys dorsalis formed a monophyletic group in the reconstructed phylogenetic trees, whereas there was no genetic evidence for the distinctiveness of the three C. picta subspecies. The mtCR network showed C. dorsalis and C. p. bellii to each form relatively distinct clusters, whereas no clustering by morphotype was found in the PAX-P1 network. Lower levels of haplotypic diversity across the range of C. p. bellii are consistent with recent postglacial expansion to the west; however, observed mismatch distributions were multimodal, which does not indicate population expansion. Overall, the addition of nuclear DNA character data and expanded sampling support the tentative designation of C. dorsalis and C.picta (encompassing C. p. picta, C. p. bellii, and C. p. marginata) as separate species. Yet, lack of accompanying morphological data and potential for oversplitting due to targeting only individuals within the core of morphotype ranges suggests that further study is warranted.