Genetic Evidence for Two New Species of Salamanders (Plethodon glutinosus complex)

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Biological diversity is important for maintaining healthy ecosystems, but human activities have resulted in increased extinction of species. Conserving biodiversity requires accurate knowledge of species diversity, yet this can be challenging when species are similar in appearance. The 16 species of Slimy Salamanders (Plethodon glutinosus complex) are distributed throughout the eastern United States are visually indistinguishable, having been described primarily using genetic data. Four species are known to occur west of the Mississippi River in Arkansas, Missouri, Oklahoma, Louisiana, and Texas, but our knowledge of species diversity and distributions in this region is based on genetic analysis of only 19 populations. Some of these species have small geographic ranges and many areas have not been sampled, meaning that additional species may remain to be discovered. To better understand species diversity in this region, we collected salamander tissue samples from >200 localities and sequenced the mitochondrial ND2 gene. Genetic analysis revealed two distinct groups of populations in southwestern Arkansas and southeastern Oklahoma that do not align with any known species. Thus, our results indicate that two undescribed species are present and additional species diversity exists in the Plethodon glutinosus complex. This is significant because it increases the number of Slimy Salamander species found west of the Mississippi River to six, representing a 50% increase from what was known previously. Assessing threats from human activities and formulating management strategies will be vital to ensure the conservation of these new species.