Geographic distributions and patterns of co-occurrence among black-bellied and shovel-nosed salamanders (Desmognathus spp.) in the Great Smoky Mountains National Park

The southern Appalachian Mountains are a global hotspot for salamander diversity. Recent taxonomic revisions driven by a growing understanding of cryptic diversity and advancements in genomic technology have increased the number of described species in the area significantly, raising questions about biogeography and community structure. Recently described species in the Desmognathus quadramaculatus-marmoratus complex are morphologically cryptic but diagnosable by mitochondrial DNA. The complex includes multiple species within each of two distinct ecomorphs, the highly aquatic ‘shovel-nosed’ (SN) ecomorph and the semi-aquatic ‘black-bellied’ (BB) ecomorph. Here, we use mitochondrial DNA and Bayesian phylogenetic analysis to clarify distributions and patterns of co-occurrence of recently described species in the Great Smoky Mountains. We present new data showing more extensive co-occurrence of two cryptic species of the black-bellied ecomorph than previously recognized. Our results are also consistent with earlier work indicating shared variation between ecomorphs within one clade. In addition, we identified a divergent mitochondrial lineage of the shovel-nosed ecomorph related to D. aureatus , a species not previously known to inhabit the Great Smoky Mountains. These results reveal a more complex and diverse assemblage of ecomorphs than previously recognized in this hotspot of salamander diversity.