Extensive regional endemism and cryptic diversity in the Tennessee and Kentucky, USA populations of the burrowing crayfish Cambarus deweesae (Bouchard & Etnier, 1979) (Decapoda: Astacidea: Cambaridae) as revealed by molecular genetics

Abstract

Abstract The southeastern United States is a global hotspot for crayfish biodiversity, with more than 300 described species in the region. Some of this diversity is unfortunately being threatened by anthropogenic activities and nearly one fifth of the North American crayfish species are currently threatened with extinction. Efforts to protect crayfish species have been hindered by a lack of information regarding their taxonomy, distribution, and conservation status. Here we target populations of the burrowing valley flame crayfish, Cambarus deweesae (Bouchard & Etnier 1979) for molecular taxonomy investigation. This species was originally known from the Clinch and Emory subdrainages in eastern Tennessee but it is currently listed as state endangered. The reporting of additional populations in Tennessee and Kentucky, however, has led to uncertainty about its conservation status. We analyzed sequence data from three mitochondrial genes (COI, 12S rRNA, and 16S rRNA) and from one nuclear gene (GAPDH) to decipher taxonomic questions regarding 15 crayfish populations, including 13 populations that are morphologically similar to C. deweesae (type locality sensu stricto). Combined analysis of all four genes demonstrated reciprocal monophyly for 14 out of 15 populations surveyed. Species delimitation methods, including GMYC and ABGD, identified between 11 and 13 new distinct genetic entities based on sequence divergence at the mitochondrial COI gene. Molecular results are combined with information on morphology and distribution in order to resolve taxonomic uncertainties within C. deweesae and its close relatives. The study highlights the need for fine-scale investigations into the phylogeography of North American burrowing crayfishes.