Phylogenetic and Morphological Diversity of the Etheostoma zonistium Species Complex with the Description of a New Species Endemic to the Cumberland Plateau of Alabama

We provide a description of the Blueface Darter, Etheostoma cyanoprosopum, which is distributed in the upper Sipsey Fork of the Mobile Basin and the upper portion of the Bear Creek system in the Tennessee River Drainage. The distinctiveness of Etheostoma cyanoprosopum is assessed through analysis of morphological variation and molecular phylogenetic diversity within the Etheostoma zonistium species complex. In addition to analyzing disparity of morphometric and meristic traits, we present phylogenetic analyses of a mitochondrial gene and two nuclear genes and identify genetic clusters through analysis of 25 microsatellite loci. In the mitochondrial DNA (mtDNA) gene tree, Etheostoma cyanoprosopumis resolved as the sister lineage to a clade containing all other species of the Etheostoma zonistium complex. Etheostoma zonistium is paraphyletic with respect to both Etheostoma pyrrhogaster and Etheostoma cervus, which do not resolve as sister species in the mtDNA gene tree. The two nuclear gene trees are much less resolved, but the S7 ribosomal protein intron 1 (S7) gene tree resolves Etheostoma cyanoprosopum and all sampled populations of Etheostoma zonistium as a clade with strong Bayesian posterior node support. Etheostoma cyanoprosopum is morphologically differentiated from Etheostoma zonistium by a shallower body, a more elongate nape, a higher number of lateral line scales, a higher number of transverse scale rows, and differences in coloration.