Data from: A new species of spottail darter endemic to the Clarks River in Kentucky and Tennessee (Percidae: Etheostomatinae: Etheostoma)

Etheostoma xanthovum, the Clarks Darter, is described as a new species
endemic to the Clarks River in Kentucky and Tennessee, USA. Etheostoma
xanthovum was previously delimited as Etheostoma oophylax, the Guardian
Darter, based on morphological trait data. Subsequent to the description
of E. oophylax, molecular phylogenetic analyses consistently resolved
specimens from the Clarks River system and E. chienense, the Relict
Darter, as sister species, which together formed a sister clade to all
other sampled populations of E. oophylax. Our analyses of morphological
traits, mitochondrial DNA (mtDNA), and genomic sampling using double
digest restriction-site associated DNA (ddRAD) sequencing support the
distinctiveness of Etheostoma xanthovum. Morphologically, Etheostoma
xanthovum, differs from Etheostoma oophylax in the number of dorsal fin
rays (12 versus 11), anal fin rays (8 versus 7), and in the number of
scale rows around the caudal peduncle (21.8 versus 20.37). Etheostoma
xanthovum does not share mtDNA haplotypes with Etheostoma oophylax or
Etheostoma chienense. Phylogenomic analysis of an average of 28,448 ddRAD
loci per sampled specimen resolves Etheostoma xanthovum and Etheostoma
chienense as sister species, and assessment of genomic divergence supports
the hypothesis that each of these two species represents a distinct and
independently evolving lineage. In addition, we report a range extension
of Etheostoma oophylax in the Obion River system, a direct tributary of
the Mississippi River.