Systematics of the subgenus Oligocephalus (Teleostei: Percidae: Etheostoma) with complete subgeneric sampling of the genus Etheostoma

The genus Etheostoma is the most diverse clade of freshwater fishes in North America. While studies have been performed with complete sampling of a single subgenus, none have included representatives of all remaining subgenera. The subgenus Oligocephalus is the largest, consisting of 25–27 species in four species groups, and its monophyly has never been clearly demonstrated. The monophyly of this subgenus and its constituent groups was tested using parsimony and Bayesian analyses of ND2 (mtDNA) and the first intron of S7 (nDNA) with complete species sampling from Oligocephalus and complete subgeneric sampling from Etheostoma. Although the subgenus Oligocephalus was not recovered as a monophyletic group in any analyses, monophyletic E. whipplei, Southwestern Darter, and E. spectabile (in part) species groups were recovered in all analyses. All analyses agree that E. okaloosae and both subspecies of E. hopkinsi are not closely related to other members of the subgenus Oligocephalus. E. exile is, however, presenting the strongest evidence yet that recognition of the subgenus Boleichthys is unwarranted.