A new barcheek darter species from Buck Creek (Cumberland River System), Kentucky (Percidae: Etheostomatinae: Catonotus: Oopareia)

Etheostoma nebra, the Buck Darter, is described as a new species endemic to the Buck Creek system of the Cumberland River drainage in Kentucky, USA. The earliest collection records of Etheostoma nebra date to 1955 and were considered a population of Etheostoma virgatum. Etheostoma nebra is delimited through morphological comparisons with Etheostoma virgatum and phylogenetic analyses using DNA sequences from a mitochondrial gene and five nuclear genes. Etheostoma nebra is distinguished from Etheostoma virgatum by a lower number of total lateral scales, fewer pored lateral scales and modally 13 compared with 12 pectoral fin rays. The two species also differ in patterns of pigmentation and nuptial male coloration. In the molecular phylogenies, Etheostoma nebra is not resolved as the sister species of Etheostoma virgatum. A review of all museum collection records of Etheostoma nebra and extensive field surveys in the Buck Creek system demonstrate a dramatic decline of the species over the p...