Data from: 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 past 30 years. Collections made from 1955 to 1981 show that Etheostoma nebra was widespread throughout the Buck Creek system, but the species is currently restricted to a small portion of Flat Lick Creek. Etheostoma nebra is critically imperiled based on its restricted geographic distribution and documented disappearance of populations within the Buck Creek system during the past three decades.

暗色镖鲈（Etheostoma nebra，俗称巴克镖鲈（Buck Darter））被描述为一新特有物种，其分布局限于美国肯塔基州坎伯兰河水系的巴克溪流域。该物种的最早采集记录可追溯至1955年，当时被归入线条镖鲈（Etheostoma virgatum）的种群范畴。研究人员通过与线条镖鲈的形态学比对，以及基于线粒体基因与5个核基因DNA序列的系统发育分析，明确界定了暗色镖鲈的物种地位。暗色镖鲈可通过以下特征与线条镖鲈区分：总侧鳞总数更少、具孔侧鳞数目更少，胸鳍鳍条的众数为13，而线条镖鲈为12；二者在色素沉着模式及繁殖期雄性体色上亦存在显著差异。在分子系统发育树中，暗色镖鲈并未被解析为线条镖鲈的姐妹物种。对暗色镖鲈全部馆藏标本记录的梳理，以及在巴克溪流域开展的大规模野外调查结果显示，该物种种群在过去30年间出现了剧烈衰退。1955年至1981年的采集记录表明，暗色镖鲈曾广泛分布于整个巴克溪流域，但目前其分布仅局限于平坦溪（Flat Lick Creek）的小片区域。基于其狭窄的地理分布范围，以及过去30年间巴克溪流域内多个种群已消失的记录，暗色镖鲈被评估为极危物种。