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.巴克镖鲈（Etheostoma nebra，英文名Buck Darter）被描述为一个新物种，其分布局限于美国肯塔基州坎伯兰河水系内的巴克溪流域。该物种最早的采集记录可追溯至1955年，当时被归为条纹镖鲈（Etheostoma virgatum）的一个种群。研究人员通过与条纹镖鲈的形态学比对，以及基于线粒体基因和5个核基因的DNA序列开展的系统发育分析，完成了对巴克镖鲈的物种界定。巴克镖鲈可通过以下特征与条纹镖鲈区分：总侧线鳞数量更少、有孔侧线鳞数目更少，胸鳍鳍条数的众数为13，而条纹镖鲈为12。二者在色素沉着模式以及繁殖期雄性体色上亦存在差异。在分子系统发育树中，巴克镖鲈并未被界定为条纹镖鲈的姊妹物种。对所有馆藏标本采集记录的梳理，以及在巴克溪流域开展的大量野外调查结果显示，该物种在过去30年间出现了种群数量的显著下降。1955年至1981年间的采集记录表明，巴克镖鲈曾广泛分布于整个巴克溪流域，但目前该物种仅残存于弗莱利克溪（Flat Lick Creek）的一小片区域。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消失的已证实记录，巴克镖鲈被评估为极危（critically imperiled）物种。