Comparative species delimitation of a biological conservation icon

The conservation of biodiversity relies on an accurate assessment of species diversity. We developed a comparative approach to species delimitation that integrates genomic and morphological data for objective assessment of the distinctiveness of species targeted for protection by governmental agencies. We apply this protocol to the Snail Darter (Percina tanasi), a freshwater fish from the Tennessee River that was the focus of the first major legal conflict over protections afforded by the United States Endangered Species Act. Here, we demonstrate the Snail Darter is not a distinct species but is a population of the Stargazing Darter (Percina uranidea) described in 1886. These results illustrate how the integration of multiple lines of evidence in a comparative framework is imperative for properly directing efforts to protect species. This dataset corresponds to the 2025 study in Current Biology titled "Comparative species delimitation of a biological conservation icon."