The taxonomy of sculpins (Cottus, Cottidae) remains one of the last major unresolved puzzles in the systematics of North American freshwater fishes. We used molecular approaches to identify candidate taxa and their distribution across western North America. We crowd-sourced the collection of specimens (n = 8272) via outreach to biologists in the western United States and Canada. From that collection, we sequenced - at up to 2 mitochondrial and 2 nuclear genes - a subset (n = 4009) of specimens from most basins in the western United States, added sequences from public sequence databases, and applied an array of species delimitation and specimen identification methods to assess phylogenetic and spatial patterns of diversity. Species delimitation methods, primarily relying on a conservative interpretation of the phylogenetic species concept, were broadly concordant and indicated that 43 candidate species were present. Some named taxa were unsupported, whereas others, if recognized, would violate the phylogenetic species concept. Specimen assignment was largely unambiguous and geographic distributions were consistent with phylogeographic patterns in other taxa. Our work establishes a benchmark for understanding the diversity of sculpin in western North America and suggests new species hypotheses both there and in eastern North America. SUPPLEMENTARY MATERIAL (1.5 MB zip file)
Young, Michael K.; Smith, Rebecca; Pilgrim, Kristine L.; Isaak, Daniel J.; Mckelvey, Kevin S.; Parkes, Sharon; Egge, Jacob; Schwartz, Michael K. 2022. A molecular taxonomy of Cottus in western North America. Western North American Naturalist 82(2): 307-345.