- Dwelling on the bottom of large rivers to high alpine streams, freshwater sculpins (genus Cottus) occur in high densities across the Pacific Northwest, with 21 currently recognized species found in the Pacific Northwest. Sculpin fill many ecological roles, with some species serving as important prey sources, and others competing with or predating upon juvenile salmonids. Fully understanding these
ecological interactions requires the ability to recognize and diagnose co-occurring species. However, Cottus contains many similar looking species, leading to frequent misidentifications and the persistence of undiscovered species. I used multilocus phylogenetics and multivariate morphometric
analysis to investigate the taxonomic status of Torrent Sculpin, Cottus rhotheus across the Pacific Northwest, and determine whether the current concept of C. rhotheus contains multiple cryptic, unrecognized species. Phylogenetic analysis reveals three distinct and geographically restricted clades, with the Columbia River and Cascade Range acting as allopatric barriers. Morphometric data corroborates the genetic divisions, identifying the presence of three cryptic species under the current species description of C. rhotheus.