Cutthroat Trout: Evolutionary Biology and Taxonomy

An Interim Classification of the Cutthroat Trout Complex, Oncorhynchus clarkii Sensu Lato, with Comments on Nomenclature

Douglas F. Markle

doi: https://doi.org/10.47886/9781934874509.ch8

Abstract.—The 2015 special workshop on the taxonomy and evolutionary biology of Cutthroat Trout highlighted the need for a modern systematic revision of Cutthroat Trout. Pending such a revision, the consensus of this panel was that Cutthroat Trout taxonomy should be based on the unified species concept. The current classification of Cutthroat Trout is based on Benhke’s “major and minor subspecies,” which is incompatible both with the unified species concept, which logically excludes subspecies, and the International Code for Zoological Nomenclature, which does not recognize major and minor subspecies. A compromise, interim classification is proposed, which captures Benhke’s ideas about Cutthroat Trout evolution and other recent information and retains trinomials for his “minor” subspecies, entities deserving re-evaluation in any subsequent systematic revision. Four species are recognized in this interim classification: Coastal Cutthroat Trout Oncorhynchus clarkii, Westslope Cutthroat Trout O. lewisi, Lahontan Cutthroat Trout O. henshawi, and Rocky Mountain Cutthroat Trout O. virginalis. The latter two contain recognized, named subspecies—O. henshawi with four (one extinct) and O. virginalis with seven (one extinct). Substantial nomenclatural problems are described, such that some common names are likely to be more stable than some scientific names until problems are resolved. Significant among these nomenclatural problems are the need to stabilize Rocky Mountain Cutthroat Trout Salar virginalis Girard with a neotype selection; the recognition of Salmo stomias Cope as a synonym of Rio Grande Cutthroat Trout Salar virginalis Girard and, consequently, the absence of a scientific name for Greenback Cutthroat Trout; the high likelihood that Salmo bouvieri Bendire is not a Yellowstone Cutthroat Trout; the high likelihood that the surviving syntype of Salmo pleuriticus Cope is a Westslope Cutthroat Trout and not a Colorado River Cutthroat Trout; and the related need to stabilize S. pleuriticus Cope, either with a lectotype designation from the surviving syntype, which might place S. pleuriticus Cope as a synonym of Westslope Cutthroat Trout, or, if it can be justified, a neotype designation using a Colorado River specimen.