Crotalus Viridis - Taxonomy

Taxonomy

The taxonomic history of this species is convoluted. Previously, seven other C. viridis subspecies were also recognized, including abyssus, caliginis, cerberus, concolor, helleri, lutosus and oreganus. However, in 2001 Ashton and de Queiroz published a paper describing their analysis of the variation of mitochondrial DNA across the range of this species. Their results agreed broadly with those obtained by Pook et al. (2000). Two main clades were identified, east and west of the Rocky Mountains, which they argued were actually two different species: on the one hand C. viridis, including the conventional subspecies viridis and nuntius, and on the other C. oreganus, including all the other traditional subspecies of C. viridis. The authors retained the names of the traditional subspecies, but emphasized the need for more work to be done on the systematics of C. oreganus.