Urocitellus mollis Kennicott, 1863
All the species of Urocitellus were previously believed to belong to the much larger genus Spermophilus, but DNA sequencing of the cytochrome b gene showed that this group was paraphyletic to the prairie dogs and marmots,, and could therefore no longer be retained as a single genus. As a result, Urocitellus is now considered as a genus in its own right.
- Herron, Matthew D.; Castoe, Todd A.; Parkinson, Christopher L. 2004. Sciurid phylogeny and the paraphyly of Holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution, 31(3). PMID 15120398.
- Helgen, Kristofer M.; Cole, F. Russel; Helgen, Lauren E.; and Wilson, Don E 2009. Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus. Journal of Mammalogy, 90(2): 270–305. doi:10.1644/07-MAMM-A-309.1. Archived from the original on 2011-10-22. http://www.webcitation.org/62dP5i1JK?url=http://www.mammalsociety.org/uploads/Helgen.
- North American Mammals: Urocitellus mollis