Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus
Helgen, Kristofer M.;
Cole, F. Russell;
Helgen, Lauren E.;
Wilson, Don E.
The substantial body of research on Holarctic ground squirrels amassed over the past century documents
considerable variability in morphological, cytogenetic, ecological, and behavioral attributes in the genus
Spermophilus F. Cuvier, 1825. Recent molecular phylogenetic studies suggest that the traditionally recognized
genera Marmota Blumenbach, 1779 (marmots), Cynomys Rafinesque, 1817 (prairie dogs), and Ammospermophilus
Merriam, 1892 (antelope ground squirrels) render Spermophilus paraphyletic, potentially suggesting that
multiple generic-level lineages should be credited within Spermophilus. Herein, we recognize 8 genera formerly
subsumed in Spermophilus, each of which is morphologically diagnosable, craniometrically distinctive, and
recovered as a monophyletic clade in phylogenetic analyses utilizing the mitochondrial gene cytochrome b.
Generic-level names are available for each of these ground squirrel assemblages, most of which are exclusively
or predominantly North American in distribution (Notocitellus A. H. Howell, 1938; Otospermophilus Brandt,
1844; Callospermophilus Merriam, 1897; Ictidomys J. A. Allen, 1877; Poliocitellus A. H. Howell, 1938;
Xerospermophilus Merriam, 1892; and Urocitellus Obolenskij, 1927). Only Spermophilus sensu stricto is
restricted to Eurasia. Generic subdivision of Spermophilus more aptly illuminates the taxonomic relationships,
ecomorphological disparity, and biogeographic history of Holarctic ground squirrels.