Xerospermophilus
Pygmy ground squirrels are small ground squirrels in the genus Xerospermophilus, family Sciuridae, containing four species from Mexico and the United States. The members of this genus were formerly placed in the large ground squirrel genus "Spermophilus". Since DNA sequencing of the cytochrome "b" gene has shown "Spermophilus" to be paraphyletic to the prairie dogs and marmots, this group is now separated, along with six other genera. Within the genus, the Mohave ground squirrel and the round-tailed ground squirrel were thought to be close relatives, sometimes a subgenus "Xerospermophilus", while the spotted ground squirrel and the Perote ground  squirrel were placed in the subgenus (now a genus) "Ictidomys". The name of the genus is a combination of the Greek word "xeros", "dry", and "Spermophilus", which also comes from Greek, meaning "seed lovers". Species. The four species in "Xerospermophilus" are listed below. These are the same species that were previously grouped in the subgenus "Otospermophilus".