Tamias is a genus of chipmunks in the tribe Marmotini of the squirrel family. The genus includes a single living species, the eastern chipmunk (Tamias striatus). The genus name Tamias means "treasurer", "steward", or "housekeeper", which is a reference to the animals' role in plant dispersal through their habit of collecting and storing food for winter use. The genus Tamias was formerly divided into three subgenera that, in sum, included all chipmunk species: Tamias, the eastern chipmunk and other fossil species; Eutamias, of which the Siberian chipmunk (E. sibiricus) is the only living member; and Neotamias, which includes the 23 remaining, mostly western, species. These classifications are subjective, and most taxonomies over the twentieth century have placed the chipmunks in a single genus. However, studies of mitochondrial DNA show that the divergence between each of the three chipmunk groups is comparable to the genetic dissimilarity between Marmota and Spermophilus, so they are now often considered as separate genera. In addition to the eastern chipmunk, some fossil species from Eurasia have been assigned to this genus: One American fossil species, Tamias aristus from the late Pleistocene, has been identified.