Formica obtusopilosa

Identification
Just approaching medium-sized, the bicolored (black, or darker brown to reddish brown, gaster with lighter colored, yellowish-red alitrunk and head) Formica obtusopilosa workers have a dense gastric pubescence. This species belongs to the sanguinea species group, which is behaviorally differentiated from other Formica species by their slavemaking habitats. They may be found in colonies that contain a mix of conspecific and heterspecific workers. Morphologically the combination of dense gastric pubescence and an indentation in the middle of the clypeus or, more technically, a median concave impression on the anterior border of the clypeus set sanguinea species apart from other North American Formica. Erect light colored hairs (whitish to whitish yellow) that are larger towards their truncate tips differentiate these ants from other sanguinea species.

Distribution
This taxon was described from the United States. It is also found in Canada. Rocky mountain region from New Mexico to Alberta. Also occurs in the Black Hills of South Dakota.

Biology
Nests in the soil in open grassy areas. Chambers may be found under stones or there may be a small earthen mound surrounding exposed ground entrances. Colonies can contain up to a few hundred workers.

Nomenclature

 *  obtusopilosa. Formica obtusopilosa Emery, 1893i: 648 (w.) U.S.A. Combination in F. (Raptiformica): Emery, 1925b: 259. Subspecies of sanguinea: Wheeler, W.M. 1901c: 713; Wheeler, W.M. 1913f: 414. Revived status as species: Emery, 1925b: 259; Cole, 1942: 377. Senior synonym of munda: Emery, 1925b: 259; Creighton, 1950a: 465; of alticola: Wilson & Brown, 1955: 128.
 * munda. Formica munda Wheeler, W.M. 1905c: 267 (w.q.) U.S.A. Junior synonym of obtusopilosa: Emery, 1925b: 259; Creighton, 1950a: 465. See also: Wheeler, W.M. 1913f: 416.
 * alticola. Formica munda var. alticola Wheeler, W.M. 1917a: 534 (w.) U.S.A. Combination in F. (Raptiformica): Creighton, 1950a: 466. Subspecies of obtusopilosa: Creighton, 1950a: 466. Junior synonym of obtusopilosa: Wilson & Brown, 1955: 128.

Additional References

 * Mackay, W. P. and E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, NY.