The last published taxonomic treatment of this species (Wilson 2003) hypothesized this is a morphologically variable, broadly distributed species that is found in a wide range of habitats. Wilson's treatment and earlier work by Cole (1950) synonymized numerous subspecies (see the bottom of the taxonomy box to the right). Future taxonomic research is likely to conclude what some North American myrmecologists already believe - that this name subsumes more than the single species P. pilifera.
See the description in the nomenclature section.
Keys including this Species
Pheidole pilifera is the most widespread and northward-reaching of all the Nearctic Pheidole. The species, as presently broadly construed, ranges from Massachusetts south to Georgia and west to California, extending through the midwest as far north as Minnesota, North Dakota and southwest to Utah, New Mexico, and Arizona. (Wilson 2003)
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Colonies of pilifera excavate crater nests in exposed soil and harvest seeds, which are stored in nest chambers. In Colorado, Gregg (1963) found the species (as subsp. coloradensis) abundant at 1500 to 2600 m, in a wide range of habitats, from short-grass prairie, roadsides, and herbaceous semi-desert to mixed canyon forest and mountain mahogany shrub. Sexuals were present in the nest from the first week in June to the last week in July. P. pilifera is also notable in Colorado as the host of the social parasite Pheidole inquilina. In Nevada, pilifera ranges between 900 and 2300 m, nesting in desert and juniper-pinyon woodland, both under stones and in the open soil, where it forms craters 25–60 mm wide (G. C. and J. Wheeler 1986). According to Stefan Cover (personal communication), “In the eastern U. S. pilifera occurs in open, grassy habitats, especially those with sandy soils containing a little clay. It is less common in pure sand, thus in pine barrens. Mating flights occur in early to mid July. Colonies are monogynous, and the newly mated queens start colonies singly. Minors are ‘shy’ foragers but recruit to good food sources. Majors seldom leave the nest except when recruited. Their primary function is to block nest passages, which they do effectively.” (Wilson 2003)
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- pennsylvanica. Pheidole pennsylvanica Roger, 1863a: 199 (s) U.S.A. Mayr, 1886d: 456 (s.w.q.m.). Junior synonym of pilifera: Emery, 1895c: 290.
- pilifera. Leptothorax pilifer Roger, 1863a: 180 (w.) U.S.A. Emery, 1895c: 290 (s.); Wheeler, G.C. & Wheeler, J. 1953b: 79 (l.). Combination in Pheidole: Emery, 1895c: 290. Senior synonym of pennsylvanica: Emery, 1895c: 290; of septentrionalis and material of the unavailable name simulans referred here: Creighton, 1950a: 186; of artemisia, coloradensis, pacifica: Wilson, 2003: 589.
- coloradensis. Pheidole pilifera var. coloradensis Emery, 1895c: 290 (s.w.) U.S.A. Wheeler, W.M. 1908e: 435 (q.m.). Subspecies of pilifera: Wheeler, W.M. 1908e: 435; Wheeler, G.C. & Wheeler, E.W. 1944: 244. Material of the unavailable name neomexicana referred here by Creighton, 1950a: 187. Junior synonym of pilifera: Wilson, 2003: 589.
- septentrionalis. Pheidole pilifera subsp. septentrionalis Wheeler, W.M. 1908e: 437 (s.w.) U.S.A. Junior synonym of pilifera: Creighton, 1950a: 186.
- pacifica. Pheidole xerophila subsp. pacifica Wheeler, W.M. 1915b: 404 (s.w.q.m.) U.S.A. Subspecies of pilifera: Creighton, 1950a: 187. Junior synonym of pilifera: Wilson, 2003: 589.
- artemisia. Pheidole pilifera subsp. artemisia Cole, 1933: 616 (s.w.) U.S.A. Cole, 1938c: 372 (q.). Junior synonym of pilifera: Wilson, 2003: 589.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
From Wilson (2003): DIAGNOSIS A member of the “pilifera complex” of the larger pilifera group, comprising Pheidole calens, Pheidole californica, Pheidole carrolli, Pheidole cavigenis, Pheidole clementensis, Pheidole creightoni, Pheidole hoplitica, Pheidole littoralis, Pheidole micula, Pheidole pilifera, Pheidole polymorpha, Pheidole rugulosa, Pheidole senex, Pheidole soritis, Pheidole tepicana and Pheidole torosa, which complex is characterized by the following traits. Major: dorsal head surface extensively sculptured; occipital lobe horizontally rugulose (or, in carrolli smooth, in littoralis foveate, and in micula and soritis carinulate); postpetiole from above diamond-shaped, trapezoidal, or spinose. Minor: eye medium-sized to large. P. pilifera is distinguished within its complex by the following combination of traits.
Major: relatively large, HW about 1.6 mm; posterior dorsal profile of head straight or slightly concave; mesonotal convexity prominent and symmetrical in side view; propodeal spines robust, long, and nearly vertical to basal propodeal face; petiolar node in side view tapering apically to a blunt point; postpetiolar node from above very broad relative to petiolar node, and bluntly spinose.
Minor: eyes medium-sized; humerus in dorsal-oblique view subangulate; all of head posterior to the clypeus and mesosoma foveolate and opaque.
Closely related to Pheidole carrolli but very different in sculpturing of the major.
My synonymy of artemisia, coloradensis, and pacifica follows Creighton (1950a) in placing them as geographic variants, or subspecies, and thence here into synonymy at the species level. However, this assignment is not well documented and thus is regarded as provisional. The pattern of geographic variation within pilifera is as follows.
Western populations (“coloradensis”) ranging from North Dakota and Colorado to Nevada display a narrowing of the transverse rugulose band to the rearmost part of the major occiput and loss of the longitudinal carinulae on the vertex (anterior to the occiput), an area that is spotted with coarse foveae and shiny interspaces. The trend is climaxed in Nevada and California (“pacifica”) by replacement of the foveae on the vertex of the major by fine punctures. Southwestward, in Utah and Arizona (“artemisia”), the broad band of occipital rugulae of the major in eastern populations (“typical” pilifera) is retained, but the carinulae of the vertex are lost and replaced by a shiny surface.
MEASUREMENTS (mm) Major (Haddam, Connecticut): HW 1.60, HL 1.72, SL 0.74, EL 0.24, PW 0.68. Minor (Haddam): HW 0.54, HL 0.60, SL 0.52, EL 0.12, PW 0.36.
COLOR Major: light reddish brown.
Minor: medium reddish brown.
Figure. Upper: major. Lower: minor. CONNECTICUT: East Haddam. Scale bars = 1 mm.
Berlin Museum für Naturkunde der Humboldt-Universität - as reported in Wilson (2003)
Gr pilifera, hairy. (Wilson 2003)
- Creighton, W. S. 1950a. The ants of North America. Bull. Mus. Comp. Zool. 104: 1-585 (page 186, Senior synonym of septentrionalis, and material of the unavailable name simulans referred here.)
- Emery, C. 1895d. Beiträge zur Kenntniss der nordamerikanischen Ameisenfauna. (Schluss). Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 257-360 (page 290, soldier described, Combination in Pheidole, Senior synonym of pennsylvanica)
- Gregg, R. E. 1963. The Ants of Colorado, With Reference to their Ecology, Taxonomy, and Geographic Distribution. Boulder: U. of Colorado Press, xvi + 792 pp.
- Roger, J. 1863a. Die neu aufgeführten Gattungen und Arten meines Formiciden-Verzeichnisses nebst Ergänzung einiger früher gegebenen Beschreibungen. Berl. Entomol. Z. 7: 131-214 (page 180, worker described)
- Wheeler, G. C.; Wheeler, J. 1953b. The ant larvae of the myrmicine tribe Pheidolini (Hymenoptera, Formicidae). Proc. Entomol. Soc. Wash. 55: 49-84 (page 79, larva described)
- Wheeler, G. C. and J. Wheeler. 1986. The Ants of Nevada. Los Angeles: Natural History Museum of Los Angeles County, vii + 138 pp.
- Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA. (page 589, fig. major, minor described, Senior synonym of coloradensis, pacifica, artemisia)