Pheidole inquilina

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Pheidole inquilina
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Pheidole
Species: P. inquilina
Binomial name
Pheidole inquilina
(Wheeler, W.M., 1903)

Pheidole inquilina casent0103145 profile 1.jpg

Pheidole inquilina casent0103145 dorsal 1.jpg

Specimen Label

In Colorado Pheidole inquilina was found by Wheeler with the host species P. pilifera (“subspecies coloradensis”) at about 2000 m, under rocks most likely in pinyon-cedar-oak woodland. The species is the least anatomically modified of the pheidoline social parasites. It is therefore not very surprising that both the major and minor workers have been discovered in addition to the usual queens and males. However, these castes are evidently in a state of evolutionary decline. In 19 infested nests of the host species excavated by A. C. Cole (1965), 8 contained a few individuals of inquilina; and of these, one nest yielded only a single minor worker of inquilina, while another contained one minor and one major. M. R. Smith (1940) noted the close resemblance of the worker castes between the two species, and suggested that inquilina was derived in evolution from pilifera or a related species. In other words, Emery’s rule that social parasites are close relatives of their hosts is exemplified. (Wilson 2003)

At a Glance • Inquiline  



See the description in the nomenclature section.

Keys including this Species


Colorado, Nebraska, and Nevada: rare (Wheeler 1910; M. R. Smith 1940; Gregg 1963; D. R. Smith 1979). In Colorado, inquilina occurs at about 2000 m. (Wilson 2003)

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • inquilina. Epipheidole inquilina Wheeler, W.M. 1903f: 664, fig. 5 (gynandromorph) U.S.A. Wheeler, W.M. 1904a: 15 (q.m.); Smith, M.R. 1940a: 106 (w.); Cole, 1965: 174 (s.). [Also described as new by Wheeler, W.M. 1904a: 15.] Combination in Pheidole: Cole, 1965: 174. See also: Wilson, 2003: 580.

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 permanent social parasite of Pheidole pilifera (including “subspecies coloradensis”). The queen is very small, and easily recognized by her subangulate occipital corners. Aside from these two traits, and possibly the rounded tips of the propodeal spines, inquilina queens are little modified in general from typical queens of other, non-parasitic species of Pheidole.

MEASUREMENTS (mm) Syntype queen: HW 0.70, HL 0.70, SL 0.64, EL 0.24, PW (not measured).

COLOR Queen: light brown.

Pheidole inquilina Wilson 2003.jpg

Figure. Syntype, queen. Majors and minors have been discovered but are not figured. Scale bars = 1 mm.

Type Specimen Labels

Type Material

COLORADO: Broadmoor, Colorado Springs, 2000 m, col. William M. Wheeler. Museum of Comparative Zoology - as reported in Wilson (2003)


L inquilina, temporary guest, lodger. (Wilson 2003)


  • Baroni Urbani, C. 1964b. Studi sulla mirmecofauna d'Italia. II. Formiche di Sicilia. Atti Accad. Gioenia Sci. Nat. (6) 16: 25-66 (page 50, figs. 15, 16 worker described)
  • Bolton, B. 1987. A review of the Solenopsis genus-group and revision of Afrotropical Monomorium Mayr (Hymenoptera: Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 54: 263-452 (page 291, junior synonym of pallidula)
  • Cole, A. C., Jr. 1965. Discovery of the worker caste of Pheidole (P.) inquilina, new combination (Hymenoptera: Formicidae). Ann. Entomol. Soc. Am. 58: 173-175 PDF (page 174, soldier described, Combination in Pheidole)
  • 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.
  • Smith, M. R. 1940a. The discovery of the worker caste of an inquilinous ant, Epipheidole inquilina Wheeler. Proc. Entomol. Soc. Wash. 42: 104-109 (page 106, worker described)
  • Wheeler, W. M. 1903h. Some new gynandromorphous ants, with a review of the previously recorded cases. Bull. Am. Mus. Nat. Hist. 19: 653-683 (page 664, fig. 5 gynandromorph)
  • Wheeler, W. M. 1904a. Three new genera of inquiline ants from Utah and Colorado. Bull. Am. Mus. Nat. Hist. 20: 1-17 (page 15, queen, male described)
  • Wheeler, W. M. 1904a. Three new genera of inquiline ants from Utah and Colorado. Bull. Am. Mus. Nat. Hist. 20: 1-17 (page 15, also described as new)
  • Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA. (page 580, fig. queen described)