Pheidole bicarinata

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Pheidole bicarinata
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Pheidole
Species: P. bicarinata
Binomial name
Pheidole bicarinata
Mayr, 1870



Specimen Label


From Wilson (2003): P. bicarinata is highly adaptable across its range in both habitat and nest site. In Colorado, Gregg (1963) recorded bicarinata between 1000 and 2100 m, nesting in rotten logs as well as various types of soil beneath stones. The habitats occupied were very diverse, comprising pinyon-cedar and mixed deciduous woodland, canyon-bottom meadows, shortgrass prairie, and sagebrush desert. In Utah and Nevada, bicarinata occurs from sagebrush desert to montane woodland, nesting under stones and pieces of wood, as well as crater nests in open soil (Ingham 1959, 1963; Cole 1966b; Allred and Cole 1979). In western Texas, it has been found in xeric habitats in open soil and under stones, cow dung, a bale of hay, and in cracks in asphalt. Beck et al., studying scavenging ants of Utah, observed workers feeding on dead rodents. Males were found in one Colorado nest in early July. In the eastern United States the species favors sandy soils with some clay content. It is often abundant in open, disturbed grassy areas, such as lawns, golf courses, and abandoned fields (Stefan Cover, personal communication). It is omnivorous in diet, and regularly harvests seeds. Diana E. Wheeler and Frederik Nijhout used bicarinata in their pioneering studies to demonstrate the role of juvenile hormone in the determination of the major and minor subcastes; they traced development through four larval instars (see Wheeler 1991).


Mackay and Mackay (2002) - For co-occuring Pheidole species in New Mexico, Pheidole bicarinata is difficult to separate from Pheidole cerebrosior. It differs in that the vertex of the head of the minor worker is smooth and polished, or finely, transversely striolate, whereas the vertex of P. cerebrosior is densely punctate. There is a considerable amount of variation in the sculpturing of the vertex of the minor worker, and it is often difficult to identify a series, as different workers may have characteristics of both species. Pheidole bicarinata could be confused with Pheidole marcidula, but can be separated as the minor lacks the clavate hairs on the dorsum of the mesosoma.

See the description in the nomenclature section.

Keys including this Species


New Jersey to northern Florida and west through Nebraska, Colorado, and Texas to Utah and Nevada. (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


This species has a preference for open sites with sandy soils and habitats that are at the moister end of dry (e.g., grasslands and valley bottoms in arid areas), at least in the west. It also inhabitats sites that have some but not all of these characteristics. Gregg (1963) stated Pheidole bicarinata in Colorado was a Sonoran Zone species. In the eastern US (Carter, 1962; Wilson 2003) this ant is common in fields and open grassy locations, including in ruderal sites (sidewalks, lawns, and along the shoulder of roads).


Nesting Biology

Nests are found underneath ground-covering objects, within rotten downed wood, or in open ground with a small crater mound. Mounds are typically incomplete, resembling a wedge or crescent.

Colony Attributes

Colonies are small, often just a few hundred workers.


Seeds are collected and may be stored in underground granaries that are part of the nest. Workers also visit extraflora nectories.

Association with Other Organisms


This species is a host for the eucharitid wasp Orasema coloradensis (a parasite) (Wheeler, 1907; Johnson et al., 1986; Baker et al., 2019; Universal Chalcidoidea Database) (primary host).


This species is a host for the fungus Myrmicinosporidium durum (a pathogen) (Espadaler & Santamaria, 2012).

Regional Notes

New Mexico

Mackay and Mackay (2002) - Occurs in grasslands (including arid sites with yuccas), scrub oak, pine and cedar, pinyon-juniper forests, oak forests, ponderosa pine forests. Pheidole bicarinata nests in rotten logs, as well as in the soil and under objects (especially stones) in grassy areas with fine sand. Brood was found in nests in March and August. They are attracted to baits on the soil surface (Vienna sausage). This species is the host of Solenopsis molesta.

Associations with other Organisms

Other Insects

The two Oresema sp. wasps shown below were found by Stefan Cover with a colony of P. bicarinata in Arizona (Specimen Labels).

The general biology of Eucharitid wasps are summarized nicely here (Lachaud, J., Cerdan, P. and Pérez-Lachaud, G. 2012 - see the original paper for the citations indicated by the numerals doi:10.1155/2012/393486):

"Within Hymenoptera, the family Eucharitidae (subdivided in three subfamilies: Oraseminae, Eucharitinae, and the Indo-Pacific Gollumiellinae) is the most numerous and diverse group of ant parasitoids [1, 2]. All of the members of this family have a highly modified life cycle [3–6]. Unlike most parasitic wasp species, eucharitid females deposit their eggs away from hosts, in or on plant tissue [2, 7]. The active first instar larva, termed planidium, is responsible for gaining access to the host ant larvae by using various phoretic behaviors including either attachment to an intermediate host (most often a potential ant prey) or to foraging ant workers, with on occasion the presence of attractive substances in or on the eggs [2, 8]. Within the nest, planidia attach themselves to ant larvae, but development is only completed when the host pupates [6, 7, 9, 10]. In almost all of the cases, adults emerge among ant brood (but see [11]) and have to leave the host nest to reproduce. Ants show only moderate aggression to newly emerged eucharitids [7, 12–17] and transport them outside as if they were refuse [11, 15, 17], ultimately enhancing wasp dispersal. Parasitism is very variable and localized in time and space [13, 18, 19]. A very high local prevalence may lead to only a very low impact at the regional scale, suggesting that these parasitoids do not have a major influence on the dynamics of their host population [19]. However, they constitute a remarkable example of both host-parasitoid coevolution and host behavior manipulation."








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

  • bicarinata. Pheidole bicarinata Mayr, 1870b: 989 (s.) U.S.A. Senior synonym of hayesi: Creighton, 1950a: 171; of longula, vinelandica (and its junior synonyms buccalis, laeviuscula, nebrascensis): Wilson, 2003: 561.
  • vinelandica. Pheidole bicarinata r. vinelandica Forel, 1886b: xlv (s.w.q.m.) U.S.A. Combination in P. (Allopheidole): Forel, 1912f: 237. Raised to species: Mayr, 1886d: 458; Dalla Torre, 1893: 97; Naves, 1985: 66. Subspecies of bicarinata: Creighton, 1950a: 172; Gregg, 1959: 18. Senior synonym of laeviuscula: Creighton, 1950a: 172; of buccalis, nebrascensis: Gregg, 1959: 18. Junior synonym of bicarinata: Wilson, 2003: 561.
  • laeviuscula. Pheidole vinelandica subsp. laeviuscula Emery, 1895c: 292 (s.w.) U.S.A. Junior synonym of vinelandica: Creighton, 1950a: 172.
  • longula. Pheidole vinelandica var. longula Emery, 1895c: 292 (s.w.) U.S.A. Subspecies of bicarinata: Creighton, 1950a: 171; Smith, D.R. 1979: 1367. Raised to species: Cole, 1956c: 114. Junior synonym of bicarinata: Wilson, 2003: 561.
  • buccalis. Pheidole vinelandica subsp. buccalis Wheeler, W.M. 1908e: 454 (s.w.q.) U.S.A. Subspecies of bicarinata: Creighton, 1950a: 171. Material of the unavailable name castanea referred here by Creighton, 1950a: 171; of the unavailable name huachucana referred here by Smith, M.R. 1958c: 120. Junior synonym of vinelandica: Gregg, 1959: 18; of bicarinata: Cole, 1956c: 114; Wilson, 2003: 561.
  • hayesi. Pheidole hayesi Smith, M.R. 1924: 251 (s.w.) U.S.A. Junior synonym of bicarinata: Creighton, 1950a: 171.

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 “bicarinata complex” belonging to the larger pilifera group and comprising Pheidole agricola, Pheidole aurea, Pheidole bajaensis, Pheidole barbata, Pheidole bicarinata, Pheidole centeotl, Pheidole cerebrosior, Pheidole ceres, Pheidole defecta, Pheidole macclendoni, Pheidole marcidula, Pheidole paiute, Pheidole pinealis, Pheidole psammophila, Pheidole xerophila, Pheidole yaqui and Pheidole yucatana, which complex is characterized by large to very large, forward-set eyes, especially in the minor; and in the major, the occipital lobes lacking any sculpturing (exception: aurea), the posterior half of the head capsule smooth and shiny, and the postpetiole from above oval, elliptical, or laterally angulate (conulate in cerebrosior). P. bicarinata is distinguished within the subgroup by the following combination of traits.

Major: humerus in dorsal-oblique view dentate to subangulate; propodeal spine moderately long and stout; petiolar node in side view tapered; lateral margins of postpetiolar node seen from about acute-angular; anterior fringe of pronotal dorsum transversely carinulate, remainder mostly smooth and shiny; lateral margins of pronotal dorsum carinulate or not; mesonotal dorsum foveolate and opaque to mostly smooth and shiny; dorsum of propodeum foveolate and opaque and carinulate or not.

Minor: humerus in dorsal-oblique view obtusely subangulate; petiole variable in size and shape, from small and equilaterally triangular to moderately elongate. P. bicarinata is a taxonomically difficult species (or, possibly, complex of closely similar species). It is highly variable, especially geographically, in propodeal and pronotal sculpturing, and as suggested above, in development of the propodeal spine, and in color. The variation among different characters is discordant to some degree, and intermediates within the respective characters occur. I believe it prudent for the present to leave the described infraspecific forms as a single species (I am indebted to Philip S. Ward for valuable information and advice on the variation and status of bicarinata).

MEASUREMENTS (mm) Major (Brown Co. State Park, Indiana): HW 1.04, HL 1.14, SL 0.54, EL 0.14, PW 0.52. Minor (Brown Co. State Park): HW 0.54, HL 0.58, SL 0.50, EL 0.12, PW 0.34.

COLOR Major: body varying geographically, from clear yellow in the western parts of the range to brownish yellow to dark brown in the east.

Minor: clear yellow to medium brown.

Pheidole bicarinata Wilson 2003.jpg

Figure. Upper: “typical” bicarinata major. Lower: “typical” bicarinata minor. INDIANA: Brown County State Park, col. E. O. Wilson. (Lower propodeum is of “vinelandica” variant major from Calvert Cliffs State Park, Calvert Co., Maryland; see description of other variation in Diagnosis and Color.) Scale bars = 1 mm.

Type Material

USA. Illinois, Naturhistorisches Museum Wien, Vienna - as reported in Wilson (2003)


L bicarinata, double-ridged, two-carinal, possibly referring to the carinae of the clypeus. (Wilson 2003)


  • Allred, D. M. and A. C. Cole, Jr. 1979. Ants from northern Arizona and southern Utah. Great Basin Nat. 39: 97–102.
  • Baker, A.J., Heraty, J.M., Mottern, J., Hang, J.Z., Hines, H.M., Lemmon, A.R., Lemmon, E.M. 2019. Inverse dispersal patterns in a group of ant parasitoids (Hymenoptera: Eucharitidae: Oraseminae) and their ant hosts. Systematic Entomology 45: 1–19 (doi:10.1111/syen.12371).
  • Ballard, J. B. and K. P. Pruess. 1979. Seed selection by an ant Pheidole bicarinata longula Emery (Hymenoptera: Formicidae) in a corn field on 4 different dates during the summer of 1977 in McPherson County, Nebraska. Journal of the Kansas Entomological Society. 52:550-552.
  • Beckmann, R. L., Jr and J. M. Stucky. 1981. Extrafloral nectaries and plant guarding in Ipomoea pandurata (L.) G.F.W. Mey. (Convolvulaceae). American Journal of Botany. 68:72-79.
  • Carter, W. G. 1962. Ant distribution in North Carolina. Journal of the Elisha Mitchell Scientific Society. 78:150-204.
  • Cole, A. C., Jr. 1966. Ants of the Nevada Test Site. Brigham Young Univ. Sci. Bull. Biol. Ser. 7(3): 1–27.
  • Creighton, W. S. 1950a. The ants of North America. Bull. Mus. Comp. Zool. 104: 1-585 (page 171, Senior synonym of hayesi)
  • Espadaler, X., Santamaria, S. 2012. Ecto- and Endoparasitic Fungi on Ants from the Holarctic Region. Psyche Article ID 168478, 10 pages (doi:10.1155/2012/168478).
  • Gregg, R. E. 1963. The ants of Colorado, with reference to their ecology, taxonomy, and geographic distribution. University of Colorado Press, Boulder.
  • Ingham, C. D. 1959. Ants of the Virgin River Basin, southwestern Utah. Thesis. U. of Utah. 140 pp.
  • Ingham, C. D. 1963. An ecological and taxonomic study of the ants of the Great Basin and Mojave Desert regions of southwestern Utah. Dissertation. U. of Utah. 212 pp.
  • Lachaud, J., Cerdan, P. and Pérez-Lachaud, G. Poneromorph Ants Associated with Parasitoid Wasps of the Genus Kapala Cameron (Hymenoptera: Eucharitidae) in French Guiana. Psyche. vol. 2012, Article ID 393486, 6 pages, 2012. [doi:10.1155/2012/393486]
  • Mackay, W. P. and E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, NY.
  • Mayr, G. 1870b. Neue Formiciden. Verh. K-K. Zool.-Bot. Ges. Wien 20: 939-996 (page 989, soldier described)
  • Wheeler, D. E. and H. F. Nijhout. 1981a. Imaginal wing discs in larvae of the soldier caste of Pheidole bicarinata vinelandica Forel (Hymenoptera: Formicidae). International Journal of Insect Morphology and Embryology. 10:131-139.
  • Wheeler, D. E. and H. F. Nijhout. 1981b. Soldier determination in ants: new role for juvenile hormone. Science (Washington D. C.). 213:361-363.
  • Wheeler, D. E. and H. F. Nijhout. 1983. Soldier determination in Pheidole bicarinata: effect of methoprene on caste and size within castes. Journal of Insect Physiology. 29:847-854.
  • Wheeler, D. E. and H. F. Nijhout. 1984. Soldier determination in Pheidole bicarinata: inhibition by adult soldiers. Journal of Insect Physiology. 30:127-135.
  • Wheeler, D. E. 1991. The developmental basis of worker caste polymorphism in ants. Am. Nat. 138: 1218–1238.
  • Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA. (page 561, fig. major, minor described, Senior synonym of vinelandica (and its junior synonyms longula, saeviuscula, buccalis, nebracensis))