Pheidole soritis

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Pheidole soritis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Pheidole
Species: P. soritis
Binomial name
Pheidole soritis
Wheeler, W.M., 1908

Pheidole soritis casent0104447 profile 1.jpg

Pheidole soritis casent0104447 dorsal 1.jpg

Specimen Label


In eastern Colorado, Gregg (1963) found P. soritis under rocks in the clay soil of cottonwood-willow woodland and shortgrass prairie, from 1000 to 1300 m. I encountered it near Datil, New Mexico, in open juniper woodland (Wilson 1957). A nuptial flight was observed in progress following rainfall on 9 August in an abandoned homesite clearing. The swarms of flying ants, which held resolutely to the clearings, consisted mostly of males. The aggregations were roughly circular in shape and hovered from about half a meter to nearly 2 meters above the surface, depending on wind conditions. Winged queens flew into the swarms and were quickly seized by a male, whereupon the pair spiraled to the ground together. After insemination, the queens shed their wings and ran off over the ground, evidently in search of a nest site. (Wilson 2003)


The major of this species is small (total length about 2 1/2 mm), the scapes expand about 1/2 way to the posterior lateral corners, the anterior 1/2 of the head is covered with fine, longitudinal rugae, the posterior half is roughly sculptured with longitudinal and transverse striae, the tops of the posterior lateral lobes have transverse striae. The humeral angles and lateral connules are poorly developed. The anterior part of pronotum is predominantly glossy, the posterior part is covered with transverse, but fine striae. The minor worker is a small black ant, in which most of the dorsum of the head is smooth and glossy, the side and top of the pronotum are smooth and glossy, the remainder of the mesosoma punctate. The hairs on the dorsum of the mesosoma are blunt tipped, but not clavate. The minors in our samples show considerable variation in the sculpturing of the head, and in the pronotal rugae, and some of them would key to Pheidole sitarches. (Mackay and Mackay 2002)

Also see the description in the nomenclature section.

Keys including this Species


Mississippi west to Colorado, Texas, Arizona, and northern Mexico. (Wilson 2003)

Latitudinal Distribution Pattern

Latitudinal Range: 40.988326° to 18.931111°.

Tropical South

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).
Neotropical Region: Mexico.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.


Association with Other Organisms

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  • This species is a host for the cestode Raillietina loeweni (a parasitoid) (Quevillon, 2018) (encounter mode secondary; indirect transmission; transmission outside nest; as Pheidole sitarches campestris).


Minor Worker

Mcz-ent00668256 Pheidole soritis hef.jpgMcz-ent00668256 Pheidole soritis hal.jpgMcz-ent00668256 Pheidole soritis had.jpgMcz-ent00668256 Pheidole soritis lbs.JPG
Worker (minor). . Owned by Museum of Comparative Zoology.

Images from AntWeb

Pheidole soritis casent0104448 head 1.jpgPheidole soritis casent0104448 profile 1.jpgPheidole soritis casent0104448 dorsal 1.jpgPheidole soritis casent0104448 label 1.jpg
Worker. Specimen code casent0104448. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.
Pheidole rufescens casent0172982 head 1.jpgPheidole rufescens casent0172982 profile 1.jpgPheidole rufescens casent0172982 dorsal 1.jpgPheidole rufescens casent0172982 label 1.jpg
Type of Pheidole soritisWorker. Specimen code casent0172982. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by MCZ, Cambridge, MA, USA.

Major Worker

MCZ-ENT00020728 Pheidole soritis hef.jpgMCZ-ENT00020728 Pheidole soritis hal.jpgMCZ-ENT00020728 Pheidole soritis had.jpgMCZ-ENT00020728 Pheidole soritis lbs.jpg
Lectotype of Pheidole soritisWorker (major). . Owned by Museum of Comparative Zoology.
MCZ-ENT00009128 Pheidole sitarches hef.jpgMCZ-ENT00009128 Pheidole sitarches hal.jpgMCZ-ENT00009128 Pheidole sitarches had.jpgMCZ-ENT00009128 Pheidole sitarches lbs.jpg
Lectotype of Pheidole sitarchesWorker (major). . Owned by Museum of Comparative Zoology.
Mcz-ent00668255 Pheidole soritis hef.jpgMcz-ent00668255 Pheidole soritis hal.jpgMcz-ent00668255 Pheidole soritis had.jpgMcz-ent00668255 Pheidole soritis lbs.JPG
Worker (major). .

Images from AntWeb

Pheidole rufescens casent0172980 head 1.jpgPheidole rufescens casent0172980 profile 1.jpgPheidole rufescens casent0172980 dorsal 1.jpgPheidole rufescens casent0172980 label 1.jpg
Syntype of Pheidole soritisWorker (major/soldier). Specimen code casent0172980. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by MCZ, Cambridge, MA, USA.


Images from AntWeb

Pheidole rufescens casent0172981 head 1.jpgPheidole rufescens casent0172981 profile 1.jpgPheidole rufescens casent0172981 dorsal 1.jpgPheidole rufescens casent0172981 label 1.jpg
Type of Pheidole sitarches rufescensQueen (alate/dealate). Specimen code casent0172981. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by MCZ, Cambridge, MA, USA.


The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • rufescens. Pheidole sitarches subsp. rufescens Wheeler, W.M. 1908e: 443 (s.w.q.) U.S.A. Junior synonym of campestris: Creighton, 1950a: 189; of soritis: Cole, 1953e: 298; of campestris: Gregg, 1959: 30. [Although both Creighton and Gregg give campestris as the senior name, rufescens has priority: Bolton, 1995b: 329.] Subspecies of sitarches: Bolton, 1995b: 329. Junior synonym of soritis: Wilson, 2003: 598.
  • sitarches. Pheidole sitarches Wheeler, W.M. 1908e: 440 (s.w.q.) U.S.A. Senior synonym of transvarians: Creighton, 1950a: 189; Gregg, 1959: 30. Junior synonym of soritis: Wilson, 2003: 598.
  • soritis. Pheidole soritis Wheeler, W.M. 1908e: 439 (s.w.) U.S.A. Subspecies of sitarches: Creighton, 1950a: 190. Revived status as species: Cole, 1953e: 298. Junior synonym of sitarches: Cole, 1956c: 115. Revived from synonymy as subspecies of sitarches: Gregg, 1959: 30; Smith, D.R. 1979: 1373. Revived status as species and senior synonym of campestris, rufescens, sitarches, transvarians: Wilson, 2003: 598.
  • transvarians. Pheidole sitarches var. transvarians Wheeler, W.M. 1908e: 442 (s.w.) U.S.A. Junior synonym of sitarches: Creighton, 1950a: 189; Gregg, 1959: 30; of soritis: Wilson, 2003: 598.
  • campestris. Pheidole sitarches subsp. campestris Creighton, 1950a: 189 (s.w.) U.S.A. [First available use of Pheidole sitarches subsp. rufescens var. campestris Wheeler, W.M. 1908e: 443; unavailable name.] Taber & Cokendolpher, 1988: 95 (k.). Junior synonym of soritis: Cole, 1953e: 298. Revived from synonymy as subspecies of sitarches: Cole, 1956c: 115 (footnote); Gregg, 1959: 30. Synonym of rufescens: Creighton, 1950a: 189; Gregg, 1959: 30. [Both references give campestris as senior synonym, but rufescens has priority and is the first available name for this taxon: Bolton, 1995b: 318.] Junior synonym of soritis: Wilson, 2003: 598.

Type Material

NEW MEXICO: Albuquerque. Museum of Comparative Zoology and American Museum of Natural History - as reported in Wilson (2003) 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 distinguished by the following traits. Major: dorsal head surface extensively sculptured; occipital lobe transversely 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. soritis is distinguished within this complex by the following combination of traits.

Major: extensive transverse carinulae of occiput curve laterally and forward, with many reaching the anterior border of the head capsule; almost entire dorsal surface of head, including clypeus, carinulate; rugulae lacking on head; humerus low and smoothly convex; postpetiole seen from above laterally angulate; small denticle present on anterior ventral surface of postpetiole in side view.

Minor: dorsal profile of promesonotum lined solely with evenly spaced pairs of clavate hairs; similar hairs occur on the waist; eye very large. The tangled infraspecific nomenclature of this species has been built mostly on variation in the sculpturing of the minor’s head. From central Texas north and west, the posterior dorsal surface is foveolate and opaque (subsp. rufescens = subsp. campestris). To the south, into Mexico, it is smooth and shiny, as illustrated here (subsp. sitarches). Westward to Arizona and Utah it is carinulate (typical soritis). Whether this variation is truly geographic within a single species or reflects the existence of sibling species around sitarches sensu str., is a question that awaits closer field and museum research.

MEASUREMENTS (mm) Lectotype soritis major: HW 1.16, HL 1.22, SL 0.60, EL 0.20, PW 0.52. Syntype sitarches minor (no type soritis minors available): HW 0.46, HL 0.50, SL 0.48, EL 0.12, PW 0.30.

COLOR Major: head and appendages light reddish brown, body a slightly contrasting medium reddish brown.

Minor: body plain light brown, appendages brownish yellow.

Pheidole soritis Wilson 2003.jpg

Figure. Upper: syntype major of synonymous sitarches. Lower: syntype minor of synonymous sitarches. Scale bars = 1 mm.

Lectotype Specimen Labels


  • 2n = 18, karyotype = 18M (USA) (Taber & Cokendolpher, 1988) (as Pheidole sitarches campestris).




References based on Global Ant Biodiversity Informatics

  • Alatorre-Bracamontes, C.E. and M Vasquez-Bolanos. 2010. Lista comentada de las hormigas (Hymenoptera: Formicidae) del norte de México. Dugesiana 17(1):9-36
  • Allred D. M. 1982. Ants of Utah. The Great Basin Naturalist 42: 415-511.
  • Allred, D.M. 1982. The ants of Utah. Great Basin Naturalist 42:415-511.
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  • Cole A. C., Jr. 1956. Observations of some members of the genus Pheidole in the southwestern United States with synonymy (Hymenoptera: Formicidae). Journal of the Tennessee Academy of Science 31: 112-118.
  • Cover S. P., and R. A. Johnson. 20011. Checklist of Arizona Ants. Downloaded on January 7th at
  • Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology
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  • Johnson R. Personnal Database. Accessed on February 5th 2014 at
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  • MacKay W. P. 1993. Succession of ant species (Hymenoptera: Formicidae) on low-level nuclear waste sites in northern New Mexico. Sociobiology 23: 1-11.
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  • Mackay, W., D. Lowrie, A. Fisher, E. Mackay, F. Barnes and D. Lowrie. 1988. The ants of Los Alamos County, New Mexico (Hymenoptera: Formicidae). pages 79-131 in J.C. Trager, editor, Advances in Myrmecololgy.
  • McDonald D. L., D. R. Hoffpauir, and J. L. Cook. 2016. Survey yields seven new Texas county records and documents further spread of Red Imported Fire Ant, Solenopsis invicta Buren. Southwestern Entomologist, 41(4): 913-920.
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  • Wilson E. O. 1958. The organization of a nuptial flight of the ant Pheidole sitarches Wheeler. Psyche (Cambridge) 64: 46-50.
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