Pheidole sciophila

Stefan Cover, whose intensive collecting in the southwestern United States has brought him into frequent contact with sciophila, reports as follows (personal communication): “This ant is not commonly collected, in large part because its nests are inconspicuous. Entrances to soil nests are cryptic and they are often located at or near the bases of desert shrubs. They can be deep also: one nest excavated in SE Arizona (elev. 1300 m) in grazed desert penetrated 1.2 m into caliche nearly as hard as a Manhattan sidewalk. Colonies are monogynous and can consist of several hundred ants. P. sciophila appears to be omnivorous; no seeds have been found in many nests excavated in southern Arizona.” (Wilson 2003)

Identification
The major of this species is tiny (total length slightly more than 2 mm, head length 1.2 mm), with the anterior half of the head longitudinally striate, the posterior half of the head and the tops of the posterior lateral lobes smooth and shining, much of the dorsum of the pronotum is smooth and glossy, the sides of the mesosoma are finely punctate, the humeral angles are poorly developed, the lateral connules are not developed. The scapes of the minor workers extend more than one funicular segment past the posterior lateral corners, the head is glossy and shining, the mesosoma is completely and densely punctate, the dorsum of the pronotum may shine in the central region, but is still punctate. (Mackay and Mackay 2002)

Also see the description in the nomenclature section.

Distribution
Central Texas to deserts of southern Arizona and California and southward into Chihuahua, Mexico, at 100–1800 m. (Wilson 2003)

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Habitat
Weedy zone of annuals, black grama grasslands, creosotebush scrub, mesquite communities, Chihuahua pine forests. (Mackay and Mackay 2002)

Biology
All the colonies of sciophila which Wheeler took came from shady areas near streams. This has been true of some of the colonies taken by the senior author, but this species is capable of utilizing fully exposed nest sites well removed from any source of water. (Creighton and Gregg 1955)

Small colonies of this species nest under stones. Foragers were attracted to peanut butter baits. Wheeler (1908) suggested that this species was entomophagous (eats insects). (Mackay and Mackay 2002)

Worker
Minor

Images from AntWeb
Major

Nomenclature

 * proserpina. Pheidole proserpina Wheeler, W.M. 1908e: 437 (s.w.) U.S.A. Junior synonym of sciophila: Creighton & Gregg, 1955: 19.
 *  sciophila. Pheidole sciophila Wheeler, W.M. 1908e: 443, pl. 26, figs. 18, 19 (s.w.q.m.) U.S.A. Senior synonym of proserpina, semilaevicephala: Creighton & Gregg, 1955: 19. See also: Wilson, 2003: 347.
 * semilaevicephala. Pheidole sciophila var. semilaevicephala Smith, M.R. 1934a: 385 (s.) U.S.A. Subspecies of sciophila: Creighton, 1950a: 188. Junior synonym of sciophila: Creighton & Gregg, 1955: 19.

Description
From Wilson (2003): An unusual species placed in the fallax group but with other traits in body form, including head form and antenna length that are intermediate to the pilifera group.

Major: head lacking rugoreticulum; bicolorous, reddish brown posteriorly and brownish yellow anteriorly; head in side view elliptical in outline, tapering conspicuously toward the occiput; antennal scape short, its tip in repose reaching halfway between the eye and occipital corner, seen in full face; pronotum weakly bilobous in dorsal-oblique view; mesonotal convexity strongly developed; all of mesosoma and waist foveolate and opaque.

Minor: gaster, clypeus, and frontal triangle smooth and shiny, and all the rest of the body foveolate and opaque; pilosity along dorsal profile of mesosoma mostly comprising evenly spaced pairs of setae.

The species exhibits considerable variation in body form and sculpturing, especially in the major caste, as noted by Creighton and Gregg (1955). The number of hypostomal teeth of the major is 3 or 5.

MEASUREMENTS (mm) Lectotype major: HW 1.04, HL 1.14, SL 0.64, EL 0.12, PW 0.56. Paralectotype minor: HW 0.48, HL 0.58, SL 0.66, EL 0.08, PW 0.34.

COLOR Major: body and posterior three-fourths of the head a rich reddish brown, with the gaster a shade darker, and the anterior fourth of the head brownish yellow.

Minor: body plain medium brown, appendages brownish yellow.



'''Figure. Upper: lectotype, major. Some specimens have a weakly developed inner pair of hypostomal teeth in addition to the more conspicuous outer pair shown here. Lower: paralectotype, minor. Scale bars = 1 mm.'''

Type Material
TEXAS: Austin, col. William M. Wheeler, and  - as reported in Wilson (2003)

Etymology
Gr sciophila, shade-lover, allusion unknown. (Wilson 2003)

References based on Global Ant Biodiversity Informatics

 * Cover S. P., and R. A. Johnson. 20011. Checklist of Arizona Ants. Downloaded on January 7th at http://www.asu.edu/clas/sirgtools/AZants-2011%20updatev2.pdf
 * Creighton W. S., and R. E. Gregg. 1955. New and little-known species of Pheidole (Hymenoptera: Formicidae) from the southwestern United States and northern Mexico. University of Colorado Studies. Series in Biology 3: 1-46.
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Des Lauriers J., and D. Ikeda. 2017. The ants (Hymenoptera: Formicidae) of the San Gabriel Mountains of Southern California, USA with an annotated list. In: Reynolds R. E. (Ed.) Desert Studies Symposium. California State University Desert Studies Consortium, 342 pp. Pages 264-277.
 * Fernandes, P.R. XXXX. Los hormigas del suelo en Mexico: Diversidad, distribucion e importancia (Hymenoptera: Formicidae).
 * Gregg R. E. 1959. Key to the species of Pheidole (Hymenoptera: Formicidae) in the United States. Journal of the New York Entomological Society 66: 7-48.
 * Johnson R. Personnal Database. Accessed on February 5th 2014 at http://www.asu.edu/clas/sirgtools/resources.htm
 * Johnson, R.A. and P.S. Ward. 2002. Biogeography and endemism of ants (Hymenoptera: Formicidae) in Baja California, Mexico: a first overview. Journal of Biogeography 29:10091026/
 * Mackay W. P., and E. E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Lewiston, New York: Edwin Mellen Press, 400 pp.
 * 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.
 * Miguelena J. G., and P. B. Baker. 2019. Effects of urbanization on the diversity, abundance, and composition of ant assemblages in an arid city. Environmental Entomology doi: 10.1093/ee/nvz069.
 * Moody J. V., and O. F. Francke. 1982. The Ants (Hymenoptera, Formicidae) of Western Texas Part 1: Subfamily Myrmicinae. Graduate Studies Texas Tech University 27: 80 pp.
 * O'Keefe S. T., J. L. Cook, T. Dudek, D. F. Wunneburger, M. D. Guzman, R. N. Coulson, and S. B. Vinson. 2000. The Distribution of Texas Ants. The Southwestern Entomologist 22: 1-92.
 * Smith M. R. 1936. A list of the ants of Texas. Journal of the New York Entomological Society 44: 155-170.
 * Van Pelt, A. 1983. Ants of the Chisos Mountains, Texas (Hymenoptera: Formicidae) . Southwestern Naturalist 28:137-142.
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Wheeler W. M. 1908. The ants of Texas, New Mexico and Arizona. (Part I.). Bulletin of the American Museum of Natural History 24: 399-485.
 * Wheeler, G.C. and J. Wheeler. 1985. A checklist of Texas ants. Prairie Naturalist 17:49-64.
 * Wilson, E.O. 2003. Pheidole in the New World: A Dominant, Hyperdiverse Genus. Harvard University Press