Pheidole sciophila

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

Pheidole sciophila casent0005771 profile 1.jpg

Pheidole sciophila casent0005771 dorsal 1.jpg

Specimen Label

Synonyms

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.

Keys including this Species

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 (type locality).
Neotropical Region: Mexico.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

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)

Association with Other Organisms

This species is a host for the eucharitid wasp Orasema wheeleri (a parasite) (Universal Chalcidoidea Database) (primary host).

Castes

Worker

Minor

Major

Nomenclature

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

  • 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.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

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.


Pheidole sciophila Wilson 2003.jpg

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.

Lectotype Specimen Labels

Type Material

TEXAS: Austin, col. William M. Wheeler, Museum of Comparative Zoology and American Museum of Natural History - as reported in Wilson (2003)

Etymology

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

References

  • Creighton, W. S.; Gregg, R. E. 1955. New and little-known species of Pheidole (Hymenoptera: Formicidae) from the southwestern United States and northern Mexico. Univ. Colo. Stud. Ser. Biol. 3: 1-46 (page 19, Senior synonym of proserpina and semilaevicephala)
  • Mackay, W. P. and E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, NY.
  • Wheeler, W. M. 1908h. The ants of Texas, New Mexico and Arizona. (Part I.). Bull. Am. Mus. Nat. Hist. 24: 399-485 (page 443, pl. 26, figs. 18, 19 soldier, worker, queen, male described)
  • Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA. (page 347, fig. major, minor described)