Pheidole cerebrosior

Creighton and Gregg (1955) report that the preferred habitat of cerebrosior is evergreen-oak-woodland in mountain canyons, with open desert less frequently occupied. The colonies are always small, and contain no more than 3 or 4 majors. Stefan Cover (unpublished specimen data) found numerous colonies in open Ephedra, mesquite, and mesquite-acacia desert, as well as riverine cottonwood forest, nesting variously under rocks beneath cow dung, and in open soil with multiple small crater nests. He found seed chambers in some nests and observed workers feeding on a dead beetle. A winged queen has been collected on 1 July. In Nevada, G. C. and Jeanette N. Wheeler (1986) found a single colony under a half-buried stone in yucca-larrea desert. (Wilson 2003)

Identification
Mackay and Mackay (2002) - For co-occuring Pheidole species in New Mexico, the major of this species is nearly identical to Pheidole bicarinata. It differs in that the vertex of the minor is punctate; it is smooth and shining to very finely striolate in PH. bicarinata. There is a considerable amount of variation in the sculpture of the vertex of the minor worker and is often very difficult to separate this species from Ph. bicarinata.

Also see the description in the nomenclature section.

Distribution
From Wilson (2003): Arizona and New Mexico, 550 to 1680 m; southern California, 950 m; Baja California, 640 m; Chihuahua, 1500 m (Creighton and Gregg 1955); numerous records by Stefan Cover (collection notes) and extreme southern Nevada (G. C. and J. Wheeler 1986).

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

Habitat
Sagebrush, riparian, evergreen-oak associations. This species usually nests in mountain canyons (including riparian sites), between 550 and 1800 meters elevation, and is rarely found in the open deserts. (Mackay and Mackay 2002)

Castes

 * Minor

Nomenclature

 *  cerebrosior. Pheidole vinelandica subsp. cerebrosior Wheeler, W.M. 1915b: 405 (s.w.) U.S.A. Raised to species: Creighton, 1950a: 175. See also: Wilson, 2003: 569.

Description
From Wilson (2003): DIAGNOSIS A member of the “bicarinata complex” of the larger pilifera group; for a characterization of the complex, see under Pheidole bicarinata.

P. cerebrosior is distinguished within the complex by the following combination of traits.

Major: postpetiole seen from above very wide and conulate; propodeal spines well-developed and backward-directed; pronotal humeri with short irregular carinulae.

Minor: mesosomal pilosity comprises rows of evenly spaced pairs of erect hairs.

MEASUREMENTS (mm) Lectotype major: HW 1.12, HL 1.32, SL 0.60, EL 0.14, PW 0.58. Paralectotype minor: HW 0.46, HL 0.56, SL 0.44, EL 0.12, PW 0.28.

COLOR Major: body light reddish yellow, except for the gaster, which is a slightly contrasting yellowish brown.

Minor: concolorous plain yellow.



'''Figure. Upper: lectotype, major. Lower: paralectotype, minor. Scale bars = 1 mm.'''

Type Material
ARIZONA: Tucson, and  - as reported in Wilson (2003)