Pheidole yaqui

The unpublished records of Stefan Cover show that yaqui occurs in southern California from desert at lower elevation to creosote-acacia-juniper scrub in the uplands. The colonies of 50 to 100 workers nest in arid soil, sometimes with a crater of excavated earth and seed chaff. At Deep Canyon, near Palm Springs, California, Wheeler and Wheeler (1973) found yaqui in desert and in palo verde and agave-ocotillo scrub, in crater soil nests; they uncovered caches of Euphorbia micromera and Oenothera clavaeformis seeds inside the nests. (Wilson 2003)

Identification
See the description in the nomenclature section.

Distribution
Known from southern California (100–1050 m) and Baja California (northern half of the peninsula), sea level to 550 m. (Wilson 2003)

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

Biology
The nests of Pheidole yaqui are always small. They usually consist of twelve to fifteen majors and about three or four times that number of minors. The majors forage with the minors occasionally but much less often than in Pheidole xerophila, where it is the rule for both majors and minors to forage. P. yaqui prefers very arid nest sites, and in this particular it agrees more closely with Pheidole gilvescens than with xerophila. The senior author was unable to get any evidence of the food preference of yaqui. No chaff piles were encountered and no seeds were found in the nests. (Creighton and Gregg 1955)

Worker
Minor

Nomenclature

 *  yaqui. Pheidole yaqui Creighton & Gregg, 1955: 43, fig. 10 (s.w.) U.S.A. See also: Wilson, 2003: 607.

Description
From Wilson (2003): DIAGNOSIS Close to and possibly a senior synonym of Pheidole bajaensis, differing as follows.

Major: occiput smooth, not rugulose; postpetiole seen from above ovoid, not literally angulate; margins of pronotal dorsum transversely carinulate.

Minor: humerus in dorsal-oblique view subangulate; occiput narrow, its corners less angulate than in bajaensis. Together, yaqui and bajaensis differ from Pheidole gilvescens and Pheidole xerophila in the major’s head shape, which is rounded (not flattened) in the dorsal profile of its posterior half, an failure of the head to taper toward the occiput; other traits exist in the major and minor as depicted.

MEASUREMENTS (mm) Paratype major: HW 1.20, HL 1.30, SL 0.62, EL 0.20, PW 0.52. Paratype minor: HW 0.50, HL 0.54, SL 0.44, EL 0.16, PW 0.32.

COLOR Major: brownish yellow.

Minor: body and appendages medium yellow except for dorsal surface of head, which is a slightly contrasting shade of light yellowish brown.



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

Type Material
CALIFORNIA: Yaqui Well, Anza Desert State Park, col. W. S. Creighton. - as reported in Wilson (2003)

Etymology
Named after either the type locality or the Yaqui people of the Sonoran desert. (Wilson 2003)