Pheidole creightoni

William S. Creighton (in Gregg 1955) found 18 earthen nests of creightoni at the type locality, frequently near nests of the much larger ant Messor (= Veromessor) andrei. The entrances were surrounded by large rings of chaff, indicating that seeds are an important part of the diet. Tissue of freshly killed ground squirrels was also accepted by the majors and minors, which foraged in files. Soil nests have also been recorded on museum labels, in California by Diane W. Davidson and in Nevada by Philip S. Ward. Nuptial flights were recorded in August and September by Davidson and by Creighton respectively; they occurred about an hour before sunset. (Wilson 2003)

Identification
The Pheidole californica complex comprises three closely related and partly sympatric species of seed harvesting ants restricted to the western Nearctic region. Pheidole clementensis Gregg may be distinguished from both Pheidole californica Mayr and Pheidole creightoni Gregg by the diagonal rather than longitudinal rugulae between the clypeus and the eye in lateral View. The closely related P. californica and P. creightoni are most readily distinguished from one another by the angle of their lateral cephalic setae. Pheidole californica has decumbent setae forming an angle of forty-five degrees or less with the lateral margins of the head in full face view, while the cephalic setae of P. creightoni emerge at an angle of approximately ninety degrees. (Burge, 2005.)

See also the description in the nomenclature section.

Key to the Pheidole of the United States

Distribution
Pheidole creightoni is found in foothill or plateau habitats in northern California, Oregon, Washington, and Nevada (Burge, 2005).

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

Biology
Nevada, Wheeler and Wheeler (1986) - One nest was surmounted by a 25-cm crater and had an entrance 1 mm in diameter. We found the beetle conibiosoma elongatum (Hom) (Coleoptera: Tenebrionidae; det. T. J. Spilman) in a nest.

Worker
Minor

Nomenclature

 *  creightoni. Pheidole creightoni Gregg, 1955a: 19, pl. 2, figs. a-c; pl. 3, figs. a-c (s.w.q.m.) U.S.A. See also: Wilson, 2003: 573.

Description
From Wilson (2003): DIAGNOSIS A member of the “pilifera complex” of the larger pilifera group; for a characterization of the complex, see under Pheidole pilifera. P. creightoni is distinguished within the complex by the following combination of traits.

Major: occiput in side view very broad, as much as 1.5X the anterior cephalic capsule border; promesonotum forms a smooth, single convexity; petiolar node tapering to a blunt point in side view and with a deeply concave border seen from behind; postpetiole from above spinose.

Minor: yellowish brown; eye very large; humerus subangulate in dorsal-oblique view; petiolar node tapers to a blunt point in side view; postpetiole seen from above trapezoidal.

MEASUREMENTS (mm) Paratype major: HW 1.22, HL 1.32, SL 0.58, EL 0.16, PW 0.48. Paratype minor: HW 0.54, HL 0.60, SL 0.52, EL 0.14, PW 0.32.

COLOR Major: most of body and head, as well as mandibles, light reddish yellow; gaster plain light brown; legs clear dark yellow.

Minor: body light yellowish brown, appendages clear dark yellow.



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

Type Material
OREGON: Applegate, Jackson Co. - as reported in Wilson (2003)

Etymology
Named after the pioneering American myrmecologist William S. Creighton. (Wilson 2003)