Pheidole senex Gregg

Wilson, E. O., 2003, Pheidole in the New World. A dominant, hyperdiverse ant genus., Cambridge, MA: Harvard University Press : 596

Pheidole senex Gregg

Pheidole senex Gregg 1952a: 1. Syn.: Pheidole pilifera subsp. anfracta Cole 1952c: 278, synonymy by Cole 1953g: 298.

Types Mus. Comp. Zool. Harvard.

Etymology L senex , old, senior, possibly alluding to rugulose sculpture of head and mesosoma.

diagnosis A member of the " pilifera complex" of the larger pilifera group, comprising calens , californica , carrolli , cavigenis , clementensis , creightoni , hoplitica , littoralis , micula , pilifera , polymorpha , rugulosa , senex , soritis , tepicana , and torosa , which complex is distinguished by the following traits. Major: dorsal head surface extensively sculptured; occipital lobes transversely rugulose (or, in carrolli smooth, in littoralis foveate, and in micula and soritis carinulate), postpetiole from above diamond-shaped, trapezoidal, or spinose. Minor: eye medium-sized to large.

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

Major: large; mesonotal convexity subangulate in dorsal-oblique view, and descends steeply to metathorax in side view; petiolar node tapers to a point in side view; postpetiole from above spinose; sides of pronotum, mesonotum, and propodeum, longitudinally carinulate; anterior dorsal profde of head flat; cephalic pilosity short and erect.

Minor: entire dorsal surface of head except mid-section of clypeus longitudinally carinulate; all of mesosoma foveolate and opaque. Measurements (mm) Paratype major: HW 1.74, HL 1.86, SL 0.78, EL 0.22, PW 0.82. Paratype minor: HW 0.64, HL 0.66, SL 0.68, EL 0.14, PW 0.40. color Major and minor: light yellowish to reddish brown.

range West-central Arizona through New Mexico to the Texas Panhandle and southern Colorado; apparently rare.

Biology Gregg (1963) reports P. senex from Campo, Colorado, in short grass prairie nesting in clay under rocks at 1300 m. Cole recorded it in New Mexico from 2000 to 2700 m. At Springerville, Arizona, I found a colony under a rock in grassy desert. In the Texas Panhandle, Moody and Francke (1982) found two colonies, one beneath a stone and the other in open soil.

Figure Upper: paratype, major. Lower: paratype, minor. COLORADO: 14 km south of Campo, Baca Co., extreme southeastern Colorado (Robert E. Gregg). Scale bars = 1 mm.