Pheidole hirtula

Pheidole hirtula Forel

Pheidole vaslitii var. hirtula Forel 1899e: 65. Raised to species level by Creighton 1950a: 211. Syn.: Pheidole (Cardiopheidole) vaslitii var. acolhua Wheeler 1914c: 48; synonymy by Creighton 1958: 211.

Types Mus. Hist. Nat. Geneve.

etymology L hirtula, little hairy one.

Diagnosis A large trimorphic species (major, supermajor, minor) placed in the pilifera group because of the 2-toothed hypostoma but with other traits conforming to the fallax group. Very close to obtusospinosa, distinguished most readily in the supermajor, as illustrated, by the rounded foveae of the rear half of the dorsum of the head, with the interspaces smooth and shiny. This form is considered by Ward (1999) to be a likely geographic subspecies of obtusopilosa rather than a full species. Measurements (mm) All from near Chapulco, Puebla. Supermajor: HW 2.60, HL 2.40, SL 1.18, EL 0.32, PW 1.34. Major: HW 1.52, HL 1.60, SL 1.10, EL 0.24, PW0.82. Minor: HW 0.66, HL 0.86, SL 1.04, EL 0.20, PW 0.48.

Color Supermajor, major, and minor: head and appendages light reddish brown to plain medium brown, rest of body medium brown.

Range According to Creighton (1958), who studied hirtula closely, the species occurs between 1070 and 2310 m, with most colonies concentrated at 1500-2100 m, from northern Chihuahua southward through Coahuila, Nuevo Leon, San Luis Potosi and Zacatecas to Hidalgo, Queretaro, and Jalisco. Barry E. Pullen (personal communication) reports the species as common in the suburbs of Mexico City.

Biology Creighton (1958) reports that mature colonies are very large, with numerous majors, and occasionally dominate the immediate surrounding area to the exclusion of other ant species. Winged reproductives are found in the nests from April to at least September, and nuptial flights evidently occur in late August into early September. According to Barry Pullen, the size variation of the workers is continuous, but with sharp modes marking the minor, major, and supermajor castes.

Figure Supermajor, head. MEXICO: km 275, Highway 150 northeast of Chapulco, Puebla.