Pheidole obtusospinosa

Stefan Cover (unpublished field notes), who has collected obtusospinosa many times in southern Arizona, has found it consistently in woodland, variously composed of different combinations of pine, oak, and juniper. It typically nests under rocks, although Cover found one colony beneath a cow pat and another 2.5 m from the ground in the dead branch of a standing oak tree (Quercus arizonica). Creighton (1958) reports that colonies are much smaller than those of the closely related Pheidole hirtula, and that in southern Arizona nuptial flights occur in early July. (Wilson 2003)

Identification
See the description in the nomenclature section.

Distribution
Known from the mountains of southern Arizona at 300–1900 m, and from Nayarit to Nuevo Leon in Mexico. (Wilson 2003)

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

Nomenclature

 *  obtusospinosa. Pheidole obtusospinosa Pergande, 1896: 889 (s.) MEXICO. Junior synonym of subdentata Pergande: Wheeler, W.M. 1914b: 50; hence first available replacement name for Pheidole subdentata Pergande, 1896: 888 [Junior secondary homonym of Oecophthora subdentata Mayr, 1853a: 145.]; designated by Bolton, 1995b: 326. See also: Wilson, 2003: 587.
 * subdentata. Pheidole subdentata Pergande, 1896: 888 (w.) MEXICO. [Junior secondary homonym of subdentata Mayr, above.] Subspecies of vasliti: Wheeler, W.M. 1914b: 50. Revived status as species: Creighton, 1958: 211. Senior synonym of obtusospinosa: Wheeler, W.M. 1914b: 50; of arizonica: Creighton, 1958: 211. Replacement name: obtusospinosa Pergande, 1896: 889; first available replacement name for subdentata Pergande: Bolton, 1995b: 326.
 * arizonica. Pheidole arizonica Santschi, 1911d: 3, fig. (s.) U.S.A. Subspecies of vasliti: Creighton, 1950a: 192. Junior synonym of subdentata: Creighton, 1958: 211; Gregg, 1959: 31.

Description
From Wilson (2003): DIAGNOSIS A large trimorphic species placed in the pilifera group because of the 2-toothed hypostoma of the major but with other traits conforming to the fallax group. Very close to Pheidole hirtula, distinguished most readily in the supermajor, as illustrated, by the elongate foveae of the rear half of the dorsum of the head, with the interspaces densely foveolate and opaque. The tangled taxonomic history of this species and the true status of Pheidole vaslitii, previously associated with it but now revealed as a junior synonym or sibling species of Pheidole hyatti (q.v.), have been presented by Ward (2000).

MEASUREMENTS (mm) Supermajor: HW 2.50, HL 2.36, SL 1.12, EL 0.26, PW 1.06. Major: HW 1.44, HL 1.46, SL 1.12, EL 0.24, PW 0.72. Minor: HW 0.62, HL 0.80, SL 0.98, EL 0.16, PW 0.44.

COLOR All castes: yellowish to reddish brown.



'''Figure. Upper: major, with heads of major (left) and supermajor (right). Lower: minor. ARIZONA: Sunnyside Canyon, Huachuca Mts., Cochise Co. (Stefan Cover). Scale bars = 1 mm.'''

Type Material
- as reported in Wilson (2003)

Type Locality Information
MEXICO. Tepic, Nayarit, col. Eisen and Vaslit. (Wilson 2003)

Etymology
L obtusospinosa, with blunt thorns, referring to the propodeal spines. (Wilson 2003)

Additional References
Creighton, W. S. 1958. A revisionary study of Pheidole vaslitii Pergande (Hymenoptera: Formicidae). J. New York Entomol. Soc. 65: 203–212.

Pergande, T. 1896. Mexican Formicidae. Proc. Calif. Acad. Sci. (2)5: 858–896.

Ward, P. S. 2000. On the identity of Pheidole vaslitii Pergande (Hymenoptera: Formicidae), a neglected ant from Baja California. J. Hym. Res. 9(1): 85–98.

Text and images from this publication used by permission of the author.