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Pheidole obtusospinosa PergandeHNS 1896: 889. Junior synonym of Pheidole subdentata PergandeHNS 1896: 888, synonymy by Wheeler, 1914c: 50; subdentata PergandeHNS is ajunior secondary homonym of Oecophthora subdentata MayrHNS 1853b: 145, later transferred to PheidoleHNS and a synonym of P. pallidula (Nylander)HNS of Eurasia; hence obtusopilosaHNS is first available name. Syn.: Pheidole arizonica SantschiHNS 191 ld: 3, synonymy by Creighton 1958: 211.
Types Nat. Mus. Nat. Hist. U. S.
Diagnosis A large trimorphic species placed in the piliferaHNS group because of the 2-toothed hypostoma of the major but with other traits conforming to the fallaxHNS group. Very close to hirtulaHNS, 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 vaslitiiHNS, previously associated with it but now revealed as a junior synonym or sibling species ofhyatti (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.
Range Known from the mountains of southern Arizona at 300-1900 m, and from Nayarit to Nuevo Leon in Mexico.
biology Stefan Cover (unpublished field notes), who has collected obtusospinosaHNS many times in southern Arizona, has found it consistently in woodland, variously composed of different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 arizonicaHNS). Creighton (1958) reports that colonies are much smaller than those of the closely related hirtulaHNS, and that in southern Arizona nuptial flights occur in early July.
Figure Upper: major, with heads of major (left) and supermajor (right). Lower: minor. ARIZONA: Sunnyside Canyon, Huachuca Mts., Cochise Co. (Stefan Cover). (Type locality: Tepic, Nayarit, collected by Eisen and Vaslit.) Scale bars = 1 mm.
Found most commonly in these habitats: 5 times found in agricultural zone, 2 times found in disturbed riparian veg., 4 times found in xerophyl scrub, 5 times found in Pastizal, 2 times found in desert scrub, 1 times found in Bosque de Encino, Manchones de pastizal, B.tropical caducifolio, 2 times found in Encino, 2 times found in Encino-pino, 1 times found in Quercus grisea- Q. emoryi woodland in broad creek valley., 1 times found in Paztizal (área de ganado), Matorral espinoso (manchon) y Bosque de Encino (Manchon), ...
Found most commonly in these microhabitats: 4 times suelo, debajo de una piedra, 2 times under stone, 3 times suelo, bajo de una piedra, 1 times nest in tree root, 1 times at bait, 3 times suelo, 1 times Under rock in shade., 1 times en tronco derribado, dentro y en el suelo, 1 times en suelo, al pie de un tallo de árbol, cerca de un cauce de agua..
Collected most commonly using these methods: 9 times pitfall, 11 times Directo, 3 times Colecta directa, 2 times search, 1 times bait, 1 times Diercto, 1 times direct collection.
Elevations: collected from 883 - 2430 meters, 1705 meters average