Pheidole titanis

The species occurs in desert scrub and deciduous thorn forest, nesting under stones. As suggested by Creighton and Gregg (1955) and proved by Feener (1988), titanis is primarily a specialized predator on termites. In Jalisco, Feener found the species most often attacking foraging columns of Nasutitermes, only occasionally scavenging for dead arthropods of other kinds. Scouts recruit nestmates until a raiding force of 200–2000 majors and minors are assembled, encircling the termites, whereupon each ant tries to seize individual prey, then returns to the nest along the chemical recruitment trail. Feener has provided a detailed account of both the raiding behavior of titanis and their defensive maneuvers against enemies, especially parasitic phorid flies. (Wilson 2003)

Identification
As the name suggests, the majors of this species are very large, with the head length of the major exceeding 2 mm. The longitudinal rugae on the dorsum of the head extend onto the anterior portions of the posterior lateral lobes, the tops of the posterior lateral lobes of the major are shiny. The pronotum of the major has several transverse striae. (Mackay and Mackay 2002)

Also see the description in the nomenclature section.

Distribution
Western Texas, southern Arizona and Jalisco, Mexico. (Wilson 2003)

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

Biology
In his original description of Pheidole titanis Wheeler observed that it prefers to nest under large boulders or where the soil is full of good-sized stones. It also seems to prefer nest sites near streams in canyons. The nest is usually placed near the top of the bank ten feet or more above the stream bottom. In the three nests which were excavated there was no evidence that the insects had been collecting seeds. But there is ample evidence that titanis eats termites. The colony taken at Sweetwater did so avidly; indeed, they would snatch their victims from between the tips of the tweezers by which the termites were presented to them. The colony taken in Brown Canyon was discovered when a column of majors and minors, most of them with termites in their jaws, was returning to the nest. (Creighton and Gregg 1955)

Worker
Minor

Nomenclature

 *  titanis. Pheidole titanis Wheeler, W.M. 1903b: 95, fig. 3 (s.w.) U.S.A. See also: Wilson, 2003: 602.

Description
From Wilson (2003): DIAGNOSIS A large member of the pilifera group further characterized by the following traits.

Major: rugoreticular patch just mesad of each frontal carina and posterior to the antennal fossa; the rest of the dorsal surface of the head except for the occiput, central piece of the clypeus, and frontal triangle longitudinally carinulate; median carina present on the clypeus; carinulae cover anterior third and sides of the pronotal dorsum, part of the propodeal dorsum, sides of the petiole, and dorsum of the postpetiolar node; postpetiolar node from above diamond-shaped.

Minor: head subrectangular in full-face view; humerus lobose in dorsal-oblique view; postpetiole bell-shaped from above.

MEASUREMENTS (mm) Lectotype major: HW 1.94, HL 2.02, SL 0.98, EL 0.30, PW 1.10. Paralectotype minor: HW 0.92, HL 0.94, SL 0.86, EL 0.24, PW 0.60.

COLOR Major and minor: concolorous light reddish brown.



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

Type Material
TEXAS: Chisos Mts., Brewster Co., southwestern Texas, col. O. W. Williams. and - as reported in Wilson (2003)

Etymology
Gr titanus, or a mythical race of giants. (Wilson 2003)