Camponotus ulcerosus

This species nests in arid habitats under large stones or boulders. The nest is surrounded by a carton shield, a paper-thin sheet of vegetable material, cemented together with salivary secretions, with at least one nest entrance. The soldier uses its head to block the nest entrance. Sexuals occur in nests in May. Minor workers are moderately common in rough, desert canyons, where they can be found foraging on large boulders. Majors capture workers of Tetramorium spinosum when they walk over their faces, as they blocks the nest entrance. (Mackay and Mackay 2002)

Identification
The head of the major is obliquely truncate, very roughly sculptured and usually has deep, eroded areas on the cheeks. Minor workers are small, black and shiny specimens with a head and mesosoma that is densely and coarsely sculptured. The mesosoma is evenly arched and is covered with long (0.25 mm), white, slightly twisted, erect hairs. (Mackay and Mackay 2002)

Distribution
United States: Arizona, New Mexico and Texas. Mexico: Chihuahua.

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

Habitat
Chihuahuan Desert and surrounding foothills, including grassy areas, herbaceous meadows with scattered junipers, blue oaks. oak-juniper woodland rocky soil, broad, mesquite dominated arroyos. (Mackay and Mackay 2002)

Nomenclature

 * bruesi. Camponotus bruesi Wheeler, W.M. 1910d: 349 (s.w.) U.S.A. Combination in C. (Myrmamblys): Forel, 1914a: 271; in C. (Myrmaphaenus): Emery, 1925b: 154. Junior synonym of ulcerosus: Creighton, 1951: 53.
 *  ulcerosus. Camponotus ulcerosus Wheeler, W.M. 1910d: 351 (s.) U.S.A. Creighton, 1951: 58 (w.q.). Combination in C. (Colobopsis): Forel, 1914a: 272; in C. (Myrmamblys): Emery, 1920b: 259; in C. (Manniella): Emery, 1925b: 160; in C. (Myrmaphaenus): Creighton, 1951: 57. Senior synonym of bruesi: Creighton, 1951: 53. See also: Creighton, 1953d: 82.

Worker
Length, 6.5 mm.

Head rather large, subrectangular, a little longer than broad, as broad in front as behind, with nearly straight posterior and very feebly concave, subparallel lateral borders; posterior corners rather angular, anterior corners produced forward as rounded lobes beyond the anterior border of the clypeus and the closed mandibles. In profile the head is high and convex behind, obliquely truncated in front, with flattened gula. The truncated surface is bordered on each side by a coarsely crenate ridge, which runs from the outer edge of the lobe-like anterior corner to a little in front of the eye, where it turns inward and subsides before reaching the frontal carina. This ridge forms the outer boundary of an elongated, irregular and rather deep impression resembling the scar 'of an ulcer. Eyes rather small, feebly convex. Mandibles apparently 4-toothed, flattened; their outer borders sinuate towards the base. Clypeus flat, ecarinate, trapezoidal, one and one-half times as long as broad, with straight, somewhat crenate anterior border, about twice as long as the posterior border, which is also straight; the sides slightly curved outward and diverging anteriorly. Frontal area distinct, triangular, as long as broad. Frontal carinae far apart, more approximated and lyrate in front, parallel behind, forming the inner boundaries of rather deep scrobes for the bases of the antennal scapes. Frontal groove distinct. Antennal scapes much curved at the base, slender, but distinctly flattened, enlarged towards their tips, which reach nearly to the posterior corners of the head. Thorax decidedly narrower than the head, rather long, gradually narrowed posteriorly, but with distinctly convex pleurae; in profile, the dorsum is rather flat, feebly arcuate; epinotum with subequal base and declivity, both slightly concave and meeting at a rounded angle. Petiole high, cuneate in profile, with thick base and narrower summit, and both anterior and posterior surfaces flattened; border obtuse; from behind, the scale is narrow at the base, expanding above, with broadly rounded, entire upper margin. Gaster of the usual shape. Legs slender.

Head opaque; occiput and posterior angles shining; the truncated anterior portion, including the mandibles, clypeus, the portions of the cheeks within the ridges and the anterior portion of the front, uneven and irregularly rugose; remainder of the head covered with dense, uniform punctures and more scattered and rather deep foveolae, which are slightly elongated on the cheeks outside the ridges. Thorax, petiole, gaster and legs densely punctate, more shining than the anterior portion of the head, less so than its posterior corners. In addition to the dense punctures, the surfaces of these parts are covered with coarse, scattered piligerous punctures.

Hairs glistening white, erect, abundant; longest on the gaster, petiole and thorax, shorter on the head; blunt on the cheeks and sides of the head. Antennae with short, delicate, erect hairs on the anterior surfaces and tips of the scapes. Hairs on legs sparse, rather long and oblique or suberect. Tibiae without bristles on their flexor surfaces. Pubescence apparently lacking.

Black; mandibles, clypeus, front and cheeks to. a little outside the ridges which bound the truncated surface, yellowish brown; posterior edges of gastric segments, antennae and tarsi, except the first joint, dark brown, antennal scapes somewhat paler and more reddish towards their bases.

Type Material
Described from a single specimen taken by Mr. O. Schaeffer at Palmerlee, Huachuca Mts., Arizona.