Strumigenys cacaoensis

This relatively large species is arboreal, nesting in rot holes in the trunks and branches of trees.

Identification
Separated from all its Afrotropical congeners by its unique dentition and strongly excavated upper scrobe margins. (Bolton 1983)

Distribution based on Regional Taxon Lists
Afrotropical Region: Central African Republic, Gabon, Ghana, Kenya, Nigeria, Uganda.

Nomenclature

 *  cacaoensis. Strumigenys cacaoensis Bolton, 1971: 59, fig. 1 (w.q.) NIGERIA. See also: Bolton, 1983: 367; Bolton, 2000: 602.

Worker
TL 2.7-3.3, HL 0.83-0.92, HW 0.72-0.80, CI 86-91, ML 0.38-0.45, MI 44-50, SL 0.48-0.50, SI 62-67, PW 0.36-0.40, AL 0.76-0.88 (11 measured).

Apical fork of left mandible with a dorsally situated small tooth and a ventrally situated denticle between the upper and lower spiniform fork teeth. Apical fork of right mandible with an intercalary denticle only. Preapical armament of both mandibular blades consisting of a pair of teeth or denticles. In general the proximal preapical tooth is very small, reduced to a denticle, and the distal is distinctly larger, but in a few specimens the two are of approximately equal size on each blade. The usual configuration seen in the rogeri-group, with the distal preapical tooth distinctly smaller than the proximal, is not found in this species. Upper scrobe margins not bordered by a lamella or flange, narrowly concave and with a pinched-in appearance immediately behind the convex frontal lobes. Posterior to this the upper scrobe margins are evenly divergent then suddenly and deeply excavated above the eye, the site of this excavation directly above the strongly developed preocular notch so that the two together form a broad deep groove running down the side of the head in front of the eye. Anterior portion of the eye detached from the head and the preocular notch continued onto the ventral surface of the head as a broad transverse impression. Antennal scapes narrow in the basal fifth than broadened, the short curved stout hairs on the leading edge defected apically and broadly spatulate to spoon-shaped. Head reticulate-punctate everywhere the ground-pilosity of dense short broadly spatulate to scale-like hairs which are curved anteriorly and quite closely applied to the surface, the hairs bordering the upper scrobe margins no longer than those sited elsewhere on the dorsum. Vertex of head without standiing hairs of any description. Pronotal humeri without projecting hairs of any description, the mesonotum bearing a single pair of stout hairs which represent the only standing pilosity on the dorsal alitrunk. Ground-pilosity of alitrunk of short sparse spatulate hairs which are closely applied to the surface. Propodeum armed with a pair of acute spines, the infradental lamellae very narrow or vestigial. Sides and dorsum of alitrunk and of pedicel segments reticulate-punctate everywhere, often with a granular appearance on the latter. Metanotal groove shallowly impressed. Spongiform appendages absent from petiole, present on postpetiole as a small ventral lobe and a narrow posterior collar. Transverse basal strip on first gastral tergite reduced to a narrow rim or carina from which the fine basigastral costulae arise. Petiole, postpetiole and gaster with stout hairs which increase in thickness from base to apex. Colour dull yellow to light yellowish brown.

Type Material
Holotype worker, paratype workers and female, NIGERIA: Gambari Exp. Sta. (Cocoa Res. Inst. of Nigeria), 10. vii.1969, rot hole in trunk of cocoa tree (B. Bolton) [examined].