Tetramorium vexator

An open habitat species, it has been collected from grasslands, fynbos and scrub. Specimens have been taken in pitfall traps and by hand. The only nest collection was discovered in grass roots.

Identification
Bolton (1980) - A fairly distinctive species in the group, characterized by its smooth mandibles, notched clypeus, dense cephalic sculpture and uniquely shaped petiole.

Distribution based on Regional Taxon Lists
Afrotropical Region: South Africa.

Nomenclature

 *  vexator. Tetramorium vexator Arnold, 1926: 269, fig. 76 (w.) SOUTH AFRICA. See also: Bolton, 1980: 265.

Worker
Bolton (1980) - TL 3.7-4.3, HL 0.92-1.02, HW 0.90-0.98, CI 93-98, SL 0.62-0.72, SI 66-73, PW 0.58-0.66, AL 1.02-1.12 (11 measured).

Mandibles smooth and shining with scattered pits. Anterior clypeal margin notched or impressed medially. Frontal carinae extending back almost to occiput, more strongly developed anteriorly, surmounted by a narrow raised rim or flange which is highest at the level of the eyes and becomes lower posteriorly. Antennal scrobes present but shallow. Eyes relatively small for a member of this group, maximum diameter 0.19-0.22, about 0.21-0.23 x HW. With the alitrunk in profile the metanotal groove impressed, usually only shallowly so but very distinctly so in some individuals. Propodeal spines stout, triangular and acute but quite short, their length about 0.14-0.16, distinctly shorter than the maximum diameter of the eye. Metapleural lobes low and broadly triangular. Petiole in profile high and narrow, roughly cuneate, much narrower above than below. Anterior face rising to a high anterodorsal angle which is the highest point of the node. Behind this the dorsal and posterior faces are united in an evenly convex shallowly curved surface which slopes away from the anterior face. In dorsal view both nodes are broader than long. Seen from behind the petiole node is high and narrow, its sides feebly convergent dorsally. Dorsum of head finely and densely longitudinally rugulose, the rugulae running from clypeus to occiput without cross-meshes or reticulation. Most individuals with 14-17 rugulae between the frontal carinae at the level of the eyes but one or two specimens with slightly more (holotype with 15). Spaces between the rugulae narrow, with superficial ground-sculpture. Dorsal alitrunk with fine, feeble longitudinal rugulae which are wider-spaced than those on the head; cross-meshes absent. Petiole, postpetiole and gaster unsculptured. Pilosity on dorsal surfaces of head and body long, fine, dense and acute apically; the first gastral tergite most densely hairy. Colour in samples examined uniform dark brown to blackish brown, but the holotype paler, yellowish brown, which leads me to suspect that the holotype is a teneral worker.

Type Material
Bolton (1980) - Holotype, SOUTH AFRICA: Pietermaritzburg, 1.vii.1917 (C. Akerman) [examined].

References based on Global Ant Biodiversity Informatics

 * Arnold G. 1926. A monograph of the Formicidae of South Africa. Appendix. Annals of the South African Museum. 23: 191-295.
 * Bolton B. 1980. The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Ethiopian zoogeographical region. Bulletin of the British Museum (Natural History). Entomology 40: 193-384.
 * Schoeman C. S., and S. H. Foord. 2012. A checklist of epigaeic ants (Hymenoptera: Formicidae) from the Marakele National Park, Limpopo, South Africa, Koedoe 54(1), Art. #1030, 7 pages. http://dx.doi.org/10.4102/koedoe.v54i1.1030
 * van Hamburg H., A. N. Andersen, W. J. Meyer, and H. G. Robertson. 2004. Ant community development on rehabilitated ash dams in the South African highveld. Restoration Ecology 12(4): 552-558.