Tetramorium pusillum

Common in fynbos, colonies of this ground nesting species can be found by turning rocks. One nest was found with an (SAM-HYM-C007545) "entrance of nest in open but with grass and sedges nearby. Entrance a neat round hole with scattered soil particles round it. Cavities with workers and larvae in top 4 cm of soil."

Identification
A member of the Tetramorium simillimum species group.

Bolton (1980) - A small, darkly coloured species separated from its closest relatives (Tetramorium altivagans and Tetramorium nigrum) by its unsculptured mandibles. It is possible that these three names represent a single variable species but on presently available evidence it seems best to keep them separate.

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

Nomenclature

 *  pusillum. Tetramorium pusillum Emery, 1895h: 38 (w.q.) SOUTH AFRICA. Senior synonym of ladismithensis, tablensis: Bolton, 1980: 318.
 * ladismithensis. Tetramorium caespitum r. ladismithensis Forel, 1913a: 117 (w.q.) SOUTH AFRICA. Subspecies of pusillum: Forel, 1914d: 223. Junior synonym of pusillum: Bolton, 1980: 318.
 * tablensis. Tetramorium pusillum var. tablensis Forel, 1914d: 223 (w.q.m.) SOUTH AFRICA. Junior synonym of pusillum: Bolton, 1980: 318.

Worker
Bolton (1980) - TL 2.1-2.3, HL 0.54-0.58, HW 0.44-0.48, CI 80-85, SL 0.36-0.40, SI 80-87, PW 0.32-0.34, AL 0.56-0.64 (10 measured).

Mandibles unsculptured, smooth and shining. Anterior clypeal margin entire, without a median notch or impression. Frontal carinae narrow and weak, usually running back beyond level of eyes but often fading out or becoming indistinguishable from remaining sculpture before reaching occiput; sometimes reaching occiput. In many specimens the frontal carinae are broken or interrupted at one or more points along their length. Antennal scrobes vestigial or absent. Eyes moderate, maximum diameter 0.10-0.12, about 0.23-0.25 x HW and with 7-8 ommatidia in the longest row. Propodeum armed with a pair of minute denticles or very short teeth, always shorter than the metapleural lobes. Petiole in dorsal view broader than long. Dorsum of head finely and quite densely longitudinally rugulose, the rugulae fine and narrow but generally sharply defined; this is enhanced by the lack of strong ground-sculpture, the surfaces having only a superficial shagreening. Dorsal alitrunk finely reticulate-punctulate; sometimes this is the only sculpture present but in most a few weak rugulae are developed on the anterior portion of the pronotum. Petiole and postpetiole only with very faint superficial shagreening or almost smooth. First gastral tergite unsculptured. All dorsal surfaces of head and body with scattered short, stout, blunt hairs. Body dark brown or blackish brown.

Type Material
Bolton (1980) - Syntype workers, females, SOUTH AFRICA: Cape Town (E. Simon) [female examined].

References based on Global Ant Biodiversity Informatics

 * Addison P., and M. J. Samways. 2000. A survey of ants (Hymenoptera: Formicidae) that forage in vineyards in the Western Cape Province, South Africa
 * Arnold G. 1917. A monograph of the Formicidae of South Africa. Part III. Myrmicinae. Annals of the South African Museum. 14: 271-402.
 * 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.
 * Emery C. 1895. Voyage de M. E. Simon dans l'Afrique australe (janvier-avril 1893). 3e mémoire. Formicides. Annales de la Société Entomologique de France 64: 15-56.
 * Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bulletin of the American Museum of Natural History 45: 711-1004