Tetramorium arnoldi

Identification
Bolton (1980) - Easily distinguished from its relatives in this group by its combination of pale yellow colour, lack of hairs on the dorsal alitrunk and unarmed or merely angular propodeum, T. arnoldi is one of the most distinctive members of the oculatum-complex. Three yellow species are known in this complex and T. arnoldi is separated from them by the characters just noted. In Tetramorium berbiculum the propodeum lacks teeth as is the case in T. arnoldi, but this species has hairs present on the alitrunk and longer antennal scapes, SI 77-80 as opposed to SI 68-72 in T. arnoldi.

Distribution based on Regional Taxon Lists
Afrotropical Region: Zimbabwe.

Nomenclature

 *  arnoldi. Triglyphothrix arnoldi Forel, 1913j: 220 (w.) ZIMBABWE. Arnold, 1917: 339 (q.). Combination in Tetramorium: Arnold, 1917: 338; Bolton, 1985: 247. See also: Bolton, 1976: 318.

Worker
Bolton (1980) - TL 2.8-3.0, HL 0.66-0.70, HW 0.57-0.65, CI 89-94, SL 0.41-0.45, SI 68-72, PW 0.40-0.46, AL 0.72-0.78 (10 measured).

Mandibles longitudinally striate. Anterior clypeal margin entire, without a trace of a median notch or impression. Frontal carinae variable but very feebly developed, in some specimens merely a narrow ridge which is no more strongly developed than the cephalic rugulae and which sometimes runs back beyond the level of the eyes. In others the carinae are broken or disjointed, or fade out posteriorly, and in some they are absent or absolutely indistinguishable from the remaining cephalic sculpture; most of these variations are visible in any single nest-sample. Antennal scrobes vestigial to absent. Eyes situated at about the midlength of the sides of the head, maximum diameter 0.18-0.19, about 0.29-0.32 x HW and with 10-11 ommatidia in the longest row. Metanotal groove impressed in profile. Propodeum unarmed, rounded or at most with feebly prominent angles, without differentiated teeth. Metapleural lobes rounded. Petiole in profile high and fairly narrow, the height of the tergal portion of the node slightly greater than the dorsal length. In dorsal view the node slightly broader than long, narrowly rounded in front and much broader behind than in front. Dorsum of head longitudinally rugulose with a fine reticulate-punctate ground-sculpture. Dorsal alitrunk finely and densely reticulate-punctulate and dull, the pronotum and sometimes also the mesonotum with weak longitudinal rugulae. Petiole and postpetiole dorsally extremely finely punctulate or granular, base of first gastral tergite finely and faintly granular or shagreened. Short, stout hairs fairly numerous and conspicuous on gaster and postpetiole, more scattered and shorter on head but completely absent from dorsal alitrunk and petiole node. Colour uniform clear pale yellow.

Type Material
Bolton (1980) - Syntype workers, RHODESIA: Victoria Falls, xii.1914 (G. Arnold) [examined].

References based on Global Ant Biodiversity Informatics

 * IZIKO South Africa Museum Collection