Tetramorium amaurum

Identification
Bolton (1980) - The four species closely related to amaurum, namely Tetramorium subcoecum, Tetramorium warreni, Tetramorium traegaordhi and Tetramorium typhlops, only have a single ommatidium or two ommatidia in the eye, whereas T. amaurum has 3-5. Beside this, T. warreni and T. typhlops are both minute species with HW < 0-50, SL < 0-35, and completely lack frontal carinae. In T. subcoecum frontal carinae are vestigial or absent but in T. traegaordhi they are about as strongly developed as in T. amaurum. Apart from the size of the eye, T. traegaordhi differs from T. amaurum by having the petiole node distinctly transverse in dorsal view, much broader than long, and by having longer, more conspicuous body pilosity than T. amaurum. To illustrate this, with the body in profile the longest hairs on both the alitrunk and the first tergite are distinctly longer than the maximum width of the hind tibia in T. traegaordhi, shorter than the hind tibial width in T. amaurum.

Distribution based on Regional Taxon Lists
Afrotropical Region: Zimbabwe.

Nomenclature

 *  amaurum. Tetramorium amaurum Bolton, 1980: 286, fig. 69 (w.) ZIMBABWE.

Worker
Holotype: TL 2.7, HL 0.70, HW 0.63, CI 90, SL 0.46, SI 73, PW 0.42, AL 0.72. Paratypes (8 measured): TL 2.6-3.1, HL 0.66-0.74, HW 0.60-0.66, CI 89-94, SL 0.44-0.50, SI 69-76, PW 0.38-0.46, AL 0.71-0.82.

Mandibles finely and faintly longitudinally striate, the sculpture not conspicuous. Anterior clypeal margin with a small median notch or impression. The central portion of the clypeus immediately behind the impression very shallowly transversely concave but the median carina running the length of the clypeus. Frontal carinae very feeble, no more than fine and narrow raised lines which end at the level of the eyes. Antennal scrobes absent. Eyes minute but quite conspicuous, of 3—4 poorly defined facets and much shorter than the maximum width of the scape. Maximum diameter of eye 0.05, about 0.08 x HW. Alitrunk in profile more or less evenly convex, with a very feeble and shallow impression at the metanotal groove that barely interrupts the outline. Propodeum armed with a pair of short triangular teeth which are about as long as their basal width. Metapleural lobes distinctly broader and very slightly longer than the propodeal teeth, lobate and rounded apically. Petiole in profile with the dorsal length less than the height of the tergal portion, both antero- and posterodorsal angles rounded. Petiole in dorsal view slightly broader than long and with all angles rounded, the dorsum merging into the sides, the anterior, and the posterior faces. Dorsum of head with a few feeble, scratch-like longitudinal rugulae which fade out before reaching the occipital region, which is only very lightly shagreened. Spaces between sparse rugulae on dorsum on head with a weak, superficial ground-sculpture. Dorsal surfaces of alitrunk, petiole, postpetiole and gaster unsculptured except for a few faint punctulations on the propodeum. Dorsal surfaces of head and body with sparse standing hairs but the middle and hind tibiae only with short pubescence which is decumbent to appressed. Colour yellow.

Paratypes: As holotype but eye with 3-5 facets, the limits of individual ommatidia generally difficult to see. Maximum diameter of eye 0.04-0.07, about 0.06-0.10 x HW.

Type Material
Holotype worker, Rhodesia: Redbank, 3.xii.1917 (G. Arnold). Paratypes, 10 workers with same data as holotype (BMNH; ; ).

References based on Global Ant Biodiversity Informatics

 * IZIKO South Africa Museum Collection