Tetramorium mossamedense

Identification
A member of the Tetramorium simillimum species group.

Bolton (1980) - In the present situation T. mossamedense separates from other members of the poweri-complex as follows. Tetramorium ghindanum and Tetramorium nefassitense have the first gastral tergite extensively and quite coarsely sculptured, unsculptured in T. mossamedense. Tetramorium pauper and poweri have the frontal carinae vestigial or absent whereas they are present and conspicuous although only fine and narrow in mossamedense. Tetramorium altivagans is a larger, more darkly coloured species than T. mossamedense, and has longer antennal scapes (compare T. altivagans HW 0.52-0.56, SL 0.44-0.50, SI 84-91 with the measurements given above). Tetramorium pusillum and Tetramorium nigrum are both small, dark species, the former with unsculptured mandibles and the latter without developed propodeal teeth. This leaves Tetramorium caldarium, the closest relative of T. mossamedense, especially those forms mentioned under T. caldarium in which the frontal carinae are relatively close together. The two are best separated by comparing the sculpture of the dorsal head. In T. caldarium the longitudinal rugulae of the cephalic dorsum are weakly developed, fine and narrow and are superimposed upon a finely reticulate-punctate or granular ground-sculpture which serves to make the rugulae even less conspicuous. In T. mossamedense on the other hand the cephalic rugulae are conspicuous and sharply defined, the effect being enhanced by the lack of strong ground-sculpture. Besides this the scapes of T. caldarium tend to be somewhat longer (SI 79-87) than T. mossamedense, although there is some overlap of the ranges.

Distribution based on Regional Taxon Lists
Afrotropical Region: Angola, Botswana, Zimbabwe.

Nomenclature

 *  mossamedense. Tetramorium caespitum var. mossamedensis Forel, 1901d: 306 (w.) ANGOLA. [Also described as new by Forel, 1903e: 560.] Subspecies of pusillum: Santschi, 1917c: 285. Raised to species, senior synonym of schultzei and material of the unavailable name tristis referred here: Bolton, 1980: 314.
 * schultzei. Tetramorium caespitum subsp. schultzei Forel, 1910f: 19 (w.) BOTSWANA. Junior synonym of mossamedense: Bolton, 1980: 314.

Bolton (1980) - As with a couple of other species in the Tetramorium simillimum species group I suspect that more than one species may be present here but I am unable to progress further due to lack of material, both of this species and of its relatives.

Worker
Bolton (1980) - TL 2.1-2.4, HL 0.54-0.60, HW 0.48-0.54, CI 86-92, SL 0.36-0.40, SI 74-80, PW 0.32-0.38, AL 0.60-0.68 (10 measured).

Mandibles longitudinally striate, conspicuously so in most specimens but only delicately marked in some. Anterior clypeal margin entire, without a median notch. The raised lateral portions of the clypeus generally strongly developed, narrowly lamellate and projecting. Frontal carinae variously developed; in many fine and narrow but running back unbroken almost to the occipital margin, distinctly finer and weaker behind the eyes than in front. In some the frontal carinae fade out at the occipital surface and in others they are broken or interrupted along their length, either resuming after a gap or having their place taken by one of the longitudinal rugulae. Antennal scrobes moderate to feeble, the majority of specimens with only an extremely weak impression in the sides of the head, but a few with the scrobes more strongly developed and roughly intermediate between the usual conditions seen in simillimum-complex and poweri-complex. Eyes moderate, maximum diameter 0.11-0.13, about 0.23-0.24 x HW and with 7-8 ommatidia in the longest row. Propodeum armed with a pair of short triangular teeth which at most are only as long as the metapleural lobes and are usually shorter. Petiole in dorsal view broader than long. Dorsum of head with fine, spaced out longitudinal rugulae, the spaces between them glossy and with only superficial weak ground-sculpture. Dorsal alitrunk with fine punctulate or shagreened ground-sculpture which is more strongly developed than that on the head, overlaid by some fine, longitudinal rugulae at least on the anterior pronotum. Petiole and postpetiole finely punctulate or shagreened, sometimes with one or two regular vestiges visible. First gastral tergite unsculptured. Dorsal surfaces of head and body with short, stout, blunt hairs. Colour varying from light brown to dark brown, the darker specimens usually those with the scrobes more strongly developed.

Type Material
Bolton (1980) - Syntype workers, ANGOLA: Mossamedes, Cubango-Cuito [examined].

References based on Global Ant Biodiversity Informatics

 * 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.
 * Forel A. 1903. Einige neue Ameisen aus Sud-Angola. Pp 559-564, in: Baum, H. Kunene-Sambesi-Expedition, 1903. Berlin: Verlag des Kolonial-Wirtschaftlichen Komitees, 593pp.
 * IZIKO South Africa Museum Collection
 * Nsengimana V., K. A. Beth, F. Frederic, K. M. M. Lombart, D. Wouter, and N. Donat. 2018. Use of soil and litter ants (Hymenoptera: Formicidae) as biological indicators of soil quality under different land uses in Southern Rwanda. Environmental Entomology 47(6): 1394-1401.
 * Samways M. J. 1990. Species temporal variability: epigaeic ant assemblages and management for abundance and scarcity. Oecologia 84: 482-490.
 * Santschi F. 1914. Formicides de l'Afrique occidentale et australe du voyage de Mr. le Professeur F. Silvestri. Bollettino del Laboratorio di Zoologia Generale e Agraria della Reale Scuola Superiore d'Agricoltura. Portici 8: 309-385.
 * 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