Tetramorium invictum

Identification
Bolton (1980) - Tetramorium invictum is most closely related to Tetramorium coloreum and Tetramorium postpetiolatum, but both these species are conspicuously bicoloured, black (or dark brown) and yellow, whereas T. invictum is uniformly dark.

Distribution based on Regional Taxon Lists
Afrotropical Region: Ghana, Ivory Coast.

Nomenclature

 *  invictum. Tetramorium invictum Bolton, 1980: 300, fig. 84 (w.) IVORY COAST.

Worker
Holotype. TL 3.3, HL 0.80, HW 0.75, CI 94, SL 0.60, SI 80, PW 0.52, AL 0.86. Paratypes (20 measured): TL 3.1—3.3, HL 0.76-0.82, HW 0.70-0.76, CI 92-95, SL 0.57-0.62, SI 77-82, PW 0.50-0.54, AL 0.82-0.92. Maximum diameter of eye 0.15-0.16, about 0.20-0.22 x HW.

Mandibles longitudinally striate. Anterior clypeal margin entire, without trace of a median notch but with an exceptionally feeble indentation medially in the holotype, difficult to see and variably absent or present in the type-series (which are from a single nest). Median clypeal carina distinct but not more strongly developed than the remaining longitudinal clypeal sculpture. Frontal carinae long, running back almost to the occipital margin but no more strongly developed than the dorsal cephalic sculpture. Antennal scrobes broad and shallow, the scapes of moderate length (SI 80 in holotype, range 77-82). Maximum diameter of eye 0.16, about 0.21 x HW. Alitrunk short and broad (see measurements), the dorsal outline in profile strongly arched from front to back. Propodeal spines long and narrow, extremely feebly sinuate along their length. Metapleural lobes spiniform, long and narrow. Petiole in profile with a narrow anterior peduncle, the node high, its dorsal length being less than the height of the tergal portion. Anterior face of node vertical or nearly so, meeting the dorsum ina blunt right-angle. Dorsum short and curving evenly into the weakly convex posterior face so that the two form a single curved surface. Petiole node in dorsal view longer than broad, rounded anteriorly, broadening posteriorly for about two-thirds of its length and then narrowing again to-the postpetiolar junction. Dorsum of head irregularly longitudinally rugulose with scattered weak cross-meshes behind the level of the eyes but without a distinct reticulum occipitally. Dorsal alitrunk irregularly rugose, predominantly longitudinal on the pronotum and reticulate elsewhere. Dorsal surfaces of petiole and postpetiole irregularly finely rugulose with fine punctulate ground-sculpture which is more conspicuous here than on the alitrunk. First gastral tergite finely striolate-punctulate basally. All dorsal surfaces of head and body with numerous short, stout standing hairs, most of which are blunt apically. Dorsal (outer) surfaces of hind tibiae with short appressed pubescence only. Colour very dark blackish brown.

Paratypes: As holotype but colour varying from uniform blackish brown to black, sometimes with the gaster slightly paler. Pronotum weakly reticulate-rugose in some and the propodeal spines variously shaped, being feebly upcurved, downcurved or sinuate.

Type Material
Holotype worker, Ivory Coast: Forét de Tai, 19.vi.1975, no. 1 (T. Diomande). Paratypes. 32 workers with same data as holotype (BMNH; ; ).

References based on Global Ant Biodiversity Informatics

 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research 3: 5-16.
 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research. 3: 5-16.
 * 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.
 * Yeo K., and A. Hormenyo. 2007. A Rapid Survey of Ants in Ajenjua Bepo and Mamang River Forest Reserves, Eastern Region of Ghana. Pp 27-29. In McCullough, J., P. Hoke, P. Naskrecki, and Y. Osei-Owusu (eds.). 2008. A Rapid Biological Assessment of the Ajenjua Bepo and Mamang River Forest Reserves, Ghana. RAP Bulletin of Biological Assessment 50. Conservation International, Arlington, VA, USA.