Tetramorium gracile

Identification
Bolton (1980) - Two close relatives of T. gracile are known and in this small complex of three species T. gracile is most closely related to Tetramorium doriae of Ethiopia and the Arabian peninsula. The two are separable on details of sculpture as T. doriae has a quite well-marked, partial or complete rugoreticulum on the pronotum. These two species are easily separable from Tetramorium praetextum, the only other known member of this group, as in this species the base of the first gastral tergite is sculptured and the sides of the head behind the eyes lack outstanding hairs in full-face view. Both other species have the base of the first tergite smooth and have outstanding hairs on the sides of the head behind the eyes.

Distribution based on Regional Taxon Lists
Afrotropical Region: Ethiopia.

Nomenclature

 *  gracile. Tetramorium gracile Forel, 1894b: 81 (w.) ETHIOPIA. Forel, 1907c: 136 (m.). See also: Bolton, 1980: 279.

Worker
Bolton (1980) - TL 3.4, HL 0.84, HW 0.71, CI 85, SL 0.78, SI 110, PW 0.50, AL 0.99.

Mandibles longitudinally striate. Anterior clypeal margin entire, the median clypeal carina a strongly raised ridge and the only sculpture traversing the clypeus. Scapes relatively long, SI > 100. Frontal carinae feeble. With the head in full-face view the carinae are strongly developed only to the level of the mid-length of the eye, behind this they quickly peter out. Eyes large, maximum diameter 0.21, about 0.29 x HW. Alitrunk in profile with metanotal groove broadly but only shallowly impressed. Propodeum armed only with a pair of minute denticles, which are little more than sharp angular projections. Metapleural lobes broadly triangular and distinctive. Petiole node in profile with the dorsal length at least equal to the height of the tergal portion, or slightly greater. Legs long and quite slender, length of hind femur 0.80. Dorsum of head with a few feeble and widely spaced rugulae, with weak anastomoses on the occiput. Spaces between the rugulae virtually unsculptured, here and there with some very feeble superficial reticulation. Promesonotal dorsum mostly unsculptured and shining, with feeble rugulae widely spaced out and the surface with only extremely faint reticulation. Petiole and postpetiole rugulose, reticulate in places. Gaster unsculptured, smooth and shining. All dorsal surfaces of head and body with elongate, quite stout hairs but the antennal scapes and the dorsal (outer) surfaces of the middle and hind tibiae only with short, fine decumbent to appressed pubescence. Ventral surface of head with a number of very long, anteriorly curved ammochaete hairs, the ventral margin of the mandibles with a complementary series of posteriorly curved long hairs. Colour uniform mid-brown, the legs and antennae yellow-brown.

Type Material
Bolton (1980) - Holotype worker, Ethiopia (‘’Siidabessinien’) (Ilg) [examined].

References based on Global Ant Biodiversity Informatics

 * 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. 1907. Fourmis d'Ethiopie récoltées par M. le baron Maurice de Rothschild en 1905. Revue d'Entomologie (Caen) 26: 129-144.
 * 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