Tetramorium africanum

Like its close relative Tetramorium aculeatum, africanum is an arboreal species which is widespread in the forests of West and Central Africa. Unlike aculeatum it does not appear to have invaded the forests and woodlands of the eastern part of the continent and both species seem to be absent from the southern portion of Africa. Where their ranges coincide africanum is always decidedly less common than aculeatum. (Bolton 1980)

Identification
Bolton (1980) - Tetramorium africanum differs from Tetramorium rimytyum as the head in the latter is coarsely sculptured, the petiole differently formed, the metapleural lobes strongly developed and the tibiae only have elevated pubescence, not long hairs. Apart from differences in petiole node construction noted in the key, africanum is separated from Tetramorium aculeatum as follows:

africanum
 * Sting appendage vestigial, reduced to a narrow strip dorsally.
 * Palp formula 4, 2.
 * Scapes shorter, SI 102-114.
 * Median clypeal carina present.
 * Dorsum of head weakly sculptured.

aculeatum
 * Sting appendage conspicuous, triangular and freely projecting dorsally.
 * Palp formula 3, 2.
 * Scapes longer, SI 124-150.
 * Median clypeal carina usually absent.
 * Dorsum of head strongly sculptured.

Distribution based on Regional Taxon Lists
Afrotropical Region: Equatorial Guinea, Ghana, Guinea.

Nomenclature

 *  africanum. Macromischa africana Mayr, 1866a: 507 (w.) GHANA. Mayr, 1895: 131 (q.). Combination in Tetramorium: Emery, 1896a: 103; in Macromischoides: Wheeler, W.M. 1922a: 188; in Tetramorium: Bolton, 1976: 363 (in text); Bolton, 1980: 355. Senior synonym of tessmanni: Brown, 1964c: 12; of lamottei: Bolton, 1980: 355.
 * tessmanni. Rhoptromyrmex tessmanni Forel, 1910e: 421 (w.) EQUATORIAL GUINEA. Combination in Macromischoides: Brown, 1964c: 12. Junior synonym of africanum: Brown, 1964c: 12.
 * lamottei. Tetramorium lamottei Bernard, 1953b: 247, fig. 13 (q.) GUINEA. Junior synonym of africanum: Bolton, 1980: 355.

Worker
Bolton (1980) - TL 3.7-4.7, HL 0.82-1.00, HW 0.74-0.94, CI 90-96, SL 0.84-1.02, SI 102-114, PW 0.54-0.66, AL 1.00-1.22 (32 measured).

Mandibles usually smooth with scattered pits but rarely some delicate striation is visible between the pits. Masticatory margin of mandible armed with 3 teeth apically, followed by a series of 5-7 denticles; usually the second denticle about as large as the third apical tooth, the first denticle (between them) being distinctly smaller. Anterior clypeal margin with a broad, very shallow indentation medially or with the margin merely flattened and very little concave; very rarely the indentation or flattening so inconspicuous that the margin appears more or less evenly arcuate and entire. Median clypeal carina present, sometimes running the length of the clypeus but sometimes not quite reaching the anterior and posterior borders. Frontal carinae feebly developed and short, ending at the level of the posterior margins of the eyes or before. Antennal scrobes absent. Scapes long, SI > 100; when the scapes are laid back on the head in full-face view they easily surpass the curve of the occipital corner. Eyes of moderate size, maximum diameter 0.17-0.24, about 0.23-0.26 x HW. With the alitrunk in profile the metanotal groove conspicuously impressed and the propodeal dorsum immediately behind the groove usually raised up in a low, broad and roughly triangular peak or tumulus. Propodeal spines elongate and narrow, acute apically; variable in length, thickness and degree of elevation. Metapleural lobes low and rounded, very inconspicuous, sometimes invisible in profile. Node of petiole in profile stout and substantial, shaped as in Fig. 131. The length of the anterior peduncle of the petiole less than to about equal to the thickness of the node at its mid-height. Node in dorsal view thick and distinctly broader than long. Dorsum of head feebly sculptured, at most with a few weak longitudinal fine rugulae, often more or less unsculptured over some or most of the surface. Dorsal alitrunk finely narrowly rugulose, sometimes quite densely so and commonly with the propodeum more densely and less regularly sculptured than the pronotum. Ground-sculpture on the dorsal alitrunk present but superficial and inconspicuous. Petiole dorsum with fine longitudinal rugular sculpture but this is vestigial or more commonly absent from the postpetiole. First gastral tergite unsculptured. All dorsal surfaces of head and body densely clothed with fine acute hairs. Similar hairs are also numerous and very conspicuous on the scapes and middle and hind tibiae where they are suberect to subdecumbent and freely projecting. Colour uniform light brown to mid-brown, sometimes with the gaster slightly darker in shade than the head and alitrunk.

Type Material
Bolton (1980) - Syntype workers, GHANA [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.
 * Brown W. L., Jr. 1964. Macromischoides africanus, new synonymy of. Pilot Regist. Zool. Card No. 12.
 * Dejean A., F. Azemar, R. Cereghino, M. Leponce, B. Corbara, J. Orivel, and A. Compin. 2015. The dynamics of ant mosaics in tropical rainforests characterized using the SelfOrganizing Map algorithm. Insect Science doi: 10.1111/1744-7917.12208
 * Forel A. 1910. Note sur quelques fourmis d'Afrique. Annales de la Société Entomologique de Belgique 54: 421-458.
 * IZIKO South Africa Museum Collection
 * Santschi F. 1910. Formicides nouveaux ou peu connus du Congo français. Annales de la Société Entomologique de France 78: 349-400.
 * 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