Tetramorium robustior Forel

Bolton, B., 1979, The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Malagasy region and in the New World., Bulletin of the British Museum (Natural History) Entomology 38, pp. 129-181 : 147

Tetramorium robustior Forel stat. n.

(Fig. 16)

Tetramorium (Xiphomyrmex) andrei st. robustior Forel, 1892: 521 . Syntype workers, Madagascar: Foret d'Andrangoloaka (Sikora) (MHN, Geneva) [examined].

Worker. TL 4.6 - 4.9, HL 1.00 - 1.04, HW 0.98 - 1.02, CI 98 - 100, SL 0.80 - 0.82, SI 78 - 80, PW 0.74 - 0.78, AL 1.30 - 1.32 (3 measured).

Mandibles striate; median clypeal carina distinct. Frontal carinae strongly developed and sinuate, diverging to the level of the eyes, converging behind the eyes and then diverging again posteriorly, each carina directed towards the occipital corner but merging with the sculpture before reaching it. Antennal scrobe a well-defined groove capable of accommodating the scape. Posteromedian portion of head in front of the occipital margin transversely shallowly concave. Pronotum and mesonotum bluntly marginate laterally. Propodeal spines long and strong, metapleural lobes elongate triangular, dentiform and acute. Petiole node in profile roughly rectangular, slightly broader above than below due to the weak concavity of both the anterior and posterior faces; a second result of this concavity is that the antero- and posterodorsal angles of the node slightly overhang the faces below them. In dorsal view the node longer than broad. Head regularly longitudinally rugose with a fine but conspicuous punctulation between the rugae. Dorsal surfaces of alitrunk and pedicel more coarsely longitudinally rugose. Gaster unsculptured. All dorsal surfaces of head and body with numerous fine, erect to suberect hairs. Leading edges of antennal scapes with short, suberect curved hairs, which are shorter than the maximum width of the scape.

T. robustior is close to andrei but is a more stockily built species with a slightly differently shaped petiole node, relatively broader head and shorter antennal scapes. In view of these differences it is my opinion that robustior is best treated as a good species, at least until more material is available and the variation of the two forms is known in more detail.

Material examined

Madagascar: no loc. (Sikora); Parc Nat. Mont. d'Ambre (W. L. & D. E. Brown); Bemanevika, Souspref.

Bealanana (A. Peyrieras).