Tetramorium steinheili 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 : 143

Tetramorium steinheili Forel

(Figs 12, 15)

Tetramorium (Xiphomyrmex) steinheili Forel, 1892: 520 . Syntype workers, females, Madagascar: Foret d'Andrangoloaka, confins de l'lmerina {Sikora) (MHN, Geneva) [examined].

Worker. TL 4.3 - 4.4, HL 1.00, HW 0.94 - 0.96, CI 94 - 96, SL 0.72 - 0.76, SI 77 - 80, PW 0.68 - 0.72, AL 118 - 1.20 (2 measured).

Mandibles striate; median clypeal carina sharp. Extensions of frontal carinae long and strong, slightly sinuate from origin to behind the level of the eyes and then strongly divergent, directed towards the occipital corners. Pronotum and mesonotum obtusely marginate at the sides, in dorsal view separated by an impression. Metanotal groove absent, not impressed in profile. Propodeal spines long and stout, metapleural lobes elongate-triangular, acute or blunted apically. Petiole node anteroposteriorly compressed, in dorsal view much broader than long. Dorsum of head regularly longitudinally rugulose, the alitrunk more coarsely rugose, predominantly longitudinal but the rugae meandering and with a few crossmeshes present. Pedicel and gaster unsculptured, smooth and shining. All dorsal surfaces of head and body with numerous fine, erect to suberect hairs. Leading (anterior) edges of antennal scapes with short, projecting, suberect to subdecumbent hairs which are shorter than the maximum width of the scape. Colour reddish brown, the gaster paler than the alitrunk.

In overall appearance steinheili resembles some of the members of the tortuosum-group, but the unsculptured pedicel segments and the fact that the petiole is distinctly anteroposteriorly compressed seem to indicate that the affinities of steinheili are with humbloti and its relatives. Despite this I feel that there is a distinct possibility that this species may truly be related to andrei and its allies, and convergent upon the weitzeckeri-group in pedicel structure.

Material examined

Madagascar: Andranobe, Route d'Andriamena (A. Peyrieras); Bemanevika, Souspref. Bealanana {A. Peyrieras).