Tetramorium ibycterum, Bolton, B., 1979

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 : 148-149

Tetramorium ibycterum sp. n.

(Fig. 26)

Holotype worker. TL 2.5, HL 0.64, HW 0.61, CI 95, SL 0.43, SI 70, PW 0.44, AL 0.68.

Mandibles with delicate sculpture resembling feeble shagreening, not longitudinally striate. Anterior clypeal margin with a median impression or notch. Frontal carinae strongly developed and surmounted by a narrow rim or flange, forming the dorsal margin of a shallow but conspicuous broad scrobe. The scrobe is bounded ventrally by a feeble longitudinal carina, running above the eye, which also forms the posterior boundary of the scrobal area. Dorsal alitrunk in profile evenly convex, without trace of metanotal groove. Propodeal spines stout and acute, metapleural lobes triangular. Shape of pedicel segments as in Fig. 26, the petiole in dorsal view very slightly broader than long, the postpetiole conspicuously so. Dorsum of head finely but irregularly longitudinally rugulose with very feeble traces of a reticulum occipitally, the interspaces with very faint ground-sculpture. Dorsal alitrunk finely reticulate-rugulose, the meshes tending to be more conspicuous on the pronotum. Petiole and postpetiole with the faintest traces of ground-sculpture dorsally, almost smooth. Gaster unsculptured. Short fine hairs present on dorsum of head but almost wholly confined to the dorsal surface of the frontal carinae. Longer fine, erect hairs present on dorsal alitrunk but very sparse, pronotum with 2 pairs, mesonotum with 1 pair, propodeum with 2 pairs in holotype, all located laterally where the dorsum meets the sides. Petiole, postpetiole and first gastral tergite without hairs, but the last with very fine appressed pubescence. Colour uniform light orange-brown.

Holotype worker, Madagascar: Cote Ouest, Jangoa, degraded for. litter, 18. i. 1966 (J-M. Betsch) (MCZ, Cambridge).

In the ranarum-group ibycterum is unique in lacking any trace of pilosity on the first gastral tergite, and in this respect it resembles the cognatum-complex in the schaufussi-group. However, the shape of the petiole node and the presence of sculpture on the mandibles indicate that the true affinities of ibycterum lie with ranarum and its allies.