Tetramorium zenatum, 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 : 151-152

Tetramorium zenatum sp. n.

(Fig. 19)

Holotype worker. TL 2.6, HL 0.64, HW 0.60, CI 94, SL 0.42, SI 70, PW 0.47, AL 0.72. Mandible coarsely longitudinally striate, anterior clypeal margin with a distinct notch or impression.

Frontal carinae strong and surmounted by a narrow rim or flange, posteriorly weaker and curving downwards around the posterior part of the scrobe, not becoming confused with the sculpture of the occipital region. Scrobes shallow but broad, bounded below by a longitudinal carina running above the eye which is upcurved posteriorly and confluent with the downcurved frontal carina. Anteriorly the scrobe divided into upper and lower portions by a feeble median carina which ends just beyond the level of the eye. Eyes with maximum diameter 0.11, about 018 x HW. Propodeal spines short and acute, the metapleural lobes elongate-triangular. Petiole in profile very distinctly shaped, see Fig. 19, the dorsum flat. In dorsal view the node about as long as broad. Dorsum of head irregularly finely rugulose, forming a reticulum occipitally. Spaces between rugulae with a punctulate ground-sculpture. Dorsal alitrunk reticulaterugulose, the dorsal surfaces of the rugulae feebly punctulate. Petiole node finely rugulose, the postpetiole and gaster unsculptured, smooth and shining. All dorsal surfaces of head and body with numerous short, fine hairs. Colour orange-brown.

Paratype worker. As holotype but teneral and without full adult colour. Slightly smaller than holotype, TL 2.5, HL 0.62, HW 0.56, CI 90, SL 0.42, SI 75, PW 0.45, AL 0.69. The eye with maximum diameter 0.10.

Holotype worker, Madagascar: Causse de Kelifely, 20 - 30. xi. 1974, forest humus and litter, dry forest AB 47 (A. Peyrieras) (MCZ, Cambridge). Paratypes. One worker and one dealate female with same data as holotype (MCZ, Cambridge; BMNH).

This species is closest related to plesiarum , both species sharing a similar strong development of the antennal scrobes, but the unique shape of the petiole node of zenatum quickly separates it from plesiarum , compare Figs 19 and 27. Also, the carina forming the lower scrobe margin is confluent with the frontal carina posteriorly in zenatum , but in plesiarum the two do not join, as indicated in Fig. 27.