Tetramorium dysalum, 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: 141-142

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Tetramorium dysalum

sp. n.

Tetramorium dysalum  HNS  sp. n.

(Fig. 24)

Holotype worker. TL 3.1, HL 0 - 72, HW 0.71, CI 99, SL 0.50, SI 70, PW 0.52, AL 0.84.

Mandibles smooth and shining, unsculptured except for minute pits. Anterior clypeal margin with an impression or notch. Frontal carinae strong, surmounted by a narrow raised rim or flange. Alitrunk sharply marginate anteriorly and laterally, the margination of the sides interrupted at the promesonotal junction and more strongly impressed at the metanotal area, between mesonotum and propodeum. Pronotal dorsum transversely flat, the propodeal dorsum transversely feebly concave. Propodeum with a pair of long, acute spines which are slightly downcurved along their length. Metapleural lobes triangular. Node of petiole in profile high and quite narrow, the anterodorsal angle somewhat higher than the posterodorsal so that the slightly convex dorsal surface slopes downwards posteriorly. Dorsum of head regularly longitudinally rugulose, the interspaces with very feeble superficial ground-sculpture. Dorsal alitrunk strongly longitudinally rugose. Petiole and gaster unsculptured but dorsum of postpetiole with very faint traces of superficial sculpture. All dorsal surfaces of head and body with numerous elongate, fine hairs. Colour uniform brown.

Paratype workers. TL 2.7 - 3.1, HL 0.64 - 0.72, HW 0.60 - 0.71, CI 95 - 100, SL 0.43 - 0.50, SI 68 - 73, PW 0.46 - 0.52, AL 0.74 - 0.84 (15 measured).

As holotype but some specimens slightly darker in shade than the holotype, often the gaster lighter in shade than the alitrunk. The entire type-series apparently represents a single nest-sample, so the normal size variation in this species is fairly large. The degree of curvature of the propodeal spines varies, most specimens being as holotype but a few have them slightly more or slightly less downcurved.

Holotype worker, Madagascar: Perinet & vic, rain forest, 17. iii. 1969 (W. L. Brown) (MCZ, Cambridge). Paratypes. 39 workers and 1 dealate queen with same data as holotype but on some pins the lower label having ' rot. wood' or ' for. litter' (MCZ, Cambridge; BMNH).


Two series collected more recently by W. L. Brown in Madagascar: vic. Andasibe (= Perinet), 2 - 6. ii. 77, and Mangabe I.: Antongil Bay, 19. ii. 77, agree well with the above description but in the Andasibe series body hairs are darker in colour than in the type-series.

This species appears to be close to marginatum  HNS  , but in that species the dorsal alitrunk is unsculptured.