Tetramorium simillimum species group

Based on Bolton 1979, 1980 and Hita Garcia and Fisher 2011.

Tetramorium species groups

This is a group encountered in most zoogeographical regions, although its primary distribution is surely in the Afrotropics. It has spread to other regions thanks to two comparatively successful tramp species, T. caldarium and T. simillimum. These species are widely distributed throughout the tropics and subtropics, and occur also in temperate zones where they are restricted to hothouses, zoos, and permanently heated buildings (Bolton, 1980). Both are also fairly common in the Malagasy region. Another group member, T. delagoense is shared between the Afrotropical and the Malagasy region, while the two other described species recorded from the Malagasy region, T. anodontion and T. scytalum, are endemics. In addition to these 5 valid species, there are 2 potentially new species from this region.

Within the species groups with 12-segmented antennae, the T. simillimum group can be identified without any difficulties. It cannot be confused with the T. bicarinatum group due to the impressed anterior clypeal margin of the latter, which is entire in the T. simillimum group. In addition, the absent or short propodeal spines separate it from the the two species of the T. tosii group, and the lack of a raised lateral clypeal portion of the clypeus clearly separates it from the T. sericeiventre group.

Diagnosis
Twelve-segmented antennae; anterior clypeal margin entire and convex; frontal carinae variable; anterior face of mesosoma well developed with distinct anterodorsal angle separating anterior face from dorsum; margination between lateral and dorsal mesosoma usually weak; propodeal spines triangular and short to absent; propodeal lobes broad, triangular and short, more voluminous and larger than propodeal spines; petiolar node in profile nodiform, in profile higher than long, in dorsal view weakly wider than long to as wide as long, anterodorsal and posterodorsal angles well-developed and of about same height; postpetiole in profile roughly rounded; mandibles smooth to weakly and finely sculptured; cephalic sculpturation distinct and predominantly longitudinally rugose; mesosoma and waist segments with distinct sculpturation; base of first gastral tergite often weakly sculptured, rest unsculptured and smooth; all dorsal surfaces of head, mesosoma, waist segments, and first gastral tergite with sparse to abundant short, stout, and blunt standing hairs, never short, dense, and appressed; sting appendage triangular.