Tetramorium simillimum species group

Based on Bolton 1979, 1980, Hita Garcia and Fisher 2011, and Agavekar et al. 2017.

Diagnosis

Hita Garcia and Fisher (2011) - 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.

Agavekar et al. (2017) - [Note: this diagnosis is only applicable to the few species occurring in the Indomalayan region, and not to the remainder of the Afrotropical group fauna]. Twelve-segmented antennae; anterior clypeal margin complete and unspecialized; eyes of moderate size; antennal scapes short to moderate, not surpassing posterior head margin; antennal scrobes either present without clear demarcation or absent; frontal carinae moderately to strongly developed but always surpassing eye level; base of first gastral tergite not concave in dorsal view, without tubercles or teeth on each side; pilosity on dorsal surfaces of body erect with short and thick hairs; sting appendage dentiform.

Notes

Hita Garcia and Fisher (2011) - 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.

Agavekar et al. (2017) - This is one of the larger species groups within Tetramorium with approximately 30 species, most of which are endemic to the Afrotropical region. Two members of the group have become extremely successful panglobal tramps: Tetramorium caldarium and Tetramorium simillimum. Both are found in all zoogeographic regions, and, not surprisingly, also in India.

Additional Resources

References

Gaurav Agavekar, G., Hita Garcia, F., Economo, E.P. 2017. Taxonomic overview of the hyperdiverse ant genus Tetramorium Mayr (Hymenoptera, Formicidae) in India with descriptions and X-ray microtomography of two new species from the Andaman Islands. PeerJ 5:e3800 (doi:10.7717/peerj.3800).
Hita Garcia and Fisher. 2011. The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region – introduction, definition of species groups, and revision of the T. bicarinatum, T. obesum, T. sericeiventre and T. tosii species groups. Zootaxa. 3039: 1-72.