Key to Malagasy Tetramorium species groups

This key is based on: 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.

The key is for workers and includes this caveat: "The following key was developed on the basis of existing species groups (Bolton, 1979), with significant additions and modifications made in order to incorporate a substantial amount of new material. However, it should be noted that this key is only of preliminary nature, and that the ongoing revision of all species groups might lead to further changes."

1

 * Species with distinctly branched hairs, usually a mixture of simple, bifid, and trifid hairs (Fig. 2.A) . . . . . T. obesum group


 * Species without branched hairs, hairs present neither bifid nor trifid, either with simple pilosity (Fig. 2.B), or with reduced pilosity but short appressed pubescence (Fig. 2.C) . . . . . 2

2
return to couplet #1
 * Antennae 11-segmented . . . . . 3
 * Antennae 12-segmented . . . . . 12

3
return to couplet #2
 * Mesosoma anterodorsally with distinct protuberance or bulge (Fig. 3.A); sculpturation on posterior head and anterior mesosoma, especially pronotum, always strongly reticulate-rugose . . . . . New species group 1 group (in parts)


 * Mesosoma anterodorsally without any protuberance or bulge (Fig. 3.B); sculpturation on posterior head and anterior mesosoma variable, but only rarely reticulate-rugose, usually with reduced sculpturation or longitudinal rugae/rugulae . . . . . 4

4
return to couplet #3


 * Both waist segments generally without any trace of rugose, rugulose, or reticulate sculpturation, generally unsculptured (Figs. 4.A, 4.B) . . . . . 5


 * One or both waist segments with conspicuous rugose, rugulose, or reticulate sculpturation (Figs. 4.C, 4.D) . . . . . 10

5
return to couplet #4
 * Both, petiolar node and postpetiole strongly squamiform and anteroposteriorly compressed (Fig. 5.A) . . . . . T. weitzeckeri group


 * Petiolar node variably shaped but postpetiole never strongly squamiform (Fig. 5.B) . . . . . 6

6
return to couplet #5


 * Petiolar node rounded high nodiform, rarely antero-posteriorly compressed; anterior and posterior faces of the node roughly parallel and all sides rounding smoothly onto the dorsal face; propodeal spines usually short to very short, very rarely otherwise (Fig. 6.A) . . . . . 7


 * Petiolar node variably shaped, usually distinctly higher and wider than long, anterior and posterior faces never parallel, in lateral view generally roughly to strongly triangular and strongly antero-posteriorly compressed dorsally, dorsum usually tapering strongly downwards posteriorly, in dorsal view strongly transverse; propodeal spines generally long and spinose (Fig. 6.B) . . . . . 8

7
return to couplet #6


 * Large, elongate species with very long and spinose propodeal spines (Fig. 7.A); mesosomal sculpturation, especially on the dorsum, weak but still present . . . . . T. severini group


 * Generally smaller, more compact species with very short to medium-sized propodeal spines or teeth (Fig. 7.B); mesosoma always distinctly sculptured, usually longitudinally rugose . . . . . T. schaufussii group

8
return to couplet #6

10
return to couplet #5