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.

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 * Tetramorium species groups (species lists, diagnosiss, distributions, etc.)
 * Tetramorium

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."

True to their word some of these groups were updated in the following year: [[Media:Hita Garcia & Fisher 2012a.pdf|Hita Garcia, F. and B. L. Fisher. 2012. The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region - taxonomy of the T. bessonii, T. bonibony, T. dysalum, T. marginatum, T. tsingy, and T. weitzeckeri species groups. Zootaxa. 3365: 1-123. PDF ]]. These changes are noted, in bold, as notes placed in relevant parts of the original 2011 key. With this in mind, the key does still work well for sorting many species to the species group level. Others, whether part of a newly suggested group that still awaits definitive revision studies or not, may not be resolved using this key.

'The T. tsingy'' group is not part of this key. Hita Garcia and Fisher (2012) - The members of the group possess an interesting character combination rendering them easily recognisable. The considerable lack of sculpture on head, mesosoma and waist segments, short to minute propodeal teeth, well-developed propodeal lobes, and an unsculptured petiolar node which is longer than wide, are not seen in any other species group.'''

1

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


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

2
return to couplet #1
 * Antennae 12-segmented (Fig. 3A); sting appendage triangular to dentiform, acute apically (Fig. 3B) . . . . . 3
 * Antennae 11-segmented (Fig. 3C); sting appendage spatulate, broadened apically (Fig. 3D) . . . . . 7

3
return to couplet #2
 * Anterior clypeal margin with distinct median impression (Fig. 4A) . . . . . T. bicarinatum group


 * Anterior clypeal margin always entire and convex, never with distinct median impression (Fig. 4B, C) . . . . . 4

4
return to couplet #3


 * Propodeum armed with long to extremely long spines (PSLI 30–49), at least 2 to 3 times longer than metapleural lobes (Fig. 5A) . . . . . T. tosii group


 * Propodeum either unarmed (Fig. 5B), armed with small triangular teeth or denticles, or armed with medium-sized spines (Fig. 5C), propodeal spines at most only as long or weakly longer than metapleural lobes, more often propodeal spines distinctly shorter than metapleural lobes . . . . . 5

5
return to couplet #4
 * Lateral portion of clypeus prominent, raised to a tooth or denticle in full-face view (Fig. 4B); propodeal spines medium-sized and spinose, approximately of same length as metapleural lobes (Fig. 5C) . . . . . T. sericeiventre group


 * Lateral portion of clypeus never modified as above (Fig. 4C); propodeum either unarmed (Fig. 5B) or armed with small triangular teeth or denticles that are shorter than metapleural lobes (Fig. 6E, F) . . . . . 6

6
return to couplet #5
 * Head in full-face view relatively thin (CI < 80) and antennal scapes very long (SI > 120) (Fig. 6A); in general appearance head, antennae, and legs elongate and slender (Fig. 6E) . . . . . T. setigerum group


 * Head in full-face view relatively thicker (CI > 85) and antennal scapes conspicuously much shorter (SI < 92) (Fig. 6B, C, D); in general appearance more compact species with thicker heads and shorter antennae and legs (Fig. 6F) . . . . . T. simillimum group

7
return to couplet #2
 * Petiolar node and postpetiole strongly squamiform, petiolar node with anterior and posterior faces parallel and well developed, straight dorsum; petiole and postpetiole always completely unsculptured, smooth, and shining; standing pilosity scarce or absent on dorsal mesosoma and waist segments, first gastral tergite without standing pilosity (Fig. 7A) . . . . . T. weitzeckeri group


 * Character combination never as above; petiole and postpetiole variably shaped, especially postpetiole never squamiform as above (Fig. 7B, C, D, E, 8C, D); if petiole squamiform and postpetiole weakly squamiform, then petiolar dorsum reduced and strongly tapering backwards posteriorly (Fig. 7F) . . . . . 8

8
return to couplet #7
 * Pronotum anterodorsally with distinct protuberance or bulge (Fig. 8A, B) . . . . . T. bonibony group (in part)


 * Pronotum anterodorsally without any protuberance or bulge (Fig. 8C, D) . . . . . 9

9
return to couplet #8
 * First gastral tergite with strongly appressed pubescence of varying length and without any standing hairs (Fig. 9A, B), or with short appressed to erect pilosity without any long, erect to suberect hairs (Fig. 9C) . . . . . 10


 * First gastral tergite usually with long, erect to suberect pilosity (Fig. 9D, E, F) . . . . . 17

10
return to couplet #9
 * Antennal scrobes well developed with sharply defined posterior and ventral margins (Fig. 10A, B) . . . . . T. ranarum group (in part)


 * Antennal scrobes usually weakly developed, never with well-defined posterior and ventral margins (Fig. 10C, D, E) . . . . . 11

11
return to couplet #10
 * In profile petiolar node rectangular nodiform with sharply angled anterodorsal and posterodorsal margins; both waist segments strongly sculptured (Fig. 11A, B) . . . . . 12


 * Petiolar node rectangular nodiform with conspicuously rounded anterodorsal and/or posterodorsal margins (Fig. 11C), high rounded nodiform (Fig. 11D), or squamiform and strongly anteroposteriorly compressed (Fig. 11E); waist segments usually completely unsculptured, smooth, and shining, rarely with very weak (Fig. 11D, E), superficial sculpture (Fig. 11C) . . . . . 13

12
return to couplet #11
 * Propodeum armed with short to moderately long spines (PSLI 18–25); dorsum of head and mesosoma without any standing pilosity (Fig. 12A, B) . . . . . T. ranarum group (in part)


 * Propodeum armed with very long spines (PSLI 50–53); dorsum of head and mesosoma with standing pilosity (Fig. 12C) . . . . . T. tortuosum group (in part)

13
return to couplet #12


 * Propodeum armed with long to extremely long spines, at least 2 to 3 times longer than propodeal lobes (Fig. 13.A) . . . . . T. tosii group
 * Propodeum either unarmed, armed with small triangular teeth or denticles, or armed with medium-sized spinose spines, propodeal spines at most only as long or weakly longer than propodeal lobes, more often propodeal spines distinctly shorter than propodeal lobes (Fig. 13.B, 13.C) . . . . . 14

14
return to couplet #13


 * Lateral portion of clypeus prominent, raised to a tooth or denticle in full-face view (Fig. 14.A); propodeal spines medium-sized and spinose, roughly of same length as propodeal lobes . . . . . T. sericeiventre group


 * Lateral portion of clypeus never modified as above (Fig. 14.B); propodeal spines usually strongly reduced to small triangular teeth or denticles that are shorter than propodeal lobes . . . . . T. simillimum group