Key to Tetramorium bessonii-group species

Based on Hita Garcia and 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. [[Media:Hita Garcia & Fisher 2012a.pdf|PDF ]])

1

 * Petiolar node strongly anteroposteriorly compressed, in profile squamiform, anterodorsal margin situated higher than posterodorsal, dorsum tapering backwards posteriorly and comparatively weakly developed, node in dorsal view strongly transverse (LPeI 26 - 39; DPeI 209 - 333) (Fig. 1) . . . . . 2


 * Petiolar node not strongly anteroposteriorly compressed, in profile high nodiform with well-developed dorsum and approximately parallel anterior and posterior faces, node in dorsal view wider than long but less transverse than above (LPeI 51 - 63; DPeI 133 - 165) (Fig. 2) . . . . . 4

2
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 * Cephalic dorsum between frontal carinae with just one strongly developed longitudinal median ruga that diverges at eye level into two rugae leading to posterior clypeal margin (Fig. 3) . . . . . Tetramorium artemis


 * Cephalic dorsum between frontal carinae with one strongly developed longitudinal median ruga that diverges at eye level into two rugae leading to posterior clypeal margin and two to five more irregularly developed longitudinal rugae at each side (Fig. 4) . . . . . 3

3
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 * Head always distinctly longer than wide (CI 92 - 96); first gastral tergite with comparatively long appressed to decumbent pubescence (Fig. 5) . . . . . Tetramorium bessonii


 * Head approximately as long as wide (CI 98 - 101); first gastral tergite with very short, appressed pubescence (Fig. 6) . . . . . Tetramorium wardi

4
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 * Promesonotal suture well-developed and conspicuous (Fig. 7) . . . . . Tetramorium orientale
 * Promesonotal suture not developed (Fig 8) . . . . . 5

5
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 * Antennal scapes comparatively shorter (SI 71 - 74); first gastral tergite with very short and strongly appressed pubescence, never with long, standing hairs (Fig. 9) . . . . . Tetramorium malagasy


 * Antennal scapes comparatively shorter (SI 76 - 78); first gastral tergite with comparatively long, dense appressed pubescence, and generally with several long, standing hairs (Fig. 10) . . . . . Tetramorium ryanphelanae