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. 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

FIGURE 1 & 2. 1. Waist segments of T. artemis in profile showing the strongly anteroposteriorly compressed and squamiform petiolar node, which tapers distinctly backwards posteriorly - CASENT0481732 (Erin Prado 2010). 2. Waist segments of T. malagasy in profile showing the high rounded nodiform petiolar node with anterodorsal and posterodorsal margins at about the same height - CASENT0449550 (Erin Prado 2010).

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

FIGURES 3 & 4. 3. Head of T. artemis in full-face view with one strongly developed median ruga between the frontal carinae - CASENT0481732 (Erin Prado 2010). 4. Head of T. bessonii in full-face view with strongly developed longitudinal median ruga and two to five more irregularly developed longitudinal rugae at each side - CASENT0247550 (Estella Ortega 2012).

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

FIGURES 5 & 6. 5. Head of T. bessonii in full-face view, head shape distinctly longer than wide - CASENT0101298 (April Nobile 2006). 6. Head of T. wardi in full-face view, head shape approximately as long as wide - CASENT0475483 (Erin Prado 2010).

4

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• Promesonotal suture well-developed and conspicuous (Fig. 7) . . . . . Tetramorium orientale

• Promesonotal suture not developed (Fig 8) . . . . . 5

FIGURES 7 & 8. 7. Mesosoma of T. orientale in dorsal view showing the well-developed and conspicuous promesonotal suture - CASENT0101744 (April Nobile 2006). 8. Mesosoma of T. malagasy in dorsal view without a promesonotal suture - CASENT0449550 (Erin Prado 2010).

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

FIGURES 9 & 10. 9. Gaster of T. malagasy in lateral view with only very short and strongly appressed pubescence on the first gastral tergite - CASENT0449550 (Erin Prado 2010). 10. Gaster of T. ryanphelanae in lateral view, first gastral tergite with comparatively long, dense appressed pubescence, and generally with several long, standing hairs - CASENT0454495 (Erin Prado 2010).