Key to Tetramorium dysalum-group species

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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

  • Mesosomal dorsum with fine, irregularly arranged rugulae and larger unsculptured areas (Fig. 69) . . . . . Tetramorium ambatovy
  • Mesosomal dorsum with distinct, longitudinally arranged rugae or rugulae (Fig. 70) . . . . . 2
FIGURES 69–70. 69. Mesosomal dorsum of T. ambatovy in dorsal view showing the fine, irregularly arranged rugulae - CASENT0124721 (William Ericson 2011). 70. Mesosomal dorsum of T. steinheili with distinctly longitudinally arranged rugae - CASENT0101257 (April Nobile 2006).

2

return to couplet #1

  • Species with short to moderately sized propodeal spines or teeth (PSLI 19 - 24) (Fig. 71) . . . . . 3
  • Species with long to very long propodeal spines (PSLI 27 - 44) (Fig. 72) . . . . . 5
FIGURES 71 & 72. 71. Mesosoma of T. robitika in lateral view displaying the comparatively short propodeal spines - CASENT0056338 (Estella Ortega 2011). 72. Mesosoma of T. vohitra in lateral view showing the comparatively long propodeal spines - CASENT0189167 (Estella Ortega 2011).

3

return to couplet #2

  • Petiolar node rounded high nodiform, anterodorsal and posterodorsal margins situated at approximately same height (Fig. 73) . . . . . Tetramorium robitika
  • Petiolar node shape moderately cuneiform with rounded margins, anterodorsal margin situated higher than posterodorsal and dorsum tapering backwards posteriorly (Fig. 74) . . . . . 4
FIGURES 73 & 74. 73. Rounded high nodiform petiolar node of T. robitika in profile with anterodorsal and posterodorsal margins situated at approximately same height - CASENT0056338 (Estella Ortega 2011). 74. Petiolar node of T. orc in lateral view, shape moderately cuneiform with rounded margins, and anterodorsal margin situated higher than posterodorsal and dorsum tapering backwards posteriorly - CASENT0040573 (Estella Ortega 2011).

4

return to couplet #3

  • Mandibles unsculptured, smooth and shining, and body colouration dark brown to black (Fig. 75) . . . . . Tetramorium orc
  • Mandibles longitudinally rugose, and body colouration yellow to light brown (Fig. 76) . . . . . Tetramorium mackae
FIGURES 75 & 76. 75. Body of T. orc in profile with dark brown colouration - CASENT0040573 (Estella Ortega 2011). 76. Body of T. mackae in in profile with yellow to light brown colouration - CASENT0189093 (Estella Ortega 2011).

5

return to couplet #2

  • In dorsal view postpetiole always more than 1.6 times wider than petiolar node, usually distinctly so (PPI 168 - 200) (Fig. 77) . . . . . Tetramorium mallenseana
  • In dorsal view postpetiole usually distinctly less than 1.5 times wider than petiolar node (PPI 119 - 152) (Fig. 78) . . . . . 6
FIGURES 77 & 78. 77. Waist segments of T. mallenseana in dorsal view with postpetiole much more than 1.6 times wider than petiolar node - CASENT0039659 (Estella Ortega 2011). 78. Waist segments of T. steinheili in dorsal view with postpetiole less than 1.6 times wider than petiolar node - CASENT0101257 (April Nobile 2006).

6

return to couplet #5

  • Antennal scape comparatively short (SI 64 - 69); anterodorsal margin of petiolar node sharply defined and situated much higher than posterodorsal margin, dorsum strongly tapering backwards posteriorly; mandibles always completely unsculptured (Figs. 79, 80) . . . . . Tetramorium dysalum
  • Antennal scape always longer than above (SI 71 - 78); anterodorsal margin of petiolar node not sharply defined as above, either anterodorsal and posterodorsal margins situated at same height, or posterodorsal margin weakly lower and dorsum only weakly tapering backwards posteriorly; mandibles usually with distinct longitudinal sculpture, rarely unsculptured (Figs. 81, 82) . . . . . 7
FIGURES 79–82. 79. Anterior head of T. dysalum in full-face view with with unsculptured mandibles - CASENT0192230 (Estella Ortega 2011). 80. Petiolar node of T. dysalum in lateral view with a sharply defined anterodorsal margin CASENT0037931 (Estella Ortega 2011). 81. Anterior head of T. steinheili in full-face view with sculptured mandibles - CASENT0142632 (Estella Ortega 2011). 82. Petiolar node of T. steinheili in profile, anterodorsal margin developed but not sharply defined - CASENT0142632 (Estella Ortega 2011).

7

return to couplet #6

  • Petiolar node high rounded nodiform with anterodorsal and posterodorsal margins at approximately the same height, dorsum not tapering backwards posteriorly (Fig. 83) . . . . . Tetramorium vohitra
  • Petiolar node high rounded nodiform or squamiform, but anterodorsal margin situated higher than posterodorsal margin, dorsum tapering backwards posteriorly (Fig. 84, 85) . . . . . 8
FIGURES 83–85. 83. High nodiform petiolar node of T. vohitra in profile, with anterodorsal and posterodorsal margins at approximately the same height and the dorsum not tapering backwards posteriorly - CASENT0218034 (Estella Ortega 2011). 84. High nodiform petiolar node of T. sargina in profile, with anterodorsal margin situated higher than posterodorsal margin and the dorsum tapering backwards posteriorly - CASENT0487390 (Estella Ortega 2011). 85. Squamiform petiolar node of T. steinheili in profile, with anterodorsal margin situated higher than posterodorsal margin and the dorsum tapering backwards posteriorly - CASENT0142632 (Estella Ortega 2011).

8

return to couplet #7

  • First gastral tergite with decumbent to subdecumbent long hairs (Fig. 86) . . . . . Tetramorium sargina
  • First gastral tergite with erect to suberect long hairs (Fig. 87) . . . . . 9
FIGURES 86 & 87. 86. First gastral tergite of T. sargina in profile showing the decumbent to subdecumbent long hairs - CASENT0487390 (Estella Ortega 2011). 87. First gastral tergite of T. steinheili in profile showing the erect to suberect long hairs - CASENT0481234 (Estella Ortega 2011).

9

return to couplet #8

  • Eyes comparatively small (OI 19 - 20); propodeal spines very long (PSLI 40 - 41); propodeal lobes very long and spinose; head, mesosoma, waist segments, and gaster of dark brown to black colouration (Figs. 88, 89) . . . . . Tetramorium yammer
  • Eyes larger (OI 21 - 23); propodeal spines long to very long (PSLI 27 - 44); propodeal lobes short and triangular to elongate-triangular and comparatively long, but never spinose and long as above; head, mesosoma, waist segments, and gaster generally of brownish colour, only rarely dark brown (Figs. 90, 91) . . . . . Tetramorium steinheili
FIGURES 88–91. 88. Head of T. yammer in full-face view with comparatively smaller eyes - CASENT0499759 (Estella Ortega 2011). 89. Body of T. yammer in profile showing very dark brown to black colouration - CASENT0499759 (Estella Ortega 2011). 90. Head of T. steinheili in full-face view with comparatively larger eyes - CASENT0024633 (Estella Ortega 2011). 91. Body of T. steinheili in profile showing reddish, light brown to moderately brown colouration - CASENT0101258 (April Nobile 2006).