Key to Tetramorium tortuosum-group species

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This key is for workers from the Tetramorium tortuosum-group species of the Malagasy region. You may also be interested in the Malagasy Tetramorium species group key and the List of Malagasy Tetromorium species groups.

Based on Hita Garcia and Fisher (2012. The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region - taxonomic revision of the T. kelleri and T. tortuosum species groups. Zootaxa. 3592:1-85. PDF )

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1

  • In profile forecoxae completely covered with very distinct, strong, longitudinal rugae (T. smaug species complex) (Fig. 11) . . . . . 2
  • In profile forecoxae without very distinct, strong, longitudinal rugae; usually unsculptured, smooth and shining, but often with traces of rugulae or punctate sculpture (Figs. 12, 13) . . . . . 9
FIGURES 11–13. 11. T. sabatra (CASENT0189240) forecoxa in profile. 12. T. elf (CASENT0045788) forecoxa in profile. 13. T. andrei (CASENT0102395) forecoxa in profile.

2

return to couplet #1

  • Propodeal spines long to extremely long (PSLI 34 - 50, generally below 45); comparatively hairy species with numerous long standing hairs on the first gastral tergite (Fig. 14) . . . . . 3
  • Propodeal spines always extremely long (PSLI 48 - 72; generally above 50); less hairy species with no or few scattered, long standing hairs (Figs. 15, 16) . . . . . 7
FIGURES 14–16. 14. T. adamsi (CASENT0247296) body in profile. 15. T. sabatra (CASENT0189240) body in profile. 16. T. latreillei (CASENT0101291) body in profile.

3

return to couplet #2

  • Petiolar node with posterodorsal margin situated higher than anterodorsal, dorsum convex (Fig. 17) . . . . . Tetramorium adamsi
  • Petiolar node with anterodorsal and posterodorsal margins at about the same height, dorsum flat to weakly convex (Fig. 18) . . . . . 4
FIGURES 17 & 18. 17. T. adamsi (CASENT0247345) petiolar node in profile. 18. T. marojejy (CASENT0247334) petiolar node in profile.

4

return to couplet #3

  • Antennal scapes comparatively long (SI 89 - 92); petiolar node higher (LPeI 81 - 88); body colour dark brown to black (Figs. 19, 20) . . . . . Tetramorium nazgul
  • Antennal scapes shorter than above (SI 79 - 85); petiolar node lower (LPeI 89 - 97); body colour orange to light brown (Figs. 21, 22) . . . . . Tetramorium marojejy
FIGURES 19–22. 19. T. nazgul (CASENT0028625) head in profile. 20. T. nazgul (CASENT0028625) body in profile. 21. T. marojejy (CASENT0247334) head in profile. 22. T. marojejy (CASENT0247334) body in profile.


7

return to couplet #2

  • First gastral tergite without any standing hairs, only with moderately dense appressed pubescence (Fig. 23) . . . . . Tetramorium latreillei
  • First gastral tergite with several standing hairs and scarce pubescence (Fig. 24) . . . . . 8
FIGURES 23 & 24. 23. T. latreillei (CASENT0101291) gaster in profile. 24. T. sabatra (CASENT0189240) gaster in profile.

8

return to couplet #7

  • Leading edges of antennal scapes with appressed hairs; mesosoma with just one to two pairs of standing hairs on the pronotal dorsum (Figs. 25, 26) . . . . . Tetramorium sabatra
  • Leading edges of antennal scapes with subdecumbent to suberect hairs; mesosoma with 7 to 14 pairs of standing hairs throughout the whole mesosomal dorsum (Figs. 27, 28) . . . . . Tetramorium smaug
FIGURES 25–28. 25. T. sabatra (CASENT0048680) antennal scape in frontal view. 26. T. sabatra (CASENT0189241) mesosoma in profile. 27. T. smaug (CASENT0121244) antennal scape in frontal view. 28. T. smaug (CASENT0121244) mesosoma in profile.

9

return to couplet #1

  • First gastral tergite with either reticulate-punctate or costulate sculpture (Figs. 29, 30) . . . . . 10
  • First gastral tergite unsculptured, smooth, and shining (T. andrei species complex) (Fig. 31) . . . . . 16
FIGURES 29–31. 29. T. jedi (CASENT0046064) first gastral tergite in dorsal view. 30. T. singletonae (CASENT0247161) first gastral tergite in dorsal view. 31. T. electrum (CASENT0280850) first gastral tergite in dorsal view.

10

return to couplet #9

  • First gastral tergite with basigastral costulae (T. noeli species complex) (Fig. 32) . . . . . 11
  • First gastral tergite differently sculptured (T. jedi species complex) (Fig. 33) . . . . . 14
FIGURES 32 & 33. 32. T. singletonae (CASENT0247161) first gastral tergite in dorsal view. 33. T. jedi (CASENT0046064) first gastral tergite in dorsal view.

11

return to couplet #10

  • In profile view, petiolar node with anterodorsal and posterodorsal margins at about the same height, and the dorsum flat to weakly convex (Fig. 34) . . . . . 12
  • In profile view, petiolar node with the posterodorsal margin situated higher than the anterodorsal margin, and the dorsum convex (Fig. 35) . . . . . 13
FIGURES 34 & 35. 34. T. aherni (CASENT0045755) petiolar node in profile. 35. T. noeli (CASENT0043554) petiolar node in profile.

12

return to couplet #11

  • Eyes comparatively moderate to large (OI 22 - 24); propodeal spines comparatively long (PSLI 41 - 45) (Figs. 36, 37) . . . . . Tetramorium aherni
  • Eyes comparatively small (OI 16 - 17); propodeal spines comparatively short (PSLI 27 - 29) (Figs. 38, 39) . . . . . Tetramorium singletonae
FIGURES 36–39. 36. T. aherni (CASENT0045755) head in full-face view. 37. T. aherni (CASENT0045755) mesosoma in profile. 38. T. singletonae (CASENT0247161) head in full-face view. 39. T. singletonae (CASENT0247161) mesosoma in profile.

13

return to couplet #11

  • Head distinctly longer than wide (CI 92 - 95); propodeal spines extremely long but comparatively shorter than below (PSLI 38 - 48); postpetiole relatively higher (LPpI 68 - 72) and broader (DPpI 119 - 129) (Figs. 40, 41) . . . . . Tetramorium noeli
  • Head weakly longer than wide (CI 97 - 98); propodeal spines extremely long but comparatively longer than above (PSLI 60 - 65); postpetiole relatively lower (LPpI 77 - 81) and narrower (DPpI 104 - 112) (Figs. 42, 43) . . . . . Tetramorium ambanizana
FIGURES 40–43. 40. T. noeli (CASENT0043554) head in full-face view. 41. T. noeli (CASENT0043554) mesosoma in profile. 42. T. ambanizana (CASENT0189238) head in full-face view. 43. T. ambanizana (CASENT0189238) mesosoma in profile.

14

return to couplet #10

  • Petiolar node in dorsal view distinctly longer than wide (DPeI 79 - 85), in profile anterodorsal and posterodorsal margins at about same height; first gastral tergite completely covered with distinct reticulate-punctate sculpture (Figs. 44, 45) . . . . . Tetramorium jedi
  • Petiolar node in dorsal view distinctly wider than long (DPeI 111 - 137); in profile anterodorsal margin situated higher than posterodorsal margin and dorsum tapering backwards; first gastral tergite never completely covered with distinct reticulate-punctate sculpture, generally with superficial reticulate-punctate sculpture restricted to the basal first half of the tergite (Figs. 46, 47) . . . . . 15
FIGURES 44–47. 44. T. jedi (CASENT0046064) petiolar node in dorsal view. 45. T. jedi (CASENT0046064) petiolar node in profile. 46. T. avaratra (CASENT0445167) petiolar node in dorsal view. 47. T. avaratra (CASENT0445167) petiolar node in profile.

15

return to couplet #14

  • Propodeal spines very long (PSLI 37 - 44); petiolar node relatively lower (LPeI 63 - 73) and narrower (DPeI 111 - 118); petiolar dorsum strongly rugose (Fig. 48) . . . . . Tetramorium pleganon
  • Propodeal spines long, but shorter than above (PSLI 27 - 37, usually below 34); petiolar node relatively higher (LPeI 54 - 66) and broader (DPeI 126 - 137); petiolar dorsum weakly rugose (Fig. 49) . . . . . Tetramorium avaratra
FIGURES 48 & 49. 48. T. pleganon (CASENT0280588) mesosoma and waist segments in profile. 49. T. avaratra (CASENT0445167) mesosoma and waist segments in profile.

16

return to couplet #9

  • Posterodorsal corner of petiolar node strongly protruding posteriorly (Fig. 50) . . . . . Tetramorium andohahela
  • Posterodorsal corner of petiolar node not protruding posteriorly (Fig. 51) . . . . . 17
FIGURES 50 & 51. 50. T. andohahela (CASENT0484449) petiolar node in profile. 51. T. ala (CASENT0038473) petiolar node in profile.

17

return to couplet #16

  • Eyes very small (OI 15 - 16); propodeal spines long (PSLI 28 - 33); anterodorsal margin of petiolar node situated slightly higher than posterodorsal margin; body orange to light reddish brown in colour (Fig. 52) . . . . . Tetramorium isectum
  • Character combination never as above; if eyes small, then propodeal spines very long to extremely long (Figs. 53, 54) . . . . . 18
FIGURES 52–54. 52. T. isectum (CASENT0172829) body in profile. 53. T. electrum (CASENT0280589) body in profile. 54. T. andrei (CASENT0102395) body in profile.

18

return to couplet #17

  • Petiolar node in profile comparatively high, between 1.3 to 1.6 times higher than long (LPeI 64 - 74); propodeal lobes strongly reduced and inconspicuous (Fig. 55) . . . . . Tetramorium electrum
  • Petiolar node in profile less high than above, between 1.1 times longer than high to 1.3 times higher than long (LPeI 76 - 105); propodeal lobes variably developed, usually conspicuous (Figs. 56, 57) . . . . . 19
FIGURES 55–57. 55. T. electrum (CASENT0280850) mesosoma and petiole in profile. 56. T. elf (CASENT0045788) mesosoma and petiole in profile. 57. T. ala (CASENT0038473) mesosoma and petiole in profile.

19

return to couplet #18

  • Propodeal spines extremely long (PSLI 58 - 64) (Figs. 58, 59) . . . . . 20
  • Propodeal spines long to very long, but always significantly much shorter than above (PSLI 29 - 45) (Figs. 60, 61) . . . . . 21
FIGURES 58–61. 58. T. elf (CASENT0045788) mesosoma in profile. 59. T. isoelectrum (CASENT0152199) mesosoma in profile. 60. T. voasary (CASENT0247162) mesosoma in profile. 61. T. nify (CASENT0163155) mesosoma in profile.

20

return to couplet #19

  • Mandibles unsculptured, smooth, and shining; body colour yellow (Figs. 62, 63) . . . . . Tetramorium elf
  • Mandibles noticeably longitudinally sculptured; body colour very dark brown to black (Fig. 64, 65) . . . . . Tetramorium isoelectrum
FIGURES 62–65. 62. T. elf (CASENT0045788) head in full-face view. 63. T. elf (CASENT0045788) body in profile. 64. T. isoelectrum (CASENT0152199) head in full-face view. 65. T. isoelectrum (CASENT0152199) body in profile.

21

return to couplet #19

  • Petiolar node in dorsal view relatively long, always more than 1.3 times longer than wide (DPeI 72 - 76) (Fig. 66) . . . . . Tetramorium ala
  • Petiolar node in dorsal view relatively wider, always between 1.0 to approximately 1.2 times longer than wide (DPeI 82 - 98) (Figs. 67, 68) . . . . . 22
FIGURES 66–68. 66. T. ala (CASENT0038473) petiolar node in dorsal view. 67. T. andrei (CASENT0102395) petiolar node in dorsal view. 68. T. nify (CASENT0163155) petiolar node in dorsal view.

22

return to couplet #21

  • Eyes relatively small (OI 16 - 17); propodeal spines relatively short (PSLI 29 - 30) (Fig. 69) . . . . . Tetramorium nify
  • Eyes always much larger (OI 19 - 25); propodeal spines relatively longer (PSLI 32 - 45) (Figs. 70, 71) . . . . . 23
FIGURES 69–71. 69. T. nify (CASENT0163155) body in profile. 70. T. andrei (CASENT0102395) body in profile. 71. T. voasary (CASENT0247162) body in profile.

23

return to couplet #22

  • Petiolar node with weakly defined and fairly rounded anterodorsal and posterodorsal margins; postpetiole relatively longer, longer than wide to slightly wider than long (DPpI 95 - 101) (Fig. 72) . . . . . Tetramorium voasary
  • Petiolar node with moderately to sharply defined anterodorsal and posterodorsal margins; postpetiole relatively wider, between 1.0 to 1.4 times wider than long (DPpI 103 - 136) (Fig. 73, 74) . . . . . Tetramorium andrei
FIGURES 72–74. 72. T. voasary (CASENT0247162) petiolar node in profile. 73. T. andrei (CASENT0101821) petiolar node in profile. 74. T. andrei '(CASENT0163560) petiolar node in profile.