Key to Malagasy Leptogenys

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This key to workers will also work for the known ergatoid queens. Key based on: Rakotonirina, J.C. & Fisher, B.L. 2014. Revision of the Malagasy ponerine ants of the genus Leptogenys Roger (Hymenoptera: Formicidae). Zootaxa 3836, 1-163. doi:10.11646/zootaxa.3836.1.1

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1

  • In full-face view, mandible either subtriangular (Fig. 1A) or elongate (Fig. 1B, 1C) but capable of closing tightly against the anterior margin of clypeus without a gap between them . . . . . 2
  • In full-face view, mandible elongate and narrow, not capable of closing tightly against the clypeus; the apices slightly crossing each other and leaving a large gap between themselves and the clypeus when closed (Fig. 1D) . . . . . 40
FIGURE 1. Head in full-face view showing shapes of mandibles and their tightness against clypeus when fully closed. A: Leptogenys edsoni. B: Leptogenys lohahela. C: Leptogenys alatapia. D: Leptogenys voeltzkowi.

2

return to couplet #1

  • With abdominal segment 3 (first gastral segment) in profile, prora generally globular and voluminous, directed anteroventrally; prora and the rounded anteroventral angle of third abdominal sternite usually separated by large indentation (Fig. 2A, 3D) . . . . . 3
  • With abdominal segment 3 (first gastral segment) in profile, prora flattened, small and directed ventrally in a vertical line; prora and anteroventral angle of third abdominal sternite not separated by large indentation, prora directly at anteroventral angle of third abdominal sternite (Fig. 2B, 2C) . . . . . 6
FIGURE 2. Anterior margin of third abdominal segment in profile. A: Leptogenys bezanozano. B: Leptogenys ralipra. C: Leptogenys coerulescens.

3

return to couplet #2

  • In full-face view head short (CI: 78–82) (Fig. 3A); in lateral view, petiolar node noticeably higher than long; prora immediately at anteroventral angle of third abdominal sternite (Fig. 3B) . . . . . Leptogenys avaratra
  • In full-face view, head more elongate (CI: 69–75) (Fig. 3C); in lateral view, petiolar node approximately as high as long; prora separated from the rounded anteroventral angle of third abdominal sternite (Fig. 3D) . . . . . 4
FIGURE 3. Form of head in full-face view, shape of petiolar node and location of prora in profile. A & B: Leptogenys avaratra. C & D: Leptogenys toeraniva.

4

return to couplet #3

  • Antennal scape with erect hairs whose length is equal to the maximum width of the scape (Fig. 4A); propodeal declivity mostly smooth; in profile, dorsal face of petiolar node sloping posteriorly (Fig. 4B) . . . . . Leptogenys bezanozano
  • Antennal scape with erect hairs whose length is shorter than the maximum width of the scape (Fig. 4C); propodeal declivity transversely striate; in profile, dorsal face of petiolar node horizontal, not sloping (Fig. 4D) . . . . . 5
FIGURE 4. Head in full-face view indicating length of hairs on antennal scape and shape of petiole in profile. A & B: Leptogenys bezanozano. C & D: Leptogenys toeraniva.

5

return to couplet #4

  • In full-face view, eye maximum diameter greater than the maximum width of antennal scape; dorsum of head coarsely sculptured, reticulate-rugulose to reticulate-punctate anteriorly and sparsely punctate posteriorly (Fig. 5A) . . . . . Leptogenys avo
FIGURE 5. Head in full-face view presenting size of eye and sculpture of head capsule. A: Leptogenys avo. B: Leptogenys toeraniva.
  • In full-face view, eye maximum diameter much less than the maximum width of antennal scape; dorsum of head mostly with scattered punctures, which become sparser posteriorly (Fig. 5B) . . . . . Leptogenys toeraniva

6

return to couplet #2

  • In full-face view, greatest width of eye roughly equal to or less than the greatest width of antennal scape (Fig. 6A); smaller species (HW: 0.60–0.83, PW: 0.59–0.70) . . . . . 7
  • In full-face view, greatest width of eye markedly greater than the maximum width of antennal scape (Fig. 6B); generally larger species (HW: 0.75–1.92, PW: 0.60–1.62) . . . . . 10
FIGURE 6. Head in full-face view indicating the size of eye. A: Leptogenys anjara. B: Leptogenys grandidieri.

7

return to couplet #6

  • Masticatory margin of mandible with three teeth, a median tooth between the sharp apical tooth and the blunt basal angle; in profile, subpetiolar process simple with only an anteroventral triangular lobe or blunt tooth, posterior lobe absent (Fig. 7A) . . . . . Leptogenys alamando
  • Masticatory margin of mandible with two teeth, a sharp apical tooth or lamella and a small, very short, preapical one or a blunt angle; in profile, subpetiolar process double, consisting of an anteroventral lobe or tubercle followed posteriorly by a thin cuticular extension or a lobe in the middle of the ventral margin (Fig. 7B, 7C) . . . . . 8
FIGURE 7. Petiolar node in profile, showing variation in subpetiolar process. A: Leptogenys alamando. B: Leptogenys fiandry. C: Leptogenys anjara.

8

return to couplet #7

  • Mandibles longitudinally striate; piligerous punctures larger and more closely spaced on dorsum of head (Fig. 8A) and the rest of body; hairs on the dorsum of body abundant, short and subdecumbent or appressed . . . . . Leptogenys rabesoni
  • Mandibles smooth and shiny, with sparse piligerous punctures; dorsum of head and rest of body generally smooth (Fig. 8B) or with scattered small punctures; hairs on dorsum of the body somewhat long and erect to suberect . . . . . 9
FIGURE 8. Head in full-face view showing sculpture of the dorsum and mandibles. A: Leptogenys rabesoni. B: Leptogenys anjara.

9

return to couplet #8

  • In profile, petiolar node roughly as long as high (LNI: 90–106); in lateral view, posterolateral border of propodeum with a distinct toothlike lobe (Fig. 9A) . . . . . Leptogenys fiandry
  • In profile, petiolar node distinctly longer than high (LNI: 88); in lateral view, propodeal lobe indistinct (Fig. 9B) . . . . . Leptogenys anjara
FIGURE 9. Mesosoma and petiole in profile. A: Leptogenys fiandry. B: Leptogenys anjara.

10

return to couplet #6

  • Distance between anterior margin of torulus and anteromedian margin of clypeus distinctly less than the distance between outer margin of torulus and outer margins of base of mandibles; mandibles elongate and narrow, strongly crossing each other or superimposed when fully closed against the anterior margin of clypeus; anterior clypeal margin widely transverse, broadly rounded or convex, dorsoventrally thick and with white yellowish lamella (Fig. 10A) . . . . . 11
  • Distance between anterior margin of torulus and anteromedian margin of clypeus equal to or greater than the distance between outer margin of torulus and outer margins of base of mandibles; mandibles short and robust, subtriangular or with convex inner margin, not strongly crossing each other, the apices meeting or slightly overlapping when fully closed against anterior margin of clypeus; anterior clypeal margin medially projecting into a triangular lobe, dorsoventrally thin, with sharp edge or subopaque lamella (Fig. 10B) . . . . . 19
FIGURE 10. Head in full-face view showing shape of mandibles and comparing distance between anterior level of torulus and anteromedian margin of clypeus with distance between outer margin of torulus and outer margins of base of mandibles. A: Leptogenys ridens. B: Leptogenys mangabe.

11

return to couplet #10

  • Clypeus without median longitudinal carina; in full-face view, distal half of mandible distinctly broadened, the inner margin of which gradually becomes narrower and broadly arched toward the sharp apical tooth; distal half of blades lacking piligerous punctures (Fig. 11A); in profile, mandible curved dorsally, with midpoint distinctly dorsal of mandible insertion . . . . . 12
  • Clypeus with median longitudinal carina; in full-face view, distal half of blades not clearly broadened, the inner margin continuously broadly concave from base to near the apical tooth; distal half of mandible with sparse piligerous punctures (Fig. 11B); in profile, mandible projecting anteriorly from base, with midpoint of mandible more or less at same level as mandible insertion . . . . . 13
FIGURE 11. Full-face view of head showing the presence of median carina on clypeus and the shape of mandibles. A: Leptogenys truncatirostris. B: Leptogenys arcirostris.

12

return to couplet #11

  • In full-face view, anterior margin of clypeus broadly rounded, the lateral portion rounding to the anterior margin; mandible clearly broadened and flattened at about mid-length, with longitudinal and fine striation, and evenly curved into a sharp apical tooth (Fig. 12A); in profile, third abdominal segment microreticulate (coriaceous) with scattered punctures; dorsum of mesosoma, petiolar node, and gaster without pubescence . . . . . Leptogenys diana
  • In full-face view, anterior margin of clypeus transverse and wide, the junction of lateral portion to the anterior margin angulate; apical half of mandible not very broadly flattened, effaced fine striation may be present (Fig. 12B); in profile, third abdominal segment densely punctulate, dorsum of mesosoma, petiolar node and gaster with abundant pubescence . . . . . Leptogenys truncatirostris
FIGURE 12. Anterior margin of clypeus in full-face view. A: Leptogenys diana. B: Leptogenys truncatirostris.

13

return to couplet #11

  • In full-face view, clypeus distinctly broadly rounded; distance between anterior margin of torulus and anteromedian margin of clypeus approximately equal to or less than maximum diameter of antennal scape; mandible blades generally following the rounded shape of anterior clypeal margin when tightly closed against the latter (Fig. 13A) . . . . . 14
  • In full-face view, clypeus not distinctly broadly rounded; distance between anterior margin of torulus and anteromedian margin of clypeus (including the white yellowish lamella) greater than the maximum diameter of antennal scape; mandible not following the shape of anterior clypeal margin when tightly closed (Fig. 13B) . . . . . 16
FIGURE 13. Head in full-face view showing shape of clypeus and its length relative to width of antennal scape. A: Leptogenys borivava. B: Leptogenys fotsivava.

14

return to couplet #13

  • In full-face view, head clearly broader than long (CI: 105–109) (Fig. 14A) . . . . . Leptogenys alatapia
  • In full-face view, head about as long as broad or longer than broad (CI: 82–97) (Fig. 14B) . . . . . 15
FIGURE 14. Shape of head in full-face view. A: Leptogenys alatapia. B: Leptogenys arcirostris.

15

return to couplet #14

  • Dorsum of head, mesosoma, petiole, and gaster covered with conspicuous pubescence but with few suberect short hairs (Fig. 15A); antennal scape relatively short (SI: 103–112); larger species (HW: 1.18–1.38, HL: 1.27–1.43, WL: 2.08–2.32) . . . . . Leptogenys arcirostris
  • Dorsum of head, mesosoma, petiole, and gaster with reduced pubescence, and covered with long standing erect and suberect hairs (Fig. 15B); antennal scape relatively long (SI: 111–129); smaller species (HW: 0.97–1.01, HL: 1.05–1.10, WL: 1.77–1.87) . . . . . Leptogenys borivava
FIGURE 15. Mesosoma and petiole in lateral view. A: Leptogenys arcirostris. B: Leptogenys borivava.

16

return to couplet #13

  • Antennal scape longer (SL: 1.67–1.99, SI: 122–129); eye maximum diameter twice as large as maximum width of antennal scape (Fig. 16A) . . . . . Leptogenys ridens
  • Antennal scape shorter (SL: 1.15–1.66, SI: 111–120); eye maximum diameter less than twice maximum scape width (Fig. 16B. . . . . 17
FIGURE 16. Head in full-face view showing length of antennal scape and size of eye. A: Leptogenys ridens. B: Leptogenys namoroka.

17

return to couplet #16

  • In full-face view, eye maximum diameter between one third and one fourth of the length of side of the head; in the same view eye extending beyond lateral border of the head (Fig. 17A) . . . . . Leptogenys fotsivava
  • In full-face view, eye maximum diameter roughly one fifth of the length of sides of the head; in the same view, eye not extending beyond lateral border of the head (Fig. 17B) . . . . . 18
FIGURE 17. Size and location of eye relative to lateral border of head in full-face view. A: Leptogenys fotsivava. B: Leptogenys tsingy.

18

return to couplet #17

  • In dorsal view, petiolar node broader than long (DNI: 134–146); dorsum of mesosoma, petiolar node and gaster with abundant short suberect hairs and reduced amount of pubescence; sculpture of these sclerites much coarser (Fig. 18A); head subquadrate; smaller species (HW: 1.20–1.34, HL: 1.42–1.56, WL: 2.17–2.39) . . . . . Leptogenys tsingy
  • In dorsal view, petiolar node approximately as broad as long (DNI: 115); dorsum of mesosoma, petiolar node and gaster with few short suberect hairs and dense pubescence; sculpture of these sclerites denser and finer (Fig. 18B); head distinctly broader anteriorly; larger species (HW: 1.38, HL: 1.58, WL: 2.47) . . . . . Leptogenys namoroka
FIGURE 18. Petiolar node and third abdominal tergite in dorsal view. A: Leptogenys tsingy. B: Leptogenys namoroka.

19

return to couplet #10

  • Dorsum of head and mesosoma smooth apart from small piligerous punctures (Fig. 19A) . . . . . 20
  • Sculpture on dorsum of head and pronotum variable, densely reticulate-rugulose, densely reticulate-punctulate, densely punctate to scattered punctures (Fig. 19B, 19C) . . . . . 32
FIGURE 19. Sculpture of head and mesosoma in dorsal view. A: Leptogenys variabilis. B: Leptogenys ralipra. C: Leptogenys oswaldi.

20

return to couplet #19

  • Third antennal segment at least twice as long as the second segment (Fig. 20A); in dorsal view, petiolar node elongate (DNI≤ 52), strongly narrowed anteriorly (Fig. 20B) . . . . . 21
  • Third antennal segment less than twice as long as the second segment (Fig. 20C); in dorsal view, petiolar node subrectangular (DNI≥ 61), only weakly narrowed anteriorly (Fig. 20D) . . . . . 23
FIGURE 20. Length of third antennal segment and anterior portion of petiolar node in dorsal view. A: Leptogenys johary. B: Leptogenys angusta. C: Leptogenys edsoni. D: Leptogenys mangabe.

21

return to couplet #20

  • Third antennal segment twice as long as the second; in dorsal view mesonotum broader than long (Fig. 21A); smaller species (HL: 1.38–1.48) . . . . . Leptogenys johary
  • Third antennal segment more than twice as long as the second; in dorsal view mesonotum as long as broad (Fig. 21B); larger species (HL≥ 1.77) . . . . . 22
FIGURE 21. Mesosoma in dorsal view. A: Leptogenys johary. B: Leptogenys angusta.

22

return to couplet #21

  • Maximum diameter of eye less than twice the maximum width of antennal scape (Fig. 22A); leg and antenna very long (SI: 263); body light reddish brown . . . . . Leptogenys zohy
  • Maximum diameter of eye two or more times the maximum width of antennal scape (Fig. 22B); leg and antennna shorter (SI: 163–203); body color dark brown to reddish brown . . . . . Leptogenys angusta
FIGURE 22. Head in full-face view showing size of eye relative to width of antennal scape. A: Leptogenys zohy. B: Leptogenys angusta.

23

return to couplet #20

  • In full-face view, eye not breaking the outline of the side of the head (Fig. 23A) . . . . . 24
  • In full-face view, eye breaking the outline of the side of the head (Fig. 23B) . . . . . 26
FIGURE 23. Location of eye when head in full-face view. A: Leptogenys malama. B: Leptogenys variabilis.

24

return to couplet #23

  • Mandible punctulate, with fine and short longitudinal striation or dense and fine elongate punctures (Fig. 24A); standing hairs present on propodeal dorsum; with petiole in profile, the anterodorsal angle without an impression; larger species (HW: 1.52–1.74, PW: 1.23–1.46); black in color with bluish reflection or opalescence . . . . . Leptogenys coerulescens
  • Mandible smooth and shining between sparse punctures (Fig. 24B); standing hairs either absent on propodeal dorsum, or present but very short and reduced in number; with petiole in profile, often with an impression immediately posterior to the anterodorsal angle; smaller species (HW: 0.96–0.98, PW: 0.80–0.83); color black without bluish reflection or opalescence . . . . . 25
FIGURE 24. Sculpture of mandible. A: Leptogenys coerulescens. B: Leptogenys malama.

25

return to couplet #24

  • Mesopleural sulcus narrow and smooth, oriented to the level of posterodorsal corner of pronotum; antennae and legs basally black to dark brown, antennal apical portion and tarsi brown (Fig. 25A); larger species (HL: 1.48–1.84, WL: 2.29–2.90) . . . . . Leptogenys malama
  • Mesopleural sulcus broad and shallow, transversely sculptured, oriented to the level of posteroventral corner of pronotum; antennae and legs brown to light brown towards apical portion (Fig. 25B); smaller species (HL: 1.32–1.43, WL: 2.09–2.25) . . . . . Leptogenys lucida
FIGURE 25. Mesosoma in profile. A: Leptogenys malama. B: Leptogenys lucida.

26

return to couplet #23

  • Mandible sculptured, longitudinally striate at least from near the base to the point of preapical tooth insertion, and then microreticulate or smooth with sparse piligerous punctures; in lateral view, posterodorsal corner of petiolar node protruding posteriorly and overhanging posterior face (Fig. 26A) . . . . . 27
  • Mandible smooth and shining between scattered piligerous punctures; in lateral view, dorsal and posterior faces of petiolar node meeting at right angle, not projecting posteriorly nor overhanging the posterior face of the node (Fig. 26B) . . . . . 28
FIGURE 26. Petiole in lateral view. A: Leptogenys grandidieri. B: Leptogenys variabilis.

27

return to couplet #26

  • In profile, metapleuron finely rugulose (Fig. 27A); sometimes dorsal and posterior portions of mesopleuron finely rugulose or with superficial rugulae . . . . . Leptogenys grandidieri
  • In profile, metapleuron generally smooth and shiny, mesopleuron smooth or with scattered punctures (Fig. 27B) . . . . . Leptogenys manongarivo
FIGURE 27. Mesosoma in profile showing sculpture of metapleuron. A: Leptogenys grandidieri. B: Leptogenys manongarivo.

28

return to couplet #26

  • In profile, portions of each side of mesometapleural suture, metapleuron, and the suture between propodeum and metapleuron finely rugose (Fig. 28A) . . . . . 29
  • In profile, each side of mesometapleural suture, metapleuron, and the suture between propodeum and metapleuron generally smooth (Fig. 28B) . . . . . 30
FIGURE 28. Mesosoma in profile showing sculpture of mesopleuron and metapleuron. A: Leptogenys edsoni. B: Leptogenys fasika.

29

return to couplet #28

  • Mandibles covered with fine microreticulation and sparse piligerous punctures; median lobe of clypeus longitudinally striate (Fig. 29A) (Comoros, Mayotte) . . . . . Leptogenys comajojo
  • Mandibles smooth and shining between scattered piligerous punctulae; median lobe of clypeus mostly smooth and not markedly striate (Fig. 29B) . . . . . Leptogenys edsoni
FIGURE 29. Head in full-face view showing sculpture of mandible and median lobe of clypeus. A: Leptogenys comajojo. B: Leptogenys edsoni.

30

return to couplet #28

  • In dorsal view, petiole elongate, node roughly twice as long as wide (DNI: 61–67) (Fig. 30A) . . . . . Leptogenys mangabe
  • In dorsal view, petiolar node broader, less than twice as long as wide (Fig. 30B, 30C) . . . . . 31
FIGURE 30. Length of petiolar node in dorsal view. A: Leptogenys mangabe. B: Leptogenys variabilis. C: Leptogenys fasika.

31

return to couplet #30

  • In dorsal view, petiole robust (DNI: 83–89), width decreasing gradually from back to front, but anterior portion of node not notably compressed laterally (Fig. 30C); in lateral view, the node approximately as long as high (LNI 100–106), anterior sharp rim separate from the anterior face of node (Fig. 31A); dorsum of body with whitish hairs; larger in size (HW: 1.20–1.31, PW: 0.98–1.11) . . . . . Leptogenys fasika
  • In dorsal view, petiolar node more elongate (DNI: 67–86), anterior portion markedly narrower and distinctly compressed laterally (Fig. 30B); in lateral view, the node longer than high (LNI: 91–105), anterior rim attached directly to anterior face of node (Fig. 31B); dorsum of body with yellowish brown hairs; generally smaller in size (HW: 0.75–1.08, PW: 0.60–0.91) . . . . . Leptogenys variabilis
FIGURE 31. Lateral view of petiolar node. A: Leptogenys fasika. B: Leptogenys variabilis.

32

return to couplet #19

  • Mandible subtriangular, inner margin at about mid-length with a distinct basal angle (Fig. 32A); in profile, posterolateral margin of petiolar node without denticle or blunt angle, dorsum of pronotum either finely reticulate-rugulose or transversely finely striate-rugulose . . . . . 33
  • Mandible subfalcate, inner margin without a basal angle at mid-length (Fig. 32B); in profile, posterolateral margin of petiolar node with small tooth, denticle or blunt angle; dorsum of pronotum densely punctate or foveate to sparsely punctate, sometimes superimposed with fine transverse rugulae . . . . . 34
FIGURE 32. Cephalic full-face view comparing shapes of mandible. A: Leptogenys mayotte. B: Leptogenys saussurei.

33

return to couplet #32

  • In full-face view, eye breaking the outline of the side of the head (Fig. 33A); dorsum of head and promesonotum reticulate-rugulose; in full-face view, masticatory margin of mandible much shorter than basal margin . . . . . Leptogenys oswaldi
  • In full-face view, eye not breaking the outline of the side of the head (Fig. 33B); head capsule reticulate-punctulate, promesonotal dorsum transversely striate, with scattered small punctures; in full-face view, masticatory margin of mandible about equal in length to basal margin . . . . . Leptogenys mayotte
FIGURE 33. Eye location and sculpture of head in full-face view. A: Leptogenys oswaldi. B: Leptogenys mayotte.

34

return to couplet #32

  • With mesosoma in dorsal view, metanotal groove distinctly visible (Fig. 34A) . . . . . 35
  • With mesosoma in dorsal view, metanotal groove indistinct (Fig. 34B) . . . . . 37
FIGURE 34. Mesosoma in dorsal view. A: Leptogenys lohahela. B: Leptogenys vatovavy.

35

return to couplet #34

  • In dorsal view, posterior margin of petiolar node medially emarginated (Fig. 35A) . . . . . Leptogenys saussurei
  • In dorsal view, posterior margin of petiolar node straight, not medially emarginated (Fig. 35B) . . . . . 36
FIGURE 35. Shape of posterior margin of petiolar node in dorsal view. A: Leptogenys saussurei. B: Leptogenys acutirostris.

36

return to couplet #35

  • Smaller species (HW 1.49–1.73, HL 2.02–2.29); in profile posterolateral margin of petiolar node with a small sharp tooth (Fig. 36A) . . . . . Leptogenys lohahela
  • Larger species (HW 1.79–1.92, HL 2.61–2.85); in profile posterolateral margin of petiolar node with a blunt lobe or angle, not a small sharp tooth (Fig. 36B) . . . . . Leptogenys acutirostris
FIGURE 36. Petiolar node in lateral view showing the shape of posterolateral margin. A: Leptogenys lohahela. B: Leptogenys acutirostris.

37

return to couplet #34

  • In dorsal view, posterior margin of petiolar node straight, not medially excised (Fig. 37A) . . . . . Leptogenys ambo
  • In dorsal view, posterior margin of petiolar node noticeably medially excised (Fig. 37B) . . . . . 38
FIGURE 37. Shape of posterior margin of petiolar node in dorsal view. A: Leptogenys ambo. B: Leptogenys andritantely.

38

return to couplet #37

  • Apical margin of mandible clearly with three teeth, the apical and two preapical teeth (Fig. 38A) . . . . . Leptogenys vatovavy
  • Apical margin of mandible with two teeth, one preapical and one apical tooth (Fig. 38B) . . . . . 39
FIGURE 38. Number of teeth on apical portion of mandible. A: Leptogenys vatovavy. B: Leptogenys ralipra.

39

return to couplet #38

  • Mandible longitudinally striate; head longitudinally rugulose, dorsum of pronotum and mesonotum densely punctate superimposed with transverse rugulae; larger species (HW: 1.77, HL: 2.29, PW: 1.45); anteromedian clypeal margin broadly angulate (Fig. 39A) . . . . . Leptogenys andritantely
  • Mandible smooth and shiny between scattered punctures; head densely punctulate to punctate; dorsum of pronotum and mesonotum punctate; smaller species (HW: 0.98–1.04, HL: 1.34–1.44, PW: 0.86–0.94); anteromedian clypeal margin bidentate (Fig. 39B) . . . . . Leptogenys ralipra
FIGURE 39. Mandibular and cephalic sculptures in full-face view, and shape of anteromedial clypeal margin. A: Leptogenys andritantely. B: Leptogenys ralipra.

40

return to couplet #1

  • In full-face view, eye diameter usually less than the greatest width of antennal scape; mandible short and more or less straight (Fig. 40A) . . . . . Leptogenys rabebe
  • In full-face view, eye diameter markedly greater than the maximum width of antennal scape; mandible long and narrow, more arched from the base to the apex (Fig. 40B) . . . . . 41
FIGURE 40. Shape of mandible and eye size relative to width of antennal scape. A: Leptogenys rabebe. B: Leptogenys manja.

41

return to couplet #40

  • Dorsum of head, mesosoma, petiolar node, and the first two gastral segments without standing hairs, but strongly shagreened and covered with dense pruinose pubescence (Fig. 41A) . . . . . 42
  • Dorsum of at least some parts of the body covered with standing hairs, not shagreened nor densely covered with pubescence (Fig. 41B) . . . . . 44
FIGURE 41. Lateral view of ant body. A: Leptogenys falcigera. B: Leptogenys gracilis.

42

return to couplet #41

  • In full-face view, translucent lamella on anterior clypeal margin broad, rounded (Fig. 42A) . . . . . Leptogenys pavesii
  • In full-face view, translucent lamella on anterior clypeal margin narrow, obtusely angulate (Fig. 42B) . . . . . 43
FIGURE 42. Full-face view of head showing shape of translucent lamella surrounding anterior clypeal margin. A: Leptogenys pavesii. B: Leptogenys maxillosa.

43

return to couplet #42

  • In dorsal view, petiolar node distinctly broader than long (DNI: 113–133) (Fig. 43A) . . . . . Leptogenys maxillosa
  • In dorsal view, petiolar node most often clearly longer than broad, at least as long as broad (DNI: 93–109) (Fig. 43B) . . . . . Leptogenys falcigera
FIGURE 43. Form of petiolar node in dorsal view. A: Leptogenys maxillosa. B: Leptogenys falcigera.

44

return to couplet #41

  • Third antennal segment approximately twice as long as the second; dorsum of head smooth apart from scattered punctures (Fig. 44A); pronotum weakly sculptured dorsally; constriction between third and fourth abdominal segments indistinct . . . . . Leptogenys stuhlmanni
  • Third antennal segment less than twice as long as the second; dorsum of head and mesosoma very strongly sculptured (Fig. 44B); constriction between third and fourth abdominal segments noticeably distinct . . . . . 45
FIGURE 44. Length of third antennal segment relative to the second and sculpture of head dorsum. A: Leptogenys stuhlmanni. B: Leptogenys imerinensis.

45

return to couplet #44

  • Anteromedian lobe of clypeus without anteriorly projecting peg-like setae near its margin above the lamella (Fig. 45A); larger species (HW: 1.87–2.49, PW: 1.37–1.47) . . . . . 46
  • Anteromedian lobe of clypeus with two, three or more anteriorly projecting peg-like setae near its margin above the lamella (Fig. 45B); smaller species (HW: 1.08–1.73, PW: 0.82–1.22) . . . . . 48
Editing File:Rakotonirina and Fisher 2014 Fig. 45.jpg

46

return to couplet #45

  • In full-face view, eye not breaking lateral margin of the head; median portion of clypeus projecting anteriorly into a narrowly angulate lobe; lamella confined to this narrowly shaped anteromedian lobe (Fig. 46A) . . . . . Leptogenys alluaudi
  • In full-face view, eye breaking lateral margin of the head; anterior clypeal margin broadly triangular, with the surrounding lamella extending to the lateral portion of clypeus (Fig. 46B) . . . . . 47
FIGURE 46. Full-face view of head indicating location of eyes and the extent of lamella covering anterior clypeal margin. A: Leptogenys alluaudi. B: Leptogenys pilaka.

47

return to couplet #46

  • Head more elongate (CI: 85), mandible broader, strongly curved near the base, entire surface of the blade with dense and fine longitudinal striations (Fig. 47A) . . . . . Leptogenys incisa
  • Head broader (CI: 94–97), mandible narrower, not strongly curved near the base, with smooth and shiny blade apart from sparse piligerous punctures; fine striation apparently effaced (Fig. 47B) . . . . . Leptogenys pilaka
FIGURE 47. Shape of head and sculpture of mandible in full-face view. A: Leptogenys incisa. B: Leptogenys pilaka.

48

return to couplet #45

  • Anterior clypeal margin a broad angle with blunt apex or generally convex; with the bordering translucent lamella, if present, extending to the lateral portion of the clypeus, not confined to the anteromedian lobe (Fig. 48A) . . . . . 49
  • Anterior clypeal margin not a broad angle, but rather consisting medially of a narrowly rounded (Fig. 48B) or triangular (Fig. 48C) lobe, or spine; and, if present, lamella confined to this anteromedian lobe . . . . . 55
FIGURE 48. Head in full-face view showing shape of anterior clypeal margin and area covered by translucent lamella. A: Leptogenys manja. B: Leptogenys vitsy. C: Leptogenys chrislaini.

49

return to couplet #48

  • Antennal scape relatively long (SI ≥130), more than its apical third extending beyond posterior margin of the head (Fig. 49A) . . . . . 50
  • Antennal scape relatively short (SI≤ 123), less than its apical third extending beyond posterior margin of the head (Fig. 49B) . . . . . 52
FIGURE 49. Length of antennal scape in full-face view. A: Leptogenys tatsimo. B: Leptogenys namana.

50

return to couplet #49

  • Mandibles finely longitudinally striate, with piligerous pits; with head in full-face view, the convex inner margin of mandible with distinct broad convexity approximately at apical third portion of the blade (Fig. 50A) . . . . . Leptogenys antongilensis
  • At least the basal half of mandibles mostly smooth and shining with scattered piligerous pits; with head in full-face view, the inner margin of mandible evenly concave (Fig. 50B) or slightly convex (Fig. 51A) along their length . . . . . 51
FIGURE 50. Shape of inner margin of mandible in full-face view. A: Leptogenys antongilensis. B: Leptogenys manja.

51

return to couplet #50

  • In full-face view, fringing lamella of the clypeus broad, width roughly the same as the minimum diameter of antennal scape; mandibles strongly curved near the base and blades much broader, the inner margins weakly convex (Fig. 51A); in dorsal view, mesosoma apparently with four distinct segments (Fig. 52A) . . . . . Leptogenys tatsimo
  • In full-face view, fringing lamella of the clypeus narrow, the width less than the minimum diameter of antennal scape; mandible not strongly curved near the base and blades narrower, the inner margins concave along their length (Fig. 51B); in dorsal view, mesosoma with three visible segments (Fig. 52B) . . . . . Leptogenys manja
FIGURE 51. Width of lamella fringing anterior clypeal margin and shape of mandible in full-face view. A: Leptogenys tatsimo. B: Leptogenys manja.

52

return to couplet #49

  • In dorsal view, mesosoma seemingly with four visible segments, an additional protruding small sclerite (a partially differentiated metanotum) distinctly visible within the metanotal groove (Fig. 52A) . . . . . 53
  • In dorsal view, mesosoma consists of three visible segments, with no additional discernible segment in the metanotal groove (Fig. 52B) . . . . . 54
FIGURE 52. Mesosoma in dorsal view showing the number of segments. A: Leptogenys suarensis. B: Leptogenys namana.

53

return to couplet #52

  • In full-face view, three to four anteriorly projecting, peg-like setae present near margin of anteromedial lobe of clypeus, above the translucent lamella; fringing lamella usually broadly rounded; mandibles mostly smooth and shiny between sparse piligerous punctures (Fig. 53A) . . . . . Leptogenys suarensis
  • In full face-view, only two anteriorly projecting peg-like setae present near margin of anteromedial clypeal portion, above the translucent lamella; translucent lamella narrowly triangular; mandibles striate at least along apical half, interspersed with punctures (Fig. 53B) . . . . . Leptogenys gracilis
FIGURE 53. Head in full-face view showing number of anteriorly projecting peg-like setae and shape of fringing lamella on anteromedian margin of clypeus A: Leptogenys suarensis. B: Leptogenys gracilis.

54

return to couplet #52

  • Median clypeal carina sharp; with head in full-face view, hypostomal teeth visible (Fig. 54A); smaller species (HW: 1.10–1.25, WL: 2.25–2.64) . . . . . Leptogenys namana
  • Median clypeal carina blunt; with head in full-face view, hypostomal teeth not visible (Fig. 54B); larger species (HW: 1.51–1.55, WL: 2.92–3.10) . . . . . Leptogenys imerinensis
FIGURE 54. Full-face view of head showing median clypeal carina and hypostomal teeth. A: Leptogenys namana. B: Leptogenys imerinensis.

55

return to couplet #48

  • Median portion of clypeus projecting anteriorly into a short, narrowly rounded lobe; antennal scape lacking erect hairs, or if present, the length less than greatest width of scape (Fig. 55A); with petiole in profile, posterior margin of node with constriction at the posteroventral angle near the junction to gaster . . . . . 56
  • Median portion of clypeus projecting anteriorly into a narrowly angulate lobe or spine; antennal scape with erect hairs whose length is as great as or greater than maximum width of scape (Fig. 55B); with petiole in profile, posterior margin of node without constriction at the posteroventral angle . . . . . 58
FIGURE 55. Shape of anteromedian lobe of clypeus in full-face view and hairs on antennal scape. A: Leptogenys voeltzkowi. B: Leptogenys barimaso.

56

return to couplet #55

  • In full-face view, eye not breaking the outline of side of the head; larger species (HW: 1.30–1.59, WL: 2.26–2.72) (Fig. 56A) . . . . . Leptogenys voeltzkowi
  • In full-face view, eye breaking the outline of side of the head; smaller species (HW: 1.08–1.32, WL: 2.26–2.47) (Fig. 56B) . . . . . 57
FIGURE 56. Location of eyes in full-face view. A: Leptogenys voeltzkowi. B: Leptogenys vitsy.

57

return to couplet #56

  • Mandible almost straight without a visible curve near the base; antennal scape and tibia with erect to suberect short hairs (Fig. 57A); third abdominal tergite densely punctate . . . . . Leptogenys vitsy
  • Mandible with curved angle near the base; antennal scape and tibia with subdecumbent, short hairs (Fig. 57B); third abdominal tergite finely reticulate-rugose . . . . . Leptogenys sahamalaza
FIGURE 57. Shape of mandible in full-face view and hair types on antennal scape. A: Leptogenys vitsy. B: Leptogenys sahamalaza.

58

return to couplet #55

  • Median portion of clypeus projecting anteriorly into a toothlike spine; basal portion of mandible broadly curved, distinctly extending laterally beyond level of outline of the side of head (Fig. 58A) . . . . . Leptogenys lavavava
  • Median portion of clypeus not projecting into a toothlike spine; basal portion of mandible slightly to distinctly curved, but not extending beyond level of outline of the side of head (Fig. 58B, 58C) . . . . . 59
FIGURE 58. Shape of anteromedian portion of clypeus and form of basal portion of mandible. A: Leptogenys lavavava. B: Leptogenys chrislaini. C: Leptogenys barimaso.

59

return to couplet #58

  • Dorsum of head and body with standing hairs longer than the maximum diameter of eyes; in full-face view, head more or less elongate (CI: 80–84), mandible not strongly arched near the base and inner margin evenly slightly concave from the base to the apex (Fig. 59A); antennal scape relatively long (SI> 133), apical third surpassing the posterior margin of head . . . . . Leptogenys barimaso
  • Dorsum of head and body with standing hairs whose length is less than the maximum diameter of eyes; in full-face view, head shorter (CI: 83–88), mandible distinctly arched near the base and becomes feebly concave to almost straight towards the apex (Fig. 59B); antennal scape usually short (SI< 133); only the apical fourth surpassing the posterior margin of head . . . . . Leptogenys chrislaini
FIGURE 59. Shape of head in full-face view and length of hairs relative to eye diameter and form of mandible. A: Leptogenys barimaso. B: Leptogenys chrislaini.