Key to Megalomyrmex males of Central America

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This key to males is based on: Boudinot, B.E. Sumnicht, T.P. and Adams, R.M.M. 2013. Central American ants of the genus Megalomyrmex Forel (Hymenoptera: Formicidae): six new species and keys to workers and males. Zootaxa 3732:1-82.

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Male-based key to Central American species

Notes: Males of five Central American species remain unknown: Megalomyrmex longinoi, M. osadrifti, M. fungiraptor, M. nocarina, and M. reina. It is predicted that M. fungiraptor males will run to couplet 3 based on the conformity of male and female wing venation and the similarity of M. fungiraptor females to those of M. adamsae and M. symmetochus; it is also predicted that the undescribed drifti complex males will run to “M. megadrifti” in couplet 7.

1

FIGURES 41–49. 41 & 42: Worker mandibles, dorsal view; 43 & 44: forewings, dorsal view; 45–47: male heads, anterodorsal oblique view; white brackets indicate maximum length of lateral ocellus; 48 & 49: male metasomata without petioles or postpetioles, profile view. 41. M. osadrifti holotype. 42. M. drifti. 43. M. adamsae queen. 44. M. mondaboroides male. 45. M. symmetochus. 46. M. silvestrii. 47. M. brandaoi. 48. M. adamsae. 49. M. symmetochus.

2

return to couplet #1

  • Dorsal face of mandible coarsely striate. Minimum distance between compound eye and lateral ocellus less than one lateral ocellus length (fig. 45) and/or scape length greater than that of antennomeres 2–4 . . . . . 3
  • Dorsal face of mandible mostly smooth. Minimum distance between compound eye and lateral ocellus greater than one lateral ocellus length (figs. 46 & 47) and scape length less than that of antennomeres 2–4 . . . . . 4

3

return to couplet #2

  • Setae on gastric tergum I coarse, stiff, somewhat dilute (fig. 48). Ventral face of petiole with two longitudinal carinulae flanking median longitudinal carinula. Panama . . . . . Megalomyrmex adamsae
  • Setae on gastric tergum I fine, flexuous, relatively dense (fig. 49). Ventral face of petiole with at least four carinulae flanking median carinula. Nicaragua to Panama . . . . . Megalomyrmex symmetochus

4

return to couplet #2

  • Occipital carina visible in full-face view (fig. 50) . . . . . 5
  • Occipital carina obscured by vertex in full-face view, well below level of ocellar region (fig. 51) . . . . . 6
FIGURES 50–55. 50 & 51: Posterior halves of male heads, full-face view; 52 & 53: male mesosomata in profile view; 54 & 55: male mandibles, anterodorsal view; arrows indicate teeth of M. wettereri. 50. M. silvestrii. 51. M. wettereri. 52. M. modestus. 53. M. silvestrii. 54. M. brandaoi. 55. M. wettereri.

5

return to couplet #4

  • Mesosoma robust. Mesoscutellum strongly bulging in profile view (fig. 52). Costa Rica to Venezuela . . . . . Megalomyrmex modestus
  • Mesosoma gracile. Mesoscutellum weakly bulging in profile view (fig. 53). Southern Mexico to northern Argentina . . . . . Megalomyrmex silvestrii

6

return to couplet #4

  • Masticatory margin of mandible with three or four large, widely-spaced teeth (fig. 54). Scape short: about three times longer than the pedicel . . . . . 7
  • Masticatory margin of mandible with six or more small, close-set teeth (fig. 55). Scape long: four to five times longer than the pedicel. Pale brown . . . . . 8

7

return to couplet #6

  • First gastric tergum with numerous (> 10) short appressed setae in addition to long suberect to erect setae. Strongly shining black. Mexico south to Brazil . . . . . Megalomyrmex megadrifti
  • First gastric tergum with sparse (< 5) or without short appressed setae in addition to long suberect to erect setae. Red-brown. Costa Rica, Ecuador . . . . . Megalomyrmex brandaoi

8

return to couplet #6

  • Postpetiole with anteroventral denticle in profile view (fig. 56). Ventral surface of petiole with rough sculpturation. All setae on scape appressed. Costa Rica and Panama . . . . . Megalomyrmex miri
  • Postpetiole without anteroventral denticle in profile view (fig. 57). Ventral surface of petiole smooth and shining. Setae on scape appressed to subdecumbent. Costa Rica and Panama . . . . . Megalomyrmex wettereri
FIGURES 56–63. 56 & 57: Male postpetioles, profile view; 58 & 59: male left antennae; black arrow indicates flattened kink; 60 & 61: male postpetioles, profile view; 62 & 63: male petioles and postpetioles, profile view. 56. M. miri. 57. M. wettereri. 58A. M. foreli, mediodorsal view. 58B. M. foreli ventral view. 59. M. male 01. 60. M. wallacei. 61. M. foreli. 62. M. mondabora. 63. M. male 01.

9

return to couplet #1

  • Occipital carina distinctly visible in full-face view (fig. 50) . . . . . 10
  • Occipital carina obscured by vertex in full-face view (fig. 51) . . . . . 13

10

return to couplet #9

  • Third antennomere apically flattened and/or bent (fig. 58). Submarginal cell 1+2 of forewing broad: less than or equal to four times as long as broad . . . . . 11
  • Third antennomere cylindrical, not apically bent (fig. 59). Submarginal cell 1+2 of forewing very narrow: five or more times as long as broad . . . . . 12

11

return to couplet #10

  • Postpetiole globose: postpetiolar node and sternum strongly convex in profile view (fig. 60). Masticatory margin of mandible with six teeth; the subapical tooth about one third the length of the apical tooth. Palpal formula 3,2. Costa Rica, Panama, Colombia, Guyana, Amazonian Brazil . . . . . Megalomyrmex wallacei
  • Postpetiole not globose: postpetiolar node and sternum weakly convex in profile view (fig. 61). Masticatory margin of mandible with five teeth; the subapical tooth about half the length of the apical tooth. Palpal formula 3,3. Costa Rica south to Andean regions of Colombia, Ecuador, and northern Peru . . . . . Megalomyrmex foreli

12

return to couplet #10

  • Petiolar node bulbous and with a distinct posterior face in profile view (fig. 62). Postpetiolar node distinct and strongly convex in profile view (fig. 62). Femora and at least first three antennomeres white; tibiae pale brown. Costa Rica . . . . . Megalomyrmex mondabora
  • Petiolar node angular and without a distinct posterior face (fig. 63). Postpetiolar node indistinct, almost linear in profile view (fig. 63). Femora, first three antennomeres, and tibiae dark brown. Chiapas, Mexico . . . . . Megalomyrmex male 01

13

return to couplet #9

  • Antenna with eleven antennomeres. Anterodorsal margin of petiole concave (fig. 64). Metabasitarsus bent about midlength and swollen apically. Southern Mexico south to Peru, Venezuela, and central Brazil; absent in Costa Rica . . . . . Megalomyrmex incisus
  • Antenna with thirteen antennomeres. Anterodorsal margin of petiole linear (fig. 65). Metabasitarsus tubular; neither bent nor swollen apically . . . . . 14
FIGURES 64–67. 64 & 65. Male petioles, profile view; 66 & 67: male propodea, profile view. 64. M. incisus. 65. M. mondaboroides. 66. M. milenae. 67. M. mondabora.

14

return to couplet #13

  • Antenna brown to honey-colored. Large (ML > 2.25 mm). Compound eyes giant, taking up most of the head (fig. 73), separated across the frons by less than one eye width in full-face view. Lateral ocellus less than one lateral ocellus length from compound eye. Dorsal face of propodeum depressed in profile view (fig. 66). Panama . . . . . Megalomyrmex milenae
  • Antenna white. Small (ML < 1.5 mm). Compound eyes smaller, not taking up most of the head (Fig. 77), separated across the frons by more than twice one eye width in full-face view. Lateral ocellus about three lateral ocellus lengths from compound eye. Dorsal face of propodeum convex in profile view (fig. 67). Costa Rica and Panama . . . . . Megalomyrmex mondaboroides