Key to Linepithema males

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This key to males is based on: *Wild, A. L. 2007a. Taxonomic revision of the ant genus Linepithema (Hymenoptera: Formicidae). University of California Publications in Entomology. 126:1-159.

Males of Linepithema anathema, Linepithema aztecoides, Linepithema cryptobioticum, and Linepithema flavescens are not known and are not included in key.

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Linepithema

1

  • Forewing with one submarginal cell; gonostylus produced as a robust lobe . . . . . 2
  • Forewing with two submarginal cells; gonostylus filamentous, Fuscum-group) . . . . . 11

2

return to couplet #1

  • Propodeum with a strongly concave posterior face; propodeum produced posterodorsally and overhanging petiole; petiolar scale in lateral view tall with a relatively sharp crest (Humile-group) . . . . . 3
  • Propodeum with posterior face convex, straight, or weakly concave; propodeum not strongly overhanging petiole; petiolar scale variable . . . . . 6

3

return to couplet #2

  • Mesosoma greatly enlarged (MML > 1.40); pronotum produced strongly forward and overhanging head; mesosoma noticeably longer than metasoma; cosmopolitan . . . . . Linepithema humile
  • Mesosoma not so enlarged (MML < 1.20); pronotum only weakly or not at all overhanging head; mesosoma subequal in length to metasoma . . . . . 4

4

return to couplet #3

  • Legs relatively long (FI > 56); compound eyes small (OI 40–44); Andean Bolivia and Argentina . . . . . Linepithema oblongum
  • Legs shorter (FI < 56); compound eyes of variable size (OI 40–49, usually > 45); South America . . . . . 5

5

return to couplet #4

  • Either pubescence moderate to sparse on head posterodorsal to compound eye with surface shining, or collected in South America from Peru northward . . . . . Linepithema gallardoi
  • Pubescence moderate to dense on head posterodorsal to compound eye, and collected in South America from Bolivia southward . . . . . Linepithema micans

6

return to couplet #2

  • First antennal segment relatively long (SI > 31); eye separated from posterolateral clypeal margin by a distance greater than or equal to width of antennal scape; Central America and the Caribbean . . . . . Linepithema dispertitum
  • First antennal segment relatively short (SI < 30); eye separated from posterolateral clypeal margin by a distance less than or equal to width of antennal scape . . . . . 7

7

return to couplet #6

  • Dorsal petiolar node low and rounded; ocelli small and emerging only slightly above posterior margin of head in full face view; posterior margin of propodeum in lateral view straight to slightly convex . . . . . 8
  • Dorsal petiolar node relatively tall and scale-like; ocelli large and emerging strongly above posterior margin of head; posterior margin of propodeum in lateral view straight to slightly concave . . . . . 9

8

return to couplet #7

  • Dorsum of petiolar node concolorous with mesosomal dorsum; widespread in Central America and the Caribbean to southern Brazil . . . . . Linepithema iniquum
  • Dorsum of petiolar node pale white and much lighter in color than mesosomal dorsum; Southeastern Brazil . . . . . Linepithema leucomelas

9

return to couplet #7

  • Head sculpture densely punctate, surface opaque; mandible usually with apical tooth much smaller than subapical tooth; Atlantic forest regions of Brazil, Paraguay and Argentina . . . . . Linepithema pulex
  • Head sculpture not densely punctate, surface shining through pubescence; mandible with apical tooth long and subapical tooth reduced or absent . . . . . 10

10

return to couplet #9

11

return to couplet #1

  • Digitus with distal arm short, less than 1/3 length of proximal arm . . . . . 12
  • Digitus with distal arm long, greater than 1/2 length of proximal arm . . . . . 13

12

return to couplet #11

  • Dorsal edge of volsella and proximal arm of digitus straight to slightly concave; eye size smaller (EL < 0.38, OI < 54); legs shorter (FL < 1.05); northwestern South America to Costa Rica . . . . . Linepithema piliferum
  • Dorsal edge of volsella and digitus strongly concave; eye size larger (EL > 0.38, OI > 54); legs longer (FL > 1.05); Ecuador and Colombia . . . . . Linepithema tsachila

13

return to couplet #11

  • Distal arm of digitus much longer than height of volsella in lateral view; eyes relatively small (EL < 0.30); Hispaniola . . . . . Linepithema keiteli
  • Height of volsella in lateral view subequal to length of distal arm of digitus; eyes larger (EL > 0.30) . . . . . 14

14

return to couplet #13

  • Proximal arm of digitus broad at base and triangular in shape; ventrodistal process of volsella absent or present as a small tooth or weak spine; legs longer (FL > 1.1, FI > 69); Costa Rica to Brazil . . . . . Linepithema angulatum
  • Proximal arm of digitus narrow at base and filamentous; ventrodistal process of volsella present as a well developed spine; legs shorter (FL < 1.1, FI < 69); Peru and Ecuador . . . . . Linepithema fuscum