Key to Nearctic Nylanderia Workers

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This worker key is based on: Kallal, R.J. & LaPolla, J.S. 2012. Monograph of Nylanderia (Hymenoptera: Formicidae) of the World, Part II: Nylanderia in the Nearctic. Zootaxa 3508, 1-64.

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1

2

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  • Mesopleuron entirely covered with pubescence . . . . . 3
  • Mesopleuron not entirely covered with pubescence . . . . . 4

3

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  • Overall color reddish-brown; typically REL less than 30; mesosoma macrosetae long (index of longest pronotal macrosetae/ propodeum height at least 60) . . . . . Nylanderia fulva or Nylanderia pubens *
Head of Nylanderia fulva worker
Profile of Nylanderia fulva worker
Head of Nylanderia pubens worker
Profile of Nylanderia pubens worker
  • Overall color dark brown to almost black; typically REL more than 30; mesosoma macrosetae short (index of longest pronotal macrosetae/propodeum height less than 60) . . . . . Nylanderia bourbonica
Head of Nylanderia bourbonica worker
Profile of Nylanderia bourbonica worker

4

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Profile of Nylanderia guatemalensis worker

5

  • Gastral macrosetae densely distributed; HW ≥ 0.59 mm; gastral pubescence densest along segmental margins . . . . . Nylanderia bruesii
Head of Nylanderia bruesii worker
Profile of Nylanderia bruesii worker
  • Gastral macrosetae sparsely distributed; HW < 0.59 mm; gastral pubescence equally distributed . . . . . Nylanderia steinheili
Head of Nylanderia steinheili worker
Profile of Nylanderia steinheili worker

6

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Head of Nylanderia phantasma worker
Profile of Nylanderia phantasma worker
  • Darker in color than above; if yellow, then macrosetae are brown to black . . . . . 7

7

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  • Head ovate with distinct medial emargination along posterior margin, and SMC at least 10, and body overall densely setose, with black macrosetae contrasting strongly with yellow cuticle . . . . . Nylanderia hystrix
Head of Nylanderia hystrix worker
Profile of Nylanderia hystrix worker
  • Not matching the combination of characters listed above . . . . . 8

8

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  • Cuticle usually with bluish reflections under microscopic examination; pronotum with distinct concavity, giving it an angular appearance in lateral view . . . . . Nylanderia austroccidua
Profile of Nylanderia austroccidua worker
  • Cuticle rarely with bluish reflections under microscopic examination; pronotum not angular in appearance in lateral view . . . . . 9

9

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  • Antennae, mesosoma and legs yellowish, and SMC 5 or more, and 3 ocelli apparent; 1st gastral tergite often yellowish and contrasting with remainder of gaster . . . . . Nylanderia flavipes
Head of Nylanderia flavipes worker
Profile of Nylanderia flavipes worker
  • Overall coloration variable; SMC variable; ocelli may or may not be apparent; 1st gastral tergite always same color as remainder of gaster . . . . . 10

10

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  • Brown in color, with mesocoxae and metacoxae whitish, contrasting strongly with mesosoma; cephalic pubescence moderate to dense . . . . . 11
  • Yellow to brown in color, typically with mesocoxae and metacoxae the same color as mesosoma; if mesocoxae and metacoxae whitish and contrasting strongly with mesosoma then cephalic pubescence sparse to absent . . . . . 12

11

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  • Scape macrosetae count 5 or more; head length typically > 0.59 mm (HL: 0.59–0.74); usually uniform brown or with darker gaster . . . . . Nylanderia faisonensis
Head of Nylanderia faisonensis worker
Profile of Nylanderia faisonensis worker
  • Scape macrosetae count less than 5; head length typically < 0.59 mm (HL: 0.47–0.59); usually bicolored with darker head and gaster . . . . . Nylanderia wojciki
Head of Nylanderia wojciki worker
Profile of Nylanderia wojciki worker

12

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13

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  • Overall brown in color, with yellowish scapes contrasting with head color . . . . . Nylanderia parvula
Head of Nylanderia parvula worker
Profile of Nylanderia parvula worker
  • Overall yellow in color, with yellowish scapes not contrasting with head color . . . . . Nylanderia trageri

14

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  • Overall moderate to dark brown, with mesocoxae and metacoxae not strongly contrasting with mesosoma; moderate to dense cephalic pubescence; with a dense, neat band of pubescence along the dorsal margin of propodeum . . . . . Nylanderia concinna
Head of Nylanderia concinna worker
Profile of Nylanderia concinna worker
  • If brown in color, cephalic pubescence sparse to absent; if yellow in color, cephalic pubescence moderate to dense, but pubescence absent on propodeum . . . . . 15

15

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16

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  • Gaster becomes brownish distally; gaster macrosetae densely distributed . . . . . Nylanderia arenivaga
Head of Nylanderia arenivaga worker
Profile of Nylanderia arenivaga worker
  • Gaster uniform yellow in color; gaster macrosetae not densely distributed . . . . . Nylanderia querna

17

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  • HL at least 0.67 mm; SL at least 0.76 mm; scapes usually with decumbent pubescence; posterior margin of head usu-ally without medial emargination . . . . . Nylanderia magnella
  • HL at most 0.67 mm; SL less than 0.76 mm; scapes usually without decumbent pubescence; posterior margin of head usually with slight medial emargination . . . . . 18

18**

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  • Head with subparallel lateral margins in full face view, appearing relatively squarish; typically REL > 24 . . . . . Nylanderia vividula
Head of Nylanderia vividula worker
Profile of Nylanderia vividula worker
  • Head with convex lateral margins in full face view, appearing relatively ovate; typically REL< 24 . . . . . Nylanderia terricola
Head of Nylanderia terricola worker
Profile of Nylanderia terricola worker


*Workers of the introduced species fulva and pubens cannot be separated based on morphology. For morphological identification males are necessary. For further details see Gotzek et al., 2012.

**Workers of vividula and terricola cannot be reliably identified to species based on morphology. It appears that western U.S. terricola specimens are lighter than vividula, but this distinction is not maintained elsewhere in their range. However, males of the two species can be easily distinguished.