Key to Afrotropical Nylanderia workers

This worker key is based on: Lapolla, J. S., C. H. Hawkes, and B. L. Fisher. 2011. Monograph of Nylanderia (Hymenoptera: Formicidae) of the World, Part I: Nylanderia in the Afrotropics. Zootaxa. 3110:10-36.

1

 * Dorsal face of propodeum much shorter than declivitous face; in lateral view, propodeum lower than remainder of dorsum, dorsally angular or gently rounded . . . . . 2


 * Dorsal face of propodeum distinctly rounded, about the same length as declivitous face; in lateral view, propodeum higher than or equal to remainder of dorsum, dorsally dome-like . . . . . 10

2
return to couplet #1
 * Fewer than 10 erect macrosetae present on each scape . . . . . Nylanderia vividula


 * More than 10 erect macrosetae present on each scape . . . . . 3

3
return to couplet #2
 * Dark brown color overall . . . . . 4


 * Lighter yellow brown color overall . . . . . 6

4
return to couplet #3
 * Mesopleuron with a dense layer of pubescence . . . . . Nylanderia bourbonica (see note "i" below)


 * Mesopleuron either without or with sparse pubescence . . . . . 5

5
return to couplet #4
 * Dorsal face of propodeum gently rounded in profile; antennae and legs only slightly lighter than remainder of body . . . . . Nylanderia vaga (see note "i" below)


 * Dorsal face of propodeum very short with straight margin in profile; antennae and legs distinctly whitish-brown, sharply contrasting with remainder of body . . . . . Nylanderia umbella

6
return to couplet #3
 * Dorsal face of propodeum very short and angular . . . . . 7


 * Dorsal face of propodeum gently rounded and convex . . . . . 8

7
return to couplet #6
 * Mesocoxae and metacoxae lighter than procoxae . . . . . Nylanderia boltoni


 * Mesocoxae and metacoxae the same color as procoxae . . . . . Nylanderia scintilla

8
return to couplet #6
 * Macrosetae on pronotum abundant (PMC = 10–22); macrosetae on head, mesosoma and legs dark, contrasting strongly with the much lighter cuticle . . . . . Nylanderia usambarica


 * Macrosetae on pronotum not particularly abundant (PMC = 3–10); macrosetae on head, mesosoma and legs about the same color as cuticle . . . . . 9

9
return to couplet #8
 * Southern Africa (Botswana, South Africa, Mozambique, and Zimbabwe) . . . . . Nylanderia natalensis (see note "ii" below)


 * Eastern, northern and western Africa . . . . . Nylanderia jaegerskioeldi (see note "ii" below)

10
return to couplet #1
 * Entire body dark brown, except for sharply contrasting, almost white protrochanters, mesocoxae and metacoxae . . . . . 11


 * Body color variable, but if dark brown then mesocoxae and metacoxae are the same color as mesosoma . . . . . 12

11
return to couplet #10
 * Head and mesopleuron cuticle smooth to sometimes slightly rugulose; head length between 0.53–0.68 mm; scape length between 0.60–0.81 mm . . . . . Nylanderia lepida


 * Head and mesopleuron cuticle distinctly rugulose; head length 0.70–0.80 mm; scape length between 0.91–0.98 mm . . . . . Nylanderia impolita

12
return to couplet #10
 * Gastral cuticular surface with distinct striations running lengthwise on dorsum; lateral portions of pronotum rugulose . . . . . Nylanderia mendica


 * Gastral cuticular surface smooth or with faint gastral cuticle striations; lateral portions of pronotum smooth . . . . . 13

13
return to couplet #12
 * Mesosomal macrosetae very short . . . . . Nylanderia brevisetula


 * Mesosomal macrosetae not short . . . . . 14

14
return to couplet #13
 * Body yellow, contrasting with darker erect setae, especially noticeable on the gaster . . . . . Nylanderia luteafra


 * Body color variable, but erect setae not conspicuously darker than remainder of body . . . . . 15

15
return to couplet #14
 * Head, mesosoma and gaster a solid dark reddish-brown; scape length between 0.95–1.04 mm . . . . . Nylanderia silvula


 * Head, mesosoma and gaster yellowish-brown; scape length between 0.74–0.8 mm . . . . . Nylanderia incallida

i - These species are thought to be introduced species to the Afrotropical region. The species boundaries of bourbonica and vaga are poorly defined and are being revised by JSL and others. One species, N. vividula, is reported from the Afrotropics, but we have not seen specimens of this species from the region. Males would be particularly useful because they have distinctive genitalia, unlike any African species. We include this species in the key because past reports have noted its presence in the Afrotropics.

ii - Workers of natalensis and jaegerskioeldi cannot be reliably identified to species. However, males of the two species can be easily distinguished. Geographically, natalensis appears to be restricted to southern Africa and jaegerskioeldi is found in East, North and West Africa.