Key to Polyrhachis aculeata group species

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The following worker key is based on: Kohout, R. J. 2013. A review of the Polyrhacis aculeata species-group of the subgenus Myrma Billberg (Hymenoptera: Formicidae), with keys and descriptions of new species. Australian Entomologist. 40:137-171.

Polyrhachis aculeata species group

subgenus Myrma

Polyrhachis


1

  • Dorsal body surfaces smooth, highly polished, mostly glabrous, only rarely with scattered long hairs or a pile of sparse whitish pubescence in some species (aculeata-complex, in part) . . . . . 2
  • Dorsal body surfaces finely sculptured, reticulate-punctate or longitudinally striate, semi-polished or opaque with sculpture often obscured by abundant, closely appressed, silvery-grey or golden pubescence . . . . . 6

2

return to couplet #1

  • Pronotal spines long and slender, more than 2x as long as width at their bases; dorsal petiolar spines relatively long . . . . . 3
  • Pronotal spines relatively short, broad-based, only about 1.5x as long as width at their bases; dorsal petiolar spines reduced to short, acute teeth (Thailand) . . . . . Polyrhachis noonananti

3

return to couplet #2

  • Distinct pile of relatively long, appressed, silvery or whitish pubescence rather abundant over most body surfaces, notably along lateral margins of mesosomal dorsum and sides; petiolar spines rather stubby, distinctly dorso-medially flattened (Sri Lanka) . . . . . Polyrhachis gibbosa
Polyrhachis gibbosa casent0910939 p 1 high.jpg
  • Short, appressed, silvery or whitish pubescence very sparse on pronotal collar and sides of mesosoma and petiole, virtually absent from most dorsal body surfaces; petiolar spines slender, only weakly flattened or almost round in cross-section . . . . . 4

4

return to couplet #3

  • Body slender with long and slender pronotal and petiolar spines; antennal scapes with numerous, erect or semierect hairs; appendages generally light reddish brown . . . . . 5
  • Body broader with shorter and thicker pronotal and petiolar spines; antennal scapes without hairs or with only a few hairs along superior edge; appendages distinctly darker, medium to dark reddish brown (Borneo, Sumatra, Java, Sulawesi, Philippines) . . . . . Polyrhachis cybele

5

return to couplet #4

  • Relatively long, erect or semierect hairs rather abundant over most body surfaces (India, Sri Lanka) . . . . . Polyrhachis aculeata
Polyrhachis-aculeata-HUMCZ001L.jpg
  • Relatively long, erect or semierect hairs present on front of head, gastral apex and appendages; hairs virtually absent from vertex of head, dorsum of mesosoma and petiole (India, Thailand, Laos) . . . . . Polyrhachis hemiopticoides

6

return to couplet #1

  • Head, mesosoma and petiole very finely sculptured, semi-polished; gaster highly polished; pilosity and pubescence virtually absent from all dorsal body surfaces (aculeata-complex, in part) (Borneo) . . . . . Polyrhachis dimoculata
  • Head, mesosoma, petiole and gaster finely or distinctly sculptured, opaque; pilosity and pubescence abundant over most body surfaces, mostly obscuring underlying sculpturation (pubescenscomplex) . . . . . 7

7

return to couplet #6

  • Eyes strongly posteriorly truncate or protracted . . . . . 8
  • Eyes normal or only weakly posteriorly truncate . . . . . 12

8

return to couplet #7

  • Node of petiole strongly transverse, distinctly wider than high . . . . . 9

9

return to couplet #8

  • Eyes very strongly protracted posteriorly, with somewhat angular outline in full face view, posterior faces virtually flat, which is notably evident when viewed from behind (Philippines) . . . . . Polyrhachis palawanensis
  • Eyes posteriorly truncate, with smooth convex outline in full face view (India, Myanmar, Thailand) . . . . . Polyrhachis alatisquamis
Polyrhachis alatisquamis holotype side.jpg

10

return to couplet #8

  • Antennal scapes with numerous short hairs; whole body with abundant, closely appressed pubescence, almost hiding underlying sculpturation (India to Borneo) . . . . . Polyrhachis pubescens
Polyrhachis pubescens casent0906795 p 1 high.jpg
  • Antennal scapes with only occasional hairs present; body pubescence relatively sparse, not completely hiding underlying sculpturation . . . . . 11

11

return to couplet #10

  • Bases of antennal scapes distinctly broadened; eyes only moderately truncate (Thailand) . . . . . Polyrhachis watanasiti

12

return to couplet #7

  • Pronotal spines relatively long, more than 1.5x as long as width at their bases; petiole with dorsolateral spines moderately long, distinctly longer than short and stubby lateral teeth . . . . . 13
  • Pronotal spines distinctly shorter, only about as long as width at their bases; petiole with dorsolateral spines relatively short, about same length as rather prominent lateral teeth . . . . . 16

13

return to couplet #12

  • Dorsum of petiole with distinct intercalary tooth; body with rather diluted, pale golden, appressed pubescence distributed over most dorsal surfaces . . . . . 14
  • Dorsum of petiole without intercalary tooth; body with rather abundant, silvery grey, appressed pubescence that almost completely hides underlying sculpturation . . . . . 15

14

return to couplet #13

Polyrhachis selecta casent0910940 p 1 high.jpg
Polyrhachis latona casent0227579 p 1 high.jpg

15

return to couplet #13

  • Antennal scapes with numerous short hairs along superior edge (Sulawesi, Sunda Strait) . . . . . Polyrhachis numeria
Polyrhachis numeria casent0906794 p 1 high.jpg
Polyrhachis diana casent0217767 p 1 high.jpg

16

return to couplet #12

  • Dorsal margin of petiole strongly raised and bluntly angular medially; dorsum of mesosoma relatively slender, only moderately convex in lateral view (Philippines) . . . . . Polyrhachis starri
Polyrhachis-murinaL2.5x.jpg
  • Dorsal margin of petiole only weakly raised with distinct intercalary tooth; dorsum of mesosoma relatively broad, distinctly convex in lateral view (Borneo, Sumatra) . . . . . Polyrhachis murina
Polyrhachis murina casent0905612 p 1 high.jpg