Key to Polyrhachis aculeata group species

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


 * 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


 * 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


 * Node of petiole about as wide as high . . . . . 10

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

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


 * 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


 * Bases of antennal scapes not broadened; eyes strongly truncate (Java) Polyrhachis kebunraya

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
 * Eyes distinctly convex (Java) Polyrhachis selecta


 * Eyes rather flat (Japan, China, Vietnam) Polyrhachis latona

15
return to couplet #13
 * Antennal scapes with numerous short hairs along superior edge (Sulawesi, Sunda Strait) Polyrhachis numeria


 * Antennal scapes without hairs (Philippines) Polyrhachis diana

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


 * 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