Key to Polyrhachis continua group species

The following worker key is based on Kohout, R.J. 2013. A review of the Polyrhachis continua species-group of the subgenus Myrma Billberg (Hymenoptera: Formicidae: Formicinae) with keys and descriptions of new species. Australian Entomologist 40(1), 13-46.

Polyrhachis continua  species group

subgenus Myrma

Polyrhachis

1

 * Petiolar node with dorsal spines short, tooth-like, barely longer than their basal width; lateral petiolar spines distinct, acute (except in P. gazelle sp. n.); eyes more-or-less protracted or truncate posteriorly (Bismarck Archipelago) (conops-complex) . . . . . 2


 * Node of petiole with dorsal spines elongated; lateral petiolar spines very short or rudimentary; eyes more-or-less normal (New Guinea, Indonesia, Australia) (continua-complex) . . . . . 6

2
return to couplet #1
 * Antennal scapes with numerous short hairs along leading edges . . . . . 3


 * Antennal scapes without hairs . . . . . 5

3
return to couplet #2
 * Dorsum of mesosoma and basal gastral tergite without hairs; eyes distinctly protracted posteriorly (New Britain) Polyrhachis conops


 * Dorsum of mesosoma and gaster with numerous erect hairs; eyes more-or-less normal or posteriorly truncate . . . . . 4

4
return to couplet #3
 * Petiolar node, including spines, with numerous short, erect hairs around base and along lateral margins; dorsum of mesosoma distinctly longitudinally striate; eyes convex, more-or-less normal (Manus I.) Polyrhachis manusensis


 * Petiolar node without hairs; dorsum of mesosoma only finely longitudinally striate; eyes rather flat, posteriorly truncate (New Ireland) Polyrhachis sinuata

5
return to couplet #2
 * Petiolar node relatively wide with lateral spines well developed; eyes distinctly protracted posteriorly (New Britain) Polyrhachis stitzi


 * Petiolar node relatively narrow with lateral spines reduced to blunt angles; eyes more-or-less normal, not protracted posteriorly (New Britain) Polyrhachis gazelle

6
return to couplet #1
 * Eyes flat, in full face view not reaching lateral cephalic outline Polyrhachis planoculata


 * Eyes convex, in full face view clearly breaking lateral cephalic outline . . . . . 7

7
return to couplet #6
 * Antennal scapes without hairs or occasionally with only a few hairs present along leading edge . . . . . 8


 * Antennal scapes with numerous short to medium length hairs along leading edge and fewer hairs along inferior edge . . . . . 10

8
return to couplet #7
 * Lateral margins of mesonotal dorsum converging posteriorly; pronotal spines relatively short, broadly based, only about 2x as long as basal width; lateral petiolar spines reduced to small acute teeth Polyrhachis continua


 * Lateral margins of mesonotal dorsum converging anteriorly or subparallel; pronotal spines relatively long and slender, distinctly longer than 2x basal width; lateral petiolar spines blunt or obsolete . . . . . 9

9
return to couplet #8
 * Dorsal petiolar spines relatively short, subparallel; lateral margins of pronotal and mesonotal dorsa virtually flat; dorsum of gaster with only a few rather short hairs Polyrhachis procera


 * Dorsal petiolar spines rather long, divergent; lateral margins of pronotal and mesonotal dorsa narrowly, but distinctly upturned; dorsum of gaster with numerous, medium length hairs Polyrhachis tapini

10
return to couplet #7
 * Lateral petiolar spines obsolete; dorsum of mesosoma finely reticulate-punctate (Australia, Cape York Pen.) Polyrhachis inusitata


 * Lateral petiolar spines produced into small, but distinct, acute teeth; dorsum of mesosoma more-or-less regularly, longitudinally striate (New Guinea) . . . . . 11

11
return to couplet #10
 * Propodeal teeth upturned, acute; propodeum with more-or-less distinct, blunt, transverse carina partly dividing dorsum from declivity; petiolar node, including spines, with numerous short, erect hairs around base and along lateral margins . . . . . 12


 * Propodeal teeth virtually lacking; propodeal dorsum descending into declivity in medially uninterrupted line; petiolar node without hairs, except a fringe of very short hairs along base and subpetiolar process . . . . . 14

12
return to couplet #11
 * Smaller (HL < 2.60), more slender species Polyrhachis neuguinensis


 * Larger (HL > 2.90), broader species . . . . . 13

13
return to couplet #12
 * Pronotal spines long and slender, almost 3x as long as basal width; clypeus in profile only weakly sinuate; antennal scapes generally longer (SI 185-199) Polyrhachis robusta


 * Pronotal spines shorter, broadly based, only about 2x as long as basal width; clypeus in profile distinctly sinuate; antennal scapes generally shorter (SI 179-188) Polyrhachis pulleni

14
return to couplet #11
 * Lateral margins of mesonotal dorsum distinctly converging posteriorly; pronotal dorsum with lateral margins flat Polyrhachis simpla


 * Lateral margins of mesonotal dorsum subparallel; pronotal dorsum with lateral margins upturned . . . . . 15

15
return to couplet #14
 * Larger species (HL > 2.80); pronotal dorsum markedly wide, about 1.5x wider than long; pronotal spines with broad, more-or-less dorsally flattened bases Polyrhachis spinifera


 * Smaller species (HL < 2.70); pronotal dorsum narrower, only about 1.13x wider than long; pronotal spines slender with dorso-medially flattened bases Polyrhachis sericeopubescens