Key to Polyrhachis continua group species

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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.

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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

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  • Antennal scapes with numerous short hairs along leading edges . . . . . 3

3

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  • Dorsum of mesosoma and basal gastral tergite without hairs; eyes distinctly protracted posteriorly (New Britain) . . . . . Polyrhachis conops
Polyrhachis conops syntype Berlin head.jpg
Polyrhachis conops syntype Berlin side.jpg
  • Dorsum of mesosoma and gaster with numerous erect hairs; eyes more-or-less normal or posteriorly truncate . . . . . 4

4

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  • 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

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  • 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

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

7

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  • 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

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  • 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
Polyrhachis continua casent0905616 h 1 high.jpg
Polyrhachis continua casent0905616 p 1 high.jpg
  • 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

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  • 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

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  • 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

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13

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  • 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
Polyrhachis simpla casent0912117 p 1 high.jpg
  • Lateral margins of mesonotal dorsum subparallel; pronotal dorsum with lateral margins upturned . . . . . 15

15

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  • 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
Polyrhachis spinifera casent0905618 h 1 high.jpg
Polyrhachis spinifera casent0905618 p 1 high.jpg
  • 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
Polyrhachis sericeopubescens casent0903439 h 1 high.jpg
Polyrhachis sericeopubescens casent0903439 p 1 high.jpg