Key to Australian Polyrhachis Subgenera
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- Mesonotum armed with a pair of upwards and backwards curved spines; petiole distinctly higher than full height of mesosoma, terminating in a pair of hook-like spines (arboreal) (Cape York Peninsula) => Polyrhachis (single species, Polyrhachis bellicosa)
- Mesonotum without spines; petiole lower than full height of mesosoma, dorsum armed with spines or teeth of various configurations or virtually unarmed => 2
- Mesosoma completely laterally immarginate => 3
- Mesosoma at least partly laterally marginate => 5
- Small species (head length 1.25-1.65mm); dorsum of mesosoma relatively short, strongly longitudinally and transversely convex; pronotal spines reduced to acute teeth or absent; body uniformly black, highly polished => 4
- Small to large species (head length 1.40-3.60mm); dorsum of mesosoma elongate, only weakly to moderately convex; pronotal spines relatively long, acute; colour of body variable, mostly black, but also reddish-brown or bicoloured (arboreal or lignicolous) (tropical Queensland and Northern Territory) => Myrmhopla (part) (species key)
- Sides of head with longitudinal carina separating gena from ventral parts of head; propodeal spines, if present, very short; petiole scale-like, armed with four spines or teeth of various lengths and configurations, only rarely reduced to mere denticles (Polyrhachis brevinoda) (arboreal) (Northern Territory, Queensland and coastal New South Wales) => Cyrtomyrma (species key)
- Sides of head without longitudinal carina; propodeal spines long; petiole columnar, armed with a pair of horizontal spines that conform to shape of first gastral segment and a pair of distinct intercalary teeth (arboreal) (Cape York Peninsula and north Queensland) => Myrmhopla (part) (single species, Polyrhachis mucronata)
- Pronotal humeri simply rounded or, at most, bluntly angular => 6
- Pronotal humeri armed with spines or acute teeth => 9
- Dorsum of petiole usually narrowly rounded, rarely with a distinct platform (Polyrhachis thusnelda), armed with a pair of more-or-less horizontal, backwards directed or diverging, acute spines; propodeal spines rarely hook-like (Polyrhachis ammonoeides); propodeal spines always present, mostly horizontal or weakly elevated (subterranean, rarely lignicolous or lithocolous) (Australia-wide, except south, south-west and Tasmania) => Hagiomyrma (species key)
- Dorsum of petiole variable, with two, three or four upward directed spines or teeth of various lengths and configurations, or petiole virtually unarmed; propodeal spines present or reduced to mere teeth => 7
- Small species (head length 1.15-1.65mm); petiole columnar with two or three spines; body light coloured, mostly yellowish- or reddish-brown (arboreal) (tropical north Queensland and Northern Territory only) => 8
- Small to large species (haed length 1.10-2.80mm); petiole scale-like, usually with four teeth or short spines, but rarely also with one (Polyrhachis pseudothrinax) or two (for example Polyrhachis prometheus) elongated spines or virtually unarmed with only shallow median emargination; body mostly black or rarely reddish-brown (Polyrhachis incerta) (subterranean or lignicolous, nocturnal and crepuscular foragers) (Australia-wide, including Tasmania) => Campomyrma (species key)
- Petiole armed with three spines, middle spine distinctly longer than lateral spines; propodeal spines acute, distinctly elevated or virtually vertical (arboreal) (Northern Territory and north Queensland) => Myrmothrinax (species key)
- Petiole armed with two short spines; propodeal spines reduced to short, upturned teeth (arboreal) (north Queensland) => Myrmatopa (part) (species key)
- Pronotal humeri produced into broad-based short teeth with lateral margins distinctly expanded, virtually laminate; mesonotal and propodeal margins often elaborate, variously incised or with laterally dilated laminate lobes (for example Polyrhachis schoopae); body mostly broad and stocky with short appendages, generally with abundant pilosity and pubescence often masking underlying sculpturation (subterranean or rarely lignicolous) (Australia-wide, except Tasmania) => Chariomyrma
- Pronotal humeri produced into spines or acute teeth with lateral margins distinct, but not laminate; mesonotal and propodeal margins simple, never elaborate; body elongate with relatively long appendages and only rarely with abundant pilosity and/or pubescence (for example Polyrhachis clotho) => 10
- Pronotal humeri produced into long, horizontal, anteriorly directed spines; propodeal spines reduced to short, upturned teeth; petiole scale-like, armed with a pair of acute, upward directed spines and a tooth or blunt angle situated below their bases (lignicolous or terrestrial) (Cape York Peninsula) => Myrma (species key)
- Pronotal humeri produced into horizontal or variously elevated, mostly anterolaterally directed spines or acute teeth; propodeal spines present or rarely reduced to acute teeth (Polyrhachis alphea); petiole columnar with a pair of horizontal or elevated spines => 11
- Small species (head length < 1.75mm); propodeal spines reduced to acute teeth; petiole armed with two, rather long, upward directed spines (arboreal) (Cape York Peninsula) => Myrmatopa (part) (species key)
- Larger species (head length > 1.75mm); propodeal spines always present; petiole with more-or-less flat dorsum, armed with a pair of horizontal or variously elevated spines => 12
- Pronotal dorsum flat; humeri armed with acute, somewhat elevated, slender spines; propodeal spines acute, usually longer than pronotal pair, variously elevated; dorsum of petiole with rather vague, posteriorly sloping platform; dorsa of head, mesosoma and petiole with characteristic vermiculate sculpturation and short, bristle-like, brown hairs (subterranean) (Queensland) => Hirtomyrma (species key)
- Pronotal dorsum more-or-less longitudinally and transversely convex; humeri armed with mostly horizontal, dorsally flattened, laterally or anterolaterally directed acute spines or teeth; propodeal spines mostly horizontal, but also elevated; dorsum of petiole with rather conspicuous platform (except in Polyrhachis clio); body sculpturation never vermiculate, ranging from rugose to rather smooth; silvery or rich golden pilosity and pubescence in various densities over most body surfaces (lignicolous or rarely lithocolous) (tropical and coastal temperate Australia, except central and southern regions) => Hedomyrma
Definitions of habitats
Based on Robson & Kohout (2007).
- In the soil with or without any cover such as rocks or fallen logs.
- On the ground beneath logs and stones, in or between grass stems.
- Within the cavities of living or dead plants, including hollow stems, bamboo internodes, the base of ferns in trees, cavities under bark, or within myrmecophyte plants.
- On or within rock crevices.
- Among leaves or twigs, either against a single surface such as a trunk or between adjacent surfaces such as leaves.
- Kohout, R.J. 2010. A review of the Australian Polyrhachis ants of the subgenera Myrmhopla Forel and Hirtomyrma subgen. Nov. (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum — Nature 55(1), 167-204.
- Robson, S.K.A. & Kohout, R.J. 2007. A review of the nesting habits and socioecology of the ant genus Polyrhachis Fr. Smith. Asian Myrmecology 1, 81–99.