Polyrhachis pseudothrinax

Polyrhachis pseudothrinax appears to be somewhat more common than other species of the P. gravis-group. It ranges from north Queensland westwards across the Northern Territory to the Kimberley region of Western Australia.

Identification
Kohout (2013): Throughout its distribution, P. pseudothrinax is relatively morphologically uniform, however, the Queensland populations appear to have a longer antennal scapes (SI 118-126 versus 112-120 in NT populations), with the exception of a single specimen from Melville Island (SI 127). When describing this species, Hung (1967) also noted differences in sculpturation of the propodeal dorsum, however, following examination of numerous specimens across the whole range of this species it is apparent that the variability in striation is similar to that displayed by other species of the P. gravis-group. Some specimens also appear to differ in the shape and length of the propodeal dorsum (Andersen, personal communication), however, subsequent examination failed to reveal any other associated taxonomically important characters and I consider they represent only variants from the “prototype” of this species.

With its single middle petiolar spine, P. pseudothrinax is easily recognised. Only Polyrhachis unicornis shares this character, however, it differs in having the spine less acute and shorter (Fig. 5D, G) and in some specimens weakly emarginate apically. They also differ in the shape of their eyes which, in P. unicornis, are larger and distinctly less convex (Fig. 5C). In addition, the sculpturation on the pronotal dorsum is distinctly transverse in P. unicornis, while it is more-or-less longitudinal in P. pseudothrinax and the bristle-like pubescence is distinctly longer and rather abundant in P. pseudothrinax, while it is much shorter and rather sporadic in P. unicornis. Their colour patterns are very similar with a black body and very distinct, light reddish-brown or orange-coloured legs, however, the anterior portion of clypeus in P. unicornis is distinctly lighter reddish-brown, while it is black throughout in the other species.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  pseudothrinax. Polyrhachis pseudothrinax Hung, 1967a: 199, figs. 1-6 (w.) AUSTRALIA. Combination in P. (Campomyrma): Kohout & Taylor, 1990: 512.

Type Material


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Additional References

 * Kohout, R.J. 2013. A review of the Polyrhachis gravis and micans species-groups of the subgenus Campomyrma Wheeler (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum, Nature 56, 92-117.