Polyrhachis isolata

Identification
With its distinct reddish-brown colour scheme and short, bristle-like pilosity, P. isolata resembles Polyrhachis lachesis and Polyrhachis schenkii. It differs from both in the outline of the pronotal humeri, the orientation of the propodeal spines and the body sculpturation. In P. isolata the lateral pronotal margins are narrowly rounded with the humeri indicated by poorly defined blunt angles, and the pronotal dorsum widest near its midlength. The pronotal dorsum in both other species is distinctly widest across the humeri, with the lateral pronotal margins strongly posteriorly converging. In P. lachesis, the humeri are produced into distinctly dilated, rounded, dorsally shallowly concave prominences, while in P. schenkii the humeri are bluntly angular. In P. isolata, the propodeal spines in profile are oblique to the main axis of the body, while in the other two species they are more-or-less horizontal. The sculpturation of the head and mesosomal dorsum consists of a relatively fine, somewhat vermiculate-rugose pattern, superimposed over irregularly spaced, shallow and rather polished punctures. In both the other species the head and body are finely reticulate-punctate. The gaster in P. isolata and P. lachesis is very smooth, highly polished, while in P. schenkii the gastral dorsum is finely shagreened with relatively abundant, closely appressed pubescence.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  isolata. Polyrhachis (Hagiomyrma) isolata Kohout, 2013: 557, figs. 11G-H (w.) AUSTRALIA.