Polyrhachis angusta

This species nests in soil and appears to be much less common and more localised than the widespread Polyrhachis ammon.

Identification
Kohout (1988): This species stands close to Polyrhachis ammon, but is consistently separable by its distinctly slender, more gracile stature. The pronotum in dorsal view is almost quadrate, 0.7-0.8 times as wide as the head, with narrowly rounded shoulders, and the lateral margins distinctly sinuate behind. The propodeal spines are oblique to the main axis of the mesosoma in side view and slightly divergent from above. In P. ammon the pronotum is more or less transverse with the shoulders broadly rounded and the lateral margins narrowed posteriorly and almost straight in outline. The propodeal spines project horizontally, and are subparallel. The appressed pubescence in P. angusta is shorter and more dilute, and the pilosity distinctly longer, than in P. ammon.

Kohout (2013): Polyrhachis angusta is very similar to Polyrhachis ammon, however it is consistently separable by its distinctly more slender body and longer spines and hairs. The reddish-golden midline patch on dorsum of the first gastral tergite is rather narrow in dorsal view and widely bordered with very distinct, silvery, appressed pubescence. In contrast, the patch in P. ammon is distinctly wider, covering most of the dorsum, and is only narrowly diffused into pale golden pubescence on the sides and venter of the gaster.

Distribution
Patchily distributed from Eungella in northern Queensland to central New South Wales.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  angusta. Polyrhachis ammon r. angusta Forel, 1902h: 524 (w.q.m.) AUSTRALIA. Combination in P. (Hagiomyrma): Forel, 1915b: 108. Raised to species: Kohout, 1988c: 431.

Additional References

 * Kohout, R.J. 2013. Revision of Polyrhachis (Hagiomyrma) Wheeler, 1911 (Insecta: Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum, Nature 56, 487-577.