Key to Australian Polyrhachis Subgenera

1

 * Thorax strongly arched, wholly unarmed or with very small teeth on propodeum => Cyrtomyrma
 * Thorax not strongly arched; armed with spines or teeth; if armed with tiny teeth the thorax is flattened and not strongly arched => 2

2

 * Both pronotum and mesonotum armed with elongate spines => Polyrhachis
 * Mesonotum never with spines, pronotum armed or unarmed => 3

3

 * Petiole armed with 3 teeth => Myrmothrinax
 * Petiole armed with 2 or 4 spines or teeth => 4

4

 * Petiole armed with 4 teeth => Campomyrma
 * Petiole armed with 2 long spines, rarely on each outer side of spine is a tiny tooth or sharp edge at base of spine => 5

5

 * Mesonotum with raised lateral crests or tubercles => Myrmatopa
 * Mesonotum without raised lateral crests or tubercles => 6

6

 * Propodeal spines, when present, much shorter than those on the pronotum => Myrma
 * Propodeal spines always much longer than those on the pronotum => 7

7

 * Pronotum without spines or strong teeth => Hagiomyrma
 * Pronotum armed with spines or teeth => 8

8

 * Thorax rather convex; long propodeal spines directed upwards => Myrmhopla
 * Thorax rather flat; long propodeal spines almost horizontal => 9

9

 * Thorax rectangular of almost uniform width, sides almost straight, usually no mesopropodeal suture, and no sharp incision on sides at this area => Hedomyrma
 * Thorax rather squat with sides contracted about mesonotum, with a mesopropodeal suture and with a deep incision on the sides at this area => Chariomyrma