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