Key to Australian Genera of Formicinae

1

 * Antennae with 10 or 11 segments (including the scape) => 2
 * Antennae with 12 segments (including the scape) => 5

2

 * Palps short, not extending along the under side of the head and with a formula of 2:3 (outer (maxillary) palps with 2 segments, inner (labial) palps with 3 segments) (Fig. a). Eyes small or absent, at most about the size of the maximum scape diameter (Fig. b) => Acropyga
 * Palps long, extending along the under side of the head and with a formula of 6:4 (outer (maxillary) palps with 6 segments, inner (labial) palps with 4 segments) (Fig. aa). Eyes present and always larger than the maximum scape diameter (Fig. bb) => 3

3

 * Propodeum with one or more pairs of spines, teeth or protuberances (sometimes these are small) (Fig. a). Upper surface of the petiole usually rounded or angular, but sometimes with a pair of spines (Fig. b) => Stigmacros
 * Propodeum smooth, without spines or teeth (Fig. aa). Upper surface of the petiole rounded or angular, never with teeth or spines (Fig. bb) => 4

4

 * Scapes surpassing the rear margin of the head by two-thirds their length or more (Fig. a). Second and third segments of the antennal funiculus (counting from the scape) about the same length as the fourth segment (Fig. b). Body elongate, the pronotum longer than wide when viewed from above (Fig. c) => Anoplolepis
 * Scapes surpassing the rear margin of the head by less than one-quarter their length (Fig. aa) and sometimes not surpassing it at all. Second and third segments of the antennal funiculus (counting from the scape) each much shorter than the fourth segment (Fig. bb). Body compact, the pronotum shorter than wide when viewed from above (Fig. cc) => Plagiolepis

5

 * Rear corner of the mesosoma above the hind leg smooth or with ridges, but never with an opening (the metapleural gland opening) or row of elongate hairs (although sometimes a few scattered hairs are present) (Fig. a). (Note that sometimes the propodeal spiracle is low on the propodeum and located above the hind leg, but it is never below the level of the attachment of the petiole while the metapleural gland opening is always below this point) => 6
 * Rear corner of the mesosoma above the hind leg with a small opening (the metapleural gland opening) which is often fringed with elongate hairs (Fig. aa) => 8

6

 * Mandibles with 10 or more teeth and with the fourth tooth (counting from the tip) longer than the third and fifth teeth (Fig. a). Node of the petiole low and rounded (Fig. b). Palps short, not extending along the under side of the head and with a formula of 5:4 (outer (maxillary) palps with 5 segments, inner (labial) palps with 4 segments) (Fig. c). Mesonotum constricted (Fig. d) and narrower than the pronotum and propodeum when viewed from above => Oecophylla
 * Mandibles with 8 or fewer teeth and with the fourth tooth about the same length as the third and fifth teeth (Fig. aa). Node of the petiole distinct and upright (Fig. bb). Palps long, extending along the under side of the head and with a formula of 6:4 (outer (maxillary) palps with 6 segments, inner (labial) palps with 4 segments) (Fig. cc). Mesonotum intermediate in width between the pronotum and propodeum (Fig. dd) when viewed from above => 7

7

 * Upper plate of the first segment of the gaster (first gastral tergite) varying from slightly less than to more than half the total length of the gaster (Fig. a). Spines present on the top of the petiole and usually also on the mesosoma (Fig. b) (in a few species the spines on the petiole are reduced to sharp angles) => Polyrhachis
 * Upper plate of the first segment of the gaster (first gastral tergite) always much less than half the total length of the gaster (Fig. aa). Spines absent from the mesosoma and petiole, the petiole rounded or angular above and never with spines (Fig. bb) => Camponotus

8

 * Antennal sockets separated from the rear margin of the clypeus by a distance greater than the smallest diameter of the scape (Fig. a) => 9
 * Antennal sockets very close to the rear margin of the clypeus and sometimes almost touching it, the distance between them always less than the smallest diameter of the scape (Fig. aa) => 12

9

 * Eyes very large and placed on the rear corners of the head so that they form part of the outline of the head when viewed from the front (Fig. a) => Opisthopsis
 * Eyes moderate in size and placed along the side of the head, never near the rear corners and never forming part of the outline of the head when viewed from the front (although they may bulge outwards past the sides of the head) (Fig. aa) => 10

10

 * Mandibles with more than 10 teeth (Fig. a). Ocelli present (Fig. b). Scapes long, surpassing the rear margin of the head by one half their length or more (Fig. c). Overall length of body (including head) 10 mm or greater. Workers highly variable in size and varying continuously from majors to minors (polymorphic) => Notostigma
 * Mandibles with 5 or 6 teeth (Fig. aa). Ocelli absent (Fig. bb). Scapes short, surpassing the rear margin of the head by less than one half their length (Fig. cc). Overall length of body (including head) less than 10 mm. All workers approximately the same size (monomorphic) => 11

11

 * Upper plate of the first segment of the gaster (first gastral tergite) more than half the total length of the gaster (Fig. a). Pronotum and mesonotum forming a single plate which is not separated by a suture (best viewed from above) (Fig. b). Node of the petiole expanded towards the sides so that it is wider than the propodeum, its upper surface flat or slightly concave and with teeth along its outer edges (Fig. c) => Echinopla
 * Upper plate of the first segment of the gaster (first gastral tergite) less than half the total length of the gaster (Fig. aa). Pronotum and mesonotum separated by a suture (best viewed from above) (Fig. bb). Node of the petiole much narrower than the propodeum, its upper and outer surfaces rounded and never with spines or teeth (Fig. cc) => Calomyrmex

12

 * Propodeum armed with a pair of distinct, elongate spines near the angle between its upper and rear faces (Fig. a) => 13
 * Propodeum usually rounded and without spines, but occasionally with very small denticles which each bear an elongate hair (Fig. aa) => 14

13

 * Petiole with a pair of teeth on its upper surface (Fig. a). Propodeum with two pairs of spines (Fig. b). Pronotum rounding from the top into the sides (Fig.c) => Pseudonotoncus
 * Petiole angled above but without teeth (Fig. aa). Propodeum with a single pair of spines (Fig. bb). Pronotum with a pair of wing-like projections on its outer edges between the upper surface and sides (Fig.cc) => Teratomyrmex

14

 * Upper surface of the head and body with pairs of large, stout, dark hairs (Fig. a) => 15
 * Upper surface of the body with randomly placed, relatively thin hairs which are not found in pairs and are often lightly coloured (Fig. aa), or lacking hairs => 18

15

 * Node of petiole upright and with anterior and posterior faces long and more or less parallel => Prolasius
 * Node of petiole strongly inclined forward and with the anterior face much shorter than the posterior face => 16

16

 * Scapes with erect hairs. Mandibles with 6-7 teeth => Nylanderia
 * Scapes lacking erect hairs. Mandibles with 5 teeth => 17

17

 * Erect hairs (1 pair) present on propodeum. Erect hairs on front of head forming 6-7 distinct pairs.  Legs lacking erect hairs => Paraparatrechina
 * Erect hairs absent from propodeum. Erect setae on front of head scattered across surface and not forming pairs.  Legs with numerous erect hairs => Paratrechina

18

 * Palps short, not extending along the under side of the head and with a formula of 2:3, 3:3 or 4:3 (outer (maxillary) palps with 2, 3 or 4 segments, inner (labial) palps with 3 segments) (3 maxillary and 3 labial palps shown in Fig. a) => Pseudolasius
 * Palps long, extending along the under side of the head and with a formula of 6:4 (outer (maxillary) palps with 6 segments, inner (labial) palps with 4 segments) (Fig. aa) => 19

19

 * Spiracle on the propodeum slit-like or comma-shaped (Fig. a). Underside of the head and mandibles usually with numerous elongate curved hairs (a psammophore) (Fig. b), but sometimes with only a few hairs on the underside of the head => Melophorus
 * Spiracle on the propodeum round or oval (Fig. aa). Underside of head and mandibles without elongate curved hairs (a psammophore), at most with short, straight hairs (Fig. bb) => 20

20

 * Spiracle on propodeum located very close to the rear face in side view (Fig. a). Scapes long, surpassing the rear margin of the head by at least 3 times their maximum diameter and often by more than one-third their length (Fig. b) => Prolasius
 * Spiracle on propodeum located at least its diameter forward of the rear face in side view (Fig. aa). Scape variable in length but never surpassing the rear margin of the head by more than one-third their length and often surpassing it by less than 3 times their maximum diameter (Fig. bb) => 21

21

 * Frontal carinae distinctly arched (Fig. a). Mandible usually with 10 to 13 teeth (Fig. b), but sometimes with as few as 6 in large individuals. Workers highly variable in size and varying continuously from majors to minors (polymorphic). Upper surface of mesosoma between the metanotum and propodeum always low and flat or concave (Fig. c) => Myrmecorhynchus
 * Frontal carinae weakly arched or flat along their entire length (except the extreme forward ends near the antennal sockets, which are curved) (Fig. aa). Mandible with 6 or 7 teeth (Fig. bb). Worker caste only slightly variable in size (monomorphic). Upper surface of mesosoma between the mesonotum and propodeum either expanded upwards into a rounded or angular process (Fig. cc) or flat (Fig. dd) => Notoncus