Trachymyrmex

1. Median pronotal spines separated (Fig. 2, B), if basally fused, then their apexes are considerably distant from each other [e.g. Trachymyrmex arizonensis (Wheeler, 1907)].

2. Mandible dorsum striated (Fig. 2, E).

3. Preocular carinae short, frequently curved towards the frontal carinae (Fig. 2, B).

4. Pilosity sparse (Fig. 2, G).

5. Postocular protuberance inconspicuous (Fig. 2, B).

6. Vertexal corners slightly rounded (Fig. 2, E).

7. Posterior margin of head with mild median impression (Fig. 2, B).

8. Postpetiole in lateral view with posteromedial impression (posterior margin concave) (Fig. 2, G, I).

9. First gastral tergite generally with inconspicuous pairs of lateral and median ridges (Fig. 2, I).

10. Propodeal projections spiny (Fig. 2, G), rarely blunt [e.g. Trachymyrmex desertorum (Wheeler, 1911)]. 11. Promesonotum with subequal-sized projections (Fig. 2, G).

12. Antennal scape never with basal lobe; microtubercles tiny (Fig. 2, B, E).