Key to the identification of Neotropical workers and queens of Probolomyrmex

1 Prora absent (Fig. 1A)................................................................................. 2 - Prora present (Fig. 1B - pr).............................................................................. 3

2 Ventral profile of the petiole with a subrectangular anterior projection. Guatemala, Mexico, and Panama (Fig. 2A - sp)................................................................................................ P. petiolatus

- Ventral profile of the petiole without a subrectangular anterior projection. Argentina and Brazil (GO, MS, MT, RO, and TO) (Fig. 2B - sp)................................................................................. P. brujitae

3 In lateral view, dorsal and posterior margins of propodeum meeting in a rounded angle, without any acute projection. Brazil (PA) (Fig. 3A - pd)..................................................................... P. lamellatus sp. n.

- In lateral view, dorsal and posterior margins of propodeum meeting in an acute angle, forming distinct teeth. (Fig. 3B - pd)..................................................................................................... 4 4 In lateral view petiole higher than long (Fig. 4A). In dorsal view petiolar teeth well developed. Brazil (PA, RO and TO) (Fig. 17C)................................................................................ P. dentinodis sp. n.

- In lateral view petiole longer than high (Fig. 4B). In dorsal view petiolar teeth absent or weakly developed (Fig. 21C)...… 5 5 In lateral view, the highest point of the dorsal profile of the first gastral tergite is at the posterior limit of the tergite. Nicaragua (Fig. 5A)................................................................................. P. cegua sp. n.

- In lateral view, the highest point of the dorsal profile of the first gastral tergite is anterior to the posterior limit of the tergite. (Fig. 5B - ppd)....................................................................................... 6