1 Mandible strongly falcate (Fig. 13A); ventral margin of petiole a deep, evenly convex lobe (Fig. 14A); common species from Mexico to Brazil and Peru...................................... guianensis

- Mandible triangular (Fig. 13B–D); ventral margin of petiole less symmetrical (Fig. 14B–D); rare species from South America....... 2

2 Ventral margin of petiole a triangular lobe with pronounced anterior tooth (Fig. 14 B)................................................. pauli

- Ventral margin of petiole a shallow lobe lacking anterior tooth (Fig. 14C and D)................................................................... 3

3 Triangular projection of medial clypeus prominent, projecting beyond the outline of the clypeolabral juncture in full face view (Fig. 13C); HW> 0.8...................................... holmgreni

- Triangular projection of medial clypeus smaller, not projecting beyond the outline of the clypeolabral juncture (Fig. 13D); HW <0.8............................................................. holmgrenita