Key to Subgenera of Ptomaphagus of Latin America (from Peck et al., 1998a)

1a Antennal club long, beginning with segment IV or at summit of III, club segments laterally expanded; Mexico to Brazil ...........................................................................................subgenus Tupania

1b Antennal club normal, beginning with segment VI or VII...................................................... 2

2a Body flatter; with erect setae; modified for life with harvester ants; probably in Mexico ...subgenus Echinocoleus [see Note]

2b Body less flat; setae recumbent; not modified for life with harvester ants............................ subgenus Adelops