Diagnosis.--Key characters: Ommatidial size coarse (Fig. 39b); prosternal process not planar, apex expanded (Fig. 18); mesal antennal spines present (Figs. 8b, 9b); pronotal impunctate regions present; pronotum without longitudinal rugosities or large, regularly-sized punctures; pronotum with prominent median and peripheral calli and acute lateral tubercles in most species; femoral carinae absent; procoxal cavities widely open laterally (Fig. 17); lateral projections into mesocoxae from mesosternum absent (Fig. 20); pro- and mesofemoral apices rounded (Fig. 26); metafemoral apices dentiform in most species (Fig. 25b); elytra without dense pubescence, nearly glabrous; tibial carinae present (Fig. 22); femora clavate (Fig. 37b); apicosutural spines of elytra absent; apicolateral spines of elytra pronounced and in normal lateral position; lateral antennal spines present on some antennomeres (Figs. 8a, 9a); lateral antennomere shape gradually widened at apices (Fig. 45c). Length: 9-15 mm.
Distribution and Diversity.--Bolivia, Brazil, Panamá, Paraguay, Peru, Guyanas, Venezuela. Eighteen species.
Discussion.--In the implied weighting phylogenetic analysis, the primarily South American Periboeum fell as the sister genus to the taxa above node B (Fig. 50). Addition of many of the unavailable South American taxa is necessary to fully understand its relationships.
The pronotum with dorsal calli and lateral tubercles, strong mesally-spined antennae with weak lateral spines, and clavate femora without distinct spines easily characterize this genus. Stizocera, which resembles Periboeum, lacks the strongly callose pronotum and acute lateral tubercles, and the laterally-spined antennae.