The genera CorinthiscusFairmaire and Germain, 1861, Morulaptoma Opitz, new genus, and Petorca Opitz, new genus, are redescribed/described, and revised. The species composition of these genera involves: Corinthiscus insignicornisFairmaire and Germain, 1861, Morulaptoma canuta Opitz, new species, Morulaptoma nigra (Chevrolat, 1876), new combination, and Petorca denticolla (Spinola, 1849), new combination. Corinthiscus nigra (Chevrolat) is now the type species of Morulaptoma. Lectotypes are designated for Corinthiscus insignicornisFairmaire and Germain, 1861, Pelonium nigrumaChevrolat, 1876, and Clerus denticollisSpinola, 1849. Biogeographical evidence suggests that these checkered beetle genera evolved in significantly different forest communities, and morphological observations indicate that they are carnivorous. It is hypothesized that the ancestor of this monophyletic assemblage diversified in a region involving Chile and Argentina, with radiation into the forested biomes of southeastern Brazil.