Key to genera of Oryssomini Gordon, 1970

1. Tibia widened, flattened, and angulated on external margin near base (Guatemala, Costa Rica, Panama, Venezuela, Trinidad and Tobago and French Guiana)....................................................... Pseudoryssomus Gordon

1’. Tibia slender, unmodified............................................................................... 2

2. Antenna with 10 segments.............................................................................. 3

2’. Antenna with 11 segments............................................................................... 4

3. Eyes normal, with many facets; female genitalia with genital plate not elongate (Panama, Honduras, Costa Rica, Mexico, Belize, Guatemala, El Salvador, Trinidad, Venezuela, Colombia, Guyana, French Guiana and Brazil)... Oryssomus Mulsant

3’. Eyes with few very large facets (Chile)................................................. Anisorhizobius Hofmann

4. Pronotum with posterior angle strongly rounded............................................................. 5

4’. Pronotum with posterior angle acute (Chile).............................................. Rhizoryssomus Hofmann

5. Body very flattened (Chile)............................................................ Neoryssomus Hofmann

5’. Body not flattened; female genitalia with genital plate not elongate (Peru, Bolivia and Brazil)................................................................................................... Gordonoryssomus Almeida & Lima