Key to species of Oryssomus Mulsant

1. Pronotum and elytra yellow with dark brown rounded discal spot Brazil (AM).......... O. unimaculatus Almeida & Lima

1’. Dorsal color pattern not as described above................................................................. 2

2. Pronotum with an elongate, median, black spot extending from base nearly to apex; elytron black with large, red spot on apical third (Mexico, Belize, Guatemala, El Salvador, Honduras, Costa Rica, Panama, Trinidad and Tobago, Venezuela, Colombia, French Guiana, Brazil)............................................................. O. subterminatus Mulsant

2’. Dorsal color pattern not as described above................................................................. 3

3. Elytra black with humeral area and diagonal stripe red (Bolivia and Trinidad and Tobago)............. O. lineatus Gordon

3’. Dorsal color pattern not as described above................................................................ 4

4. Elytra black with a slender yellowish brown line at border on the posterior 1/3 of elytra (Brazil)........ O. paschoali sp. nov.

4’. Dorsal color pattern not as described above................................................................. 5

5. Elytra reddish brown with chalice-shaped black spot in the middle that does not reach humeral callus (French Guiana)............................................................................................. O. calix sp. nov. 5’. With a different color pattern........................................................................... 6

6. Elytra reddish brown with black large spot in base comprising 2/3 of total length of the elytra (French Guiana)............................................................................................... O. guillermo sp. nov.

6’. Dorsal color pattern not as described above................................................................. 7

7. Postcoxal line extending just beyond middle of first ventrite; elytra brownish yellow with a rhomboidal black spot on the middle of the dorsum (French Guiana)........................................................ O. rhombus sp. nov.

7’. Postcoxal line almost touching the posterior margin of the first abdominal ventrite; elytra brownish yellow with black area not rhomboidal......................................................................................... 8

8. Elytra with a triangular black spot almost extending to apex (French Guiana).................... O. guyanensis sp. nov.

8’. Elytra with a large black spot arrow shaped (Brazil)............................................ O. rogeri sp. nov.