Key to species of Oectropsis (adapted from Barriga & Cepeda 2005)

1. Pronotum with two distinct tubercles; each elytron with two distinct protuberances (Figs. 1–4, 18). Chile, Argentina .................................................................................... O. latifrons Blanchard, 1851

- Pronotum with tubercles slightly elevated or absent; elytra with two protuberances slightly elevated or lacking protuberances ................................................................................................... 2

2(1). Pronotum coarsely, distinctly punctate except smooth central area (Figs. 5–13). Chile, Argentina (?)..... O. chilensis sp. nov.

- Pronotum finely, densely punctate except smooth central area (Figs. 14–17). Chile ........... O. pusillus (Blanchard, 1851)