Key to the species of Luispenaia (based on males, females unknown)

1. Pronotum approximately subhexagonal (Fig. 12). Antennae with 8 antennomeres................................... 2

- Pronotum approximately suboval (Fig. 11). Antennae with 9 antennomeres....................................... 3

2. Lateral margin between clypeal base and ocular canthus projected as external rounded lobule (Fig. 12). Antennal club with 3 antennomeres, slightly longer than antennomeres 2–4; antennomeres 3–4 subequal, antennomere 5 disc shaped (Fig. 16)......................................................... Luispenaia paulseni Mondaca, Pizarro-Araya, & Alfaro

- Lateral margin between clypeal base and ocular canthus rounded, no projected as lobule (Fig. 11). Antennal club with 4 antennomeres subequal in length, longer than antennomeres 1–4 combined; antennomere 3 two times longer than antennomere 4; antennomere 5 lamellate (Fig. 15)........................... Luispenaia paposo Mondaca, Pizarro-Araya, & Alfaro 3. Clypeus subquadrate or broadly rounded (Fig. 13). Antennal club with 5 antennomeres; antennomere 4 subcylindrical (Fig. 14)................................................................................. L. paradoxa Martínez

- Clypeus rounded. Antennal club with 6 antennomeres; antennomere 4 lamellate (Fig. 17)....................................................................................... L. atacamensis Mondaca, Pizarro-Araya, & Alfaro