Key to the South American species of Megachoriolaus

1. Integument black, except red prothorax and brownish legs. Brazil (Rondônia, Mato Grosso, Goiás, Minas Gerais) (Fig. 10) ............................................................................................... M. bicolor (Gounelle, 1911)

- Integument with different patterns and coloration.......................................................................................2

2. Head, antennae and pronotum light brown–reddish. Brazil (Amazonas) (Fig. 9) ........................................ .......................................................................................................................... M. atripennis (Bates, 1870)

- Head and antennae with different colors; pronotum with a median longitudinal black line.......................3

3. Anterior half of the elytra bright red. Colombia (Fig. 11) ................................. M. venustus (Breme, 1844)

- Anterior 2/3 of the elytra yellowish. Brazil (Rondônia), Bolivia (Fig. 12) ............ M. clarkei new species