Promecognathus

Promecognathus is a genus of ground beetles in the family Carabidae. There are at least two described species in Promecognathus. Both species of Promecognathus are known to predate upon Xystocheir dissecta, which is a species of flat-backed millipede that produces hydrogen cyanide as a chemical defense. The beetles do not avoid exposure to the defense, meaning they are likely physically resistant to hydrogen cyanide.

Species
These two species belong to the genus Promecognathus:
 * Promecognathus crassus LeConte, 1868
 * Promecognathus laevissimus (Dejean, 1829)