Promecognathus contractus, Promecognathus corpulentus, Promecognathus grandiceps Promecognathus crassus is a species of ground beetle in the family Carabidae.

It is found along the Pacific coast of North America, from British Columbia to California.

[1] P. crassus, like its close relative Promecognathus laevissimus, uses its large jaws to feed on millipedes, including those that produce hydrogen cyanide and benzaldehyde, like Xystocheir dissecta.

It displays a high tolerance to these toxins.

This Scaritinae-related article is a stub.