Abstract The genus Chiasognathus Stephens is revised and now consists of seven species, all of which are endemic to southern South America. The genus-level names Bomansodus Chalumeau & Brochier, Carmeniella Molino-Olmedo, and Ramireziella Molino-Olmedo are all confirmed to be synonyms of Chiasognathus. A new species of Chiasognathus is described from the Biobio Region of Chile. The species Chiasognathus mniszechii Thomson is removed from synonymy and is a valid species with Chiasognathus schoenemanni Kriesche as its junior synonym. In order to promote nomenclatural stability, a lectotype is designated for the name Chiasognathus reichei Thomson, and a neotype is designated for the name Chiasognathus pygmaeus Dallas.