Trephionus inexpectatus, is a species of beetle belonging to the family Carabidae. It is endemic to Japan.[1]
The specific name inexpectatus is due to unexpected discovery, where it was taken as another congeneric species.
Body length of male is about 8.8 mm. Dorsal surface blackish brown to black. Endophallus stout in shape. No hind wings. Dorso-apical lobe conical. Apex of aedeagus truncate.