In this study, data are presented for the designation of the new subgenus (Bajacanthon) for Canthon obliquus Horn, 1894 (Deltochilini). The new subgenus Bajacanthon is described based on a multiple evidence approach using morphological and molecular characters. This new subgenus has some unique characters, and is the remnant of an old South American migratory movement into the Mexican Transition Zone. This beetle species has survived in isolation in the south half of the peninsula of Baja California (Mexico). Results based on molecular clock inference showed that the split between the lineages leading to the subgenus Bajacanthon and Boreocanthon took place nearly 16 Mya, whereas the radiation within Bajacanthon was dated to 3.7 Mya.
