Aulacothorax is a genus of flea beetles in the family Chrysomelidae. There are at least 20 described species in Aulacothorax, found in the Palearctic, North America, Indomalaya, and Australasia. The genus was originally created in 1858 for a single species described from Tahiti, Aulacothorax exilis, which was placed in Scydmaenidae (now considered a subfamily of Staphylinidae). Recently, the holotype of this species was rediscovered in the collections of the Swedish Museum of Natural History, and it was found to belong to the flea beetle genus Orthaltica. Aulacothorax is the earliest available name for the genus, so the genus Orthaltica was formally placed in synonymy with it in 2017.