The genus Amithao Thomson, 1878 is comprehensively revised. Redescriptions of previously known species, a key for identification, and illustrations of the 13 species are provided. Guatemalica marginicollis (Burmeister) is transferred to Amithao. The following new synonyms are established: Desicasta nonfriedi Schoch and Amithao erici Mitter are Amithao erythropus (Burmeister); Amithao thomsoni (Janson) is Amithao haematopus (Schaum); Amithao niveosparsus Moser and Amithao sparsus Casey are Amithao lafertei (Thomson); and Amithao spence (Gory and Percheron) is Amithao tristis (F.). Amithao obscurus Schoch is a female of Tiaocera rhinoceros (Gory and Percheron). Amithao staudingeri Schürhoff is rediscovered. Amithao tristis (F.) is transferred from junior to senior synonymy. Amithao anthracinus Ratcliffe from Panama is described as a new species.