The species of the African genus Gargilius Fairmaire, 1891 (Tenebrionidae: Diaperinae) are revised. Two new species are described: G. apicalis sp. nov. (Democratic Republic of the Congo) and G. gebieni sp. nov. (Cameroon, Gabon, Ghana). The following species are placed in synonymy: G. bicornutus Fairmaire, 1891 (= G. incornutus Pic, 1916 syn. nov., = G. rectangularis Gebien, 1921 syn. nov.), G. rufitarsis Fairmaire, 1894 (= G. affinis Gebien, 1921 syn. nov., = Gargilius mocquerysi Pic, 1916 syn. nov.), G. trispinosus Fairmaire, 1891 (= G. rhodesianus Pic, 1916 syn. nov., = G. ancey Pic, 1926 syn. nov.). Lectotypes for Gargilius antilope Gebien, 1921, G. bicornutus Fairmaire, 1891, G. incornutus Pic, 1916, G. rectangularis Gebien, 1921, G. rufitarsis Fairmaire, 1894, G. affinis Gebien, 1921, G. mocquerysi Pic, 1916, G. rhodesianus Pic, 1916, G. anceyi Pic, 1926 are designated to fix the taxonomic status of these species. The representatives of Gargilius can be easily distinguished by the shape of the sexually dimorphic head and pronotum, in combination with a relatively stable elytral colour pattern. The genus is restricted to arboreal habitats of central and southeastern Africa.