It was impossible to confirm either WARBUTON's conservative nor TONELLI RONDELLI's opposite belief on the number of valid species after studying many lots of ticks of the ovale group, mainly from Brazil. Two species are recognized: Amblyomma ovale Koch, 1844 and Amblyomma aureolatum (Pallas, 1772), corresponding respectively to A. fossum Neumann, 1898 and A. stratum Koch, 1844. A list of synonyms is presented. Both species are redescribed and intraspecific morphological variation show to be the cause of the multiplication of species by those working with insufficient material. Color plates of both species are presented and hosts and localities of captures are recorded.

An attempt is made to clear the nomenclature of some netropical species of the genus Amblyomma. Amblyomma myrmecophagium Schulze, 1933 and Amblyomma brasiliense guyanense Floch et Abonnenc, 1933, are synonyms of Amblyoma scalpturatum Neumann, 1906. Amblyomma superbrasiliense Schulze, 1941, is cospecific with Amblyomma incisum Neumann, 1906. Amblyomma ypsilophorum Schulze, 1941, is a synonym of Amblyomma cooperi Nuttal et Warburton, 1907.