A new key to the subgeneric classification of Mecynorhina Hope - one the most spectacular African Goliathini genera - is proposed by the authors. Furthermore, subgenus Megalorhina Westwood is thoroughly revised, leading to unanticipated, substantial taxonomical changes. All valid and former taxa - including a new taxon, Mecynorhina ( Megalorhina ) harrisii dedzaensis, n. ssp. - are identified, described and illustrated. Dichotomic keys and distribution maps are provided that enable the identification of all valid taxa. Photographs of 55 specimens (including most of the traceable type specimens), as well as a rich iconography showing details of structural and aedeagal characters, are presented in 16 high-quality colour plates.