The history of the genus Caralluma is briefly outlined and characters of potential generic significance are discussed. 29 species of Caralluma — the ‘ango group’ and a few isolated southern African species — plus 2 species currently included in Stultitia are transferred to Pachycymbium. The species remaining are divided amongst four subgenera: Caralluma s. str. restricted to the ‘eucarallumas’, Urmalcala subgen. nov. and Boucerosia and Desmidorchis previously described as genera. The species are listed and several lectotypified. C. fulleri is transferred to Rhytidocaulon, two subspecies raised to full species (Caralluma edwardsiae and Pachycymbium laticoronum) and two new species described: Caralluma longiflora and Pachycymbium laikipiense.