Duvalia Haw. in Syn. Pl. Succ.: 44 (1812).
Type: Duvalia elegans (Masson) Haw.
Etymology: Henry Auguste Duval (1777-1814), French medicine doctor and botanist, who named genera Haworthia and Gasteria.
Distribution: southern Africa (South Africa, Swaziland, Namibia, Angola, Botswana, Zimbabwe, Zambia, Moçambique, Malawi, Free State), eastern Africa (Somalia, Ethiopia, Djibouti, Sudan) and Arabian Peninsula (Yemen, Saudi Arabia).
Number of species: 18 with 3 infra-specific taxa (Plowes in press).
History: Francis Masson described in 1796 three species of Duvalia as Stapelia (S. caespitosa, S. reclinata and S. elegans). Adrian Hardy Haworth decribed the genus in 1812 and transfered all three Masson's plants and Sims's Stapelia radiata to it as D. elegans, D. caespitosa, D. reclinata and D. radiata and decribed four new taxa: D. tuberculata, D. laevigata, D. glomerata and D. compacta.
Nicholas Edward Brown revived the genus in 1908 with 19 species and 8 infra-species after some authors had placed the species of Duvalia back in Stapelia. Alain White and Boyd Sloane recognised 15 species with 10 infra-specific taxa in 1937.
Ulrich Meve made a revison of the genus in 1997. He recognized 17 species in two sections: Duvalia with 13 species and 1 infra-specific taxa and Arabica with 4 species and 2 infra-specific taxa.
Peter Bruyns reduced the section Duvalia to 10 species with 2 subspecieses in 2005, while the section Arabica was not included in the book.