New remarks on the identity of Aloe deltoideodonta Baker (Xanthorrhoeaceae) and new name, Aloe horombensis nom. nov., for the Aloe of Southern Betsileo.

The identity of the mysterious Aloe deltoideodonta Baker is studied here. In the light of ancient writings of Rev. R. Baron which allow us to follow his trips and locate his harvests in Madagascar, of the study of the herbarium sheets from Kew and Paris, and of the morphological study of the plants in their natural habitat, I come to the same conclusion than J.-J. Lavranos, that A. madecassa H. Perrier from around Antananarivo is synonymous with A. deltoideodonta. New combinations and new names are proposed to solve the taxonomic problems caused by this synonymy: South Betsileo and Androy Aloe formerly named A. deltoideodonta var. brevifolia and A. deltoideodonta var. intermedia are renamed A. horombensis nom. nov. and the other former varieties or subspecies of A. deltoideodonta (candicans, fallax, ruffingiana, amboahangyensis) become subspecies of A. horombensis. Finally, a new subspecies from the Fort-Dauphin area is described here: A. horombensis subsp. andavakana subsp. nov.