Iosanthus (Hyacinthaceae subfam. Urgineoideae), a new genus from Southern Africa to include Ornithogalum toxicarium and its removal from Ornithogaloideae

In the framework of a taxonomic revision of subfamily Urgineoideae based on morphological and genetic data covering numerous samples from its whole range of distribution, we here describe a new genus from Southern Africa. Iosanthus gen. nov. includes Ornithogalum toxicarium, a highly toxic species originally placed in subfamily Ornithogaloideae. However, our morphological studies support its inclusion in subfamily Urgineoideae based on the small bracts with a slight curve or short spur abaxially, the withered perigone circumscissile below and forming an apical cap and widely winged seeds with loose testa, a treatment also supported by its isolated phylogenetic position within this subfamily that facilitates the description of the new genus. Moreover, we also show that the holotype collection of this species represents a mixed collection of O. toxicarium in flower and an Albuca sp. in fruit, and therefore a lectotype is selected to maintain the current concept of this species.