A taxonomic revision of the genus Rothia (Crotalarieae, Fabaceae)

Abstract

Rothia Pers. is a genus of papilionoid legumes that consists of two species, R. indica (L.) Druce and R. hirsuta (Guill. & Perr.) Baker. The genus is a member of the tribe Crotalarieae and is widely distributed in Africa, Asia and Australia. Recent molecular systematic studies have shown the genus to be closely related to Robynsiophyton Wilczek and Pearsonia Dümmer; however, it is easily distinguished from these by its 10 small, rounded anthers and subequally lobed calyx (as opposed to the large, elongate anthers of Pearsonia or the 9 stamens of Robynsiophyton). These three genera share characters such as uniform anthers, straight styles and the presence of angelate esters of lupanine-type alkaloids. Leaf and fruit anatomy of Rothia and Robynsiophyton were also studied but revealed no informative differences. Both genera have dorsiventral leaves with mucilage cells in the epidermis and thin-walled fruits. A taxonomic revision of Rothia is presented, including a key to the species, correct nomenclature, descriptions, illustrations and distribution maps.