The genus Mangonia Schott was described in 1857 with one species (M. tweedieana Schott) and later illustrated in his Genera Aroidearum (Schott, 1858). Hicken (1917) described a new genus, Fe/ipponia Hicken, with a single species, Fe/ipponia uruguaya Hicken. Later Hicken (1928) changed the generic name to Felipponiella because his earlier name was a later homonym of a moss genus described by Brotherus in 1912. When one of the authors (Bogner, 1973) studied Felippone's material (Felippone S/-297 and Fe/ippone 5772) it was clearly a second species of Mangonia and thus a separate genus is unnecessary. As circumscribed here the genus Mangonia contains two species. In this paper a comprehensive description of Mangonia tweedieana is presented based on observations made during a visit to Uruguay in 1999. Unfortunately we were unable to recollect M. uruguaya (Hicken) Bogner during the trip in 1999, although it has been very recently recollected at Cerro Largo in the Sierra de Rios. Bogner (1973) published an account of M. uruguaya.