According to Literature, the group ofMicrogonium erosumwould be represented in continental Africa by the following five species, originally described as members ofTricbomanesand still mostly ascribed to it:M. erosum, M. aerugineum, T. palmicola, M. chamaedrysandM. ballardianum.Divergent opinions have been expressed on the identity and taxonomical value of these species; they are mainly due partly to an imperfect knowledge of the types and partly to an erroneous valuation of the importance of the distintive characteristics. The typification of each species is carefully investigated and established; the field of variability of the various characteristics is taken into consideration and the diagnostic value of them is ascertained.