Siphoneugena Berg (Myrtaceae, Myrteae) is a small eugenioid genus with eight species ranging from Puerto Rico to Northern Argentina with the centre of diversity in Southeastern Brazil. Keys to the species and varieties are provided, as well as synonyms, descriptions, illustrations and a map of geographical occurrence. Two new taxa are described from Brazil: Siphoneugena guilfoyleiana C. Proença, the only species to occur in sandy maritime vegetation on the Ilha do Cardoso, state of São Paulo and S. densiflora Berg var. cipoensis C. Proença, an endemic of the Serra do Cipó mountain range in the state of Minas Gerais. A new combination S. dussii (Krug & Urban) C. Proença based on Marlierea dussii, is made for a species that grows in Venezuela, Guyana, Surinam and the West Indies. This study confirms current opinions as to the low taxonomic value of open versus closed calyces in establishing natural genera within the Myrtaceae.
