The American proteaceae

The American Proteaceae are outliers from the main centres of diversity of the family in Australia and South Africa. There are about 83 species in eig ht genera which all belong to the monophyletic subfamily Grevilleoideae. Th ree genera, Embothrium, Oreocallis and Lomatia, are placed in the tribe Emb othrieae (sensu Johnson and Briggs), four Euplassa, Gevuina, Panopsis and R oupala in the Macadamieae and the single genus Orites in the Oriteae. There are five genera endemic to America and three also have species in Australi a and New Guinea (Gevuina, Lomatia and Orites). The Proteaceae appear to ha ve arrived in South America via two routes. The larger genera Euplassa, Pan opsis and Roupala, which are all endemic to America and have a general dist ribution in northern South America and south-eastern Brazil, are derived fr om Gondwanaland before it separated from South America. The remaining gener a are distributed either in temperate South America or in the high Andes an d appear to have arrived more recently via the Australia-Antarctica-South A merican connection. Three of these genera have species in both regions. The centres of species diversity of Euplassa, Panopsis and Roupala fall outsid e hypothesised forest refugia, indicating that they are not true rainforest species but species of seasonal habitats like those achieved at higher alt itudes where they are commonly found. Two genera, Panopsis and Roupala, have reached Central America after the ce ntral American land bridge was formed six million years ago. The exact rela tionship to genera on other continents is still unclear and there is a need for a cladistic biogeographic analysis of the group based on both morpholo gical and molecular data.