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The molecular phylogenetic placement of Diclinanona (Annonaceae) has been debated in the literature for a decade. On the basis of morphological studies the genus was thought to be related to genera now all placed in subfam. Annonoideae. This early hypothesis was supported by the first phylogenetic analyses of Annonaceae. However, more recently a placement in subfam. Malmeoideae was hypothesised based on an analysis of more plastid data, thus contradicting older but also new morphological findings and previous phylogenetic work. The current study uses newly sequenced plastid data for two species of Diclinanona to show that the earlier hypothesised placement was correct and discusses the (little) anatomical and morphological data on Diclinanona that is available in a phylogenetic framework. Furthermore, an online revision of the three species oí Diclinanona is presented in order to update the taxonomic knowledge of this genus. [ABSTRACT FROM AUTHOR]

The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species--less diverse than the North American tree flora--accounts for half of the world's most diverse tree community.