Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests.Amazonia | floristics | rain forests | seed plants | species diversity

Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even though the tropics occupy 40% of the Earth’s land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Amazon forest and Cerrado savanna), predicting major differences among biomes in relation to temperature and precipitation regimes. Precipitation explained most of litter inputs and storage, which were generally higher in more humid biomes (litterfall: 384, 422 and 308 g m−2 y−1, storage: 55, 113 and 38 g m−2, on average in Atlantic forest, Amazon and Cerrado, respectively). Temporal dynamics varied across biomes in relation to precipitation and temperature, with uniform litter inputs but seasonal storage in Atlantic forest streams, seasonal inputs in Amazon and Cerrado streams, and aseasonal storage in Amazon streams. Our findings suggest that litter dynamics vary greatly within the tropics, but point to the major role of precipitation, which contrasts with the main influence of temperature in temperate areas.

No abstract

Subfamily Gochnatioideae is the sister group of ∼96% of the species in Compositae (Asteraceae). It is of particular interest not only because of its position in the phylogeny, but also because, in recent molecular studies, the node it occupies is not strongly supported making difficult any inferences on the direction of character evolution in the family. The recognition of tribe Gochnatieae was one of the results of a comprehensive molecular analysis of the family that showed the traditional circumscription of the Mutisieae to be non–monophyletic. The four genera of Gochnatieae (Cnicothamnus, Cyclolepis, Gochnatia, Richterago) were defined by the presence of apiculate anther appendages and dorsally smooth style branches. Gochnatia, which contained about 70 species, was the largest and most complex genus and in the last decade some of its sections have been moved (or returned) to the rank of genus. This study includes a large selection of potential outgroups and over 60% of all species in the tribe, including all the genera and all but one of the sections of Gochnatia, to examine evolutionary relationships among the taxa. Both cpDNA and nrDNA were used in a phylogenetic analysis using parsimony, likelihood, and Bayesian approaches. The results suggest a non–monophyletic Gochnatia that is here resolved by the recognition of segregate genera. Morphological characters support these new genera and allow the adoption of a new classification for the Gochnatieae. A biogeographic analysis shows a possible southern South American/Andean origin followed by movement in three directions: into the Central Andes, into central and northern Brazil, and into Mexico and the Caribbean. The dating analysis gives an age of the split of the core Gochnatieae from the Wunderlichieae–Cyclolepis clade, and hence the age of the tribe, of 36–45 Ma and an age of 23–25 Ma for the first split within the core Gochnatieae (Andean vs. Brazil–Mexico–Caribbean). Cnicothamnus remains in Gochnatieae but Cyclolepis is designated incertae sedis.

RESUMO -(A família Euphorbiaceae nas caatingas arenosas do médio rio São Francisco, BA, Brasil). Euphorbiaceae é uma das famílias mais representativas da caatinga, particularmente nas áreas sobre dunas arenosas do médio rio São Francisco, no Estado da Bahia, Brasil. O levantamento das espécies de Euphorbiaceae nessa formação foi efetuado com base em coletas realizadas na região e materiais de herbário. A família está representada nas áreas estudadas por 20 espécies, distribuídas nos seguintes gêneros: Alchornea Swartz (uma espécie); Chamaesyce S.F. Gray (3); Cnidoscolus Pohl (4)(1). Chamaesyce alsinifolia (Boiss.) Sátiro, C. chamaeclada (Ule) Sátiro, Croton paludosus Mull. Arg., Manihot catingae Ule e M. heptaphylla Ule são endêmicas do Estado da Bahia. Cnidoscolus quercifolius Pohl e C. urnigerus (Pax) Pax são restritas às regiões de caatinga do Brasil. São apresentadas chaves para gêneros e espécies, descrições, ilustrações, dados sobre distribuição geográfica e habitat, bem como comentários sobre as espécies. Palavras-chave: Euphorbiaceae, dunas arenosas, médio rio São Francisco, florísticaABSTRACT -(The family Euphorbiaceae on the sand dunes of the middle São Francisco River, Bahia State, Brazil). Euphorbiaceae is one of the most representative families in the caatinga especially on the sand dunes of the middle São Francisco River, in the state of Bahia, Brazil. The survey of Euphorbiaceae species from this formation was based on field work and herbaria collections. The family is represented in the study area by 20 species: Alchornea Swartz (one species); Chamaesyce S.F. Gray (3); Cnidoscolus Pohl (4)