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

Molecular phylogenetic studies have become a major area of interest in plant systematics, and their impacts on historical biogeographic hypotheses are not to be disregarded. In Brazil, most historical biogeographic studies have relied on animal phylogenies, whereas plant biogeographic studies have largely lacked a phylogenetic component, having a limited utility for historical biogeography. That country, however, is of great importance for most biogeographic studies of lowland tropical South America, and it includes areas from a number of biogeographic regions of the continent. Important biogeographic reports have been published as part of phylogenetic studies, taxonomic monographs, and regional accounts for small areas or phytogeographic domains, but the available information is subsequently scattered and sometimes hard to find. In this paper we review some relevant angiosperm biogeographic studies in Brazil. Initially we briefly discuss the importance of other continents as source areas for the South American flora. Then we present a subdivision of Brazil into phytogeographic domains, and we cite studies that have explored the detection of biogeographic units (areas of endemism) and how they are historically related among those domains. Examples of plant taxa that could be used to test some biogeographic hypotheses are provided throughout, as well as taxa that exemplify several patterns of endemism and disjunction in the Brazilian angiosperm flora. Key words angiosperms, biogeography, Brazil, disjunction, distribution patterns, endemism.Brazil is the fifth largest country in the world, with more than 8.5 million km 2 , and one of the most diverse in vascular plant species, with an estimated 55,000-60,000 species (Prance, 1994;Giulietti et al., 2005). The territory occupied by Brazil encompasses most of the world's remaining areas of tropical rainforests (primarily in the Amazon), as well as considerable areas of tropical savannas (the central Brazilian Cerrado) and seasonally dry tropical forests (SDTFs; mostly in the Caatinga). The country is also one of the few that includes two hotspots for the conservation of biodiversity sensu Myers et al. (2000), the Atlantic Forest and the Cerrado.Despite its unquestionable importance for the study of South American biogeography in general, there is a serious lack of biogeographic synthesis about Brazilian plants. Most studies so far have emphasized the detection of patterns of geographic distribution by mapping occurrence data, relegating the explanations on how these patterns were achieved to a somewhat speculative level. Because the vast majority of the available studies lack a phylogenetic perspective (e.g., Prance, 1979Prance, , 1988Giulietti & Pirani, 1988; Acevedo-Rodríguez, 1990; Alves et al., 2003;Gonçalves, 2004;Cavalcanti, 2007;Fiaschi & Pirani, 2008), the information generated has been regarded as having little relevance for historical biogeography, as the detection of areas of geographic distribution correspond only to the very first step of any h...

The Brazilian Atlantic Forest is considered one of the world's most important sites for biodiversity conservation, and within this biome there are regions with diVering levels of species richness, species composition, and endemism. The present study was undertaken in southern Bahia, Brazil, and employed a standardized sampling method to compare the density of arboreal species in this region with other areas throughout the world known for their high tree species density. A total of 144 tree species with DBH > 4.8 cm were sampled within a 0.1 ha plot of old-growth forest (OGF), and these data were then compared with 22 other world sites that had been sampled using the same methodology and likewise demonstrated high densities of arboreal species. Only one site of ombrophilous forest in Colombia demonstrated a higher tree species density (148 spp. in 0.1 ha) than was encountered in southern Bahia. Other areas of Brazil, including other Atlantic Forest sites, showed signiWcantly inferior tree species densities. These results indicate that this region of southern Bahia has one of the greatest numbers of tree species in Brazil and in the world. These results, associated with the high levels of endemism there, indicate the high biological importance of this region. It is therefore fundamental

Foi realizado um levantamento florístico de três remanescentes de floresta montana localizados na Mata Atlântica do sul da Bahia. Durante os anos de 2004 a 2008 foram feitas coletas periódicas de material botânico, principalmente ao longo de trilhas no interior dos fragmentos das áreas: Reserva Serra da Pedra Lascada - SPL, Reserva Serra das Lontras - SLO e Reserva Particular do Patrimônio Natural Serra Bonita - SBO. A riqueza florística em cada área foi comparada entre si e com outras áreas de Mata Atlântica na Bahia e no Sudeste do Brasil. Foi registrado um total de 1.129 espécies em 467 gêneros e 124 famílias. O hábito arbóreo representou 46,9% das espécies, seguido de herbáceas (20,1%), epífitas (19,5%) e trepadeiras (13,5%). As famílias Araceae, Asteraceae, Bromeliaceae, Fabaceae, Lauraceae, Melastomataceae, Myrtaceae, Orchidaceae, Piperaceae, Poaceae, Rubiaceae e Solanaceae apresentaram a maior riqueza florística nas três áreas em conjunto. O gênero Psychotria (Rubiaceae) apresentou o maior número de espécies em todas as áreas (21 spp.), destacando-se também Miconia (20 spp.), Solanum (20 spp.), Piper (19 spp.), Ocotea (16 spp.), Leandra (16 spp.), Peperomia (15 spp.) e Myrcia (14 spp.). Os resultados confirmam a elevada riqueza de angiospermas no sul da Bahia e evidenciam, pela primeira vez, a ocorrência de espécies características de regiões montanhosas da Mata Atlântica do Sudeste do Brasil nessa região.

-(Floristic composition and structure of the arboreal component of a transitional area of Atlantic forest in southern Bahia, Brazil). The purpose of this study was to attempt to detect a floristic transition in forest along an altitudinal gradient on a mountain side in southern Bahia, Brazil. The study site is located at the east-west transition from tropical moist to semideciduous forests. A belt transect of one hectare (10 × 1000 m) was established running up the slope (from ca. 350 m to 750 m elevation). All included trees and lianas ≥ 5 cm in diameter at breast height were numbered, collected, and measured. Density, dominance, frequency, and importance values (IV) were calculated for each species. We encountered 1400 individuals and 264 species of woody plants in 56 families. Cariniana legalis (Mart.) Kuntze had the highest IV, based on the dominance of a small number of trees. Discocarpus pedicellatus Fiaschi & Cordeiro and Ampelocera glabra Kuhlm. were the most frequent trees, with 90 and 86 individuals respectively. Ninety-six species were represented by a single individual. The Fabaceae and Myrtaceae were the most diverse families with 37 and 31 species respectively. Cluster analysis and correspondence analysis (DCA) revealed that the composition of the forest along the uppermost 30 percent of the transect was distinct from the rest. The lower and upper forests can be considered respectively as semideciduous and moist forests. Although there are some well-marked floristic differences between these forests, both clearly belong to the southern Bahian sector of the Atlantic coastal forests.Key words -altitudinal gradient, Atlantic coastal forest, Bahia, tropical semi-deciduous forest RESUMO -(Composição florística e estrutura do componente arbóreo de uma área transicional de Floresta Atlântica no sul da Bahia, Brasil). O objetivo deste estudo foi averiguar a existência de uma possível transição florística ao longo de um gradiente altitudinal numa floresta serrana do sul da Bahia, Brasil. A área amostrada situa-se em uma zona de transição (leste-oeste) entre florestas ombrófilas e estacionais. Um transecto linear abrangendo um hectare (10 × 1.000 m) foi situado na encosta da serra (de ca. 350 a 750 m.s.m.). Todas as árvores e lianas com DAP ≥ 5 foram numeradas, coletadas e medidas. Foram calculados valores de densidade, dominância, frequência e valor de importância (VI) para cada espécie amostrada. Foram amostrados 1.400 indivíduos agrupados em 264 espécies e 56 famílias de angiospermas. Cariniana legalis (Mart.) Kuntze teve o maior VI, devido à elevada dominância de poucos indivíduos. Discocarpus pedicellatus Fiaschi & Cordeiro e Ampelocera glabra Kuhlm. foram as espécies mais frequentes, com 90 e 86 indivíduos respectivamente. Noventa e seis espécies foram representadas por apenas um indivíduo. As famílias mais diversas foram Fabaceae e Myrtaceae com 37 e 31 espécies respectivamente. Análises de agrupamento e correspondência (DCA) revelaram que a composição florística da floresta situada na porção...