Pedro Fiaschi

Amazon plant diversity revealed by a taxonomically verified species list

Significance Large floristic datasets that purportedly represent the diversity and composition of the Amazon tree flora are being widely used to draw conclusions about the patterns and evolution of Amazon plant diversity, but these datasets are fundamentally flawed in both their methodology and the resulting content. We have assembled a comprehensive dataset of Amazonian seed plant species from published sources that includes falsifiable data based on voucher specimens identified by taxonomic specialists. This growing list should serve as a basis for addressing the long-standing debate on the number of plant species in the Amazon, as well as for downstream ecological and evolutionary analyses aimed at understanding the origin and function of the exceptional biodiversity of the vast Amazonian forests. 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.

Tovomita megantha: A new species of Clusiaceae from the Brazilian Atlantic Forest

Tovomita megantha, a new species presumably endemic to submontane Atlantic Forest in southern Bahia, Brazil is described, illustrated, and its diagnostic features compared to those of similar species. The new species belongs to the informal group Chrysochlamydifoliae. It differs from Tovomita choisyana and Tovomita longifolia by having much larger pedicels, flower buds, and floral diameters. The species here described is the tallest of the known species of Tovomita in the Atlantic Forest.ResumoTovomita megantha, uma nova espécie presumivelmente endêmica da Floresta Atlântica brasileira do sul da Bahia, é aqui descrita, ilustrada e suas características diagnósticas são comparadas e discutidas com espécies similares. A nova espécie pertence ao grupo informal Chrysochlamydifoliae. Difere de Tovomita choisyana e Tovomita longifolia pelos pedicelos, botões florais e diâmetro das flores muito maiores. A espécie aqui descrita é a mais alta dentre as espécies conhecidas de Tovomita da Floresta Atlântica.

Three new species of Tovomita (Clusiaceae) from the Amazon River basin and first record of papillae for Tovomita

Tovomita trachycarpa, T. vismiifolia and T. volkeri (Clusiaceae) are described, illustrated and mapped, and their diagnostic features are compared with those of similar species. Papillae are recorded for the first time for the genus, on the leaf blades, inflorescences and flower buds of T.vismiifolia, giving these structures a ferruginous color. Morphology of pollen grain and selected features of the leaf blade are discussed for the new species.

A new species of Dendropanax (Araliaceae) from the Brazilian Atlantic Forest

Abstract. Dendropanax fluminensis, a new species of Araliaceae from the Atlantic Forest of Rio de Janeiro state, Brazil, is here described and illustrated. It is compared with morphologically similar species from the Brazilian Atlantic Forest, especially D. monogynus, from which it can be distinguished by the inflorescences with 2–5 secondary axes, shorter pedicels in flower and in fruit, and 3- or 4-carpellate ovaries. The new species has been found in lowland rainforests from sea-level to about 200 m elevation in the central portion of Rio de Janeiro state. Information on the geographic distribution, habitat preferences, and conservation status according with IUCN Red List categories and criteria are also presented.Resumo. Dendropanax fluminensis, uma nova espécie de Araliaceae da Mata Atlântica do estado do Rio de Janeiro, Brasil, é aqui descrita e ilustrada. A espécie é comparada a espécies morfologicamente semelhantes da Mata Atlântica brasileira, especialmente D. monogynus, da qual o novo táxon pode ser distinto pelas inflorescências com 2–5 eixos secundários, pedicelos das flores e dos frutos mais curtos e ovários com 3−4 carpelos. A espécie tem sido encontrada em florestas pluviais de terras baixas do nível do mar a até ca. 200 m de altitude na porção central do Rio de Janeiro. Informações sobre a distribuição geográfica, o hábitat preferencial e o estado de conservação de acordo com as categorias e critérios da Lista Vermelha da IUCN também são fornecidos.

The taxonomic significance of pollen morphology in Tovomita Aubl. (Clusiaceae: Clusieae) and related genera

Tovomita (Clusiaceae, tribe Clusieae) comprises about 45 species with Neotropical distribution. Thirty of these species occur in the Brazilian Amazon and Atlantic forest, but have only been poorly sampled in studies of pollen morphology. Pollen grains of ten species of Tovomita and one of Tovomitopsis are characterized and illustrated here and morphologically compared with those from other extant genera of Clusiaceae s.s., as well as the fossil genus Paleoclusia (which shares with Tovomita prolate triaperturate pollen grains with reticulate exines and sexine elements inside the lumina). The pollen grains of the analyzed species of Tovomita were found to be tricolporate, with amb circular to subtriangular, and exine psilate to microreticulate. Tovomita pollen differs markedly from Tovomitopsis in terms of the tectum surface, which is smooth with regular baculate in the former, versus irregular and not smooth, with some twisted baculate processes, in the latter. Other pollen features among species of Clusiaceae are discussed in order to better characterize Tovomita and help elucidate generic limits among related genera.

Three new species and a revised key to species of Oxalis section Polymorphae (Oxalidaceae)

Three new species of Oxalis sect. Polymorphae are here described and illustrated: Oxalis artemioides, O. calcicola, and O. monochasiata. These species have narrow geographic distributions, each being known from just one location. Oxalis artemioides differs from other species of the section by the glabrous stem, narrow terminal leaflets (8–10.5 × 2 mm), and inflorescences with elongated dichasial branches bearing flowers only in the distal portion. Oxalis calcicola differs from other species by having the young stem with adpressed-retrorse trichomes, inflorescences shorter than adjacent leaves, short dichasial branches (0.5–3 mm long) with flowers densely grouped along the entire length, and glabrous pedicels. Oxalis monochasiata is remarkable because of its monochasial inflorescence and the two-ovulate carpels, both features unique within Oxalis sect. Polymorphae. The new species are compared to similar species of the section, and information on distribution and habitat, phenology, and conservation status according with IUCN criteria are provided. Geographic distribution maps, lists of examined materials and an identification key for species of this section are also presented.

Sobrevivência de plântulas, características fotossintéticas e crescimento de Discocarpus pedicellatus (Phyllanthaceae)

Resumo Discocarpus pedicellatus e uma especie arborea endemica da Mata Atlântica que apresenta regeneracao natural por meio da formacao de bancos de plântulas, ocorrendo em populacoes com manchas de elevada densidade de arvores adultas nas florestas semideciduas do sul da Bahia. Foram realizados dois estudos, um no campo e outro em casa de vegetacao, visando analisar a sobrevivencia de plântulas e os efeitos do sombreamento nas caracteristicas fotossinteticas e no crescimento de plantas jovens de D. pedicellatus . No inicio das avaliacoes no campo a densidade de plântulas foi muita elevada, em torno de 700 plântulas m -2 . Ao final de dois anos esses valores variavam entre 5 e 190 plântulas m -2 , sendo raros os individuos que apresentavam folhas verdadeiras. Em casa de vegetacao, os valores da taxa fotossintetica liquida em saturacao de radiacao luminosa (A max ), da irradiância de compensacao (Ic), da taxa de respiracao no escuro (Rd), da taxa de crescimento relativo (TCR) e da taxa assimilatoria liquida (TAL), indicam que essa especie apresenta crescimento lento, tipico de especies que regeneram no interior de florestas com dossel fechado. Alem disso, com o aumento do sombreamento observou-se uma diminuicao significativa da Rd, indicando que a sobrevivencia no sub-bosque esta associada com baixas taxas metabolicas e de crescimento. Os resultados obtidos indicam que a estrategia de regeneracao por bancos de plântulas e a capacidade de ajustar o seu metabolismo em funcao da radiacao luminosa disponivel sao fatores importantes para o estabelecimento de populacoes de D. pedicellatus com manchas de elevada densidade populacional nas florestas semideciduas do sul da Bahia. Seedling survival, photosynthetic characteristics and growth of Discocarpus pedicellatus Abstract Discocarpus pedicellatus is an endemic tree species in the Atlantic Forest. It presents natural regeneration from seedling banks and populations with patches of high-density of adult trees in the semideciduous forests of southern Bahia, Brazil. Two studies were conducted, in the field and under greenhouse conditions, aiming to analyze seedling survival and the effects of shade on growth and on photosynthetic characteristics of D. pedicellatus saplings. In the field, the density of seedlings was very high at the beginning of the study, in some cases exceeding 700 seedlings m -2 . After two years of observations, density values were between 5 and 190 seedlings m -2 and few individuals showed the first true leaves. In greenhouse, the results obtained for light-saturated net photosynthetic rate (A max ), the compensation irradiance (Ic), the dark respiration rate (Rd), the relative growth rate (TCR) and the net assimilation rate (TAL), suggest that this species presents slow growth, typical of species that regenerate in the understory of mature forests under closed canopies. Also, in response to increase in shading there was a significant decrease in Rd, indicating that the survival in the forest understory may be associated to low metabolic and growth rates. The results indicate that the regeneration strategy by seedling banks and the ability to adjust their metabolism in response to the low available light radiation are important factors that explain the establishment of high-population density patches of D. pedicellatus in the semideciduous forests of southern Bahia, Brazil.