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Chiococca insularis (Ridley) C.M.Taylor & M.R.V.Barbosa (Rubiaceae) was described by Henry Nicholas Ridley in 1890, based on a collection he made on the island of Fernando de Noronha (Pernambuco, Brazil) in 1887. Since then, this species had not been collected again and has been treated as probably extinct. After 130 years, we discovered two new populations in the southwestern portion of the island, and the conservation status of the species is reassessed. A full description of the species, with previously unseen or unmeasured characters, habitat information and photographs of the plant and environment are provided.

Phyllanthus (Phyllanthaceae) is widely distributed within Brazilian phytogeographic domains where 101 species occur, including a number of poorly-known taxa, such as P. allemii, which was until now only known from the type collection. Here we report the rediscovery of P. allemii, which was recently collected during a floristic inventory carried out in the Estação Ecológica Serra Geral do Tocantins, which is located on the border between Bahia and Tocantins states in the Cerrado domain. We provide an updated and detailed morphological description of the species, including plates and field images, as well as a taxonomic key for species of Phyllanthus sect. Phyllanthus subsect. Clausseniani that occur in the Cerrado. We also provide habitat, ecology and distribution data, and, finally, a conservation assessment of this rare species.

A new species, Rhamnidium riograndense, from southern Brazil, is here described and illustrated. We present information about its distribution, habitat, phenology, conservation status and a key for all the South American species of the genus is provided. The new species is endemic to the central part of the state of Rio Grande do Sul, in the transition between Paraná and Pampean provinces in rocky habitats, mostly mountain slopes, where only four populations are currently known.

The inventory of ferns and lycophytes was carried out in Cerro da Pedra do Lagarto, a vegetation refuge with distinct phytophysiognomies (forest and natural grassland, respectively) located in the district of Santo Antao, North of the Municipality of Santa Maria, Rio Grande do Sul State. The aim of this study was to contribute to the knowledge of the flora of fern and lycophytes in the poorly sampled central Region of the State, supplying ecologic and biological data and a dichotomous key for the identification of the species observed. There are 34 fern species and two lycophyte species, belonging to 28 genera of 14 botanical families. Polypodiaceae was the richest family with eight species, followed by Pteridaceae, with seven. Most species were terrestrial and the only arborescent specie was Cyathea atrovirens. The inventoried data represent 9.5% of the known species of ferns and lycophytes for the State of Rio Grande do Sul.

Modelos ecológicos de distribuição de espécies (DAEs) em uma comunidade arbórea foram investigados para constatar: (i) se as variáveis ambientais são divididas de maneira estocástica e de modo similar entre as espécies; (ii) se cada espécie exaure mais da metade do nicho ecológico existente; (iii) se a comunidade arbórea possui muitas espécies com níveis intermediários de abundância e poucas espécies raras e comuns; (iv) e se, na sucessão secundária, as espécies colonizadoras tardias têm as maiores necessidades de um nicho especializado, de tal modo que são mais raras que as espécies colonizadoras iniciais. Obteve-se os dados em oito unidades amostrais de dimensões de 20m x 50m, distribuídas sistematicamente, perfazendo 0,8ha de amostra; ajustaram-se cinco modelos de DAEs (broken-stick, niche-preemption, log-normal, Zipf e Zipf-Mandelbrot) para a amostra e para as unidades amostrais; os critérios de acurácia dos modelos foram: Akaike, Bayesiano e Deviance. O modelo ecológico de DAEs que descreveu o ranking/abundância das espécies para a comunidade arbórea foi o Zipf-Mandelbrot. Os modelos ecológicos de DAEs que caracterizaram as unidades amostrais foram: niche-preemption, Zipf e Zipf-Mandelbrot. O modelo Zipf-Mandelbrot postula a colonização das espécies sob as exigências de condições ambientais prévias para o estabelecimento, assim, detecta-se uma comunidade arbórea em estágio de maturidade. Os modelos ecológicos de DAEs obtidos para as unidades amostrais, separadamente, evidenciam a disparidade da distribuição de abundância de espécies no interior da comunidade arbórea, que se interpretou como o efeito da heterogeneidade das condições e dos recursos ambientais, além de perturbações naturais, que originam um mosaico vegetacional. Ecological Models of Species abundance distribution (SADs) of a tree community were investigated to find: (i) if environmental variables are divided stochastically and similarly between species; (ii) if each species exhausts more than half of the existing ecological niche; (iii) if the tree community has many species with intermediate levels of abundance and a few rare and common species; (iv) and if, in secondary succession, the later colonizing species have greatest needs for a specialized niche, so, they are more rare than the initial colonizers species. The data were obtained in eight sampling units with dimensions of 20m x 50m, distributed in a systematic way, totaling 0.8 ha sample; grouped in five models of SADs (broken-stick, niche-preemption, lognormal, Zipf and Zipf-Mandelbrot) for the sample of the tree community and the eight sampling units; the criteria of accuracy of the models were: Akaike, Bayesian and Deviance. The ecological model described the SADs that rank/abundance of tree species for ecological community which was the Zipf-Mandelbrot. The ecological models of SADs that characterized the eight sampling units were niche-preemption, Zipf and Zipf-Mandelbrot. The Zipf-Mandelbrot model postulates the colonization of species under the requirements of environmental preconditions for the establishment of the species, and thus detects up an arboreal community stage of maturity. The ecological models of SADs obtained for the sampling units, separately, show the disparity in the distribution of species abundance within the tree community that was interpreted as the effect of heterogeneity of conditions and environmental resources, and natural disturbances, originating a mosaic vegetation.