Ephemeroptera de 23 riachos foram amostrados a fim de avaliar a influencia dos fatores ambientais e espaciais sobre a fauna. Uma regressão parcial para abundância e riqueza e uma Análise de Redundância parcial para composição foram usadas com o objetivo de particionar os efeitos específicos do ambiente e do espaço. As variáveis espaciais foram obtidas usando o método PCNM considerando as distâncias através da matriz terrestre e ao longo do ambiente lótico. Considerando respectivamente as distâncias terrestres e aquáticas, o ambiente explicou 11,4% e uma porção não significativa da abundância, o ambiente indissociável do espaço explicou 20,8% e 31,7% e o espaço 27,5% e 31,7%. A riqueza, independentemente do tipo de matriz de distância utilizada, não foi explicada por nenhum dos componentes. Por outro lado, os fatores ambientais explicaram 19,5% e 12,6% da composição baseada na abundância, e 17,1% e 11,6% baseada em dados de incidência, considerando respectivamente as distâncias terrestres e aquáticas, em ambos os casos o espaço não foi significativo. Nossos resultados sugerem que para Ephemeroptera: 1) o tamanho do riacho pode ser um bom preditor da abundância total, mas não da riqueza; 2) a fauna se enquadra no modelo de metacomunidade Species Sorting e a dispersão é suficiente para manutenção da possibilidade dos táxons chegarem aos diferentes riachos, nos quais o estabelecimento é determinado pela combinação de fatores locais.The Role of Environmental and Spatial Factors on the Fauna of Ephemeroptera (Insecta) in Atlantic Forest Streams Abstract. Ephemeroptera of 23 streams were sampled in order to evaluate the influence of environmental and spatial factors on the fauna. A multiple partial regression to abundance and richness and a partial Redundancy Analyses to composition were used with the aim to partition the specific effects of the environment and space. The spatial variables were obtained using the PCNM method considering both, the distance through the overland matrix and along the lotic environment. Considering respectively overland and aquatic distances, the environment explained 11.4% and a not significant portion of abundance, the environment undistinguishable from space explained 20.8% and 31.7% and the space 27.5 % and 31.7%. The richness, independent of type of distance matrix used, were not explained by any of the components. On the other hand, the environmental factors explained 19.5% and 12.6% of composition based on abundance, and 17.1% and 11.6% based on incidence, considering respectively overland and aquatic distances, in both cases the space did not significant. Our results suggest that to Ephemeroptera: 1) the size of stream can be a good predictor of total abundance, but it not true for richness; 2) the fauna fits the Species Sorting metacommunity model and the dispersion is sufficient to maintain the possibillity of taxa arrive at different streams, in which the establishment it is determined by combination of local factors.

Austrolimnius cleidecostae sp. nov. is one of the smallest species of Elmidae from the Neotropical region. The new species is described and illustrated based on male and female specimens. This species represents the first record in Elmidae of mandibles with an articulated, sclerotized process on inner subapical edge. The specimens were collected from streams in the Atlantic rainforest of São Paulo and Santa Catarina, and habitat notes are given. An updated key for the Austrolimnius Carter & Zeck, 1929 of Brazil is provided. Austrolimnis browni Hinton, 1971 and A. musgravei Hinton, 1939 are recorded for the first time from Brazil.

We studied specimens of Anacroneuria (Plecoptera: Perlidae) collected from the region of Goiás City, Goiás State, Brazil. Two new species of Anacroneuria, A. meloi Bispo & Novaes and A. corae Bispo & Novaes are described and A. debilis (Pictet) is recorded for the first time from Goiás State.