The araneofauna of the Neotropical region can be considered undersurveyed and lacking standardized inventories that can be used as a base for biodiversity studies. Spiders are recognized as important components of forest ecosystems and appear to be good organisms for studies concerning biodiversity standards. A survey was carried out in the Parque Estadual do Turvo, Rio Grande do Sul, Brazil to determine the richness and composition of the spider fauna. The Park is a protection area that includes the only remainder of the Floresta do Alto Uruguai in Brazil. Four expeditions were conducted over the period of two years, in Spring and Autumn (2003-2005). The main sampling technique was the beating tray, sampling the vegetation along the trails inside the park. Additionally, pitfall-traps, Winckler extractors, nocturnal manual collecting and random samplings were used. Shannon-Wiener (H') diversity indices and rarefaction curves were calculated for the beating tray samplings. A total of 8724 spiders belonging to 37 families were collected. Of these, 34% (2946) were adults, distributed in 31 families, 157 genera and 447 morphospecies. The richest families were Salticidae (23%) followed by Araneidae (18%), Theridiidae (16%) and Thomisidae (9%). In the beating tray samples 29 families were recorded. The most abundant families (including young individuals) were Salticidae (23%), Araneidae (18%), Thomisidae (14%), Theridiidae (12%) and Anyphaenidae (12%). Nineteen species presented a percentage higher than 1% of the total of collected adult individuals. The most abundant being Thwaitesia affinis O. P.-Cambridge, 1881 (Theridiidae), Tariona sp.1 (Salticidae) and Misumenops argenteus (Mello-Leitão, 1929) (Thomisidae). The Spring periods revealed more adult individuals and species and the Shannon-Wiener (H') diversity was considered higher in the periods of Autumn. The rarefaction curves did not reach asymptote, suggesting the existence of non-sampled species. The spider richness registered in this survey is the greatest observed for Rio Grande do Sul, and the second greatest for Brazil. These information show the importance of this ecosystem for biodiversity conservation in Brazil.Keywords: spiders, inventory, Neotropical, biodiversity. A região Neotropical é considerada pouco amostrada com relação à sua araneofauna, carecendo de inventários padronizados que possam servir de base para estudos de biodiversidade. As aranhas são consideradas como importantes componentes dos ecossistemas florestais e aparentam ser organismos ideais para estudos de padrões de biodiversidade. Neste estudo foi efetuado um levantamento da riqueza e composição da fauna de aranhas do Parque Estadual do Turvo, Rio Grande do Sul, Brasil, local que protege o único remanescente representativo da Floresta do Alto Uruguai no Brasil. Foram realizadas quatro expedições semestrais, durante dois anos, no outono e na primavera (2003)(2004)(2005). Como principal técnica de coleta foi empregado o guarda-chuva entomológico, com o qual amostou-se a vegetação arbór...

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, 17 samples were taken, distributed in three periods: before seeding, during the development of the rice plants and after the harvest. Samples were done in the morning using sweeping nets (35 cm diameter), 50 sweeps in each of four randomly chosen transects. A total of 918 spiders were sampled, distributed in 14 families, mostly Araneidae, Anyphaenidae, Oxyopidae and Tetragnathidae. Among the adults, 38 morphospecies were found, the most abundant were Alpaida veniliae (Keyserling, 1865), Tetragnatha nitens (Audouin, 1826), Ashtabula sp.1 and Tetragnatha aff. jaculator, the four together comprising more than 45% of the adult specimens. Of the species richness estimators used, Chao 1 was closer to the observed richness; 87,4% of the potentially present species were effectively sampled. Both abundance and species richness showed an increasing trend, accompanying rice development (and thus increasing habitat complexity), with a stern decrease after harvesting. A constant colonization of the habitat is thus postulated, also given the high number of young spiders found at all times. There were no significant correlations between climatic factors (temperature and rainfall) and neither abundance nor species richness, except a positive one between rainfall and richness. Among the functional groups, ambushing hunters dominated, followed by orb-web builders. An analysis of similarity (ANOSIM) found significant differences among the fauna of the three evaluated periods. Thus, system disturbance, in the form of rice sowing and harvesting, brutally altering environmental structure, leads to strong spider diversity changes both in terms of species richness and species composition. The results suggest biodiversity studies in agroecosystems can help us understand not only applied but also basic problems.

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ABSTRACT. List of spiders species (Arachnida, Araneae) of the state of Rio Grande do Sul, Brazil. A spiders species list including 808 species of 51 families occurring in the state of Rio Grande do Sul, Brazil, is presented. Type locality, municipalities of occurrence and taxonomic bibliography concerning these species are indicated. KEYWORDS.Inventory revision, type localities, municipalities records, Neotropical.RESUMO. É apresentada uma lista de 808 espécies de aranhas, incluídas em 51 famílias ocorrentes no Rio Grande do Sul, Brasil. São indicados localidade-tipo, municípios de ocorrência e a bibliografia taxonômica de cada espécie. PALAVRAS-CHAVES.Inventário, localidades-tipo, registros municipais, Neotropical.A ordem Araneae reúne atualmente 110 famílias distribuídas em 3821 gêneros e 42055 espécies, mostrando nas últimas décadas um aumento progressivo no conhecimento das espécies e sua distribuição mundial (PLATNICK, 2011). Na Europa do século XIX, era prática usual promover expedições com a finalidade de colecionar animais para os museus de história natural. Pesquisadores contavam com o auxílio de colaboradores ou de naturalistas viajantes para obtenção de espécimes. No Brasil inúmeras aranhas foram coligidas em localidades do Rio de Janeiro e Santa Catarina pelos naturalistas Emílio Goeldi e Fritz Plaumann, respectivamente.Para o Rio Grande do Sul, um número significativo de espécimes foi reunido por Hermann von Ihering, médico e naturalista, nascido na Alemanha. Residiu em Taquara do Mundo Novo de 1880-1883, região que incluía o atual município de Taquara além de municípios limítrofes, em Rio Grande (1884/1885) e posteriormente em São Lourenço do Sul, locais onde colecionou centenas de aranhas. As coletas desses períodos foram enviadas ao aracnólogo alemão Eugen von Keyserling, o qual publicou os resultados em uma expressiva obra, "Die Spinnen Amerikas" (KEYSERLING, 1880b;1884a;1886;1892;1893). Um dos volumes, "Die Spinnen Amerikas. Brasilianische Spinnen" (1891), é dedicado às aranhas brasileiras, com ênfase aos estados do Rio de Janeiro e Rio Grande do Sul. A maioria dessas aranhas está depositada em museus europeus da Inglaterra e da Polônia.Posteriormente, MELLO-LEITÃO (1931) assinalou para o Rio Grande do Sul a ocorrência de três novas espécies de Cacimbinhas, atual município de Pinheiro Machado.O primeiro catálogo de aranhas do estado do Rio Grande do Sul foi apresentado por MELLO-LEITÃO (1943), o qual relacionou 431 espécies, pertencentes a 173 gêneros e 31 famílias. Registrou as 219 espécies descritas por Keyserling em "Die Spinnen Amerikas" e relacionou mais 212 espécies, entre as quais 67 novas para a ciência. A maior parte dessas aranhas foi coletada pelo Padre Balduino Rambo, tendo sido depositadas no Museu Nacional do Rio de Janeiro. Ainda para o Rio Grande do Sul, BÜCHERL (1952) realizou um estudo sobre aranhas e teceu comentários sistemáticos, ecológicos, biológicos e ação da peçonha.A partir de 1970, intensificaram-se as pesquisas aracnológicas no Museu de Ciências Naturais (MCN), estab...

The distribution of beta diversity is shaped by factors linked to environmental and spatial control. The relative importance of both processes in structuring spider metacommunities has not yet been investigated in the Atlantic Forest. The variance explained by purely environmental, spatially structured environmental, and purely spatial components was compared for a metacommunity of web spiders. The study was carried out in 16 patches of Atlantic Forest in southern Brazil. Field work was done in one landscape mosaic representing a slight gradient of urbanization. Environmental variables encompassed plot- and patch-level measurements and a climatic matrix, while principal coordinates of neighbor matrices (PCNMs) acted as spatial variables. A forward selection procedure was carried out to select environmental and spatial variables influencing web-spider beta diversity. Variation partitioning was used to estimate the contribution of pure environmental and pure spatial effects and their shared influence on beta-diversity patterns, and to estimate the relative importance of selected environmental variables. Three environmental variables (bush density, land use in the surroundings of patches, and shape of patches) and two spatial variables were selected by forward selection procedures. Variation partitioning revealed that 15% of the variation of beta diversity was explained by a combination of environmental and PCNM variables. Most of this variation (12%) corresponded to pure environmental and spatially environmental structure. The data indicated that (1) spatial legacy was not important in explaining the web-spider beta diversity; (2) environmental predictors explained a significant portion of the variation in web-spider composition; (3) one-third of environmental variation was due to a spatial structure that jointly explains variation in species distributions. We were able to detect important factors related to matrix management influencing the web-spider beta-diversity patterns, which are probably linked to historical deforestation events.

Wetlands (e.g. ponds, meadows) can be found in many landscapes, playing an important role in maintaining regional biodiversity and supporting heterogeneous communities. Spiders are diversified predators that are highly influenced by changes in plant community structure, heterogeneous habitats sustain high spider diversity and abundance. We investigated the characteristics of spider biodiversity in ponds with different habitat structures, by examining patterns across habitats of ponds with different vegetation levels. Sampling took place in four occasions over a year. We compared spider abundance, species richness and composition among ponds including distinct vegetation variables, related to life form, type of leaves, coverage and height. Overall 1174 individuals (194 adults) of 11 families and 37 morphospecies were sampled. We found mostly expected differences in the manner that communities were structured between different habitats. Thus, higher variability of abundance was explained for higher habitat structure of ponds. We also found differences in species composition between ponds with low emergent vegetation and higher habitat structures. Additionaly, spiders were consistently structured more by turnover than nestedness components, with a greater beta diversity of web‐builders. Our results suggest varying levels of habitat structures and species substitution shape pond spider communities, depending on habitat heterogeneity and spider guild. Those findings demonstrate the clear role of spatial habitat structure, with more spider species preferring to build webs or actively hunt at vegetated environments on ponds.

ABSTRACT. The Araneidae is a speciose family including web-spinning spiders that are very abundant in various terrestrial ecosystems. Several studies demonstrate that changes in vegetation surrounding rivers, streams and brooks affect the associated araneofauna. The aim of this research was to compare differences found in diversity (abundance and richness), composition and phenology of Araneidae spiders sampled in different habitats in four riparian forest catchments in southern Brazil. Samples were taken from riparian forests in four rivers of Rio Grande do Sul State: Piratini, Camaquã, Sinos and Maquiné rivers, each in a different hydrographic basin. Samples were taken twice seasonally on each basin during two years, sampling the araneofauna of the tree-shrub strata with beating tray. Six transects were employed on each basin, two per habitat: edge with grassland, forest interior and river edge. Araneids totalled 20 genera and 65 species. Comparing riparian forests significant differences are found. Spider abundance differed among riparian forests as well as species richness. Overall, Piratini river riparian forest had the higher abundance and richness for Araneidae; the lower values were in Sinos river forest. The stronger degradation and fragmentation of the riparian forests of Sinos river probably influenced the results, with human disturbance gradients associated negatively to web building. We present data on the diversity of these spiders, which were very abundant in the riparian forest interior and very rich in species in the grassland/riparian forest edge. Species composition also differs among the studied habitats (the above plus river/riparian forest edge). For the most abundant species the phenological pattern across the seasons was also analysed.KEYWORDS. Spiders, habitats, Rio Grande do Sul, abundance, richness.RESUMO. Diversidade, composição e fenologia de aranhas construtoras de teias (Araneae, Araneidae) associadas com matas ciliares no sul do Brasil. Araneidae é uma das famílias com maior número de espécies, incluindo aranhas construtoras de teias que são muito abundantes em diversos ecossistemas terrestres. Vários estudos demonstram que mudanças na vegetação circundante de rios, córregos e riachos pode afetar a araneofauna associada. O objetivo deste estudo foi avaliar aspectos sobre a diversidade (abundância e riqueza), composição e fenologia de aranhas Araneidae foram amostradas em diferentes habitats em quatro bacias de mata ciliar no sul do Brasil. Foram coletadas amostras de matas ciliares em quatro rios do Rio Grande do Sul, todos em diferentes bacias hidrográficas: nos rios Piratini, Camaquã, dos Sinos e Maquiné. As amostras foram realizadas duas vezes por estação em cada bacia, durante dois anos, a amostragem da araneofauna do estrato arbóreo-arbustivo foi realizada com guardachuva entomológico. Seis transecções foram empregadas em cada mata ciliar, dois por habitat: borda com campo, interior da floresta e borda do rio. Araneídeos totalizaram 20 gêneros e 65 espécies. Comparando-se as ...