ABSTRACT. Distribution, abundance and diversity of Simuliidae (Diptera) in an impacted watershed in southern Brazil. This study was carried out in two areas with different degrees of environmental degradation in the Caí river basin, in Rio Grande do Sul. One sampling area is less altered and the other is strongly impaired by organic pollutants from avian and swine production. The larvae and pupae of simulids were collected using artificial substrates that remain submersed in streams for 14 days. In all sampling sites water was collected simultaneously for physical-chemical and microbiological analysis. In the less disturbed area eleven species were collected with the following frequencies: Psaroniocompsa incrustata (42.95%), P. auripellita (17.66%), Chirostilbia pertinax (16.86%), Inaequalium subclavibranchium (8.43%), I. nogueirai (5.80%), P. anamariae (3.69%), I. clavibranchium (1.58%), C. riograndense (0.92%), Lutzsimulium hirticosta (0.92%), I. botulibranchium (0.79%), Thyrsopelma itaunense (0.40%). In the more disturbed area only six species were collected: C. pertinax (84.31%), C. riograndense (7.52%), T. itaunense (4.68%), P. incrustata (2.94%), I. subclavibranchium (0.33%), Ectemnaspis dinellii (0.22%). The concentrations of nitrate and nitrite had the greatest variations and allowed us to distinguish the sampling sites by to water quality. The nitrate concentration was significatively correlated with the occurrence of C. pertinax (r 2 = 0,54; P < 0,03) and T. itaunense (r 2 = 0,55; P < 0,03) while the nitrite concentration with C. riograndense (r 2 = 0,64; P < 0,02). These data can be useful for integrated black flies control programs, currently in use in at least 170 municipalities of Rio Grande do Sul.

Macroinvertebrate communities are one of the most used groups in assessments of water quality, since they respond directly to the level of contamination of aquatic ecosystems. The main objective of this study was the assessment of the water quality of the Sinos River basin (Rio Grande do Sul state, Brazil) through biotic indices based on the macroinvertebrate community ("Family Biotic Index -FBI", and "Biological Monitoring Working Party Score System -BMWP"). Three lower order streams (2 nd order) were selected in each one of three main regions of the basin. In each stream, the samplings were performed in three reaches (upper, middle, and lower), totalling 27 reaches. Two samplings were carried in each reach over one year (winter and summer). A total of 6,847 macroinvertebrates distributed among 54 families were sampled. The streams from the upper region were of better water quality than the lower region. The water quality did not change between the upper, middle and lower reaches of the streams. However, the upper reaches of the streams were of better water quality in all the regions of the basin. The water quality of the streams did not vary between the summer and the winter. This result demonstrated that water quality may be analysed in both studied seasons (summer and winter) using biotic indices. The analysis of the results allows us to conclude that the biotic indices used reflected the changes related to the water quality along the longitudinal gradient of the basin. Thus, aquatic macroinvertebrates were important bioindicators of the water and environmental quality of the streams of the Sinos River basin.Keywords: hydric resources, bioindicator, biomonitoring, water quality, biotic indices. Os arroios da bacia hidrográfica do Rio dos Sinos estão com boa qualidade da água?Os macroinvertebrados aquáticos podem responder a questão Resumo A comunidade de macroinvertebrados aquáticos é um dos grupos mais utilizados na avaliação da qualidade da água, pois respondem de forma diferente ao grau de contaminação dos ecossistemas aquáticos. O principal objetivo deste estudo foi avaliar a qualidade da água na bacia hidrográfica do Rio dos Sinos (Rio Grande do Sul, Brasil) através de índices bióticos baseados em comunidades de macroinvertebrados aquáticos (Family Biotic Index -FBI, e Biological Monitoring Working Party Score System -BMWP). Três arroios de pequena ordem (2º ordem) foram selecionados em cada uma das três principais regiões da bacia. Em cada arroio foram realizadas coletas em três trechos (superior, médio e inferior), totalizando 27 trechos. Foram realizadas duas coletas ao longo de um ano em cada trecho de arroio (inverno e verão). Um total de 6.847 macroinvertebrados distribuídos em 54 famílias foi coletado nos arroios. Os arroios da região superior da bacia apresentaram uma melhor qualidade da água do que os da região inferior. A qualidade da água não variou entre os trechos superior, médio e inferior dos arroios. Entretanto, os trechos superiores dos arroios apresentaram uma melhor qualidade ...

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Abstract. In southern Brazil there are several problems regarding the hematophageal activity of black flies, and the information on the distribution of species are still insufficient. In this study, our main goals were to recognize Simuliidae species and to analyze abiotic factors regarding the distribution of immature stages (larva and pupa) in streams from the Ijuí River basin, Northwest of Rio Grande do Sul, Brazil. We sampled simulids specimens in 27 study sites, covering three regions (high, intermediate and low altitude). Concomitantly, we recorded abiotic factors in the studied sites, such as: temperature, electrical conductivity, dissolved oxygen, atmospheric pressure, pH, altitude and stream width. For data analysis, we performed Kruskal-Wallis, ANOVA, Principal Component Analysis (PCA), Analysis of Indicator Species and Canonical Correspondence (CCA). A total of 10 species of black Flies was recorded. Simulium pertinax Kollar, Simulium incrustatum Lutz and Simulium orbitale Lutz were the most frequent. There was no significant difference in richness and density of the species between the different regions studied, except for Simulium jujuyense Paterson & Shannon. The sampled environments were segregated according to the location within the basin, and only S. jujuyense was considered an indicator species of the upper region. These results can be explained by the homogeneous conditions of the Ijuí River basin, which have suffered anthropogenic pressure mainly due to agricultural activities, resulting in losses in local aquatic biodiversity. Also, it may indicate that the control must be conducted considering the basin as a whole, and not only as isolated stretches of the streams.Diversidade e distribuição espacial de borrachudos (Diptera: Simuliidae) na bacia hidrográfica do rio Ijuí, Rio Grande do Sul, BrasilResumo. No sul do Brasil existem problemas com atividade hematofágica de borrachudos e as informações referentes à distribuição das espécies ainda são insuficientes. O presente estudo visa reconhecer as espécies de Simuliidae e analisar fatores abióticos quanto a distribuição dos estágios imaturos (larva e pupa) em riachos da Bacia do Rio Ijuí, no Noroeste do Rio Grande do Sul, Brasil. Foram coletados simulídeos em 27 pontos de estudo, cobrindo três regiões da bacia (alta, intermediária e baixa altitude). Concomitantemente, foi feito o registro de fatores abióticos nos trechos estudados, tais como: temperatura, condutividade elétrica, oxigênio dissolvido, pressão atmosférica, pH, altitude e largura do riacho. Foram realizadas análises de Kruskal-Wallis ou ANOVA, Análise de Componentes Principais (PCA), Análise de Espécie Indicadora e de Correspondência Canônica (CCA). Foi registrado um total de 10 espécies de Simuliidae. Simulium pertinax Kollar, Simulium incrustatum Lutz e Simulium orbitale Lutz foram as mais frequentes. Não ocorreu diferença na riqueza e na densidade das espécies entre as diferentes regiões estudadas, exceto para Simulium jujuyense Paterson & Shannon. Os ambientes nos pontos de amostragem foram segregados de acordo com a sua localização na bacia, e apenas S. jujuyense foi considerada uma espécie indicadora da região alta. Tais resultados podem ser explicados pelas condições homogêneas da Bacia do Rio Ijuí, que vêm sofrendo pressão antropogênica principalmente devido às atividades agrícolas, resultando em perdas na biodiversidade aquática local. Também, indicam que o controle deve ser realizado considerando a bacia como um todo e não apenas em trechos isolados dos riachos.

The Piratinim River is located in the northwest of Rio Grande do Sul, and represents an important effluent from the Uruguay River, with streams located far from urbanized areas, in conditions similar to those of environmental integrity, but under the influence of agricultural activities. In this study, we aim at investigating the structure of the aquatic macroinvertebrate community in streams of the Piratinim river basin by observing both spatial and local scales. The sampling was carried out in six streams distributed in three regions (upper, middle and lower) of the basin, thus exploring its upstream, intermediate and downstream stretches, during spring and autumn. Macroinvertebrates were collected using aquatic dipnets and were identified at the family level; trophic-functional categories were established according to the classification adapted to the state of Paraná. The spatial and temporal variations of the groups and of the biotic attributes (density, richness, diversity and equitability) were subjected to Kruskal-Wallis non-parametric tests and a posteriori Dunn’s tests. The abiotic variables were obtained to verify possible influence on the composition of the macroinvertebrate community, evaluated through a Canonical Correspondence Analysis. We sampled 11,564 macroinvertebrate individuals from 72 taxa, and found a predominance of the collector-filter trophic group. Abundance and richness were different between streams; the highest densities were found in the streams located in the upper region of the watershed (Chuní and Itú). The highest taxon richness was found in the lower region of the watershed (Guaracapa stream), and the lowest richness was found in the two streams for the intermediate region (Santana and Ximbocu). Diversity and equitability did not vary; temporal variations were not found. Canonical correspondence analysis explained 31.7% of the data variability. The main environmental variables that influenced macroinvertebrates distribution were temperature, electrical conductivity, dissolved oxygen, altitude and extension of the riparian forest. Seasonality and the longitudinal gradient along the basin represented determining factors for the structure and distribution of the macroinvertebrate community in the tributary streams of the Piratinim River.

É acrescentado um novo caráter pupal para a espécie T. hirtipupa (Lutz,1910). É evidenciada a existência de dentes no cibário da fêmea de T. guianense (Wise,1911), principal espécie envolvida na transmissão da filaria Onchocerca volvulus (Leuckart,1893) no foco da região amazônica. É proposta uma nova relação para os artículos antenais da larva de T. guianense. É descrita uma nova espécie para o gênero Thyrsopelma Enderlein,1934, T. jeteri sp.n., proveniente da bacia hidrográfica do rio Uruguai, no Estado do Rio Grande do Sul. São apresentados os parâmetros físico-químicos do criadouro de onde provem o material tipo. É apresentada uma chave para diferenciação das pupas das espécies constantes neste gênero.

ABSTRACT. The female of Thyrsopelma itaunense (d'Andretta & González, 1964) is described and illustrated for the first time. T. itaunense and T. orbitale are morphologically compared. New records on geographical distribution are aslo presented.

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