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Given the extreme importance of understanding biodiversity in the contemporary context, this study performed a taxonomic survey of planktonic green algae from a subtropical river in Paraná state, broadening knowledge of the group’s geographic distribution and the environmental conditions related to its occurrence. Monthly samplings of phytoplanktonic material were carried out from February 2015 to January 2016, resulting in the identification of 26 taxa belonging to the classes Chlorophyceae and Trebouxiophyceae, distributed among 16 genera and six taxonomic families. Among the taxa identified, seven are new citations for Paraná. Resumo Dada a extrema importância do entendimento da biodiversidade no contexto contemporâneo, este estudo realizou um levantamento taxonômico das algas verdes planctônicas de um rio subtropical do estado do Paraná, ampliando o conhecimento da distribuição biogeográfica do grupo e as condições ambientais relacionados com a sua ocorrência. Foram realizadas coletas mensais do material fitoplanctônico no período de fevereiro de 2015 a janeiro de 2016, resultando na identificação de 26 táxons pertencenteas as classes Chlorophyceae e Trebouxiophyceae, distribuídos em 16 gêneros e seis famílias taxonômicas. Dentre os táxons identificados, sete são novas citações para o estado do Paraná.

The diversity of phytoplankton traits provides a powerful means of addressing ecological questions and can be adopted to simplify and predict the community structure and the function of the multiple environmental filters that operate in the different ecosystems. We evaluated the response of phytoplankton functional groups in samples from two subtropical rivers, identifying the main environmental filters associated with the presence of the different groups and their functional traits during a seasonal cycle. Using multivariate analysis, we found environmental dissimilarity that was predicted by the presence of different functional groups (FGs) in the two rivers. Six FGs were recorded: J (chlorophyceans chlorococcales), M (colonial cyanobacteria), N (desmids), W1 (euglenophyceans), X2 (flagellated unicellular chlorophyceans) and F (flagellated colonial chlorophyceans). The FGs J, M and N were exclusive to Cascavel River, while X2 and F were exclusive to Quati River. The FG W1 was recorded in both rivers; however, its greatest contribution was in Quati River. Thus, the FGs reflected the environmental dissimilarity, mainly related to the conditions of water flux, conductivity, light availability and depth of the environments. Based on these results, the functional groups are considered to provide a relevant tool in phytoplankton ecology, offering a practical means of investigating the relationship between phytoplankton and ecosystem functioning, and contributing to the management and conservation of biodiversity in lotic environments.

Aim: The aim of this study was to assess the taxonomic aspects and geographical distribution of the periphytic desmids from two different substrates in the littoral zone of an urban artificial lake. Methods Samples of epiphytic and epilithic desmids were collected by grass and rock scraping, respectively, in two stations in the Cascavel municipal lake, Paraná, during April 2015, and March 2016 and 2017. In the laboratory, the taxa obtained from the samples were photographed and their morphometric characteristics recorded. The species composition of the desmid was characterized, and the frequency of occurrence as well as the geographic distribution of each taxon in the Paraná State were recorded. Results We identified 35 taxa, distributed in 10 genera. The most representative were Closterium Nitzsch ex Ralfs and Cosmarium Corda ex Ralfs. A high occurrence of sporadic taxa (60%) was observed and among the recorded taxa, the most frequent were Cosmarium pseudoconnatum Nordstedt var. pseudoconnatum and Desmidium grevillei (Kützing ex Ralfs) De Bary. Nine taxa were exclusive to the epilithic substrate and only Netrium digitus (Ralfs) Itzigsohn & Rothe var. digitus was exclusive to the epiphytic substrate, while the remaining 25 taxa occurred in both substrates. Seven taxa are new records for the Paraná State. Conclusion Although our results are of qualitative nature, they provide baseline data on the biogeographic distribution of taxa, which are crucial for future taxonomic and ecological studies that might contribute to the preservation of the biodiversity. Resumo Objetivo: O objetivo deste estudo foi avaliar os aspectos taxonômicos e a distribuição geográfica das desmídias perifíticas de dois substratos diferentes na zona litorânea de um lago artificial urbano. Métodos Amostras de desmídias epífitas e epilíticas foram coletadas por raspagem de gramíneas e rochas, respectivamente, em duas estações no lago municipal de Cascavel, Paraná, durante abril de 2015 e março de 2016 e 2017. No laboratório, os táxons obtidos a partir das amostras foram fotografados e suas características morfométricas foram registradas. A composição das espécies de desmídias foi caracterizada e a frequência de ocorrência, bem como a distribuição geográfica de cada táxon no Estado do Paraná foram registradas. Resultados Nós identificados 35 táxons, distribuídos em 10 gêneros. Os gêneros mais representativos foram Closterium Nitzsch ex Ralfs e Cosmarium Corda ex Ralfs. Uma alta ocorrência de táxons esporádicos (60%) foi observada, e entre os táxons registrados, os mais frequentes foram Cosmarium pseudoconnatum Nordstedt var. pseudoconnatum e Desmidium grevillei (Kützing ex Ralfs) De Bary. Nove táxons foram exclusivos para o substrato epilítico e somente Netrium digitus (Ralfs) Itzigsohn & Rothe var. digitus foi exclusivo para o substrato epifítico, enquanto os demais 25 táxons ocorreram em ambos os substratos. Sete táxons são novas ocorrências para o estado do Paraná. Conclusão Embora nossos resultados sejam de natureza qualitativa, eles fornecem uma base de dados sobre a distribuição biogeográfica dos táxons, os quais são cruciais para futuros estudos taxonômicos e ecológicos que podem contribuir para a preservação da biodiversidade.