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MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M., LUDWIG, T.V. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotropica. 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200Abstract: We conducted a taxonomical study of epiphytic diatoms on the macrophytes Polygonum hydropiperoides, Ludwigia peruviana and Alternanthera philoxeroides collected in the mesotrophic reservoir Piraquara II flooded in 2009, located in the state of Paraná. A total of 135 infrageneric taxa were identified, among them five at generic level and other five are first records to the state. We provided illustration, valve metrics, meristics limits and taxonomic reference for each taxon. Also, life forms and species frequency are given. The most frequent diatoms totalized 15.3% of total identified taxa and sporadic species represented 54.7%. Achnanthidium minutissimum (Kützing) Czarnecki and Brachysira neoexilis Lange-Bertalot occurred in more than 90% of analyzed samples. Among the very frequent diatoms we found other species included in Achnantidium, Fragilaria and Eunotia. The solitary Discotella stelligera (Cleve & Grunow) Houk & Klee and the short chain Aulacoseira tenella (Nygaard) Simonsen are free living species that entangle among diatoms from the biofilm. Keywords: Bacillariophyta, freshwater, macrophytes, mesotrophic, periphyton, taxonomy. Diatomáceas epifíticas (Diatomeae) no reservatório urbano Piraquara II, estado do ParanáResumo: Realizamos um estudo taxonômico das diatomáceas epifíticas nas macrófitas: Polygonum hydropiperoides, Ludwigia peruviana e Alternanthera philoxeroides, coletadas no reservatório Piraquara II, uma represa urbana mesotrófica inundada em 2009, localizado no estado do Paraná. Um total de 135 táxons infragenéricos foi determinado, entre os quais cinco foram citações pioneiras para o Estado. Ilustrações, limites métricos, merísticos e referências taxonômicas para cada táxon foram providenciadas. Também, dados sobre formas de vida e frequência das espécies foram adicionados. As diatomáceas mais frequentes totalizaram 15,3% dos táxons determinados e as espécies esporádicas representaram 54%. Achnanthidium minutissimum (Kützing) Czarnecki and Brachysira neoexilis Lange-Bertalot ocorreram em mais de 90% das amostras analisadas. Dentre as diatomáceas muito frequentes encontram-se outras espécies de Achnanthidium, Fragilaria e Eunotia. Discostella stelligera (Cleve & Grunow) Houk & Klee, uma diatomácea solitária, e Aulacoseira tenella (Nygaard) Simonsen, com cadeias curtas, são espécies livres que se emaranham entre as diatomáceas do biofilme.

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Periphytic algae are important components of aquatic ecosystems. However, the factors driving periphyton species richness variation remain largely unexplored. Here, we used data from a subtropical floodplain (Upper Paraná River floodplain, Brazil) to quantify the influence of environmental variables (total suspended matter, temperature, conductivity, nutrient concentrations, hydrology, phytoplankton biomass, phytoplankton species richness, aquatic macrophyte species richness and zooplankton density) on overall periphytic algal species richness and on the richness of different algal groups defined by morphological traits (cell size and adherence strategy). We expected that the coefficients of determination of the models estimated for different trait-based groups would be higher than the model coefficient of determination of the entire algal community. We also expected that the relative importance of explanatory variables in predicting species richness would differ among algal groups. The coefficient of determination for the model used to predict overall periphytic algal species richness was higher than the ones obtained for models used to predict the species richness of the different groups. Thus, our first prediction was not supported. Species richness of aquatic macrophytes was the main predictor of periphyton species richness of the entire community and a significant predictor of the species richness of small mobile, large mobile and small-loosely attached algae. Abiotic variables, phytoplankton species richness, chlorophyll-a concentration, and hydrology were also significant predictors, depending on the group. These results suggest that habitat heterogeneity (as proxied by aquatic macrophytes richness) is important for maintaining periphyton species richness in floodplain environments. However, other factors played a role, suggesting that the analysis of species richness of different trait-based groups unveils relationships that were not detectable when the entire community was analysed together.

TREMARIN, P.I., FREIRE, E.G., ALGARTE, V.M., LUDWIG, T. Acanthoceras and Urosolenia species (Diatomeae) in subtropical reservoirs from South Brazil: Ultrastructure, distribution and autoecology.http://dx

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Abstract:Pithophora is the only genus recorded of the Pithophoraceae family in Brazil. Pithophora specimens were found close to banks of Hydrilla verticillata (L.F.) Royle in the Upper Paraná River floodplain. The specimens showed intercalary akinetes isospores in the same individual and morphologic similarities with Pithophora oedogonia reported in previous studies. This species constitutes a new citation for the Upper Paraná River floodplain and the third report for Brazil.

The present study investigated the species composition and taxonomic similarity of periphytic algae on three species of macrophytes (Eichhornia azurea Kunth, Nymphaea amazonum Martius & Zuccarini and Oxycaryum cubense (Poeppig & Kunth) Lye) and also some limnological variables in a lake permanently connected to the Paraná River at the Upper Paraná River floodplain, Brazil, from June 2008 to March 2009. During the study period, the Paraná River showed irregular flood pulses and indistinct hydrological periods. In this same period, 406 taxa of periphytic algae were identified, distributed mainly in the classes Zygnemaphyceae, Bacillariophyceae, Chlorophyceae; and Cyanobacteria. Similarity analysis based on taxonomic composition of sampling periods and substrates showed low values and primarily represented a temporal segregation of periphytic algal community, mainly in June 2008 from others. Secondly, the microespacial segregation occurred to a lesser extent, according to the type of substrate, especially between O. cubense and others. It comprises first steps for understating the comparative structure of periphytic algal community in these distinct substrates at the Paraná River floodplain.