Occurrence of Arcellidae (Amorphea, Arcellinida) in a coastal stream in the State of Rio de Janeiro

The aim of this study was to elaborate a taxonomic survey on the testate amoebae of the Family Arcellidaein coastal streams in the State of Rio de Janeiro. Six samplingswere conducted in Ubatiba coastal stream (Maricá, RJ). In total, 130 liters water were filtered through a conical net of 60-μm mesh and preserved in 4% formalin. Organisms were identified with the aid of an inverted trinocular microscope. The morphological characteristics (lobose testate amoebae with shell composed of granular chitinoid elements) of each species were recorded. The species were described and illustrated. For the verification of new taxa records of Arcellidae in Rio de Janeiro and their distribution in Brazil, a search based on indexarticles by Scopus, Web of Science and Google Scholar using the keywords "tecamebas", "testate amoebae", "Arcella", "Arcellidae", "Brazil" and "Rio de Janeiro", was performed. Eight Arcellidaespecies were recorded. Some ecological and taxonomic information was provided. Due to the small amount of information on testate amoebae, this study is important because it reduces the knowledge gap regarding this community in the State of Rio de Janeiro. Furthermore, we suggest new studies on species identification to be conducted to expand regional knowledge about these organisms.

Testate amoebae (Protozoa Rhizopoda) in two biotopes of Ubatiba stream, Maricá, Rio de Janeiro State / Amebas testáceas (Protozoa Rhizopoda) de dois biótopos do riacho Ubatiba, Maricá, Estado do Rio de Janeiro

Four samplings were carried out during the dry and rainy seasons in 2014, in two biotopes (plankton and aquatic macrophytes) to assess the composition and species richness of testate amoebae community in a coastal stream in the state of Rio de Janeiro, Brazil. Results showed great representation of Difflugiidae, Centropyxidae, Lesquereusiidae and Arcellidae families. Higher richness was observed in the plankton samples and higher densities of testate amoebae were reported among the aquatic vegetation during the dry season. Current investigation is a pioneer study conducted in the Ubatiba stream. Further researches on these protists, especially in Rio de Janeiro, should be undertaken.

Com o intuito de avaliar a composição e a riqueza de espécies da comunidade de amebas testáceas de um riacho costeiro, localizado no estado do Rio de Janeiro, foram realizadas quatro campanhas em 2014 (estação seca e estação chuvosa), em dois biótopos (plâncton e macrófitas aquáticas). Os resultados mostraram maior representatividade das famílias Difflugiidae, Centropyxidae, Lesquereusiidae e Arcellidae. Maiores riquezas foram registradas no plâncton e maiores densidades de amebas testáceas entre a vegetação aquática, ambos no período seco. O estudo foi pioneiro no riacho Ubatiba e evidencia a necessidade de intensificar as pesquisas sobre estes protistas, sobretudo no Rio de Janeiro.