Horizontal distribution patterns of testate amoebae (Rhizopoda, Amoebozoa) in plankton samples of the Corumbá reservoir area, state of Goiás, Brazil

Abstract

The purpose of this study was to discuss the horizontal variations in the testate amoebae assemblages occurring in different regions of the Corumbá reservoir. A total of 61 taxa were identified representing 8 families. Difflugiidae was the most rich. The greatest number of taxa were found in the lotic environments. The increase in the velocity of current, discharge and the washout of the marginal vegetation resulted in an increase in species richness in the lotic environments. On the other hand, the presence of many accidental species in the lacustrine and transitional zones of the reservoir might be due to the fact that these are deep and extensive regions. Centropyxis aculeata was constant in all regions, with the exception of lacustrine zone of the reservoir. Other taxa were constant only in lotic environments (upstream Corumbá river and tributaries) and riverine zone of the reservoir: Arcella conica, A. costata, A. discoides, A. vulgaris, Centropyxis ecornis and Difflugia gramen