Turbelários límnicos (Platyhelminthes) em ecossistemas de arroz irrigado da Planície Costeira do sul do Brasil

Turbellarians occur in a variety of wetlands, being also abundant in temporary water bodies. Several turbellarians are top predators in their microhabitats, many of them feeding on zooplankton. However, they are seldom taken into account in biodiversity studies. Information on turbellarian diversity in Brazilian freshwater ecosystems mainly came from taxonomical studies. In southern Brazil, there are a high number of wetlands, most of them represented by rice fields. Despite their impact on natural areas, these managed ecosystems can play an important role in freshwater biodiversity conservation. The aim of the present work was to report on an inventory done in irrigated rice fields of three areas of the Coastal Plain of southern Brazil, viz. Cachoeirinha, Santo Antônio da Patrulha e Camaquã. We found 144 species of freshwater turbellarians, distributed in six taxonomic groups (Catenulida, Macrostomida, Lecithoepitheliata, Proseriata, Rhabdocoela, and Tricladida). Twenty-three species are recorded for the first time for Brazil. Catenulida showed the highest relative abundance in Cachoeirinha, followed by Rhabdocoela. In Santo Antônio and Camaquã, Tricladida had the highest relative abundance, followed by Catenulida. Results suggest that some turbellarian species show a high level of habitat specificity with only 38% of the registered turbellarians occurring in a single study area. Although there is a paucity of turbellarian inventories in Brazilian natural wetlands, hampering a comparison between natural and managed wetlands, results indicate high species richness in the areas studied.

microturbellarians; triclads; diversity; inventory; temporary wetlands