Predatory behavior of Frontonia leucas (Ehrenberg, 1833) (Alveolata, Ciliophora, Hymenostomatida) in aquatic sites in the semiarid region of Brazil

To investigate the predatory behavior of the ciliated microeukaryote Frontonia leucas (Ehrenberg, 1833) in aquatic environments in the semiarid region of Brazil. Methods: Water samples were collected in three lotic and two lentic aquatic sites in southwestern Bahia State, Brazil. Individuals of Frontonia leucas were observed and recorded in vivo for a total of 20 hours using an optical microscope with an attached camera. The following physical-chemical variables were recorded during sample collection: total dissolved solids, water transparency, pH, electrical conductivity, and water temperature. Results: The ingestion of 18 food types were observed – i) Amoebozoa (7 taxa), ii) Bacillariophyta (2 taxa), iii) Ciliophora (1 taxa), iv) Zygnematophyceae (5 taxa), and v) Rotifera: (3 taxa). Thirteen food items were recorded here for the first time (5 species of testate amoebas from the genera Cylindrifflugia, Difflugia, and Netzelia, one genus of the ciliate Vorticella, four genera of microalgae, three desmids [Micrasterias, Pleurotaenium, and Cosmarium], one filamentous Zygnematophyceae [Spirogyra], and three micrometazoans taxa Rotifera [Lecane, and Bdelloidea]. The size of the food items ranged from 50 to 1100 µm in length, with many of them larger than the ciliate predator itself. Conclusions: The results indicate F. leucas as an omnivorous predator that can contribute to population control in aquatic ecosystems.