Biology and morphology of freshwater rapacious flagellate Colponema aff. loxodes Stein (Colponema, Alveolata)

The biology, morphology, and ultrastructure of the freshwater rapacious flagellate Colponema aff. loxodes, which attacks bodonids and chrysomonads, are studied. The flagellate is characterized by three-membrane alveolar pellicle, vesicular nucleus, two heterodynamous flagella, two microtubule bands which armor the longitudinal groove, and mitochondria with tubular cristae. Toxicysts (thread-organelles) are found in the cytoplasm. The posterior flagellum is characterized by the proximal fold. Micropores are completely absent. After being caught, the prey is taken into the longitudinal groove. Vegetative swimming cells are present in the life cycle. No reproduction or latent cysts are found. The taxonomical position of Colponema aff. loxodes is discussed in comparison with other colponemids and protists.