Ultrastructure of the Trichomonad Flagellate Stephanonympha nelumbium

ABSTRACT Stephanonympha nelumbium is a large trichomonad measuring 45–60 μm in length and 20–40 μm in width. It is a member of the multinucleate and multiflagellate family Calonymphidae. While the numerous flagella arise in groups of four at the anterior cell pole, the posterior body portion is covered with attached spirochetes and rod-like bacteria. Generally, in the apical body portion of S. nelumbium , 50–100 nuclei are arranged in five to seven circular rows. Each nucleus is associated with a typical mastigont system, comprised of three anterior flagella, one recurrent flagellum being attached to the cell surface for a certain distance, and several typical root structures. Akaryomastigonts and costas do not occur. The fine structure of S. nelumbium corresponds with that of other calonymphids. The main difference to Calonympha is that the axostyle does not embrace the nucleus but passes it in form of a flattened rod.