ULTRASTRUCTURE OF COCHLOSOMA-ANATIS KOTLAN, 1923 AND TAXONOMIC POSITION OF THE FAMILY COCHLOSOMATIDAE (PARABASALA, TRICHOMONADIDA)

The fine structure of Cochlosoma anatis is described from scanning and transmission electron microscopy. These flagellates are asymmetrical and uninucleate, with a conspicuous adhesive disc formed from the modi fied pelta. Six flagella arise from the anterior end. Four of them eme rge anterolaterally from the lateral groove. The fifth flagellum is re current and adheres to the cell body by a well developed undulating me mbrane, formed by a cytoplasmic fold with the marginal lamella. The ki netosome of the recurrent flagellum is situated at an angle to the kin etosomes of the anterior flagella. This kinetosomal complex is associa ted with fibrillar appendages characteristic of a trichomonad mastigon t. The kinetosome of the sixth flagellum is located outside the comple x of the other kinetosomes, on the dorsal side of the protozoan body. The undulating membrane is supported by the prominent costa with Type B periodicity and passes throughout the lateral groove extending to th e end of the parasite's body. There is a parabasal apparatus composed of a Golgi complex and a single parabasal fiber. The axostyle, formed from a single layer of microtubules, passes through the body, protrudi ng caudally in a short projection. Anteriorly it overlaps the inside o f the pelta. An extranuclear mitotic spindle is formed during the nucl ear division. The cytoplasm contains double membrane bound organelles similar to hydrogenosomes. These observations show high degree of homo logy of Cochlosoma with Trichomonadida Kirby, 1947 warranting inclusio n of the family Cochlosomatidae Tyzzer, 1930 into this order.