title: Morphogenesis of Bipartition in two species of the genus Ptychostomum (Ciliophora, Hysterocinetidae).
abstract: Two new species of Hysterocinetidae ciliates living parasitically in the alimentary tract of Alma nilotica are described along with the process of stomatogenesis in these species. The buccal primordium of the opisthe originates from the multiplication of kinetosomes of some somatic kineties forming a disorganized field. One row of kinetosomes, a second and a third are successively isolated from this field. As soon as this stage with three rows of kinetosomes is reached, the peristomial infraciliature of the old buccal infraciliature progressively migrates to the equator of the cell. There, it gives rise to the buccal infraciliature of the proter through resorption and reorganization of the old buccal infraciliature. The description of this morphological development is related to both nuclear division stages and the organization of the sucker cytoskeleton of the ciliates. Our findings contradict the well admitted idea concerning the autonomous characteristic of the stomatogenesis within the Hysterocinetidae. We propose that these ciliates should be considered as a separate group within the Oligohymenophora.
authors.affiliation: University of Sciences, General Biology, Yaounde, Cameroun.
authors.forename: T
authors.initials: T
authors.lastname: Njine
authors.forename: P
authors.initials: P
authors.lastname: Ngassam