Morphology and morphogenesis of Disematostoma colpidioides (ciliophora, frontoniidae): Its systematic implications

Disematostoma colpidioides, until now, Wenrichia colpidioides, is a reniform ciliate with a strong torsion at the equatorial plane. The nuclear apparatus consists of a long macronucleus and a spherical micronucleus. The oral infraciliature is made up by a paroral kinety and three peniculi with 4,4, and 3 rows of kinetosomes, respectively. At the right slope of the buccal cavity there are 3-5 vestibular kineties. The somatic infraciliature consists of dikinetids which form a preoral and a postoral suture. On the dorsal side, D. colpidioides has the genus-specific "dorsal polar band", comprised of a row of pairs of kinetosomes in its middle part. These pairs are irregularly spaced, and each one has a long fibrillar derivate. These features, principally the existence of a dorsal polar band, suggest that this species must be transferred from the genus Wenrichia to the genus Disematostoma. Stomatogenesis commences with the proliferation of kinetosomes belonging to the paroral kinety. From this proliferation originate both, the penicular primordia by elineation, and the paroral primordium by reorganization of an elongated anarchic field of kinetosomes. Moreover, a reorganization of the parental paroral kinety also takes place. Finally, the oral apparatus is the origin of cortical destabilization during the bipartition process which is also implicated by the fission furrow. The cortical destabilization begins at the right side of the buccal cavity and follows a left-right gradient.