Present state of the problem of the origin of infusorians the phylum ciliophora doflein 1901
Zoologicheskii Zhurnal 65(12): 1763-1768
An elaborated point of view concerning the problem of infusorian origin is absent in modern ciliatology. Only a general conception exists which insists that Ciliophora originated from flagellates (the phylum Mastigophora), It is explained, first of all, by the fact that there is no unanimous opinion about the most primitive group of infusorians up to now. The complex of conservative ultrastructural diagnostic criteria forming a structural plan of representatives of the phylum Ciliophora is proposed to be utilized for objective revealing of such a group. Protozoans of the genus Isotricha and the suborder Archistomatina show the most primitive structural plan. In connection with special importance of these ciliates due to their primitiveness, the author is proposing to unite them in a new order, Archiciliatida ordo n., which should represent the basis of the Ciliophora modern system. When the preliminary comparison of structural plans between the archiciliatids and different classes of flagellates was carried out (Seravin, 1980), members of the class Chloromonada showed the greatest similarity to primitive infusorians; this fact gives grounds for insisting that the both groups developed from a common ancestor.