Phylogenetic Taxonomy of Rumen Ciliate Protozoa Based on Their Morphology and Distribution

Abstract

Imai, S. 1998. Phylogenetic taxonomy of rumen ciliate protozoa based on their morphology and distribution. J. Appl. Anim. Res., 13: 17–36. The ciliates belonging to the family Ophryoscolecidae in the suborder Entodiniomorphina peculiarly inhabit the rumen of various ruminants. They possess specialized and complicated bodies which seem to have evolved with the evolution of their hosts. Comparative morphology of these ciliates would be interesting as a model of co-evolution between these parasites and their hosts. As a result of morphologic comparison of 14 genera of this family, a temporary phylogenetic tree containing a line connected continuously from simpler species to more complicated ones, and a line independently derived on the way from the genus Diplodinium can be created However, there is no evidence that the morphologic relation of ophryoscolecid genera expresses the correct phylogenetic relation of this family. Thus it is necessary to examine this problem by another approach. When the relation of the distribution of respective genera of Ophryoscolecidae, in which the geographic factor is excluded as far as possible, to an advanced phylogenetic tree of host mammals is examined, we can draw another temporary phylogenetic tree. As compared to this figure with the morphologic relation of ophryoscolecid ciliates, the phylogenetic relation of these ciliates seems to agree as a rule. Accumulation of more detailed data from various hosts and their careful comparison would be necessary in future. In such examinations the species which are interesting phylogenetically may be discovered from unexamined animals, especially wild ones.