An Ultrastructural Approach to Planarian Taxonomy

Abstract

The use of the fine structure of ooplasmic inclusions in the classification of freshwater triclads has led to an examination of numerous planarian species. In the genera Dugesia and Cura autosynthetic yolk is present while in Polycelis, Planaria, Plagnolia and Dendrocoelum only cortical granules are present, which are localized in the peripheral cytoplasm of mature oocytes. These findings are consistent with the recently proposed phylogenetic theory of Ball, in which the primary division of the freshwater triclads is into the Dugesiidae and the Planariidae plus Dendrocoelidae.