STUDIES ON THE EVOLUTION OF THE OPHRYOSCOLECIDAE (CILIATA: OLIGOTRICHA): II. ON THE ORIGIN OF THE HIGHER OPHRYOSCOLECIDAE

Abstract

A comparison of the structure of Diplodinium s. str. and Entodinium of the "caudatum–laterale" group leads to the conclusion that Diplodinium originated from Entodinium as the result of torsional displacement of the nuclear apparatus, the left lateral groove, and the contractile vacuole from the dorsal side to the ventral. The ventral side of Entodinium was thus transformed into the "dorsal" side of Diplodinium The probable influence of this new conception of the comparative morphology of the Ophryoscolecidae is discussed.