Light microscopical observations on two marine dysteriid ciliates from Japan, including a description of Dysteria yagiui nov. spec. (Ciliophora, Cyrtophorida)

Two cyrtophorid ciliates, Dysteria yagiui nov. spec. and D. derouxi, were isolated from fish-farming waters at the New Fishing Port of Nagasaki, Japan. Their morphology and infraciliature were investigated using observation of living cells and protargol impregnation. D. yagiui nov. spec. is a large marine species distinguished from its congeners by the presence of 13 ventral kineties in the right field, of which six extend apically and 6-8 short fragments of kineties in the left equatorial field. D. derouxi has the characteristics previously described except that ciliates of this population possess nine ventral kineties in the right field, of which four extend apically.