Pseudendoclonium - stages of Stigeoclonium exhibited on planktic Daphnia

The surface of the carapace of the planktic crustacean Daphnia magna sample d from a fertilised fishpond in W Slovakia was densely covered by a green a lga. This green alga formed a simple prostrate 2-4-celled uniseriate or 5-8 -celled biseriate single filaments as seen in the ulotrichacean genera Prot oderma or Pseudendoclonium. Under laboratory conditions these short filamen ts changed into pseudoparenchymatous plates with erect and prostrate filame nts radiating from a centre, and these finally giving rise to long ramified Stigeoclonium-like filaments. This paper describes and discusses the life cycle and main diagnostic features of the alga and its possible systematic position.