STUDIES ON SCENEDESMUS-COSTATO-GRANULATUS SKUJA

52 strains of Scenedesmus costato-granulatus-related taxa from differe nt continents were studied, using light and electron microscopy. While most of the strains produced only 2-celled coenobia some produced coe nobia and single cells, and others only single cells. This was not inf luenced by the presence of bacteria. The cell wall ornaments of all st rains are large single warts and rib-like aggregates of these warts, s mall warts and rosettes. The large single warts are variable in number and the rib-like aggregates, which are often not found on single cell s, are variable in length and arrangement. We include the single-celle d Chlorella ultrasquamata Clemencon et Fott nom. inval. as well as the Scenedesmus elegans f. regularis Peterfi with its special regular rib arrangement in Scenedesmus costato-granulatus Skuja. The S. similagin eus Hortob. sensu Kom. et Ludv. is related. Further synonyms for S. co stato-granulatus Skuja are Didymocysis inermis (Fott) Fott and its var . minima Tell, D. polonica Bucka, Scenedesmus elegans Peterfi nom. inv al., S. granulatus f. salinus Crawf. and f. verruco-costatus Hortob. a nd all combinations of these names.