Pediastrum species [Hydrodictyaceae, Sphaeropleales] in phytoplankton of Sumin Lake [Leczna-Wlodawa Lakeland]

During studies of phytoplankton in Sumin Lake (Łęczna-Włodawa Lakeland), conducted from May till September 2001 and 2002, 15 taxa of the genus Pediastrum (Hydrodictyaceae, Sphaeropleales) were found. Among them there were common species as Pediastrum boryanum, P. duplex, P. tetras and P. simplex, but also rare species as P. integrum or P. kawraiskyi. An especially interesting species was P. orientale, the taxon that until now has not been noted in phytoplankton of Polish water bodies. The paper gives descriptions of the genus Pediastrum coenobia and physico-chemical conditions of the habitat. The original documentation of Pediastrum taxa is added.