Frenopyxis stierlitzi gen. nov., sp. nov.—new testate amoeba (Amoebozoa: Arcellinida) from the urban parks with notes on the systematics of the family Centropyxidae Jung, 1942

New species, Frenopyxis stierlitzi, is described from tree hollows in the urban parks in Moscow (Russia) and Potsdam (Germany). The species belongs to the new genus of the family Centropyxidae and characterized by unique character, i.e. an internal thick organic lip surrounding an aperture and continuing in a bridle, which connects an aperture with the internal side of a shell wall and broaden in the place of connection of a bridle and a shell wall. The systematics of the family Centropyxidae is discussed and the importance of the structures, which divide inner shell volume into compartments, is underlined.