Pediastrum duplex Meyen 1829

    Colonies circular to oval plate, ellipsoidal, 16-32 (-64) sometime even 128 cells; colonies 23-190 μm in diameter. Colonies with small lens shape intercellular spaces between cells. Outer cells with two hornlike processes and gradually tapered towards the apices, inner cells quadrate to angular. Outer and inner cells concave or slightly incised on the outer sides; cells walls finely reticulate or highly granulates. Outer cells 17-33 μm long, 13-26 μm in diameter. Inner cells 12-19 μm long, 13-25 μm in diameter.