Müller, 1856
Spicules cylindrical, tapering distally, with sharp tips. Basal ends pyramidal, fused into central body. Cell body polygonal, with yellow, reddish to brownish pigment grains. Central capsule thin-walled. Nuclei (ca. 400) usually distributed around periphery of endoplasm. Calymma single-layered. Each spicule with 32 or more myonemes. Diameter of cell body: 0.23 mm; spicule length: 0.25 mm.