(Haeckel, 1860)
Two main spicules 3 times longer and 2 times thicker than other 18. Spicules 4-edged in cross section, 2 opposite edges finely serrate, others smooth. Six to eight myonemes. Cytoplasm brown or reddish, granulose. Cell body size: 0.24 by 0.16 mm; length of main spicules: 0.56 mm, secondary: 0.2 mm.