Ostenf., in Ostenfeld & Schmidt (1902: 141)
Throndsen (1997: 664, pl. 12)
Phycoma stage: Cells spherical, 10 µm diameter (13 µm including alae); walls with low curved parallel alae in a hexagonal arrangement.
Coastal waters, Davis Station, East Antarctica.
Material from the Antarctic resembles P. polygonum Ostenf., which has a cell body of 30 µm diameter and alae in a pentagonal pattern (Throndsen, 1997: 664, pl. 12). Members of the genus were discussed by Parke et al. (1978).