A&B = Phycoma stage in Lugol under different pressure of cover slip (DIC); C = Pores (=arrows) and papillate zone of the outer wall (DIC)
Life-form: Phycoma phase and solitary flagellate
Size: Diameter often=120-200 µm
Distinctive features: One ring of distinct irregularly spaced pores and a broad band appearing finely and evenly papillose on either side of ala
Similar species: Pterosperma eurypteron Pterosperma rotundatum
Parke, M., Boalch, G. T., Jowett, R. & Harbour, D. S. 1978. The genus Pterosperma (Prasinophyceae): species with a single equatorial ala. J. Mar. Biol. Ass. U.K. 58: 239-276.