All Taxa

Stephanodiscaceae: Stephanodiscus

Cells solitary or in chains.

Cells cylindrical in girdle view, mostly circular in valve view.

Valve face flat or concentrical, rarely transversally, undulate.

Valve surface plain or with granules.

No differentiation in ornamentation between central and marginal area.

Fascicles radial, separated by interfascicles, the latter can be raised. External areola openings on valve face circular, internally occluded by domed cribra.

Spines present at valve face/mantle junction. Separation spines conical of different length, linking spines can be present.

Marginal fultoportulae can be present, situated on interfascicles, fultoportulae can be present in centre of valve face.

Fultoportulae with simple, round external openings or short tube, internally with central tube and satellite pores.

Marginal rimoportulae inserted in ring of spines.

Girdle composed of several copulae.

Numerous small, peripheral chloroplasts.