All Taxa

Melosiraceae: Melosira

Frustules isovalvar, radially symmetrical. Cells cylindrical to ± spherical; circular in outline. Isolated valves lie in valve or girdle view. Cells form chain-like colonies, attached to each other by mucilage pads on the valve face.

Valves chambered (loculate), though this is not obvious in LM; chambers opening externally by many tiny pores, internally by rather larger pores. The loculi are randomly arranged or lie in rows radiating from the centre. Small spines and granules may be present externally, especially in the region where adjacent cells touch and link together; a circular flange (collar=carina) may be present at some distance from the valve centre.

The central part of the valve is often differently structured and has more irregularly arranged chambers.

Several wide porous bands are present. Chloroplasts several to many, plate-like, lobed, each with a central pyrenoid.