Psammodictyon Guide2
  1. Valves constricted or panduriform
  2. Raphe eccentric
  3. Longitudinal undulation on valve face
  4. Fibulae bifurcated by central nodule

Valves are linear to panduriform, with the diagonal symmetry characteristic of other nitzschioid genera. A longitudinal undulation, similar to that found in Tryblionella, is present. As in other nitzschoid genera, Psammodictyon posseses an eccentric, keeled, fibulate raphe system. Fibulae are bifurcated by a central nodule. Striae are composed of coarse, simple poroids, numbering one more rows per stria. Girdle bands are open.

Most of the taxa described in the genus Psammodictyon are marine, although some taxa in the genus are founr in freshwater and brackish environments.