Lange-Bertalot 2004      Category: Monoraphid
TYPE SPECIES: Platessa bavarica Lange-Bertalot and Hofmann in Lange-Bertalot




Image Credit: Marina Potapova

CLASS: Bacillariophyceae
  ORDER: Achnanthales
    FAMILY: Achnanthaceae

  1. External raphe fissures straight with distinct central and terminal pores
  2. Striae may be uniseriate or multiseriate
  3. Raphe valve slightly concave
  4. Rapheless valve slightly convex

Cells form single cells or short chains. External raphe fissures are straight with distinct central and terminal pores. Platessa lacks terminal deflections or hooks of the raphe fissures. Girdle bands are narrow and lack ornamentation.

The genus Platessa was established (Lange-Bertalot 2004) and contains the former Achnanthes conspicua Mayer and species within the A. holsatica Hustedt group. Members of this genus are widely reported, but low in abundance in collections. Species within Platessa have misidentified or overlooked.

Cite This Page:
Spaulding, S., and Edlund, M. (2008). Platessa. In Diatoms of the United States. Retrieved September 15, 2014, from

Contributor: Sarah Spaulding | Mark Edlund - December 2008