Agardh 1824      Category: Araphid
TYPE SPECIES: Meridion vernale Agardh




Image Credit: Pat Kociolek, Natalie Hoidal, Loren Bahls

CLASS: Fragilariophyceae
  ORDER: Fragilariales
    FAMILY: Fragilariaceae

  1. Valves clavate
  2. Frustules linear to wedge-shaped in girdle view
  3. Frustules may be joined in colonies
  4. Costae present

Frustules of Meridion are clavate (club-shaped) in valve view and wedge-shaped in girdle view. Septae (attached to girdle elements) are present. An apical porefield is present at one end. Valves may have 1-2 rimoportulae. Cells are joined together to form fan-shaped colonies. Chloroplasts are multiple and plate-like in living cells.

Meridion includes the common species, M. circulare and M. anceps. Some species have been considered as species of Diatoma, based on the presence of costae.

Cite This Page:
Spaulding, S., and Edlund, M. (2008). Meridion. In Diatoms of the United States. Retrieved June 30, 2015, from

Contributor: Sarah Spaulding | Mark Edlund - December 2008