Pseudostaurosira Guide
Credit: Eduardo Morales
  1. Striae uniseriate, less than 4 areolae
  2. Spines present
  3. Areolae elliptic

Frustules of Pseudostaurosira form chains with frustules linked valve face to valve face. Frustules are rectangular in girdle view. Striae are uniseriate, composed of a few (usually not more than 4) elliptic areolae. Spines are present on the valve margin and may be branched. Note that, for some species, the uniseriate striae and spines are features that are visible in SEM.

Pseudostaurosira includes the former Fragilaria brevistriata and is distinguished by the structure of the striae, rather than the shape of the valve face.