Fragilaria Vaucheriae Guide
Credit: Eduardo Morales
  1. Central area expanded to one side of valve (or in some specimens, to both sides of the valve)
  2. Central margin of valve expanded on one side
  3. Striae broad
  4. Striae widely spaced
  5. Rimoportula present

Frustules are linear with rostrate to subcapitate apices. The central margin of valves is expanded to one side. The striae are broadly spaced, that is, costae are wide. The striae are interrupted by an expanded central area usually extending to one, or less commonly, to both sides of the valve. In some specimens, the striae continue through the central area. A single rimoportula is present near the valve apex.