Fragilaria Syngrotesca Guide
Credit: Nick Schulte
  1. Apices capitate or subcapitate
  2. Central area unilateral
  3. Striae parallel and opposite
  4. Axial area narrow to absent
  5. Two rimoportulae present

Valves are elongated and narrow, with capitate to subcapitate apices. In most specimens, the central area is unilaterally expanded and hyaline. The central area may extend almost to the opposite margin, or it may be restricted to one side of the transapical axis. A very narrow, to non-existent, axial area separates parallel, opposite striae. Each pole has a rimoportula near the apical margin.