Cyclotella Distinguenda Guide
Credit: Mark Edlund, David Burge, Kalina Manoylov
  1. Central area 1/3 -1/2 valve face
  2. Central area tangentially undulate
  3. Striae taper in width near the center
  4. Striae crossed by shadow line

The circular central area is about 1/3 to 1/2 the valve face and is tangentially undulate. Striae taper from the margin toward the center, terminating at an equal distance to one another. The marginal striae are crossed by a shadow line.