Fallacia Longitudinalis Guide
Credit: Marina Potapova
  1. Valves linear
  2. Striae not resolvable under LM
  3. Conopeum covering valve almost entirely, except two openings at each apex
  4. Fascicles of pores on canopeum are slightly visible along raphe

Valves are linear, with rounded ends. Vavles are 4.5-5.6 ┬Ám wide. The striae cannot be resolved with under LM, but the upper surface of the valve is covered by a conopeum, which has small pores arranged into fascicles that look like striae or "wrinkles" along the raphe under LM. The axial area is very narrow and there is a small elliptic central area. At each apex there are two openings between conopeum and the valve margin. The proximal raphe ends are very close together and slightly bent to the primary side of the valve.