Cyclostephanos Tholioformis Guide
Credit: David Burge
  1. Valves concentrically undulate
  2. Fascicles weakly organized in the central area
  3. Annulus present
  4. Central fultoportulae 1-3

Valves are small and concentrically undulate. One to three central fultoportulae are present. Striae are arranged in fascicles, which radiate from a central annulus. Fascicles are uniseriate and weakly organized in the central area, becoming multiseriate near the valve margin.