Meridion Anceps Guide
Credit: Ian Bishop
  1. Valve symmetric to the transapical axis
  2. Ends subcapitate to capitate
  3. Costae 3.3-4.9 in 10 µm
  4. Central sternum present
  5. Distinct subapical rimoportula present

Valves are symmetric and linear, with subcapitate to capitate ends. Costae measure 3.3-4.9 in 10 µm. Striae are visible in LM, but individual areolae are not resolved. The sternum is central and well-defined. Each valve has a single, sub-apical rimoportula.