Psammothidium Nivale Guide
Credit: Marina Potopova
  1. Valves elliptic
  2. Raphe valve with rectangular to oval central area
  3. Rapheless valve with rhomboid-lanceolate axial area
  4. Rapheless valve with areolae visible with LM

Valves are elliptic. The raphe valve has a transapically rectangular to oval central area. The raphe has simple distal ends. The rapheless valve has an axial area that is narrow at apices and widens toward valve center, in a rhombic-lanceolate shape. Striae are slightly radiate, coarser on rapheless valve as compared to the raphe valve. Areolae on the rapheless valve are visible with LM.