Stephanodiscus minutulus

Valves are small and disc-shaped, with a concentrically undulate valve face. Valve faces are complementary, with scutate (raised) and lacunate (depressed) valves. Areolae are scattered at the valve center and arranged in multiseriate fascicles toward the margin. Areolae number 2-3 per fascicle near the margin, but in many specimens, the areolae may not be resolvable at the margin. The interfascicles are narrow and uniform in width. They may vary across specimens by being either wavy or straight. A small spine is present between each fascicle, at the interfascicle and face/mantle junction. A single fultoportula is present near center of the valve face, a feature is usually not observable in LM. Marginal strutted processes are located on the mantle beneath every 4-5th spine.