E Yellowstonianum Guide
Credit: Friedel Hinz
  1. Ventral margin slightly expanded
  2. Valves relatively narrow
  3. Central, dorsal striae 10-11 in 10 µm
  4. Rows of dorsal areolae closest to the central area oval, becoming lineolate

Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is slightly expanded. The number of dorsal, central striae is important in distinguishing this species from similar species, as well as the density of areolae in a central, dorsal striae. Ventrally, central striae number 10-11 in 10 μm, and distal striae number 5 in 5 μm. The density of areolae within a central, dorsal stria is 8 in 5 μm.