Surirella Arctica Guide
Credit: Jana Veselá, Marina Potapova
  1. Craticula-like structure
  2. Valves slender, isopolar
  3. Apices cuneate
  4. Each 4th or 5th external ridge depressed

The most prominent feature of this taxon is the craticula-like structure (internally thickened median area and transverse costae) on the interior valve surface. Valves are slender, and mostly isopolar with cuneate apices. Each 4th or 5th external ridge is depressed below the level of the valve face. The geographic distribution is limited, to date, to the high Arctic of North America.