A Eutrophilum Guide
Credit: Marina Potapova
  1. Striae radiate throughout both valves
  2. Valve rhombic

Frustule monoraphid, raphe valve concave and rapheless valve convex. Valves rhombic-elliptical to rhombic-lanceolate. Striae radiate throughout both valves, uniseriate. Two or three striae in the middle of the raphe valve are more distant from one another than other striae. Axial area narrow, only slightly widened at valve center.