Caloneis Lewisii Guide
Credit: Barry Rosen, Matthew Keith
  1. Valve margin triundulate
  2. Central area with lunate markings
  3. Central area large, rhomboidal
  4. Apices round to cuneate

The species can be easily identified by its triundulate shape. The central area is large, rhomboidal and contains two lunate markings on each side of the central nodule.