Brachysira Hannae Guide
Credit: Paul Hamilton
  1. Rhombic valve with straight sides
  2. Length to width ratio 2:1 to 3:1
  3. Alternating long and short striae near the central area

Valves are rhombic with straight margins. The valve length is two to three times the valve width. Within each stria, the orientation and irregular size of the areolae creates a wavy appearance of the striae. Striae at the center valve margin are short, and not interrupted.