Achnanthes Mauiensis Guide
Credit: Rex Lowe
  1. Valves linear
  2. Center valve gibbous
  3. Raphe valve with broad central area
  4. Rapheless valve with eccentric axial area

Valves are linear, with a gibbous center. The ends are narrow, rostrate ends and may be asymmetric to the apical axis. The raphe valve has a narrow axial area, with a central area expanded to the valve margins. The rapheless valve with the axial area positioned near valve margin. Striae are punctate.