Achanthidium Crassum Guide2
  1. Striae parallel at center valve
  2. Striae radiate at apices
  3. Axial area narrow

Both raphe and rapheless valves have striae that are parallel at the center valve, becoming radiate at the apices. The axial area is narrow, but widened at the valve center. Areolae are unresolvable in LM.