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Guide to Psammothidium helveticum

(Hust.) Bukht. and Round 2007

P Helveticumi Copy
Credit: Marina Potapova
  1. Valves linear-elliptic
  2. Raphe with long terminal fissures, curved to opposite sides
  3. Rapheless valve with large central area

Valves are linear-elliptic. The raphe valve has a bow tie-shaped central area. The raphe has long terminal raphe fissures curved to opposite sides of the valve. The rapheless valve has a large rounded, hexagonal or diamond-shaped central area. Striae are radiate on both valves, 24-30 in 10 µm.