Diatoms of North AmericaDiatoms of North America
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Guide to Semiorbis rotundus

G.Reid and D.M.Williams 2010

Semiorbis Rotundus Guide
Credit: David Burge
  1. Valves semi-circular
  2. Dorsal wing-like projections present
  3. Apices subrostrate

Valves are strongly arched and semicircular. Apices are subrostrate and may be recurved. Transapical striae are separated by externally thickened transapical costae, which form wing-like projections at the dorsal margin.