Diatoms of North AmericaDiatoms of North America
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Guide to Pinnularia subgibba

Krammer 1992

Pinnularia subgibba guide
  1. Valve margin weakly convex
  2. Apices subcapitate to broadly subrostrate
  3. Central area with 4 indistinct marks
  4. Central area variable

Valves are linear, with weakly convex sides and subcapitate to broadly subrostrate apices. The central area is variable and may have one absent marginal striae on one, or both sides, to a broad asymmetric transverse fascia. Four indistinct marks are visible in the central area of some specimens.