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Guide to Platessa oblongella

(Østrup) C.E. Wetzel, Lange- Bertalot and Ector 2017

Karayevia Oblongella Guide
Credit: Marina Potapova
  1. Valves elliptic to linear-elliptic
  2. Raphe valve with striae at least twice as dense as rapheless valve striae
  3. Raphe valve with transversely rectangular or bow tie-shaped central area
  4. Rapheless valve with narrow, lanceolate axial area

Valves are elliptic to linear-elliptic. The raphe valve has a narrow linear axial area and a transversely rectangular or bow tie-shaped central area. The raphe valve has striae that are slightly radiate in the valve center and strongly radiate and curved at apices, 24-30 in 10 µm. The rapheless valve has a narrow lanceolate axial area. Striae on rapheless valve are broader than those on the raphe valve. The rapheless valve striae are punctate, parallel in the center, and radiate at apices, 9-12 in 10 µm.