Guide to Platessa oblongella
Credit: Marina Potapova
- Valves elliptic to linear-elliptic
- Raphe valve with striae at least twice as dense as rapheless valve striae
- Raphe valve with transversely rectangular or bow tie-shaped central area
- 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.