Platessa Conspicua Guide
Credit: Marina Potapova
  1. Valves linear-elliptical
  2. Raphe valve with transversely rectangular central area reaching valve margins
  3. Striae biseriate
  4. Terminal raphe fissures absent

Valves are linear-elliptical. The raphe valve has a narrow axial area and transversely rectangular central area that reaches valve margins. The rapheless valve has a lanceolate axial area and no distinct central area or the two middle striae may be slightly more distant from each other than other striae. The raphe is straight, with slightly expanded terminal and central ends, without terminal raphe fissures. Striae are almost parallel in the valve center, but become strongly radiate through both valves, biseriate, 12-16 in 10 ┬Ám.