Cyclopyxis aplanata (Penard, 1911) Deflandre, 1929
Diagnosis: The shell is large, flattened in profile, the transition of the dorsal side to the ventral rounded, the dorsal side arcuately curved. The mouth is central, rounded, the contour is slightly irregular.
Dimensions: Diameter of test: 187-209 µm.
Remarks: C. aplanata microstoma Schoenborn, 1966. It differs from the typical form by a small mouth. The diameter of the shell is 125-126 microns, the height of the shell is 40-42 µm, the mouth diameter is 26 µm.
C. aplanata minima Van Oye. It differs from the typical form in smaller sizes. The diameter of the test is 130 µm, the mouth diameter is 25 µm.