Cyclostephanos invistitatus and C. costalimbus both have a flat valve face.
Cyclostephanos dubius has a lower fascicle density and alveolate striae.
For comparison of C. tholiformis and C. delicatus, see text.
LM scalebar = 10 µm
Diameter
9.1-15.3 µm
Striae in 10 µm
10-14 fascicles based on circumferential density