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
Cytholiformis1 Cytholiformis2 Missrcytholiformis Cytholiformis 5 Cytholiformis 6 Cytholiformis 7
9.1-15.3 µm
Striae in 10 µm
10-14 fascicles based on circumferential density

Cyclostephanos dubius

(Fricke) Round in E.C.Ther. et al. 1987

Cyclostephanos dubius LM5 Cyclostephanos dubius LM3 Cyclostephanos dubius LM4 Cyclostephanos dubius LM2 Cyclostephanos dubius LM1
8.6-18.5 µm

Cyclostephanos invisitatus

(M.H.Hohn and Hellermann) E.C.Ther., Stoermer and Håk. 1998

Cyinvisitatus 1 Cyinvistatus 2 Cyinvisitatus 3 Cyinvisitatus 4A Cyinvisitatus 5 Cyinvisitatus 6
7.8-15.1 µm
Striae in 10 µm
15-16 based on chord count, 12-15 based on circumferential density

Also compare to

Cyclostephanos costatilimbus

(H.Kobayasi & H.Kobayashi) Stoermer, Håk. and E.C.Ther.

Cyclostephanos delicatus

(Genkal) Håk. and H.J.Kling