Taxon Account

Cyclostephanos dubius (Fricke) Round; 1982; 326

Key references

Håkansson H. 2002. A compilation and evaluation of species in the genera Stephanodiscus, Cyclostephanos and Cyclotella with a new genus in the family Stephanodiscaceae. Diatom Research. 17(1): 1-139.


3-35 µm in diameter (Houk et al. 2014).

Cells singular or forming chains. Cells cylindrical in girdle view, circular in valve view.

Valve strongly concentrically undulate with convex or concave central part.

Radiate fascicles, multiseriate with 2-4 areolae at valve face/mantle junction, becoming uniseriate towards valve centre. Interfascicles 8-12 in 10 µm (Houk et al. 2014). Central area with random arrangement of areolae.

Other features
Conical spines located on interfascicles at valve face/mantle junction.

SEM morphology
A ring of marginal fultoportulae on valve mantle, one to several valve face fultoportulae. One rimoportula situated on valve mantle.


References are given in chronological order.

Hustedt F. 1930. Die Kieselalgen Deutschlands, Österreichs und der Schweiz mit Berücksichtigung der übrigen Länder Europas sowie der angrenzenden Meeresgebiete. 1.Teil. Lieferung 2. Akademische Verlagsgesellschaft m.b.H. Leipzig. 273-464 pp Morphology; Illustrations; Taxonomy
Descourtieux-Coqueugniot C. 1981. Stephanodiscus dubius (Fricke) Hustedt: Etude en microscopie optique et en microscopie électronique. Bulletin Mensuel de la Société Linnéenne de Lyon. 8: 244-249. Morphology; Illustrations
Round F.E. 1982. Cyclostephanos - new genus within the Sceletonemaceae. Archiv für Protistenkunde. 125: 323-329. Morphology; Taxonomy; Illustrations
Theriot E., Stoermer E., Håkansson H. 1987. Taxonomic interpretation of the rimoportula of freshwater genera in the centric diatom family Thalassiosiraceae. Diatom Research. 2(2): 251-265. Illustrations; Morphology
Theriot E., Håkansson H., Kociolek J.P., Round F.E., Stoermer E.F. 1987. Validation of the centric diatom genus name Cyclostephanos. British Phycological Journal. 22(4): 345-347. Taxonomy
Hickel B., Håkansson H. 1987. Dimorphism in Cyclostephanos dubius (Bacillariophyta) and the morphology of initial valves. Diatom Research. 2(1): 35-46. Morphology; Illustrations
Pienaar C., Pieterse A.J.H. 1990. Observations on the morphology of Cyclostephanos dubius from the Vaal River, South Africa. Diatom Research. 5(1): 201-205. Morphology; Illustrations
Håkansson H. 2002. A compilation and evaluation of species in the genera Stephanodiscus, Cyclostephanos and Cyclotella with a new genus in the family Stephanodiscaceae. Diatom Research. 17(1): 1-139. Morphology; Taxonomy; Illustrations
Wojtal A.Z., Kwandrans J. 2006. Diatoms of the Wyżyna Krakowsko-Częstochowska upland (S Poland) - Coscinodiscophyceae (Thalassiosirophycidae). Polish Botanical Journal. 51(2): 177-207. Morphology; Ecology; Illustrations
Kobayasi H., Idei M., Mayama S., Nagumo T., Osada K. 2006. H. Kobayasi's Atlas of Japanese Diatoms based on electron microscopy. Volume 1. Uchida Rokakuko Publishing Co., Tokyo. 59 + 533 pp., 180 pls. Morphology; Illustrations
Kiss K.T., Klee R., Ector L., Ács E. 2012. Centric diatoms of large rivers and tributaries in Hungary: morphology and biogeographic distribution. Acta Botanica Croatica. 71(2): 1-53. Morphology; Illustrations
Reavie E.D., Kireta A.R. 2015. Centric, Araphid and Eunotioid Diatoms of the Coastal Laurentian Great Lakes. 62. Bibliotheca Diatomologica. 184 pp Morphology; Ecology; Illustrations
Genkal S.I., Kulikovskiy M.S., Kuznetsova I.V. 2020. The Recent Freshwater Centric Diatoms of Russia. Filigran, Yaroslavl. 433 pp Morphology; Illustrations
Rott E., Kofler W. 2021. Planktonic centric diatoms from the Eastern Alps: morphology, biogeography and ecology. Plant and Fungal Systematics. 66(1): 1-36. Morphology; Illustrations; Ecology
This page should be cited as:

Jüttner I., Schultz K., Wetzel C.E., Ector L., Sayer C., Bennion H., Jones V., Flower R. Cyclostephanos dubius (Fricke) Round; 1982; 326. In: Jüttner I., Carter C., Chudaev D., Cox E.J., Ector L., Jones V., Kelly M.G., Kennedy B., Mann D.G., Turner J. A., Van de Vijver B., Wetzel C.E., Williams D.M.. Freshwater Diatom Flora of Britain and Ireland. Amgueddfa Cymru - National Museum Wales. Available online at [Accessed:  ].
Record last modified: 22/04/2021