Cyclostephanos
Round ex Theriot, Håkansson, Kociolek, Round & Stoermer 1987 Category: Centric
TYPE SPECIES: Cyclostephanos novaezeelandiae (Cleve in Cleve & Moller) Round ex Theriot et al.
CLASS: Coscinodiscophyceae
ORDER: Thalassiosirales
FAMILY: Stephanodiscaeae
- Striae fasciculate, extending from valve face to mantle
- Costae extending from valve face to mantle, forming two branches
- Rimoportulae positioned near spines
The striae of Cyclostephanos are organized into bundles, or fascicules, that extend from the valve face onto the mantle. The costae, or thickened ribs, also extend from the valve face to mantle. The costae branch on the valve mantle below the plane of the marginal spines. Marginal rimoportulae are positioned near the spines. The branching costae distinguish this genus from Cyclotella and Stephanodiscus. Note that many of these features can seen only with SEM, particularly in the smaller species.
Although species within the genus are found in a variety of habitats, some are indicators of eutrophy. In North America, smaller species of Cyclostephanos often dominate the plankton flora during spring and summer in eutrophic lakes and rivers. Many of the species are tolerant of elevated levels of total dissolved solids and are present in highly calcareous or saline waters. Cyclostephanos is probably more common that currently reported in surveys because of difficulties in identifying this genus. The genus includes C. dubius, C. damasii, C. invisitatus, C. costatilimbus, and C. tholiformis.
Cite This Page:
Spaulding, S., and Edlund, M. (2009). Cyclostephanos. In Diatoms of the United States. Retrieved May 19, 2013, from http://westerndiatoms.colorado.edu/taxa/genus/Cyclostephanos
Contributor: Sarah Spaulding | Mark Edlund - January 2009
Reviewer: Sam Rushforth
Citations
Stoermer, E.F. and Julius, M.L. (2003). Centric Diatoms. In: Freshwater Algae of North America (J.D. Wehr and R.G. Sheath, eds) Elsevier Science pp. 559-594.
Stoermer, E.F., Håkansson, H. and Theriot, E.C. (1987). Cyclostephanos species new to North America: C. tholioformis sp. nov. and C. costatilimbus comb. nov.. British Phycological Journal 22: 349-358.
Theriot, E.C. and Kociolek, J.P. (1986). Two new pliocene species of Cyclostephanos (Bacillariophyceae) with comments on the classification of the freshwater Thalassiosiraceae. Journal of Phycology 22: 121-128.
Theriot, E.C., Håkansson, H., Kociolek, J.P., Round, F.E. and Stoermer, E.F. (1987). Validation of the centric diatom genus Cyclostephanos. British Phycological Journal 22: 345-347.