Thalassiosira
Cleve 1873 Category: Centric
TYPE SPECIES: Thalassiosira nordenskioeldii Cleve
CLASS: Coscinodiscophyceae
ORDER: Thalassiosirales
FAMILY: Thalassiosiraceae
- Valve face flat or tangentially undulate
- Fultoportulae one to several near the center valve
- Valve margin with spines or occluded processes
- Mantle narrow
The valve face of most freshwater species of Thalassiosira is flat, although some are tangentially undulate. The mantle is usually relatively narrow. Striae are radial and not arranged in fascicles. Marginal fultoportulae are positioned near marginal spines, or occluded processes. One to several fultoportulae are also located near the center of the valve face, often in a circular array.
Species of Thalassiosira grow primarily in marine waters. The fultoportulae, or strutted processes, secrete ß-chitin, which is considered to offer resistance to sinking and keep cells buoyant. Some species within the genus are found in estuaries, high conductance waters and rivers, polluted ponds, and other aquatic systems that have been impacted by human activities.
Cite This Page:
Spaulding, S., and Edlund, M. (2009). Thalassiosira. In Diatoms of the United States. Retrieved May 21, 2013, from http://westerndiatoms.colorado.edu/taxa/genus/Thalassiosira
Contributor: Sarah Spaulding | Mark Edlund - January 2009
Citations
Edlund, M.B., Taylor, C.M., Schelske, C.L. and Stoermer, E.F. (2000). Thalassiosira baltica (Bacillariophyta), a new exotic species in the Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences 57: 610-615.
Hasle, G.R. and Lange, C.R. (1989). Freshwater and brackish water Thalassiosira (Bacillariophyceae): taxa with tangentially undulated valves. Phycologia 28:120-135.
Hasle, G.R. (1962). The morphology of Thalassiosira fluviatilis from the polluted inner Oslofjord. Nytt Mag. Bot. 9:151-154.