Home / Charophyceae / Desmids / Unicells / Placoderms / Closterium
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Name derivation:
Classification:
Closterium Nitzsch ex Ralfs 1848; 141 of 1,234 species descriptions are currently accepted taxonomically (Guiry and Guiry 2013). Order Desmidiales; Family Closteriaceae
Molecular sequences:
Nuclear small subunit (SSU) rDNA of 19 species clarifies monophyly in Closterium (Takashi et al. 2001)
Morphology:
Unicellular lunate desmids up to 660 µm long (Neindl and Url 1985) with two large chloroplasts, one per semicell. Lack an isthmus (found in many desmid genera) yet the overlap of the two hemicell walls is often evident, often by a change in color (older wall stained by iron oxide, etc.). Near each cell terminus is a transparent spherical or elongate vacuole containing from one to many barium sulfate granules (Brook et al. 1980) visible with light microscopy, that may act as gravity sensors. Some species "walk" by tumbling end over end across substrates.
Similar genera:
Habitat:
Freshwater lake plankton and benthos
References:
Brook, A.J., A. Forheringham, J. Bradly and A. Jenkins. 1980. Barium accumulations by desmids of the genus Closterium (Zygnemaphyceae). British Journal of Phycology 15:261-264. Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 22 May 2013. Meindl, U., and W.G. Url 1985. Observation of electron dense fibrillar bodies in the desmid Closterium lunula. Phyton (Austeria) 25(2):297-300. Ralfs, J. 1848. The British Desmidieae. pp. [i]-xxii, [i], [1]-226, pls I-XXXV. London: Reeve, Benham and Reeve. Takashi, D., D. Hendrayanti, and T. Ichimura 2001. Monophyly of the genus Closterium and the order Desmidiales (Charophyceae, Chlorophyta) inferred from nuclear small subunit rDNA data. Journal of Phycology 37:1063-1072.