• Source: Coelastrum

Coelastrum is a genus of green algae in the Scenedesmaceae family. It is a common component of the phytoplankton in freshwater habitats such as ponds, lakes, waterfalls, and temporary pools of water, particularly eutrophic ones. The genus has a more or less cosmopolitan distribution, although some species appear to have more restricted geographical distributions.




Description


Coelastrum consists of round colonies of cells (termed coenobia) of 4, 8, 16, 32, or 64 cells. Cells are spherical to polygonal, and are connected to each other via extensions of their cell walls to form hollow spheres. The cells may have various ornamentation such as protuberans, and have one parietal chloroplast with a single pyrenoid.
Coelastrum reproduces asexually. Prior to reproduction, cell nuclei undergo mitosis, forming multinucleate cells. The cell then undergoes cytokinesis and a new daughter colony is formed within the parental cell.




= Identification

=
Species of Coelastrum are distinguished from each other by their morphologies—in particular, their cell size and shape, number of cells per coenobia, and the nature of the ornamentation surrounding the cells and connecting the cells to each other. However, a great deal of morphological variability exists, which complicates species delimitation and therefore identification.
A similar genus is Hariotina, also part of the subfamily Coelastroideae. Hariotina can be distinguished by having cells connected by one to three strands at the top (rather than at their base), and by having colonies surrounded by mucilage (while Coelastrum lacks mucilage).




Taxonomy


Coelastrum was once classified as a member of its own family, the Coelastraceae, which has always considered to be similar to the Scenedesmaceae. With molecular phylogenetic analyses, Scenedesmaceae was found to paraphyletic with respect to Coelastraceae and therefore Coelastraceae placed into Scenedesmaceae as its own subfamily, Coelastroideae.




Uses


Species of Coelastrum have been tested for uses in biotechnology, such as lipid or astaxanthin production and wastewater treatment. In paleoecology, they serve as a marker for eutrophication.




Species list



Coelastrum astroideum
Coelastrum cambricum
Coelastrum chodatii
Coelastrum crenatum
Coelastrum giganteum
Coelastrum indicum
Coelastrum irregulare
Coelastrum microporum
Coelastrum morus
Coelastrum naegelii
Coelastrum printzii
Coelastrum probiscideum
Coelastrum pseudomicroporum
Coelastrum pulchellum
Coelastrum pulchrum
Coelastrum reticulatum
Coelastrum schizodermaticum
Coelastrum sphaericum
Coelastrum stuhlmanii
Coelastrum triangulare
Coelastrum verrucosum




References



D. Garbary & A. Comas (2004-08-18). "Coelastrum Genus detail". AlgaeBase. Retrieved 2007-09-19.

Kata Kunci Pencarian:

• Coelastrum
• Scenedesmaceae
• Hariotina
• Paleobiota of the Green River Formation
• Dimorphococcus
• List of Chlorophyceae genera