Coelastrum

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Coelastrum
Coelastrum okular.jpg
coenobium of Coelastrum sp.
Scientific classification OOjs UI icon edit-ltr.svg
Clade: Viridiplantae
Division: Chlorophyta
Class: Chlorophyceae
Order: Sphaeropleales
Family: Scenedesmaceae
Genus: Coelastrum
Nägeli, 1849
Type species
Coelastrum sphaericum
Nägeli, 1849
Species

See text

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, [1] particularly eutrophic ones. [2] The genus has a more or less cosmopolitan distribution, [3] although some species appear to have more restricted geographical distributions. [4] The name comes from the Greek terms koilos, meaning hollow, and astron, meaning star. [5]

Contents

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. [1]

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. [6]

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. [6] However, a great deal of morphological variability exists, which complicates species delimitation and therefore identification. [7]

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). [7]

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. [7]

Uses

Species of Coelastrum have been tested for uses in biotechnology, such as lipid or astaxanthin production and wastewater treatment. [2] In paleoecology, they serve as a marker for eutrophication. [2]

Species list

Coenobium of Coelastrum sp. Coelastrum.jpg
Coenobium of Coelastrum sp.

References

  1. 1 2 Shubert, Elliot; Gärtner, Georg (2014). "Chapter 7. Nonmotile Coccoid and Colonial Green Algae". In Wehr, John D.; Sheath, Robert G.; Kociolek, J. Patrick (eds.). Freshwater Algae of North America: Ecology and Classification (2 ed.). Elsevier Inc. ISBN   978-0-12-385876-4.
  2. 1 2 3 Liang, Hongping; Wang, Hongli; Xu, Yan; Li, Linzhou; Melkonian, Barbara; Lorenz, Maike; Friedl, Thomas; Sahu, Sunil Kumar; Yu, Jin; Liu, Huan; Melkonian, Michael; Wang, Sibo (2020). "The Draft Genome of Coelastrum proboscideum (Sphaeropleales, Chlorophyta)" (PDF). Protist. 171 (5). doi:10.1016/j.protis.2020.125758. PMID   33126018. S2CID   225359754.
  3. ↑ Bicudo, Carlos E. M.; Menezes, Mariângela (2006). Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições (2 ed.). RiMa Editora. p. 508. ISBN   857656064X.
  4. ↑ Lukavský, Jaromír (2006). "Coelastrum pascheri sp. n., a new green alga from lakes of the Bohemian Forest". Biologia. 61: S485 –S490. doi:10.2478/s11756-007-0068-6. S2CID   29102851.
  5. ↑ Graham, J.E.; Wilcox, L.W.; Graham, L.E. (2009). Algae, 2nd Edition. Pearson. p. 616. ISBN   9780321603128.
  6. 1 2 Guiry, M.D.; Guiry, G.M. "Coelastrum". AlgaeBase . University of Galway . Retrieved 2023-11-23.
  7. 1 2 3 Hegewald, Eberhard; Wolf, Matthias; Keller, Alexander; Friedl, Thomas; Krienitz, Lothar (2010). "ITS2 sequence-structure phylogeny in the Scenedesmaceae with special reference to Coelastrum (Chlorophyta, Chlorophyceae), including the new genera Comasiella and Pectinodesmus". Phycologia. 49 (4): 325–335. Bibcode:2010Phyco..49..325H. doi:10.2216/09-61.1. S2CID   85145401.
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