Asterococcus: Difference between revisions
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'''''Asterococcus''''' is a [[genus]] of [[green algae]] in the order [[Chlamydomonadales]].<ref name=AB_t43405>{{AlgaeBase genus|name=Asterococcus|id=43405}}</ref> It is [[planktonic]] in freshwater ponds and lakes, or [[benthic]] within mires and swamps. It is a common and widespread genus, but is rarely abundant.<ref name=Shubert2014/> |
'''''Asterococcus''''' is a [[genus]] of [[green algae]] in the order [[Chlamydomonadales]].<ref name=AB_t43405>{{AlgaeBase genus|name=Asterococcus|id=43405}}</ref> It is [[planktonic]] in freshwater ponds and lakes, or [[benthic]] within mires and swamps. It is a common and widespread genus, but is rarely abundant.<ref name=Shubert2014/> |
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==Description== |
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''Asterococcus'' consists of colonies in powers of two (two, four, eight, 16, rarely up to 64), or occasionally single cells, embedded within a conspicuous, often layered mucilaginous envelope. The cells are usually spherical to ellipsoidal and are either dispersed in the envelope or attached to the end of a branched, mucilaginous stalk. Cells are 10–40 μm in diameter with smooth [[cell wall]]s, a single [[cell nucleus|nucleus]] and usually with two [[contractile vacuole]]s. Cells contain a single [[chloroplast]] in the center of the cell with a central [[pyrenoid]], with numerous radiating lobes flattened against the cell wall.<ref name=Shubert2014>{{cite book |editor-first1=John D.|editor-last1=Wehr|editor-first2=Robert G.|editor-last2=Sheath|editor-first3=J. Patrick|editor-last3=Kociolek |date= 2014 |edition=2 |title= Freshwater Algae of North America: Ecology and Classification |last1= Shubert|first1=Elliot| last2=Gärtner |first2=Georg |chapter= Chapter 7. Nonmotile Coccoid and Colonial Green Algae |url= |location= |publisher= Elsevier Inc. |page= |isbn=978-0-12-385876-4 }}</ref><ref name=AB_t43405/> |
''Asterococcus'' consists of colonies in powers of two (two, four, eight, 16, rarely up to 64), or occasionally single cells, embedded within a conspicuous, often layered mucilaginous envelope. The cells are usually spherical to ellipsoidal and are either dispersed in the envelope or attached to the end of a branched (dendroid), mucilaginous stalk. Cells are 10–40 μm in diameter with smooth [[cell wall]]s, a single [[cell nucleus|nucleus]] and usually with two [[contractile vacuole]]s. Cells contain a single [[chloroplast]] in the center of the cell with a central [[pyrenoid]], with numerous radiating lobes flattened against the cell wall.<ref name=Shubert2014>{{cite book |editor-first1=John D.|editor-last1=Wehr|editor-first2=Robert G.|editor-last2=Sheath|editor-first3=J. Patrick|editor-last3=Kociolek |date= 2014 |edition=2 |title= Freshwater Algae of North America: Ecology and Classification |last1= Shubert|first1=Elliot| last2=Gärtner |first2=Georg |chapter= Chapter 7. Nonmotile Coccoid and Colonial Green Algae |url= |location= |publisher= Elsevier Inc. |page= |isbn=978-0-12-385876-4 }}</ref><ref name=AB_t43405/> |
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Reproduction in ''Asterococcus'' occurs [[asexual reproduction|asexually]] by the formation of [[aplanospore]]s or [[zoospore]]s, of which two to eight are produced per cell. Once formed, they are released through the dissolution of the parent cell wall. [[Sexual reproduction]] has never been observed in this genus.<ref name=AB_t43405/> |
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==Species== |
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There are currently five recognized species within the genus:<ref name=Nakazawa/> |
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* ''[[Asterococcus limneticus]]'' {{Au|G.M.Smith}} |
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* ''[[Asterococcus spinosus]]'' {{Au|Prescott}} |
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Species identification in ''Asterococcus'' depends on morphological criteria such as the form of the colony (dendroid or not), characteristics of the cell wall, and whether the colonial envelope is lamellated or not.<ref name=Nakazawa>{{cite journal | doi=10.2216/i0031-8884-43-6-711.1 | title=Taxonomic study of ''Asterococcus'' (Chlorophyceae) based on comparative morphology and ''rbc''L gene sequences | date=2004 | last1=Nakazawa | first1=Atsushi | last2=Yamada | first2=Toshihiro | last3=Nozaki | first3=Hisayoshi | journal=Phycologia | volume=43 | issue=6 | pages=711–721 | bibcode=2004Phyco..43..711N | s2cid=84880791 }}</ref> |
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==References== |
==References== |
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[[Category:Chlamydomonadales genera]] |
[[Category:Chlamydomonadales genera]] |
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[[Category:Chlamydomonadales]] |
[[Category:Chlamydomonadales]] |
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[[Category:Freshwater algae]] |
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{{Chlorophyceae-stub}} |
{{Chlorophyceae-stub}} |
Revision as of 23:22, 17 January 2024
Asterococcus | |
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Asterococcus superbus | |
Scientific classification | |
(unranked): | Viridiplantae |
Division: | Chlorophyta |
Class: | Chlorophyceae |
Order: | Chlamydomonadales |
Family: | Palmellopsidaceae |
Genus: | Asterococcus Scherffel[1] |
Species | |
See text |
Asterococcus is a genus of green algae in the order Chlamydomonadales.[1] It is planktonic in freshwater ponds and lakes, or benthic within mires and swamps. It is a common and widespread genus, but is rarely abundant.[2]
Description
Asterococcus consists of colonies in powers of two (two, four, eight, 16, rarely up to 64), or occasionally single cells, embedded within a conspicuous, often layered mucilaginous envelope. The cells are usually spherical to ellipsoidal and are either dispersed in the envelope or attached to the end of a branched (dendroid), mucilaginous stalk. Cells are 10–40 μm in diameter with smooth cell walls, a single nucleus and usually with two contractile vacuoles. Cells contain a single chloroplast in the center of the cell with a central pyrenoid, with numerous radiating lobes flattened against the cell wall.[2][1]
Reproduction in Asterococcus occurs asexually by the formation of aplanospores or zoospores, of which two to eight are produced per cell. Once formed, they are released through the dissolution of the parent cell wall. Sexual reproduction has never been observed in this genus.[1]
Species
There are currently five recognized species within the genus:[3]
- Asterococcus korschikoffii Ettl
- Asterococcus limneticus G.M.Smith
- Asterococcus papillatus Nakazawa
- Asterococcus spinosus Prescott
- Asterococcus superbus (Cienkowski) Scherffel
Species identification in Asterococcus depends on morphological criteria such as the form of the colony (dendroid or not), characteristics of the cell wall, and whether the colonial envelope is lamellated or not.[3]
References
- ^ a b c d Guiry, M.D.; Guiry, G.M. "Asterococcus". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.
- ^ a b 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.
- ^ a b Nakazawa, Atsushi; Yamada, Toshihiro; Nozaki, Hisayoshi (2004). "Taxonomic study of Asterococcus (Chlorophyceae) based on comparative morphology and rbcL gene sequences". Phycologia. 43 (6): 711–721. Bibcode:2004Phyco..43..711N. doi:10.2216/i0031-8884-43-6-711.1. S2CID 84880791.