{{Short description|Genus of algae}} {{Automatic taxobox | image = Prochazkova et al 2018 Chlainomonas Fig 7.jpg | image_caption = ''Chlainomonas'' sp. | taxon = Chlainomonas | authority = Christen | subdivision_ranks = Species | type_species = ''Chlainomonas ovalis'' | type_species_authority = H.R.Christen<ref name=AlgaeBase/> | subdivision = * ''Chlainomonas kolii'' * ''Chlainomonas ovalis'' * ''Chlainomonas rubra'' | synonyms = }}
'''''Chlainomonas''''' is a genus of algae in the family Chlamydomonadaceae.<ref>See the NCBI [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=412006 webpage on Chlainomonas]. Data extracted from the {{cite web | url=https://ftp.ncbi.nih.gov/pub/taxonomy/ | title=NCBI taxonomy resources | publisher=National Center for Biotechnology Information | access-date=2007-03-19}}</ref> They are found in freshwater habitats or on snow, where they are one of the main algae responsible for causing watermelon snow.<ref name=Remias/>
==Description== ''Chlainomonas'' consists of single, ovate cells with four apical flagella attached at the tip. The protoplast is separated from the cell wall by a thick, hyaline layer; it is often filled with red pigments. There is a single chloroplast filling the cell. Pyrenoids are absent, or may be otherwise difficult to observe within the cytoplasm. There are typically two contractile vacuoles at the apex of the cell. Some species have a stigma.<ref name=AlgaeBase>{{AlgaeBase genus|id=45030|name=Chlainomonas|access-date=2023-12-24}}</ref>
===Life cycle=== ''Chlainomonas'' reproduces asexually; no sexual reproduction has been observed in this genus.<ref name=AlgaeBase/> The mode of asexual reproduction in ''Chlainomonas'' is highly unusual. During ''Chlainomonas'', new cells are produced when the protoplasm is squeezed through the cell envelope in a thin stream. This leads to the protoplast being divided into two halves, one of which is outside of the parent cell.<ref name=Novis/> After this, the protoplast quickly becomes surrounded by a gelatinous layer, similar to the parent cell.<ref name=Hoham>{{cite journal|title= New findings in the life history of the snow alga, ''Chlainomonas rubra'' (Stein et Brooke) comb. nov. (Chlorophyta, Volvocales)|last1=Hoham|first1=R. W.|date= 1975|journal=Syesis|volume=7|pages=239–247}}</ref>
When in snow, ''Chlainomonas'' is typically found as a resting spore<ref name=Hoham/> (also known as a cyst),<ref name=Matthews>{{cite journal | date = 2016 | last1=Matthews | first1=Robin A. | title=Freshwater Algae in Northwest Washington, Volume II, Chlorophyta and Rhodophyta | url= https://cedar.wwu.edu/cedarbooks/1/ | journal = A Collection of Open Access Books and Monographs | publisher = Western Washington University | doi=10.25710/fctx-n773 }}</ref> and may be in one of two different morphologies. In the first form, the spore is ellipsoidal and is covered with spines. In the second form, the resting spore forms a thick wall but no spines. Both are surrounded by an external envelope, with four grooves where the flagella would extend.<ref name=Hoham/>
==Habitat== Two species of ''Chlainomonas'' are commonly found in snow (''Chlainomonas kolii'' and ''C. rubra''.<ref name=Remias>{{cite journal|doi=10.1093/femsec/fiw030 |title=Ecophysiology, secondary pigments and ultrastructure of ''Chlainomonas'' sp. (Chlorophyta) from the European Alps compared with ''Chlamydomonas nivalis'' forming red snow |date=2016 |last1=Remias |first1=Daniel |last2=Pichrtová |first2=Martina |last3=Pangratz |first3=Marion |last4=Lütz |first4=Cornelius |last5=Holzinger |first5=Andreas |journal=FEMS Microbiology Ecology |volume=92 |issue=4 |article-number=fiw030 |pmid=26884467 |pmc=4815433 }}</ref> They have been reported from mountains in the Pacific Northwest and in New Zealand.<ref name=Novis/> The third species, ''Chlainomonas ovalis'', is a freshwater species.<ref name=Novis>{{cite journal|doi=10.1111/j.1529-8817.2008.00545.x |title=Two snow species of the quadriflagellate green alga ''Chlainomonas'' (Chlorophyta, Volvocales): ultrastructure and phylogenetic position within the ''Chloromonas'' clade |date=2008 |last1=Novis |first1=Philip M. |last2=Hoham |first2=Ronald W. |last3=Beer |first3=Thomas |last4=Dawson |first4=Murray |journal=Journal of Phycology |volume=44 |issue=4 |pages=1001–1012 |pmid=27041619 |bibcode=2008JPcgy..44.1001N |s2cid=28424764 }}</ref>
==Phylogeny== The genus ''Chlainomonas'' is monophyletic. However, it is embedded within a clade containing most of the species ''Chloromonas'', rendering the latter genus paraphyletic.<ref name=Nakada2014>{{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= Nakada|first1=Takashi| last2=Nozaki |first2=Hisayoshi |chapter= Chapter 6. Flagellate Green Algae |url= |location= |publisher= Elsevier Inc. |page=|isbn=978-0-12-385876-4 }}</ref> It is most closely related to other snow-inhabiting species in the genus ''Chloromonas'', but is not closely related to ''Chlamydomonas nivalis'', a morphologically similar red snow alga.<ref name=Novis/>
==References== {{Reflist|1}}
{{Taxonbar|from=Q5102702}}
Category:Chlamydomonadaceae Category:Chlamydomonadales genera Category:Snow algae