{{Short description|Genus of algae}} {{Automatic taxobox | image = Volvulina steinii.jpg | image_caption = ''Volvulina steinii'' | taxon = Volvulina | authority = Playfair | type_species = Volvulina steinii | type_species_authority = Playfair<ref name=AlgaeBase>{{AlgaeBase genus | id=43498 | title=''Volvulina'' Playfair, 1915 | access-date=2025-04-04 }}</ref> | subdivision_ranks = Species | subdivision_ref = <ref name=AlgaeBase/> | subdivision = * ''Volvulina compacta'' * ''Volvulina pringsheimii'' * ''Volvulina steinii'' }}
'''''Volvulina''''' is a genus of colonial green algae in the family Volvocaceae.<ref>See the NCBI [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=47792 webpage on Volvulina]. 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> It is cosmopolitan, but rare.<ref name=AlgaeBase/>
==Description== ''Volvulina'' is a multicellular organism. The colony, termed a coenobium, is broadly ellipsoidal or spherical and consists of a fixed number of cells, usually 16 in mature individuals (rarely 4, 8 or 32). The cells are located at periphery of the coenobium and separated from each other by being embedded in a gelatinous matrix. The cell body is lens-shaped or hemispherical when mature, with two equal flagella. The chloroplast is dish- or bowl-shaped. Pyrenoids may be absent or present (located at the base of the chloroplast); eyespots are present, with eyespots in anterior cells larger than those in posterior cells.<ref name=AlgaeBase/> The nucleus is centrally located<ref>[http://protist.i.hosei.ac.jp/PDB/images/Chlorophyta/Volvulina/index.html Protist Images: ''Volvulina''.]</ref> and there may be two contractile vacuoles at the base of each flagella, or several scattered contractile vacuoles.<ref name=AlgaeBase/>
''Volvulina'' reproduces both asexually and sexually. In asexual reproduction, each cell of the colony develops into a daughter colony through successive cell divisions, and then subsequent colony inversion. Sexual reproduction is isogamous.<ref name=AlgaeBase/>
==Species== Three species of ''Volvulina'' are well-characterized: ''Volvulina steinii'', ''Volvulina pringsheimii'', and ''Volvulina compacta''.<ref name=AlgaeBase/> The three species differ from each other in morphology, namely: the shape of the cells and whether they are contiguous, and the presence or location of pyrenoids.<ref name=Nozaki1990>{{cite journal|doi=10.2216/i0031-8884-29-4-410.1 |title=''Volvulina compacta'' sp. nov. (Volvocaceae, Chlorophyta) from Nepal |date=1990 |last1=Nozaki |first1=H. |last2=Kuroiwa |first2=T. |journal=Phycologia |volume=29 |issue=4 |pages=410–417 |bibcode=1990Phyco..29..410N }}</ref> In addition to these three species, there is also ''Volvulina playferiana'' which is poorly described and may be an immature form of ''V. steinii'',<ref name=Nozaki1990/> and ''Volvulina boldii'' which is a nomen nudum.<ref>{{cite journal|doi= 10.51033/jjapbot.85_6_10256|date= 2010|volume= 85|last1= Nakada|first1=T.|last2=Tomita|first2=M.|last3=Nozaki|first3=H.|title= ''Volvulina compacta'' (Volvocaceae, Chlorophyceae), new to Japan, and its phylogenetic position |journal= Journal of Japanese Botany}}</ref>
== Phylogeny == Molecular phylogenetic studies show that ''Volvulina'' is paraphyletic with respect to ''Pandorina'':<ref name=Lindsey2021>{{cite journal|doi=10.1186/s12915-021-01087-0|doi-access=free |title=Phylotranscriptomics points to multiple independent origins of multicellularity and cellular differentiation in the volvocine algae |date=2021 |last1=Lindsey |first1=Charles Ross |last2=Rosenzweig |first2=Frank |last3=Herron |first3=Matthew D. |journal=BMC Biology |volume=19 |issue=1 |page=182 |pmid=34465312 |pmc=8408923 |bibcode=2021BMCB...19..182L }}</ref><ref>{{cite journal|doi=10.1093/gbe/evad142 |title=A Reinvestigation of Multiple Independent Evolution and Triassic–Jurassic Origins of Multicellular Volvocine Algae |date=2023 |last1=Ma |first1=Xiaoya |last2=Shi |first2=Xuan |last3=Wang |first3=Qiuping |last4=Zhao |first4=Mengru |last5=Zhang |first5=Zhenhua |last6=Zhong |first6=Bojian |journal=Genome Biology and Evolution |volume=15 |issue=8 |pmid=37498572 |pmc=10410301 }}</ref><ref name=Lindsey2024>{{Cite journal |last1=Lindsey |first1=Charles Ross |last2=Knoll |first2=Andrew H. |last3=Herron |first3=Matthew D. |last4=Rosenzweig |first4=Frank |date=2024-04-10 |title=Fossil-calibrated molecular clock data enable reconstruction of steps leading to differentiated multicellularity and anisogamy in the Volvocine algae |journal=BMC Biology |volume=22 |issue=1 |pages=79 |doi=10.1186/s12915-024-01878-1 |issn=1741-7007 |pmid=38600528 |doi-access=free|pmc=11007952 |bibcode=2024BMCB...22...79L }}</ref>
{{clade |1= {{clade |1=''Platydorina'' + ''Colemanosphaera'' (outgroup) |2={{clade |1=''Volvulina steinii'' |2={{clade |1= {{clade |1="''Volvulina boldii''" |2=''Pandorina colemaniae'' }} |2=''Pandorina morum'' |3={{clade |1=''Volvulina compacta'' ''pro parte'' |2={{clade |1=''Volvulina compacta'' ''pro parte'' |2=''Volvulina pringsheimii'' }} }} }} }} }} }}
==References== {{Reflist|1}}
==External links== * [http://protist.i.hosei.ac.jp/pdb/Images/Chlorophyta/Volvulina/index.html Volvulina] - Description with pictures
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Category:Chlamydomonadales genera Category:Chlamydomonadales
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