{{Short description|Genus of algae}} {{Automatic taxobox | image = Pediastrum simplex EPA.jpg | image_caption = ''Monactinus simplex'' | taxon = Monactinus | authority = Corda, 1839 | type_species = ''Monactinus simplex'' | type_species_authority = (Meyen) Corda<ref name=AlgaeBase>{{AlgaeBase genus|id= 50035 |name=Monactinus|access-date=2024-11-29}}</ref> | subdivision_ranks = Species | subdivision = * ''Monactinus asymmetricus'' * ''Monactinus simplex'' }}
'''''Monactinus''''' is a genus of green algae in the family Hydrodictyaceae.<ref>See the NCBI [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=427906 webpage on Monactinus]. 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 very common in freshwater regions throughout the world.<ref>{{cite journal | doi=10.1111/j.1529-8817.2010.00940.x | title=Molecular Phylogenetic Relationships in the Freshwater Family Hydrodictyaceae (Sphaeropleales, Chlorophyceae), with an Emphasis on ''Pediastrum duplex'' | year=2011 | last1=McManus | first1=Hilary A. | last2=Lewis | first2=Louise A. | journal=Journal of Phycology | volume=47 | issue=1 | pages=152–163 | pmid=27021721 | bibcode=2011JPcgy..47..152M | s2cid=20549311 }}</ref>
==Description== ''Monactinus'' forms flat colonies, termed coenobia, of cells in powers of two, usually four, eight, or 16. Coenobia are disc-shaped in outline, and marginal cells are drawn out into one lobe or point. This distinguishes it from ''Pediastrum'' and closely related genera, which have marginal cells which are drawn out into two lobes or points.<ref name=Bicudo_and_Menezes2006>{{cite book | title= Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições | edition=2 | year=2006 | first1=Carlos E. M. |last1=Bicudo | first2=Mariângela | last2= Menezes | publisher= RiMa Editora | pages=508 | isbn= 857656064X }}</ref> ''Monactinus'' shows a considerable amount of morphological diversity, with cells displaying different shapes, cell wall surface granulations, and inter-cellular gaps (or lack thereof).<ref>{{cite journal | doi=10.1590/S2236-89062012000100002 | title=Chlorococcales (exceto Scenedesmaceae) de pesqueiros da Região Metropolitana de São Paulo, SP, Brasil: Levantamento florístico | year=2012 | last1=Rosini | first1=Edna Ferreira | last2=Sant'Anna | first2=Célia Leite | last3=Tucci | first3=Andréa | journal=Hoehnea | volume=39 | pages=11–38 | doi-access=free }}</ref> Cells have one chloroplast filling the cell, each with a single pyrenoid.<ref name=Bicudo_and_Menezes2006/>
==Taxonomy== Although ''Monactinus'' was first described by August Carl Joseph Corda in 1839, for most of its history it was considered to be a synonym of ''Pediastrum''. In 2005, molecular phylogenetic analyses showed that ''Pediastrum'' ''sensu lato'' was paraphyletic with respect to ''Hydrodictyon''. Therefore, ''Pediastrum'' was split up into several genera, including ''Monactinus''.<ref>{{cite journal | doi=10.1111/j.1529-8817.2005.00129.x | title=Phylogeny of the Hydrodictyaceae (Chlorophyceae): Inferences from rDNA Data | year=2005 | last1=Buchheim | first1=Mark | last2=Buchheim | first2=Julie | last3=Carlson | first3=Tracy | last4=Braband | first4=Anke | last5=Hepperle | first5=Dominik | last6=Krienitz | first6=Lothar | last7=Wolf | first7=Matthias | last8=Hegewald | first8=Eberhard | journal=Journal of Phycology | volume=41 | issue=5 | pages=1039–1054 | bibcode=2005JPcgy..41.1039B | s2cid=83698514 }}</ref>
==References== {{Reflist|1}}
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Category:Sphaeropleales genera Category:Sphaeropleales Category:Freshwater algae
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