{{Short description|Genus of algae}} {{Automatic taxobox | image = Peyssonnelia squamaria.jpg | image_caption = ''[[Peyssonnelia squamaria]]'' | taxon = Peyssonnelia | authority = [[Joseph Decaisne|Decaisne]], 1841 }}

'''''Peyssonnelia''''' is a genus of thalloid [[red alga]],<ref name=WoRMS/><ref name=Schneider1987>{{cite journal |author1=Schneider, C. W. |author2=Reading, R. P. | title = A revision of the genus ''Peyssonnelia'' (Rhodophyta, Cryptonemiales) from North Carolina, including ''P. atlantica'' new species | year = 1987 | journal = Bulletin of Marine Science | volume = 40 | issue = 2 | pages = 175–192 | url = http://www.ingentaconnect.com/content/umrsmas/bullmar/1987/00000040/00000002/art00001 }}</ref> named after naturalist [[Jean-André Peyssonnel]] (1694–1759) It includes the algae commonly known as '''rumoi-iwanokawa''', '''mayoi-iwanokawa''' and '''akase-iwanokawa'''. Specimens can reach around 20&nbsp;cm in size. ''Peyssonnelia'' produces tetraspores.

== Taxonomy and Nomenclature == ''Peyssonnelia'' belongs to class Florideophyceae, of the order Peyssonneliales and Family Peyssonneliaceae. There are 89 currently recognized species as of 2021.<ref name=":0">{{Cite journal|last1=Pestana|first1=Edilene Maria dos Santos|last2=Nunes|first2=José Marcos de Castro|last3=Cassano|first3=Valéria|last4=Lyra|first4=Goia de Mattos|date=2021-10-13|title=Taxonomic revision of the Peyssonneliales (Rhodophyta): Circumscribing the authentic ''Peyssonnelia'' clade and proposing four new genera and seven new species |url=http://dx.doi.org/10.1111/jpy.13207|journal=Journal of Phycology|volume=57|issue=6|pages=1749–1767|doi=10.1111/jpy.13207|pmid=34448497 |s2cid=237321243 |url-access=subscription}}</ref> Its lectotype is ''Peyssonnelia squamaria''.<ref name=WoRMS>{{cite WoRMS |title=''Peyssonnelia'' Decaisne, 1841 |year=2024 |id=144051 |db=AlgaeBase |access-date=26 March 2024}}</ref> The genus is the largest in the Peyssonneliaceae.

=== Segregate Genera === The genera ''[[Cruoriella]]'' and ''[[Cruoriopsis]]'' are sometimes considered to be part of ''Peyssonnelia'', but a 2007 dissertation by Krayesky separates them.<ref name="krayesky2007">{{Cite thesis | title = Phylogenetic and developmental studies in selected red algae, with a focus on taxa from the Gulf of Mexico | author = Krayesky, David M | year = 2007 | publisher = University of Louisiana at Lafayette |location=Lafayette, Louisiana |type=PhD dissertation | url = http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=8975478&q=Cruoriopsis&uid=1180768 }}{{Dead link|date=January 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

== Morphology == [[File:Peyssonnelia squamaria (S. G. Gmelin) Decaisne, 1839 1.jpg|thumb|''Peyssonnelia squamaria'' (S. G. Gmelin) Decaisne, 1839 (Gery, 2011)]] The genus is calcareous and is characterized by crustose, prostrate thalli attached to the substrate by uni- or multicellular rhizoids. Thalli may be partially or fully calcified, with calcium carbonate deposited as aragonite crystals. It also exhibits a dorsiventral thallus arrangement. The cells are arranged in 2 or 3 layers: The hypothallus or the basal layer lies more or less parallel to the substratum, with the perithallus layer lying over it in the form of erect filaments. In some species, a middle layer known as a mesothallus is present. Most species have a simple morphology and a highly variable anatomy. They differ from other coralline algae such as [[Corallinaceae|Corallineaceae]] via their reproductive structures, which are confined to nemathecia - external pustules which form from the surface cells.<ref name=":0" /><ref name=":1">{{Cite journal|last1=Krayesky|first1=David M.|last2=Norris|first2=James N.|last3=Gabrielson|first3=Paul W.|last4=Gabriel|first4=Daniela|last5=Fredericq|first5=Suzanne|date=2009|title=A new order of red algae based on the Peyssonneliaceae, with an evaluation of the ordinal classification of the Florideophyceae (Rhodophyta)|url=http://dx.doi.org/10.2988/08-43.1|journal=Proceedings of the Biological Society of Washington|volume=122|issue=3|pages=364–391|doi=10.2988/08-43.1|s2cid=86232035 |url-access=subscription}}</ref><ref name=":2">{{Cite journal|last1=Ballantine|first1=David L.|last2=Ruiz|first2=Hector|date=2010|title=Two new deepwater ''Peyssonnelia species'', ''Peyssonnelia iridescens'' and ''Peyssonnelia gigaspora'' (Peyssonneliaceae, Rhodophyta) from Puerto Rico, Caribbean Sea|url=http://dx.doi.org/10.2216/09-88.1|journal=Phycologia|volume=49|issue=6|pages=537–544|doi=10.2216/09-88.1|s2cid=86043337 |url-access=subscription}}</ref>

== Distribution == The genus is distributed in arctic and temperate to subtropical and tropical waters.<ref name=":1" /><ref name=":0" />

== Ecology == [[File:Peyssonnelia squamaria (S. G. Gmelin) Decaisne, 1839.jpg|thumb|''Peyssonnelia squamaria'' (S. G. Gmelin) Decaisne, 1839 (Gery, 2011)]] ''Peyssonnelia'' occurs in intertidal to shallow subtidal waters, and have also been found to occur in deep-water habitats, existing as far as 288 m depths in the Bahamas, which makes them some of the deepest occurring photosynthetic organisms.<ref name=":0" /><ref name=":1" /><ref name=":2" /> Being a calcareous alga, ''Peyssonnelia'' contributes to consolidating and building coral reefs. This also makes them among the algae which are vulnerable to ocean acidification.<ref>{{Cite journal|last1=Horta|first1=Paulo Antunes|last2=Riul|first2=Pablo|last3=Amado Filho|first3=Gilberto M.|last4=Gurgel|first4=Carlos Frederico D.|last5=Berchez|first5=Flávio|last6=Nunes|first6=José Marcos de Castro|last7=Scherner|first7=Fernando|last8=Pereira|first8=Sonia|last9=Lotufo|first9=Tito|last10=Peres|first10=Letícia|last11=Sissini|first11=Marina|date=2016|title=Rhodoliths in Brazil: Current knowledge and potential impacts of climate change|journal=Brazilian Journal of Oceanography|volume=64|issue=spe2|pages=117–136|doi=10.1590/s1679-875920160870064sp2 |doi-access=free}}</ref> However, a study in 2018 found that while CO<sub>3</sub> concentrations of ''Peyssonnelia squamaria'' decreased after exposure to elevated CO<sub>2</sub> levels, the photosynthetic performance actually increased, suggesting that the species has the capacity for self-regulation under acidic conditions, and may benefit from a more acidified ocean.<ref>{{Cite journal|last=Yıldız|first=Gamze|date=2018-08-10|title=Physiological Responses of the Mediterranean Subtidal Alga ''Peyssonnelia squamaria'' to Elevated CO<sub>2</sub> |url=http://dx.doi.org/10.1007/s12601-018-0044-9|journal=Ocean Science Journal|volume=53|issue=4|pages=691–698|doi=10.1007/s12601-018-0044-9|bibcode=2018OSJ....53..691Y |s2cid=91998672 |url-access=subscription}}</ref>

== Life History == [[File:Peyssonnelia sp..jpg|thumb|''Peyssonnelia sp.'' from Reunion Island (Bourjon, 2014)]] A study conducted on nine ''Peyssonnelia'' species collected from Spain found that most species possessed fertile tetrasporophytes in Autumn, suggesting this is the season of peak reproduction, followed by spring.<ref>{{Cite journal|last=Boisset|first=F.|date=1992|title=On the Reproductive Phenology of Some Species of ''Peyssonnelia'' (Cryptonemiales, Rhodophyta) from the Mediterranean Coasts of Spain|url=http://dx.doi.org/10.1515/botm.1992.35.1.47|journal=Botanica Marina|volume=35|issue=1|doi=10.1515/botm.1992.35.1.47|s2cid=84388858 |url-access=subscription}}</ref> Information on the life cycle of ''Peyssonnelia'' is limited, however, based on culture studies, tetraspores grow into discs and can reach up to 300 um in 10 days. Gametangial sori develop and release gametes and develop into carposporangia.<ref>{{Cite journal|last1=Maggs|first1=Christine A.|last2=Irvine|first2=Linda M.|date=1983|title=''Peyssonnelia immersa'' sp. nov. (Cryptonemiales, Rhodophyta) from the British Isles and France, with a survey of infrageneric classification|journal=British Phycological Journal|volume=18|issue=3|pages=219–238|doi=10.1080/00071618300650241 |doi-access=free|hdl=10379/9470|hdl-access=free}}</ref>

== Chemical Composition == A study in 2009 found that extracts of a certain ''Peyssonnelia'' species contained peyssonoic acids A-B (1-2), which are growth inhibitors for bacteria (''Pseudoalteromonas bacteriolytica'') and fungal pathogens (''Lindra thalassiae'') of marine algae, as evidenced by strong antimicrobial activities in the ecological assays.<ref name=":3">{{Cite journal|last1=Lane|first1=Amy L.|last2=Mular|first2=Laurlynn|last3=Drenkard|first3=Elizabeth J.|last4=Shearer|first4=Tonya L.|last5=Engel|first5=Sebastian|last6=Fredericq|first6=Suzanne|last7=Fairchild|first7=Craig R.|last8=Prudhomme|first8=Jacques|last9=Le Roch|first9=Karine|last10=Hay|first10=Mark E.|last11=Aalbersberg|first11=William|date=2009|title=Ecological leads for natural product discovery: novel sesquiterpene hydroquinones from the red macroalga ''Peyssonnelia'' sp.|url=http://dx.doi.org/10.1016/j.tet.2009.11.042|journal=Tetrahedron|volume=66|issue=2|pages=455–461|doi=10.1016/j.tet.2009.11.042|pmid=20661312 |pmc=2908918 }}</ref> It was also reported that ''Peyssonnelia sp.'' inhibited another fungal pathogen, ''Dendryphiella salina,'' but not through peyssonoic acids A-B (1-2), suggesting it has other secondary metabolites to defend against the fungus which remain unexplored. Peyssonoic acids A-B (1-2) were also tested for inhibition of human ovarian cancer cell lines, with 2 showing higher inhibitory activity than 1.<ref name=":3" /> These results suggest the pharmaceutical potential of ''Peyssonnelia'' and warrant further research into the chemical components of this genus.

== Cultivation and Utilization == Currently there does not appear to be any literature on the cultivation or utilization of ''Peyssonnelia'' since information regarding its chemical composition is currently rather limited.

==Species== The species currently recognized are: {{Columns-list|colwidth=20em| *''P.&nbsp;abyssica'' *''P.&nbsp;antiqua'' *''P.&nbsp;armorica'' *''P.&nbsp;asiatica'' *''P.&nbsp;atropurpurea'' *''P.&nbsp;balanicola'' *''P.&nbsp;bicolor'' *''P.&nbsp;boergesenii'' *''P.&nbsp;bornetii'' *''P.&nbsp;boudouresquei'' *''P.&nbsp;calcea'' *''P.&nbsp;capensis'' *''P.&nbsp;caulifera'' *''P.&nbsp;clarionensis'' *''P.&nbsp;conchicola'' *''P.&nbsp;coriacea'' *''P.&nbsp;crispata'' *''P.&nbsp;dawsonii'' *''P.&nbsp;delicata'' *''P.&nbsp;distenda'' *''P.&nbsp;dubyi'' *''P.&nbsp;evae'' *''P.&nbsp;flavescens'' *''P.&nbsp;foliosa'' *''P.&nbsp;foveolata'' *''P.&nbsp;guadalupensis'' *''P.&nbsp;hairii'' *''P.&nbsp;hancockii'' *''P.&nbsp;hariotii'' *''P.&nbsp;harveyana'' *''P.&nbsp;imbricans'' *''P.&nbsp;immersa'' *''P.&nbsp;inamoena'' *''P.&nbsp;indica'' *''P.&nbsp;intermedia'' *''P.&nbsp;involvens'' *''P.&nbsp;japonica'' *''P.&nbsp;johanseni'' *''P.&nbsp;lemoinei'' *''P.&nbsp;luciparensis'' *''P.&nbsp;luzonensis'' *''P.&nbsp;magdalenae'' *''P.&nbsp;magna'' *''P.&nbsp;mariodinalis'' *''P.&nbsp;maris-rubri'' *''P.&nbsp;mariti'' *''P.&nbsp;meridionalis'' *''P.&nbsp;mexicana'' *''P.&nbsp;neocaledonica'' *''P.&nbsp;nitida'' *''P.&nbsp;nordstedtii'' *''P.&nbsp;novae-hollandiae'' *''P.&nbsp;obbesii'' *''P.&nbsp;obscura'' *''P.&nbsp;orientalis'' *''P.&nbsp;pacifica'' *''P.&nbsp;polymorpha'' *''P.&nbsp;profunda'' *''P.&nbsp;rara-avis'' *''P.&nbsp;replicata'' *''P.&nbsp;rosa-marina'' *''P.&nbsp;rosenvingei'' *''P.&nbsp;rubra'' *''P.&nbsp;rugosa'' *''P.&nbsp;rumoiana'' *''P.&nbsp;simulans'' *''P.&nbsp;splendens'' *''P.&nbsp;squamaria'' *''P.&nbsp;stoechas'' *''P.&nbsp;thomassinii'' *''P.&nbsp;valentinii''}}

==References== {{Reflist}}

==External links== *[http://www.algaebase.org/search/pictures/?currentMethod=imgs&fromSearch=yes&displayCount=20&query=Peyssonnelia Images] of ''Peyssonnelia'' at [[Algaebase]]

{{Taxonbar|from=Q7179613}}

[[Category:Red algae genera]] [[Category:Peyssonneliales]] [[Category:Taxa named by Joseph Decaisne]]