Prasiola

{{Automatic taxobox

| image = Prasiola japonica.png

| image_caption = Prasiola japonica

| taxon = Prasiola

| authority = (C.Agardh) Meneghini{{AlgaeBase genus|title=Prasiola Meneghini, 1838, nom. cons. |id=29|access-date=2024-12-31}}

| type_species = Prasiola crispa

| type_species_authority = (Lightfoot) Kützing

| subdivision_ranks = Species

| subdivision = See below

| synonyms =

}}

Prasiola is a genus of macroscopic green algae, found in a variety of habitats ranging from terrestrial, freshwater, to marine. The genus has a cosmopolitan distribution, ranging from the Arctic to the Antarctic.{{Rp|page=227}}

Plants belonging to the genus Prasiola were first described by John Lightfoot in 1777 in his series Flora Scotica, as the name Ulva crispa. In 1838, Giuseppe Giovanni Antonio Meneghini circumscribed the genus.{{cite journal|doi=10.1111/j.1529-8817.2004.04012.x |title=The Prasiolales (Chlorophyta) of Atlantic Europe: an assessment based on morphological, molecular, and ecological data, including the characterization of Rosenvingiella radicans (Kützing) comb. nov. |date=2004 |last1=Rindi |first1=Fabio |last2=McIvor |first2=Lynne |last3=Guiry |first3=Michael D. |journal=Journal of Phycology |volume=40 |issue=5 |pages=977–997 |bibcode=2004JPcgy..40..977R }}

Species of Prasiola are edible and are often harvested for food, particularly Prasiola japonica, in countries such as Japan and Myanmar.{{cite journal|doi=10.1111/pre.12124 |title=Prasiola (Prasiolales, Trebouxiophyceae) in Japan: A survey of freshwater populations and new records of marine taxa |date=2016 |last1=Sutherland |first1=Judy E. |last2=Miyata |first2=Masahiko |last3=Ishikawa |first3=Motoyasu |last4=Nelson |first4=Wendy A. |journal=Phycological Research |volume=64 |issue=2 |pages=110–117 }}

Description

Prasiola forms single-layered blades which may range in shape from fan-shaped, ribbon-shaped, to wedge-shaped and may or may not have a distinct stipe. In some species, plants start as uniseriate, unbranched filaments or thin ribbons. Blades may be attached to a substrate or may be freely floating or lying. Individual cells are quadrangular, and arranged in regular rows, sometimes grouped into blocks of four or eight. Individual cells are uninucleate (with a single nucleus) and contain a star-shaped chloroplast with a single central pyrenoid.{{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= John|first1=David M.| last2=Rindi |first2=Fabio |chapter= Chapter 8. Filamentous (Nonconjugating) and Plantlike Green Algae |url= |location= |publisher= Elsevier Inc. |page= |isbn=978-0-12-385876-4 }}

Reproduction

Life history and reproductive strategies of Prasiola differ between species. Asexual reproduction occurs by fragmentation or aplanospores. Sexual reproduction has only been reported in some species, and is oogamous, with flagellated sperm and non-motile egg cells. During sexual reproduction, the thallus may become polystromatic (thicker than one cell). Both male and female gametes may be produced on the same thalli (i.e. are monoecious) or different thalli (i.e. are dioecious).

Evolution

Molecular phylogenetic studies have found that Prasiola is sister to a clade containing the similar genus Rosenvingiella and Rosenvingiellopsis.{{Cite journal |last1=Nelson |first1=Wendy A. |last2=Sutherland |first2=Judy E. |date=2018-04-03 |title=Prasionema heeschiae sp. nov. (Prasiolales, Chlorophyta) from Campbell Island, New Zealand: first record of Prasionema in the southern hemisphere |url=https://www.tandfonline.com/doi/full/10.1080/09670262.2018.1423577 |journal=European Journal of Phycology |language=en |volume=53 |issue=2 |pages=198–207 |doi=10.1080/09670262.2018.1423577 |bibcode=2018EJPhy..53..198N |s2cid=90343215 |issn=0967-0262}} The genera Prasiola and Rosenvingiella were sometimes considered to be congeneric.{{cite journal|doi=10.1080/09670262.2015.1115557 |title=Prasiolales (Trebouxiophyceae, Chlorophyta) of the Svalbard Archipelago: Diversity, biogeography and description of the new genera Prasionella and Prasionema |date=2016 |last1=Heesch |first1=Svenja |last2=Pažoutová |first2=Marie |last3=Moniz |first3=Mónica B.J. |last4=Rindi |first4=Fabio |journal=European Journal of Phycology |volume=51 |issue=2 |pages=171–187 |bibcode=2016EJPhy..51..171H }} The studies have also shown that freshwater and marine species of Prasiola are representatives of a lineage that back-colonized their habitats from a terrestrial ancestor; this is the opposite situation of colonization from sea to land and with few documented examples. Prasiola forms a nearly monophyletic group, but the subaerial alga Prasiococcus was found to be nested within the Prasiola clade.{{cite journal|doi=10.1111/j.1529-8817.2007.00372.x |title=Molecular phylogeny of the green algal order Prasiolales (Trebouxiophyceae, Chlorophyta) |date=2007 |last1=Rindi |first1=Fabio |last2=McIvor |first2=Lynne |last3=Sherwood |first3=Alison R. |last4=Friedl |first4=Thomas |last5=Guiry |first5=Michael D. |last6=Sheath |first6=Robert G. |journal=Journal of Phycology |volume=43 |issue=4 |pages=811–822 |bibcode=2007JPcgy..43..811R }}

Ecology

Prasiola species are found in freshwater, marine, and terrestrial habitats. Freshwater species in this genus are common in cold-water streams. Terrestrial species often inhabit soil, rocks, and tree trunks; they are particularly common in nitrogen-rich areas such as guano deposits.{{Rp|page=416}} Marine species are mostly found in the intertidal or splash zone; each individual plant is small but they usually grow side by side to form a dense green turf on rock surfaces.{{Cite book|last1=Bunker|first1=Francis|url=https://books.google.com/books?id=hKO3DwAAQBAJ&dq=Prasiola+calophylla&pg=PA227|title=Seaweeds of Britain and Ireland: Second Edition|last2=Brodie|first2=Juliet A.|last3=Maggs|first3=Christine A.|last4=Bunker|first4=Anne R.|date=2017-06-05|publisher=Princeton University Press|isbn=978-0-9955673-3-7|language=en}} In areas like Antarctica, Prasiola is one of the most important primary producers.{{cite journal|doi=10.1111/j.1529-8817.2012.01172.x |title=Molecular phylogeny of Antarctic Prasiola (Prasiolales, Trebouxiophyceae) reveals extensive cryptic diversity |date=2012 |last1=Moniz |first1=Mónica B. J. |last2=Rindi |first2=Fabio |last3=Novis |first3=Phil M. |last4=Broady |first4=Paul A. |last5=Guiry |first5=Michael D. |journal=Journal of Phycology |volume=48 |issue=4 |pages=940–955 |pmid=27009004 |bibcode=2012JPcgy..48..940M }}

Marine Prasiola often have the ascomycete fungus Mastodia tessellata (also known as Kohlmeyera complicatula, Turgidosculum complicatulum) growing within their thalli. When the two species grow together, the thalli of Prasiola change in morphology, to becoming olive green and with a rough and convoluted surface.{{cite book|title= Taxonomy and biogeography of Macquarie Island seaweeds|last1= Ricker|first1=R.W.|date= 1987|pages= 1–344|publisher= British Museum (Natural History)|location=London|isbn= 0-565-00998-2}} The true nature of their relationship is unclear. It has been variously described as a mycophycobiosis, a lichen-like symbiosis, or a parasitic relationship.{{cite journal|doi=10.3732/ajb.0900323 |title=Symbiotic lifestyle and phylogenetic relationships of the bionts of Mastodia tessellata (Ascomycota, incertae sedis ) |date=2010 |last1=Pérez-Ortega |first1=Sergio |last2=Ríos |first2=Asunción de los |last3=Crespo |first3=Ana |last4=Sancho |first4=Leopoldo G. |journal=American Journal of Botany |volume=97 |issue=5 |pages=738–752 |pmid=21622440 }}

Species

There are about 35 species in the genus.

Traditionally, species were differentiated from each other based on morphological characters, such as the size and shape of the blade and the stipe. However, species delimitation has been problematic due to extensive morphological variability.{{cite journal|title= Taxonomy and distribution of freshwater Prasiola (Prasiolales, Chlorophyta) in central Mexico | last1= Ramírez Rodríguez|first1= R.|last2=Carmona Jiménez|first2=J.|journal= Cryptogamie, Algologie|volume=26|issue=2|pages= 177–188|url=https://sciencepress.mnhn.fr/en/periodiques/algologie/26/2/taxonomy-and-distribution-freshwater-prasiola-prasiolales-chlorophyta-central-mexico}} This has been corroborated by genetic studies, which have found the existence of cryptic species.

References

Category:Trebouxiophyceae genera

Category:Prasiolales