Dictyotaceae

{{Short description|Family of brown algae}} {{Redirect|Dictyotales|the order of silicoflagellates|Dictyochales}} {{Automatic taxobox | image = Capo Gallo Dicotoma.jpg | image_alt = Dictyota dichotoma | image_caption = ''Dictyota dichotoma'' | taxon = Dictyotaceae | parent_authority = Bory de Saint-Vincent, 1828 | authority = Lamouroux ex Dumortier, 1822 | synonyms = * Scoresbyellaceae {{au|Womersley, 1987}} | synonyms_ref = <ref name="UpdatedPhaeophyceae"/> | subdivision_ranks = Genera | subdivision_ref = <ref name="UpdatedPhaeophyceae"/> | subdivision = 21 genera }}

'''Dictyotaceae''' is large family of brown algae (class Phaeophyceae).<ref>{{cite web |last = Guiry|first = MD|author2=GM Guiry|title = AlgaeBase version 4.2|publisher = World-wide electronic publication, National University of Ireland, Galway|year = 2006|url = http://www.algaebase.org |accessdate =2010-12-22}}</ref> It is the only family in the monotypic order '''Dictyotales''' ({{etymology|gre|diktyotos|netlike}}).<ref name="Graham 2022 Dictyotales"/> Members of this family generally prefer warmer waters than other brown algae and are prevalent in tropical and subtropical waters thanks to their many chemical defenses to ward off grazers. They display an isomorphic haplodiploid life cycle and are characterized by vegetative growth through a single apical cell. One genus in this family, ''Padina'', is the only calcareous member of the brown algae.<ref name="Lee 1999">{{cite book |last = Lee|first = RE|title = Phycology|url = https://archive.org/details/phycology00robe|url-access = registration|publisher = Cambridge University Press|year = 1999|edition=Third|location = Cambridge|isbn = 978-0-521-63883-8}}</ref> ''Lobophora variegata'' (= ''Pocockiella varieagata'') often presents a beautiful blue iridescence due to microscopic bacteria which live on the surface of the blades {{Citation needed|reason=Interesting observation but needs citation, clearly there are bacteria on the blades but are they the source of the iridescence?|date=August 2021}}. A number of genera are known as forkweed (e.g. ''Dictyota'', ''Glosophora'', ''Dilophus'', ''Dictyopteris'', ''Pachydictyon'' and ''Lobospira''.

== Biology ==

[[File:Dictyota-dichotoma-19880601-a.jpg|thumb|left|''Dictyota dichotoma'', Galicia, Spain]]

Dictyotales are an order of brown algae (Phaeophyceae), a lineage of multicellular photosynthetic protists composed by a thallus that has a certain level of tissue differentiation. The reference organism of Dictyotales used to study their general characteristics is ''Dictyota dichotoma''.<ref name="Lee 2018"/>

=== Vegetative growth ===

Dictyotales are composed of flattened, parenchymatous thalli. They display apical growth: a single apical cell forms the flattened thallus, the vegetative part of the organism, through mitosis. The mature thallus is composed of three layers: one middle layer of large cells lacking chloroplasts, surrounded by two layers of small cells packed densely with chloroplasts<ref name="Lee 2018"/> lacking pyrenoids. Some taxa exhibit blue-green iridescence when submerged. Some species of ''Dictyopteris'' and ''Spatoglossum'' have cellular vacuoles with very low pH (between 0.5 and 0.9).<ref name="Graham 2022 Dictyotales"/>

=== Life cycle and reproduction ===

[[File:FMIB_53542_Dictyota-_Thalle_encroute_le_plus_souvent_par_le_calcaire,_qui_lui_donne_une_couleur_gres_vert,_rampant_ou_dresse,_foliace_ou.jpeg|thumb|''Dictyota dichotoma'' thallus. 1) Tetrasporangia seen from above. 2) Cross-section of oogonia. 3) Cross-section of antheridia.]]

Dictyotales displays, like other brown algae, an isomorphic alternation of two generations: the gametophytes (the haploid generation), which generate gametes through mitosis; and the sporophytes (the diploid generation), which generate spores through meiosis, both of them similar in shape and structure. The gametophytes form sex organs (female oogonia and male antheridia) in sori. Both sex organs develop from surface cells. The reproduction is oogamous, with a small and mobile male gamete (sperm cell) and a big immobile female gamete (egg cell).<ref name="Lee 2018"/><ref name="Graham 2022 Dictyotales"/>

* The female sori, deep-brown in color, usually have 25–50 oogonia, with sterile oogonia localized at the margin. To develop an oogonium, a surface cell divides into a stalk cell and the oogonium proper. Each oogonium produces one egg cell that is released through a gelatinized apex in its wall.<ref name="Lee 2018"/> * The male sori, resembling white glistening spots, are surrounded by elongated sterile cells regarded as undeveloped antheridia. They can be recognized early in their development due to the disintegration of chloroplasts in their cells. To develop an antheridium, the surface cells enlarge and divide horizontally into a stalk cell and a primary spermatogenous cell, which in turn divides vertically and horizontally into 650–1500 compartments or locules, each producing one sperm cell. Each sperm cell is pear-shaped, with an anterior eyespot and only one flagellum inserted laterally, although two basal bodies are present, indicating an origin from a biflagellate ancestor. They are released from the antheridium through dissolution of the walls.<ref name="Lee 2018"/>

The egg cell secretes a pheromone, dictyotene, to attract the sperm cell. After the fertilization between the two gametes, the resulting diploid zygote grows into the sporophyte generation. On their surface, modified sporangia typically produce through meiosis four haploid non-flagellated aplanospores, but a few genera produce eight spores per sporangium (''Lobophora'', ''Zonaria'') or flagellated spores (''Exallosorus''), two features considered primitive.<ref name="De Clerck 2006"/> The spores, while naked are released through the gelatinized apex of the sporangium. Soon after, they grow a cellulose wall and grow into gametophytes.<ref name="Lee 2018"/>

== Ecology ==

[[File:Padina boergesenii (leafy rolled-blade algae Bahamas.jpg|thumb|''Padina boergesenii'' (leafy rolled-blade algae), San Salvador Island, Bahamas]]

Dictyotales are most diverse in tropical and subtropical waters, but extend into temperate regions.<ref name="Graham 2022 Dictyotales"/> They are one of the few brown algal orders whose species can form a conspicuous, even dominant component of tropical and temperate marine floras. Their ecological success is often linked to their ability to deter grazers in habitats subject to strong grazing pressure, making them an important competitor of corals and other sessile benthic life in many coastal ecosystems.<ref name="De Clerck 2006"/> Some species, in particular within the genus ''Dictyota'', produce terpenoids (such as pachydictyol) that inhibit grazing by herbivorous amphipods, sea urchins and fish.<ref name="Lee 2018"/> The species ''Lobophora variegata'' produces a cyclic lactone, lobophorolide, that in low concentrations is an active compound against pathogenic and saprophytic marine fungi.<ref name="Graham 2022 Dictyotales"/>

''Dictyota'' dominates 70% of the benthos biomass in the Florida Keys reef tract.<ref name=Beach2000>{{cite journal |author1=Beach, Kevin S |author2=Walters, Linda J |title=''Dictyota'' bloom in Florida Keys National Marine Sanctuary: Fragments and fouling. |journal=In: Hallock and French (Eds). Diving for Science...2000. Proceedings of the 20th Annual Scientific Diving Symposium |year=2000 |url=http://archive.rubicon-foundation.org/8994 |archive-url=https://archive.today/20130416041732/http://archive.rubicon-foundation.org/8994 |url-status=usurped |archive-date=April 16, 2013 |access-date=2011-01-07}}</ref> The successful spread of this alga is due in part to its ability to asexually reproduce from fragments created by "biotic and abiotic disturbances".<ref name=Beach2000/>

Dictyotales contains the only calcareous genus of brown algae, ''Padina''. Its margins contain a layer of apical cells with hairs that create a microenvironment where aragonite nucleation occurs, if isolated from the water flow.<ref name="Lee 2018"/>

== Classification ==

The order Dictyotales contains only one family, '''Dictyotaceae''', described by French biologist Jean Vincent Félix Lamouroux, and later validly published by Belgian botanist Barthélemy Charles Joseph Dumortier in 1822.<ref name="Dumortier 1822"/><ref name="UpdatedPhaeophyceae"/> Originally, this order also included two provisional families, each with one genus:<ref name="De Clerck 2006"/> '''Scoresbyellaceae''', described by Australian phycologist Hugh Bryan Spencer Womersley in 1987,<ref name="Womersley 1987">{{cite book|vauthors=((Womersley HBS))|date=1987|title=The Marine Benthic Flora of Southern Australia. Part II|publisher=Australian Biological Research Study|publication-place=Adelaide|pages=484}}</ref> and '''Dictyotopsidaceae''', described by phycologist Bruce M. Allender in 1980.<ref name="Dictyotopsidaceae">{{cite journal | vauthors = Allender BM | date = 1980 | title = ''Dictyotopsis propagulifera'' (Phaeophyta)–an algal enigma | journal = Phycologia | volume = 19 | issue = 3 | pages = 234–236 | doi = 10.2216/i0031-8884-19-3-234.1 | bibcode = 1980Phyco..19..234A }}</ref> Posterior phylogenetic analyses showed that both families branch within Dictyotaceae, thus they were synonymized.<ref name="UpdatedPhaeophyceae"/><ref name="DictyotalesPhylo"/>

The latest revision of brown algae, published in 2014, recognizes 19 genera within Dictyotales, as well as 7 genera that have been synonymized with the accepted genera.<ref name="UpdatedPhaeophyceae"/>

* ''Canistrocarpus'' {{au|De Paula & De Clerck in De Clerck et al., 2006}} * ''Chlanidophora'' {{au|J. Agardh, 1894}} * ''Dictyopteris'' {{au|J.V. Lamouroux, 1809 ''nom. cons.''}} * ''Dictyota'' {{au|J.V. Lamouroux, 1809 ''nom. cons.''}}{{br}}= ''Dilophus'' {{au|J. Agardh, 1882}}{{br}}= ''Glossophora'' {{au|J. Agardh, 1882}}{{br}}= ''Glossophorella'' {{au|Nizamuddin & Campbell, 1995}}{{br}}= ''Pachydictyon'' {{au|J. Agardh, 1894}} * ''Dictyotopsis'' {{au|Troll, 1931}} * ''Distromium'' {{au|Levring, 1940}} * ''Exallosorus'' {{au|J.A. Phillips, 1997}} * ''Herringtonia'' {{au|Kraft, 2009}} * ''Homoeostrichus'' {{au|J. Agardh, 1894}} * ''Lobophora'' {{au|J. Agardh, 1894}}{{br}}= ''Pocockiella'' {{au|Papenfuss, 1943}} * ''Lobospira'' {{au|Areschoug, 1854}} * ''Newhousia'' {{au|Kraft, G.W. Saunders, Abbott & Haroun, 2004}} * ''Padina'' {{au|Adanson, 1763}}{{br}}= ''Dictyerpa'' {{au|Collins & Harvey in Collins, 1901}}{{br}}= ''Vaughaniella'' {{au|Børgesen, 1950}} * ''Padinopsis'' {{au|Ercegovic, 1955}} * ''Rugulopteryx'' {{au|De Paula & De Clerck in De Clerck et al., 2006}} * ''Scoresbyella'' {{au|Womersley, 1987}} * ''Spatoglossum'' {{au|Kützing, 1843}} * ''Stoechospermum'' {{au|Kützing, 1843}} * ''Stypopodium'' {{au|Kützing, 1843}} * ''Taonia'' {{au|J. Agardh, 1848}} * ''Zonaria'' {{au|C. Agardh, 1817}}

==References== {{Reflist|refs=

<ref name="UpdatedPhaeophyceae">{{cite journal|vauthors=Silberfeld T, Rousseau F, de Reviers B|title=An Updated Classification of Brown Algae (Ochrophyta, Phaeophyceae)|journal=Cryptogamie, Algologie|volume=35|issue=2|pages=117–156|date=2014|doi=10.7872/crya.v35.iss2.2014.117|bibcode=2014CrypA..35..117S |url=https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/cryptogamie-algologie2014v35f2a2.pdf}}</ref>

<ref name="DictyotalesPhylo">{{cite journal|vauthors=Bittner L, Payri CE, Couloux A, Cruaud C, de Reviers B, Rousseau F|title=Molecular phylogeny of the Dictyotales and their position within the Phaeophyceae, based on nuclear, plastid and mitochondrial DNA sequence data|journal=Molecular Phylogenetics and Evolution|volume=49|issue=1|date=2008|pages=211–226|doi=10.1016/j.ympev.2008.06.018 |pmid=18652904 |bibcode=2008MolPE..49..211B }}</ref>

<ref name="Dumortier 1822">{{cite journal|vauthors=Dumortier BC|title=Commentationes botanicae: observationes botanique|journal=Observations botaniques, dédiées à la Société d'Horticulture de Tournay|publication-place=Tournay|publisher=C. Casterman-Dieu|date=1822|volume=[i]|pages=[1]–116|doi=10.5962/bhl.title.10534|doi-access=free}}</ref>

<ref name="Lee 2018">{{cite book|chapter=Heterokontophyta, Phaeophyceae|title=Phycology|edition=5th|vauthors=Lee RE|date=2018|doi=10.1017/9781316407219|publisher=Cambridge University Press|isbn=978-1-107-55565-5}}</ref>

<ref name="Graham 2022 Dictyotales">{{cite book|vauthors=Graham LE, Graham JM, Wilcox LW, Cook ME|title=Algae|edition=4th|publisher=LJLM Press|date=2022|isbn=978-0-9863935-4-9|chapter=Photosynthetic Stramenopiles III: Phaeophycean Diversity and Systematics: Dictyotales|pages=14-23–14-24}}</ref>

<ref name="De Clerck 2006">{{cite journal|title=A revised classification of the Dictyoteae (Dictyotales, Phaeophyceae) based on ''rbc''L and 26S ribosomal DNA sequence analyses|journal=Journal of Phycology|vauthors=De Clerck O, Leliaert F, Verbruggen H, Lane CE, De Paula JC, Payo DA, Coppejans E|volume=42|pages=1271–1288|date=2006|issue=6 |doi=10.1111/j.1529-8817.2006.00279.x}}</ref>

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==Further reading== {{Wikispecies}} {{Refbegin}} * {{cite journal|last1=Gauna|first1=Cecilia|last2=Caceres|first2=Eduardo|last3=Parodi|first3=Elisa|title=Temporal variations of vegetative features, sex ratios and reproductive phenology in a ''Dictyota dichotoma'' (Dictyotales, Phaeophyceae) population of Argentina|journal=Helgoland Marine Research|date=December 2013|volume=64|issue=4|pages=721–732|doi=10.1007/s10152-013-0357-0|bibcode=2013HMR....67..721G |url=https://hmr.biomedcentral.com/articles/10.1007/s10152-013-0357-0|access-date=12 February 2015|hdl=11336/3000|hdl-access=free}} * {{cite journal|last1=Lozano-Orozco|first1=Jorge G.|last2=Sentíes|first2=Abel|last3=Díaz-Larrea|first3=Jhoana|last4=Pedroche|first4=Francisco F.|last5=de Clerck|first5=Olivier|title=The occurrence of ''Dictyota canariensis'' (Dictyotales, Phaeophyceae) in the Gulf of Mexico|journal=Botanica Marina|date=1 January 2014|volume=57|issue=5|pages=359–365|doi=10.1515/bot-2013-0111 |bibcode=2014BoMar..57..359L }} *{{cite journal|last1=Vieira|first1=Christophe|last2=D'hondt|first2=Sofie|last3=De Clerck|first3=Olivier|last4=Payri|first4=Claude E.|title=Toward an inordinate fondness for stars, beetles and Lobophora? Species diversity of the genus ''Lobophora'' (Dictyotales, Phaeophyceae) in New Caledonia|journal=Journal of Phycology|date=December 2014|volume=50|issue=6|pages=1101–19|doi=10.1111/jpy.12243|pmid=26988791|bibcode=2014JPcgy..50.1101V |access-date=13 February 2015|url=http://hal.upmc.fr/hal-01102821/document}} {{Refend}}

==Further reading== {{Portal|Marine life}} {{cite journal|last1=De Paula|first1=Joel Campos|last2=Vallim|first2=Magui A|last3=Teixeira|first3=Valeria Laneuville|title= What are and where are the bioactive terpenoids metabolites from Dictyotaceae (Phaeophyceae)|journal= Revista Brasileira de Farmacognosia|date=April 2011|volume=21|issue=2|pages=216–228|doi=10.1590/S0102-695X2011005000079|doi-access=free}}

Category:Monotypic eukaryote orders Category:Aquatic plants Category:Brown algae families Category:Dictyotaceae Category:Dictyotales Category:Ochrophyta Category:Plants described in 1822 Category:Taxa described in 1828 Category:Seaweeds