View source for Psora

{{Short description|Genus of lichens}}
{{For|a taxonomic synonym of a genus of plants|Centaurea}}
{{Automatic taxobox
| image = Psora decipiens 458948729.jpg
| image_caption = ''Psora decipiens''
| taxon = Psora
| authority = [[Hoffm.]] (1796)
| type_species = ''[[Psora decipiens]]''
| type_species_authority = ([[Hedw.]]) Hoffm. (1794)
| subdivision_ranks = Species
| subdivision = 
| synonyms_ref = <ref name="Species Fungorum synonymy"/>
| synonyms = *''Fritzea'' {{small|Stein (1879)}}
*''Chrysopsora'' {{small|[[Lagerh.]] (1892)}}
*''Lecidea'' sect. ''Chrysopsora'' {{small|Vain. [as 'Chrysospora'] (1934)}}
*''Peltiphylla'' {{small|M.Choisy (1950)}}
*''Chrysopsora'' {{small|([[Vain.]]) [[M.Choisy]] (1951)}}
}}

'''''Psora''''' is a [[genus]] of [[lichen]]-forming [[fungi]] in the family [[Psoraceae]].<ref name="Wijayawardene et al. 2020"/> Members of the genus are [[List of common names of lichen genera|commonly called]] '''fishscale lichens'''.<ref name =USDA>[https://plants.usda.gov/java/nameSearch USDA Natural Resources Conservation Service Name Search]</ref><ref>[http://eol.org/pages/16369/overview Fishscale Lichen (Psora), Encyclopedia of Life]</ref> Lichens in the genus ''Psora'' generally have a [[Squamulose lichen|squamulose]] [[thallus]] and [[anthraquinone]]s in the [[hymenium]].<ref name="Timdal 1984"/> {{lichengloss|Photobiont}} partners of ''Psora'' lichens include members of the green algal genera ''[[Asterochloris]]'', ''[[Chloroidium]]'', ''[[Myrmecia (alga)|Myrmecia]]'', and ''[[Trebouxia]]''.<ref name="Sanders & Masumoto 2021"/>

==Taxonomy==
The genus ''Psora'' was first [[validly published name|validly]] published in 1796 by the German lichenologist [[Georg Franz Hoffmann]]. His {{lichengloss|diagnosis}} of the genus was brief: {{lang|la|Crusta effigurata. Scutellae marginatae, convexae.}} "Crust patterned. Scutellae (small shields) bordered, convex.") He included 26 species in the genus.<ref name="Hoffmann 1796"/>

==Description==
Genus ''Psora'' comprises lichens recognised for their relatively large, thick {{lichengloss|squamules}}, which are the leaf-like structures making up the lichen's body. These squamules, ranging in colour from yellow to red-brown and typically measuring between 2 and 6&nbsp;mm in diameter, are notable for their absence of a [[prothallus#In lichens|prothallus]], which is an initial growth phase seen in some lichens. The upper cortex of these lichens is thick and well-developed, while the lower cortex may be poorly developed or entirely absent. Instead of a lower cortex, ''Psora'' species often anchor themselves with a well-developed network of fungal [[hypha]]e, which can either lack [[calcium oxalate]] crystals and have a brown pigmentation or be colourless, shorter, and densely covered in these crystals.<ref name="Cannon et al. 2022"/>

The symbiotic partner of ''Psora'', the {{lichengloss|photobiont}}, is {{lichengloss|chlorococcoid}}, meaning it consists of spherical [[green algae]], forming a continuous layer. The [[medulla (lichenology)|medulla]], the innermost layer of the lichen, is well-developed but does not contain [[iodine]]-reactive substances (I–).<ref name="Cannon et al. 2022"/>

Reproductive structures, known as [[apothecia]], are {{lichengloss|sessile}} (attached directly by their base), and can be found along the margins or on the surface ({{lichengloss|laminal}}) of the squamules. These structures are typically brown-black, starting flat or slightly convex in their youth, and may become highly convex or semi-spherical as they mature, occasionally with a white or yellow powdery coating ({{lichengloss|pruina}}). Unlike some lichens, ''Psora'' does not have a {{lichengloss|thalline margin}} around its apothecia. The {{lichengloss|true exciple}}, a ring of hyphae surrounding the apothecial {{lichengloss|disc}}, is colourless to pale brown and often becomes obscured as the apothecia mature.<ref name="Cannon et al. 2022"/>
[[File:Psora mediterranea Fig11.tif|thumb|Illustration of ''Psora mediterranea'']]
The {{lichengloss|epithecium}}, the topmost layer inside the apothecia, is red-brown or brown and contains [[anthraquinone]]s compounds, such as [[parietin]], which react red or purple-red when treated with a potassium hydroxide solution (K+), but do not react with a [[nitric acid]] solution (N–). The [[hymenium]], another internal layer, also does not react to iodine (I–). The {{lichengloss|hypothecium}} beneath it is pale brown to colourless and filled with calcium oxalate crystals.<ref name="Cannon et al. 2022"/>

''Psora''{{'}}s supporting filamentous structures, or [[paraphyses]], are unbranched or sparingly branched and tightly bound together, with slightly swollen tips. The [[ascus|asci]], the spore-bearing cells, are {{lichengloss|clavate}} (club-shaped) with eight spores each and have a distinctive blue reaction when stained with [[iodine]], indicative of the ''[[Porpidia]]''-type asci without an ocular chamber. Ascospores are colourless, smooth, [[ellipsoid]]al, and lack a [[septum]] or a thick outer layer ({{lichengloss|perispore}}). The genus also produces [[pycnidia]], a type of [[asexual reproduction|asexual reproductive]] structure, which are immersed within the squamules and release elongate-{{lichengloss|bacilliform}} (rod-shaped), colourless [[conidia]].<ref name="Cannon et al. 2022"/>

Chemically, ''Psora'' has a range of compounds including [[depside]]s, [[depsidone]]s, [[anthraquinone]]s, various acids such as [[pulvinic acid|pulvinic]] and [[usnic acid]]s, and [[triterpene]]s.<ref name="Cannon et al. 2022"/>

==Species==
{{As of|2024|February}}, [[Species Fungorum]] (in the [[Catalogue of Life]]) accept 16 species of ''Psora''.<ref name="CoL"/> However, there are additional accepted species that have not yet been added. Although nearly 400 names have been published in this genus, most of these have been reduced to synonymy, transferred to other genera, or are older names that have not been examined with molecular methods.
[[File:Psora pseudorussellii Timdal 814945.jpg|thumb|''Psora pseudorussellii'']]
*''[[Psora altotibetica]]'' {{small|Timdal, Obermayer & Bendiksby (2016)}}<ref name="Timdal 2016"/>
*''[[species:Psora brunneocarpa|Psora brunneocarpa]]'' {{small|Timdal (2002)}}
*''[[species:Psora crenata|Psora crenata]]'' {{small|(Taylor) Reinke  (1895)}}
*''[[Psora crystallifera]]'' {{small|(Taylor) Müll.Arg. (1888)}}
*''[[species:Psora decipiens|Psora decipiens]]'' {{small|(Hedw.) Hoffm. (1794)}}
*''[[species:Psora elenkinii|Psora elenkinii]]'' <small>Rass. (1940)</small>
*''[[species:Psora globifera|Psora globifera]]'' {{small|(Ach.) A.Massal. (1852)}}
*''[[species:Psora gresinonis|Psora gresinonis]]'' <small>B. de Lesd.</small> <small>(1930)</small>
*''[[species:Psora himalayana|Psora himalayana]]'' <small>(C. Bab.) Timdal (1986)</small>
*''[[species:Psora hyporubescens|Psora hyporubescens]]'' {{small|Timdal (2002)}}
*''[[species:Psora icterica|Psora icterica]]'' {{small|(Mont.) Müll.Arg. (1888)}}
*''[[species:Psora indigirkae|Psora indigirkae]]'' {{small|Timdal & Zhurb. (2004)}}
*''[[species:Psora mediterranea|Psora mediterranea]]'' <small>Evankow & Timdal</small> <small>(2025)</small><ref>{{Cite journal |last=Evankow |first=Ann M. |last2=Yin |first2=Ancheng |last3=Zulfiqar |first3=Rizwana |last4=Ahmad |first4=Uswa Fatima |last5=Nordenhaug |first5=Petter |last6=Khalid |first6=Abdul Nasir |last7=Wang |first7=Lisong |last8=Timdal |first8=Einar |date=2025-03-27 |title=Psora mediterranea (Lecanorales, Psoraceae), a new lichen species from Europe, including a new concept for P. himalayana and a revised key to the European species |url=https://link.springer.com/article/10.1007/s11557-025-02045-8 |journal=Mycological Progress |language=en |volume=24 |issue=1 |pages=26 |doi=10.1007/s11557-025-02045-8 |issn=1861-8952|doi-access=free }}</ref>
*''[[species:Psora peninsularis|Psora peninsularis]]'' {{small|Timdal (2002)}}
*''[[species:Psora pseudorussellii|Psora pseudorussellii]]'' <small>Timdal (1986)</small>
*''[[species:Psora pruinosa|Psora pruinosa]]'' {{small|Timdal (2002)}}
*''[[species:Psora rubiformis|Psora rubiformis]]'' {{small|(Wahlenb. ex Ach.) Hook. (1833)}}
*''[[species:Psora saviczii|Psora saviczii]]'' <small>(Tomin) Follmann & A. Crespo</small> <small>(1975)</small>
*''[[Psora taurensis]]'' {{small|Timdal, Bendiksby, Kahraman & Halıcı (2017)}}<ref name="Timdal et al. 2017"/>
*''[[species:Psora testacea|Psora testacea]]'' {{small|Hoffm. (1790)}}
*''[[species:Psora vallesiaca|Psora vallesiaca]]'' <small>(Schaer.) Timdal</small> <small>(1984)</small><ref name="Timdal 1984" />

==References==
{{Reflist|refs=

<ref name="Cannon et al. 2022">{{cite book |last1=Cannon |first1=P. |last2=Aptroot |first2=A. |last3=Coppins |first3=B. |last4=Orange |first4=A. |last5=Sanderson |first5=N. |last6=Simkin |first6=J. |year=2022 |title=Lecanorales: Psoraceae, including the genera ''Brianaria'', ''Protoblastenia'', ''Protomicarea'' and ''Psora'' |series=Revisions of British and Irish Lichens |volume=28 |pages=8–9 |url=https://britishlichensociety.org.uk/sites/default/files/Psoraceae.pdf}}</ref>

<ref name="CoL">{{Catalogue of Life |id=74DT |title=''Psora'' |access-date=2 February 2024}}</ref>

<ref name="Hoffmann 1796">{{cite journal |last=Hoffmann |first=G.F. |year=1796 |title=Deutschlands Flora oder botanisches Taschenbuch. Zweyter Theil für das Iahr 1795 |journal=Cryptogamie |page=161 |language=la |url=https://www.biodiversitylibrary.org/page/52833998}}</ref>

<ref name="Sanders & Masumoto 2021">{{cite journal |last1=Sanders |first1=William B. |last2=Masumoto |first2=Hiroshi |title=Lichen algae: the photosynthetic partners in lichen symbioses |journal=The Lichenologist |volume=53 |issue=5 |year=2021 |doi=10.1017/S0024282921000335 |pages=347–393 |doi-access=free}}</ref>

<ref name="Species Fungorum synonymy">{{cite web |title=Synonymy. Current Name: ''Psora'' Hoffm., Deutschl. Fl., Zweiter Theil (Erlangen): 161 (1796) [1795] |url=http://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=4513 |publisher=[[Species Fungorum]] |access-date=2 February 2024}}</ref>

<ref name="Timdal 1984">{{cite journal|last=Timdal |first=Einar |year=1984 |title=The delimitation of ''Psora'' (Lecideaceae) and related genera, with notes on some species |journal=Nordic Journal of Botany |volume=4 |issue=4 |pages=525–540 |doi=10.1111/j.1756-1051.1984.tb02059.x}}</ref>

<ref name="Timdal 2016">{{cite journal |last1=Timdal, E |last2=Obermayer, W. |last3=Bendiksby |first3=M. |year=2016 |title=''Psora altotibetica'' (Psoraceae, Lecanorales), a new lichen species from the Tibetan part of the Himalayas |journal=MycoKeys |issue=13 |pages=35–48|doi=10.3897/mycokeys.13.8824 |doi-access=free |hdl=10852/50296 |hdl-access=free }}</ref>

<ref name="Timdal et al. 2017">{{cite journal |last1=Timdal |first1=E. |last2=Bendiksby |first2=M. |last3=Kahraman |first3=A.M. |last4=Halıcı |first4=M.G. |year=2017 |title=''Psora taurensis'' (Psoraceae, Lecanorales), a new lichen species from Turkey |journal=MycoKeys |issue=21 |pages=1–12|doi=10.3897/mycokeys.21.11726 |doi-access=free |hdl=10852/55765 |hdl-access=free }}</ref>

<ref name="Wijayawardene et al. 2020">{{cite journal |display-authors=6 |last1=Wijayawardene |first1=Nalin |last2=Hyde |first2=Kevin |first3=Laith Khalil Tawfeeq |last3=Al-Ani |last4=Somayeh |first4=Dolatabadi |last5=Stadler |first5=Marc |last6=Haelewaters |first6=Danny |last7=Tsurykau |first7=Andrei |last8=Mesic |first8=Armin |last9=Navathe |first9=Sudhir |last10=Papp |first10=Viktor |last11=Oliveira Fiuza |first11=Patrícia |last12=Vázquez |first12=Víctor |last13=Gautam |first13=Ajay |last14=Becerra |first14=Alejandra G. |last15=Ekanayaka |first15=Anusha |last16=K. C. |first16=Rajeshkumar |last17=Bezerra |first17=Jadson |last18=Matočec |first18=Neven |last19=Maharachchikumbura |first19=Sajeewa |last20=Suetrong |first20=Satinee |year=2020 |title=Outline of Fungi and fungus-like taxa |journal=Mycosphere |volume=11 |pages=1060–1456 |doi=10.5943/mycosphere/11/1/8 |doi-access=free|hdl=10481/61998 |hdl-access=free }}</ref>

}}

{{Taxonbar|from=Q7256114}}

[[Category:Lecanorales]]
[[Category:Lichen genera]]
[[Category:Lecanorales genera]]
[[Category:Taxa described in 1796]]
[[Category:Taxa named by Georg Franz Hoffmann]]