Psoroma

The genus was circumscribed by the French botanist André Michaux in 1803.

Some species formerly in Psoroma were transferred to the new genera Psorophorus and Xanthopsoroma in 2010. The genus Joergensenia was erected in 2008 to contain the species formerly known as Psoroma cephalodinum.

The genus Psoroma is characterised by its small scale-like thallus, with an underlying layer that is barely noticeable. It houses a green algal {{lichengloss|photobiont}}, possibly the algae Myrmecia, which collaborates with the fungus to perform photosynthesis. Psoroma species have cephalodia, structures containing the cyanobacterium Nostoc.

The reproductive organs, known as ascomata, are apothecial in form—essentially sessile and somewhat cup-shaped with a raised, enduring edge. Within these structures, the supporting filaments, or paraphyses, may be simple or branch towards their tips, which do not expand or form a cap, staining a dusky blue when iodine is applied. The spore-producing asci are elongated, either club-shaped or cylindrical, featuring a distinctive structure at their tips where a central tube stains blue with iodine within a lighter-staining area, surrounded by a clear amyloid ring.

Spores produced by Psoroma are single-celled, colourless, and often contain one or two large oil droplets. Their shape is ellipsoidal, with a surface that is warty or ridged, and somewhat pointed at the ends. For asexual reproduction, Psoroma develops pycnidia, which are pale brown, and produces simple, rod-shaped, colourless conidia.

Chemically, Psoroma usually lacks detectable secondary metabolites (lichen products) through thin-layer chromatography, although in rare cases, porphyrilic acid and related compounds may be present.

{{As of|2024|March}}, Species Fungorum (in the Catalogue of Life) accepts 28 species of Psoroma.

File:Pannaria sphinctrina (Mont.) Tuck. (AM AK327853-2).jpg

• Psoroma absconditum {{au|Øvstedal (2008)}}
• Psoroma antarcticum {{au|S.G.Hong & Elvebakk (2018)}} – Antarctica
• Psoroma asperellum {{au|Nyl. (1869)}}
• Psoroma caliginosum {{au|Stirt. (1877)}}
• Psoroma capense {{au|Elvebakk, S.G.Hong & Rämä (2020)}} – South Africa
• Psoroma cinnamomeum {{au|Malme (1925)}}
• Psoroma cyanosorediatum {{au|P.M.Jørg. (2004)}}
• Psoroma dichroum {{au|(Hook.f. & Taylor) P.M.Jørg. (2014)}}
• Psoroma echinaceum {{au|P.M.Jørg. & Wedin (1999)}}
• Psoroma esterhuyseniae {{au|Elvebakk (2020)}} – South Africa
• Psoroma filicicola {{au|P.M.Jørg. & Sipman (2006)}}
• Psoroma fruticulosum {{au|P.James & Henssen (1983)}}
• Psoroma geminatum {{au|P.M.Jørg. (1999)}}
• Psoroma hirsutulum {{au|Nyl. ex Cromb. (1875)}}
• Psoroma hypnorum {{au|(Vahl) Gray (1821)}}
• Psoroma inflatum {{au|Elvebakk (2021)}} – New Zealand
• Psoroma macquariense {{au|C.W.Dodge (1970)}} – Antarctica
• Psoroma macrosporum {{au|(P.M.Jørg. & Palice) P.M.Jørg. (2014)}}
• Psoroma multifidum {{au|P.M.Jørg. (2004)}}
• Psoroma nigropunctatum {{au|Elvebakk & Elix (2021)}} – Australia
• Psoroma nivale {{au|Fryday, Elvebakk, F.L.Anderson & J.Gagnon (2019)}} – Quebec, Canada
• Psoroma obscurius {{au|(Nyl.) P.M.Jørg. (2014)}}
• Psoroma orphninum {{au|(Hue) P.M.Jørg. (2014)}}
• Psoroma paleaceum {{au|(Fr.) Nyl. (1855)}}
• Psoroma pholidotoides {{au|(Nyl.) Trevis. (1869)}}
• Psoroma polychidioides {{au|(Zahlbr.) P.M.Jørg. (2014)}}
• Psoroma saccharatum {{au|Scutari & Calvelo (1995)}} – Argentina
• Psoroma sphinctrinum {{au|(Mont.) Nyl. (1855)}}
• Psoroma xanthorioides {{au|(P.M.Jørg.) P.M.Jørg. (2014)}}
• Psoromaria rosulata {{au|(P.M.Jørg. & D.J.Galloway) P.M.Jørg. & H.L.Andersen (2015)}}
• Psoromaria versicolor {{au|(Müll.Arg.) P.M.Jørg. & H.L.Andersen (2015)}}

{{Reflist|colwidth=30em|refs=

{{cite book |last1=Cannon |first1=P. |last2=Aptroot |first2=A. |last3=Coppins |first3=B. |last4=Sanderson |first4=N. |last5=Simkin |first5=J. |year=2021 |title=Peltigerales: Pannariaceae, including the genera Fuscopannaria, Leptogidium, Nevesia, Pannaria, Parmeliella, Pectenia, Protopannaria and Psoroma |series=Revisions of British and Irish Lichens |volume=9 |page=14 |url=https://britishlichensociety.org.uk/sites/default/files/Pannariaceae.pdf}}{{OA}}

{{cite journal |last1=Ciferri |first1=R. |last2=Tomaselli |first2=R. |title=Saggio di una sistematica micolichenologica |journal=Atti dell'Istituto Botanico della Università e Laboratorio Crittogamico di Pavia |year=1953 |volume=10 |issue=1 |pages=25–84 |language=it}}

{{Catalogue of Life |id=6434W |title=Psoroma |access-date=31 March 2024}}

{{cite journal |last1=Elvebaak |first1=A. |last2=Robertsen |first2=E.H. |last3=Park |first3=C.H. |last4=Hong |first4=S.G. |title=Psorophorus and Xanthopsoroma, two new genera for yellow-green, corticolous and squamulose lichen species, previously in Psoroma |journal=The Lichenologist |year=2010 |volume=42 |issue=5 |pages=563–585 |doi=10.1017/S0024282910000083}}

{{cite journal |last=Dodge |first=C.W. |year=1970 |title=Lichenological notes on the flora of the Antarctic Continent and the Subantarctic islands. IX-XI |journal=Nova Hedwigia |volume=19 |issue=3–4 |pages=439–502}}

{{cite journal |last1=Elvebakk |first1=Arve |last2=Hong |first2=Soon Gyu |last3=Park |first3=Chae Haeng |last4=Rämä |first4=Teppo |title=Psoroma capense and P. esterhuyseniae (Pannariaceae), two new alpine species from South Africa |journal=The Lichenologist |volume=52 |issue=5 |year=2020 |pages=345–352 |doi=10.1017/S0024282920000377|hdl=10037/20103 |hdl-access=free}}

{{cite journal |last=Elvebakk |first=Arve |year=2021 |title=Psoroma inflatum, a new alpine lichen from New Zealand |journal=Australasian Lichenology |volume=89 |pages=49–53 |url=https://www.anbg.gov.au/abrs/lichenlist/AL89.pdf}}

{{cite journal |last1=Elvebakk |first1=Arve |last2=Elix |first2=John A. |year=2021 |title=Psoroma nigropunctatum sp. nov., an alpine lichen in south-eastern Australia related to P. buchananii |journal=Australasian Lichenology |volume=89 |pages=54–61 |url=https://www.anbg.gov.au/abrs/lichenlist/AL89.pdf}}

{{cite journal |last1=Fryday |first1=Alan M. |last2=Elvebakk |first2=Arve |last3=Anderson |first3=Frances L. |last4=Gagnon |first4=Jean Y. |year=2019 |title=Psoroma nivale (Pannariaceae, lichenized Ascomycota) a new species with dark, elongate squamules and bacilliform ascospores from arctic Québec, Canada |journal=The Lichenologist |volume=51 |issue=5 |pages=419–429 |doi=10.1017/S0024282919000288|hdl=10037/18052 |hdl-access=free }}

{{cite journal |last1=Henssen |first1=A. |last2=Renner |first2=B. |last3=Marton |first3=K. |last4=James |first4=P.W. |last5=Galloway |first5=D.J. |year=1983 |title=Studies in the lichen genus Psoroma 2. Psoroma fruticulosum and Psoroma rubromarginatum |journal=Mycotaxon |volume=18 |issue=1 |pages=29–48 |url=http://www.cybertruffle.org.uk/cyberliber/59575/0018/001/0029.htm}}

{{cite journal |last1=Jørgensen |first1=P.M. |last2=Wedin |first2=M. |title=On Psoroma species from the Southern Hemisphere with cephalodia producing vegetative dispersal units |journal=Lichenologist |year=1999 |volume=31 |issue=4 |pages=341–347 |doi=10.1017/S0024282999000456}}

{{cite journal |last=Jørgensen |first=P.M. |title=Further contributions to the Pannariaceae (lichenized Ascomycetes) of the Southern Hemisphere |journal=Bibliotheca Lichenologica |year=2004 |volume=88 |pages=229–253}}

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{{cite journal |last1=Park |first1=Chae Haeng |last2=Hong |first2=Soon Gyu |last3=Elvebakk |first3=Arve |year=2018 |title=Psoroma antarcticum, a new lichen species from Antarctica and neighbouring areas |journal=Polar Biology |volume=41 |issue=6 |pages=1083–1090 |doi=10.1007/s00300-018-2265-x|bibcode=2018PoBio..41.1083P }}

{{cite journal |last1=Passo |first1=A. |last2=Stenroos |first2=S. |last3=Calvelo |first3=S. |title=Joergensenia, a new genus to accommodate Psoroma cephalodinum (lichenized Ascomycota) |journal=Mycological Research |year=2008 |volume=112 |issue=12 |pages=1465–1474 |doi=10.1016/j.mycres.2008.06.025 |pmid=18675347}}

{{cite journal |last1=Scutari |first1=N.C. |last2=Calavelo |first2=S. |year=1995 |title=A new species of Psoroma (pannariaceae, lichenized Ascomycotina) from Tierra del Fuego, Argentina |journal=Annales Botanici Fennici |volume=32 |issue=1 |pages=5–61 [56]}}

{{cite web |title=Psoroma Ach. ex Michx. 1803 |url=http://www.mycobank.org/MycoTaxo.aspx?Link=T&Rec=4521 |publisher=MycoBank. International Mycological Association |accessdate=2012-02-25}}

{{cite journal |last=Zahlbruckner |first=A. |title=Lichenes Novae-Zelandiae a cl H. H. Allan eiusque collaboratoribus lecti |journal=Denkschriften der Akademie der Wissenschaften (Wien), Math.-nat. Kl. |year=1941 |volume=104 |pages=249–380 [275] |language=de}}

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Category:Pannariaceae

Category:Peltigerales genera

Category:Lichen genera

Category:Taxa described in 1803

Category:Taxa named by André Michaux