{{Short description|Genus of lichens}} {{Use dmy dates|date=July 2025}} {{Use Oxford spelling|date=July 2025}} {{Automatic taxobox | image = | image_caption = | taxon = Euopsis | authority = Nyl. (1881) | type_species = ''Euopsis granatina'' | type_species_authority = (Sommerf.) Nyl. (1881) | subdivision_ranks = Species | subdivision = ''E. granatina''<br /> ''E. pulvinata'' }}
'''''Euopsis''''' is a small genus of lichen-forming fungi in the family Harpidiaceae.<ref name="CoL_CD8DL"/> The genus contains two species.<ref name="Wijayawardene et al. 2022"/> The genus was established in 1881 by the Finnish lichenologist William Nylander, who transferred species from the genus ''Pyrenopsis'' based on differences in their reproductive structures. These lichens form dark reddish-brown crusts that become jelly-like when wet and grow primarily on damp, acidic rock faces and mossy surfaces.
==Taxonomy==
The genus was circumscribed by Finnish botanist William Nylander in 1881. Nylander established Euopsis after determining that certain species previously placed in ''Pyrenopsis'' differed significantly in the form and structure of their apothecia. He transferred ''Pyrenopsis haemaleuca'' and ''P. granulatina'' to the new genus based on these morphological distinctions. In his description, Nylander noted the taxonomic complexity surrounding related genera, observing that ''Stictis'' forms well-developed apothecia similar to those found in parmeliaceous lichens, with distinctive marginal features. He suggested that the establishment of subgenera might be appropriate given the morphological variation he observed across these related groups.<ref name="Nylander 1875"/> Nylander did not designate a type species for the genus; the type, ''E. granatina'', was designated by Gerhard Eigler in 1969.<ref name="IF: Euopsis"/>
==Description==
''Euopsis'' forms a dark reddish-brown crust that ranges from a granular film to a patchwork of minute, scale-like {{lichengloss|lobes}}. When damp the thallus absorbs water and takes on a gelatinous consistency. It lacks a distinct protective {{lichengloss|cortex}}; instead, the fungal hyphae weave around the {{lichengloss|photobiont}} in a loose mesh, though pockets of tissue can become more brick-like ({{lichengloss|pseudoparenchymatous}}) where a green alga replaces the usual cyanobacterium. The principal {{lichengloss|photobiont}} is ''Gloeocapsa'', whose single cells or small clusters near the surface are wrapped in reddish-brown jelly that turns purplish in the K spot test. Some specimens also harbour ''Trebouxia'', a more conventional green alga.<ref name="Cannon et al. 2025"/>
Reproductive bodies are glossy-brown apothecia that sit flush with the thallus. Each bears a well-raised rim of thallus tissue, while the encircling wall ({{lichengloss|exciple}}) is narrow and composed of tightly parallel hyphae. A pale-brown {{lichengloss|epithecium}} covers a colourless hymenium that shows no iodine staining reaction (I−). Beneath lies a colourless to faintly brown {{lichengloss|hypothecium}} of tangled hyphae. Slender paraphyses thread the hymenium; they branch only sparingly and never swell at the tips. Cylindrical, thick-walled asci contain eight ascospores apiece; both the inner ascus wall and the {{lichengloss|tholus}} stain blue in the potassium-iodide reagent (K/I+), yet the tiny apical dome does not. The spores are smooth, ellipsoidal, single-celled and colourless, with no extra outer coat.<ref name="Cannon et al. 2025"/>
Asexual propagation occurs in sunken pycnidia scattered through the thallus. Inside, chains of elongate, flask-shaped conidiogenous cells bud off rod-like, colourless conidia. Thin-layer chromatography has so far failed to detect any secondary metabolites (lichen products) in the genus.<ref name="Cannon et al. 2025"/>
==Ecology==
Species of ''Euopsis'' grow chiefly on damp, acidic rock faces but can also spread over cushions of moss, thin soil, or patches of peaty debris in similarly moist settings.<ref name="Cannon et al. 2025"/>
==Species== *''Euopsis granatina'' {{au|(Sommerf.) Nyl. (1881)}} *''Euopsis pulvinata'' {{au|(Schaer.) Vain. (1881)}}
==References== {{Reflist|refs=
<ref name="Cannon et al. 2025">{{cite book |last1=Cannon |first1=P. |last2=Coppins |first2=B. |last3=Aptroot |first3=A. |last4=Sanderson |first4=N. |last5=Simkin |first5=J. |year=2025 |title=Miscellaneous lichens and lichenicolous fungi, including ''Aphanopsis'' and ''Steinia'' (Aphanopsidaceae), ''Arthrorhaphis'' (Arthrorhaphidaceae), ''Buelliella'', ''Hemigrapha'', ''Melaspileella'', ''Stictographa'' and ''Taeniolella'' (Asterinales, family unassigned), ''Phylloblastia'' (Chaetothyriales, family unassigned) ''Cystocoleus'' (Cystocoleaceae), ''Sclerococcum'' (Dactylosporaceae), ''Eiglera'' (Eigleraceae), ''Epigloea'' (Epigloeaceae), ''Euopsis'' (Harpidiaceae), ''Lichenothelia'' (Lichenotheliaceae), ''Lichinodium'' (Lichinodiaceae), ''Melaspilea'' (Melaspileaceae), ''Epithamnolia'' and ''Mniaecia'' (Mniaeciaceae), ''Lichenostigma'' (Phaeococcomycetaceae), ''Pycnora'' (Pycnoraceae), ''Racodium'' (Racodiaceae), ''Chicitaea'' and ''Loxospora'' (Sarrameanaceae), ''Schaereria'' (Schaereriaceae), ''Strangospora'' (Strangosporaceae), ''Botryolepraria'' and ''Stigmidium'' (Verrucariales, family unassigned), and ''Biatoridium'', ''Mycoglaena'', ''Orphniospora'', ''Piccolia'', ''Psammina'' and ''Wadeana'' (order and family unassigned) |series=Revisions of British and Irish Lichens |volume=57 |page=57 |url=https://britishlichensociety.org.uk/sites/default/files/Miscellaneous%20genera_0.pdf}}{{Open access}}</ref>
<ref name="CoL_CD8DL">{{Catalogue of Life |id=CD8DL |title=''Euopsis'' |access-date=12 July 2025}}</ref>
<ref name="IF: Euopsis">{{cite web |title=Record Details: ''Euopsis'' Nyl., Flora, Regensburg 58: 363 (1875) |url=https://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=1931 |publisher=Index Fungorum |access-date=12 July 2025}}</ref>
<ref name="Nylander 1875">{{cite journal |last=Nylander |first=W. |year=1875 |title=Addenda nova ad lichenographiam Europaeam. Contin. XXII |journal=Flora (Regensburg) |volume=58 |pages=358–364 |language=la |url=https://www.biodiversitylibrary.org/page/62869}}</ref>
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Category:Pezizomycotina Category:Ascomycota families Category:Taxa described in 1881 Category:Taxa named by William Nylander (botanist) Category:Lichen genera