{{Short description|Genus of lichen-forming fungi}} {{Use dmy dates|date=June 2025}} {{Use Oxford spelling|date=June 2025}} {{Speciesbox | image = | image_caption = | parent_authority = Lumbsch & Heibel (1998) | taxon = Coppinsia minutissima | authority = Lumbsch & Heibel (1998) }}

'''''Coppinsia''''' is a fungal genus in the family Trapeliaceae.<ref name="CoL_3TQN"/> It is a monotypic genus, containing the single species '''''Coppinsia minutissima''''', a lichen. This extremely small lichen forms an almost invisible, paint-thin crust on contaminated soil and produces tiny orange-pink fruiting bodies just 0.2–0.6&nbsp;mm across. It specializes in growing on heavy metal-polluted sites such as abandoned lead mines and spoil heaps, where few other lichens can survive.

==Taxonomy==

''Coppinsia'' was erected in 1998 by H. Thorsten Lumbsch and Esther Heibel to accommodate a minute soil- and bryophyte-dwelling lichen that could not be placed satisfactorily in any previously circumscribed genus.<ref name="Lumbsch & Heibel 1998"/> The material had been sent to Lumbsch by the British lichenologist Brian John Coppins—who had provisionally labelled it "Trapelia vezdaeoides"—during a systematic review of the suborder Agyriineae. Formal publication recognised the distinctive combination of a thallus consisting only of an algal layer topped by an {{lichengloss|epinecral}} film, extremely small {{lichengloss|biatorine}} apothecia with a cup-like but often greatly reduced hyaline {{lichengloss|exciple}}, unbranched or only slightly branched paraphyses, a ''Trapelia''-type ascus and simple ovoid ascospores. The holotype was collected from metalliferous spoil at Esgair Fraith Mine, Cardiganshire, Wales, on 22 March 1993.<ref name="Lumbsch & Heibel 1998"/>

Morphologically, ''Coppinsia'' shows affinities to ''Trapelia''—both share a ''Trapelia''-type ascus, sparsely branched paraphyses and one-celled spores—but it differs in its reduced, hyaline true exciple and in lacking both cortex and medulla in the vegetative body. It also diverges from ''Anzina'', ''Agyrium'' and ''Amylora'', which either possess annular or carbonised exciples, stratified thalli or multicellular, halonate spores. Because these distinctions fall within character suites traditionally used to delimit genera in the Agyriaceae, Lumbsch and Heibel considered the material generically isolated and erected ''Coppinsia'' to preserve taxonomic clarity. No DNA sequence data were available at the time of description, and the phylogenetic position of the genus within the family therefore rests on morphological evidence alone. The generic name honours Coppins for his wide-ranging contributions to British lichenology, while the specific epithet ''minutissima'' (Latin for 'smallest') refers to the lichen's almost imperceptible thallus and tiny apothecia.<ref name="Lumbsch & Heibel 1998"/>

==Description==

''Coppinsia minutissima'' forms an exceedingly thin, crust-like thallus that sits flush against its substrate like a coat of paint. Where visible, the thallus appears greenish-grey, but it often manifests only as a faint discolouration of the bark or rock it grows on. Its upper surface is protected by a delicate {{lichengloss|epinecral layer}}—a film of dead fungal cells that helps reduce water loss—yet it lacks the more robust cortex and inner medulla that many lichens possess. The photosynthetic partner ({{lichengloss|photobiont}}) consists of tiny, spherical green algae (a {{lichengloss|chlorococcoid}} alga). No dark {{lichengloss|prothallus}} line surrounds the colony, and thin-layer chromatography has detected no characteristic lichen products.<ref name="Orange 2021"/>

The reproductive structures are minute, stalkless apothecia just 0.2–0.6&nbsp;mm across. They are {{lichengloss|biatorine}}, meaning the {{lichengloss|disc}} and its rim are the same pale orange-to-pinkish colour and the margin is not blackened or greyed with protective pigments. Inside, the true exciple—a cup of intertwined, colourless hyphae—is up to 25&nbsp;micrometres (μm) thick in young apothecia but becomes inconspicuous with age. The hymenium, a clear layer 120–160&nbsp;μm tall, contains slender paraphyses (1.5–2.5&nbsp;μm wide) that remain unbranched or only slightly branched and thicken only marginally at their tips. Asci are ''Trapelia''-type cylinders (110–140 × 15–22&nbsp;μm) that stain only faintly bluish in iodine and show a tube-shaped amyloid structure in the apex ({{lichengloss|tholus}}). Each ascus produces eight single-celled, colourless ascospores that are ovoid and measure 12–18 × 7–9.5&nbsp;μm. No asexual fruiting bodies (conidiomata) have been observed.<ref name="Orange 2021"/>

==Habitat and distribution==

''Coppinsia minutissima'' grows on bare or lightly vegetated ground in sites where heavy metals hinder most other lichens. It forms a thin film on mineral soil, decaying mosses, dying lichen thalli and fine plant detritus in and around abandoned lead mines, metal-rich spoil heaps and railway embankments. Because the thallus is almost invisible, the species is probably under-recorded.<ref name="Orange 2021"/>

Verified records come from south-west England, with additional occurrences in West Sussex, East Suffolk, the Scottish Highlands and western Wales. At these localities ''C.&nbsp;minutissima'' frequently co-occurs with the diminutive metal-tolerant lichens ''Vezdaea acicularis'' and ''V.&nbsp;cobria''.<ref name="Orange 2021"/>

==References== {{Reflist|refs=

<ref name="CoL_3TQN">{{Catalogue of Life |id=3TQN |title=''Coppinsia'' |access-date=16 June 2025}}</ref>

<ref name="Lumbsch & Heibel 1998">{{cite journal |last1=Lumbsch |first1=H.T. |last2=Heibel |first2=E. |year=1998 |title=''Coppinsia minutissima'', a new genus and species in the Agyriaceae from the British Isles |journal=The Lichenologist |volume=30 |issue=2 |pages=95–101 |doi=10.1006/lich.1997.0120 |bibcode=1998ThLic..30...95L |url=https://www.researchgate.net/publication/231985294}}</ref>

<ref name="Orange 2021">{{cite book |last1=Orange |first1=A. |last2=Cannon |first2=P. |last3=Aptroot |first3=A. |last4=Coppins |first4=B. |last5=Sanderson |first5=N. |last6=Simkin |first6=J. |year=2021 |title=Baeomycetales: Trapeliaceae, including the genera ''Coppinsia'', ''Placopsis'', ''Placynthiella'', ''Rimularia'', ''Trapelia'' and ''Trapeliopsis'' |series=Revisions of British and Irish Lichens |volume=18 |page=3 |url=https://britishlichensociety.org.uk/sites/default/files/Trapeliaceae.pdf}}</ref>

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{{Taxonbar|from=Q112796}}

Category:Baeomycetales Category:Baeomycetales genera Category:Lichen genera Category:Taxa described in 1998 Category:Taxa named by Helge Thorsten Lumbsch