# Inoderma

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{{Short description|Genus of lichen-forming fungi}}
{{Use dmy dates|date=October 2025}}
{{Use Oxford spelling|date=October 2025}}
{{bots|deny=Citation bot}}
{{Automatic taxobox
| image = Inoderma byssaceum.png
| image_caption = ''Inoderma byssaceum'', a lichen [indicator](/source/bioindicator) of well-preserved forest sites<ref name="Ertz 2024"/>
| taxon = Inoderma
| authority = ([Ach.](/source/Ach.)) [Gray](/source/Samuel_Frederick_Gray) (1821)
| type_species = ''Inoderma byssaceum''
| type_species_authority = ([Weigel](/source/Christian_Ehrenfried_von_Weigel)) Gray (1821)
| synonyms_ref = <ref name="Species Fungorum synonymy"/>
| synonyms = *''Phaeothrombis'' {{au|[Clem.](/source/Clem.) (1909)}}
*''Thrombium'' {{au|[Wallr.](/source/Wallr.) (1831)}}
*''Verrucaria ††††† Inoderma'' {{au|Ach. (1810)}}
*''Verrucaria sect. Inoderma'' {{au|(Ach.) [W.Mann](/source/W.Mann) (1825)}}
*''Wernera'' {{au|[Zschacke](/source/Zschacke) ex [Werner](/source/Roger-Guy_Werner) (1934)}}
*''Werneromyces'' {{au|Werner (1976)}}
| subdivision_ranks = Species
| subdivision =''[I. afromontanum](/source/Inoderma_afromontanum)''<br />
''[I. applanatum](/source/Inoderma_applanatum)''<br />
''[I. byssaceum](/source/Inoderma_byssaceum)''<br />
''[I. nipponicum](/source/Inoderma_nipponicum)''<br />
''[I. platygraphellum](/source/Inoderma_platygraphellum)''<br />
''[I. sorediatum](/source/Inoderma_sorediatum)''<br />
''[I. subabietinum](/source/Inoderma_subabietinum)''
}}

'''''Inoderma''''' is a [genus](/source/genus) of [lichen](/source/lichen)-forming [fungi](/source/fungi) in the family [Arthoniaceae](/source/Arthoniaceae).<ref name="Wijayawardene et al. 2022"/> First named by [Erik Acharius](/source/Erik_Acharius) in 1810 and formally published at genus rank by [Samuel Frederick Gray](/source/Samuel_Frederick_Gray) in 1821, the genus was resurrected in 2015 for a small group of species characterised by elevated, white frost-like [pycnidia](/source/pycnidia) ([asexual](/source/asexual_reproduction) fruiting bodies) and white-dusted [apothecia](/source/apothecia) ([sexual](/source/sexual_reproduction) fruiting bodies). These lichens typically form broad, pale whitish to light olive-grey patches on bark or other [substrates](/source/substrate_(biology)), partnering with the orange-pigmented green alga ''[Trentepohlia](/source/Trentepohlia_(alga))'' as their [photosynthetic partner](/source/photobiont). The genus comprises seven described species, most of which are bark-dwelling lichens of long-undisturbed, old-tree woodland, including [old-growth](/source/old-growth_forest) temperate forests. It has a mainly [temperate](/source/temperate) distribution across the Northern Hemisphere and Australasia, with one species known from [afromontane](/source/afromontane) rainforest in East Africa.

==Taxonomy==

The name ''Inoderma'' first appears in Acharius's ''Lichenographia Universalis'' (1810),<ref name="Species Fungorum synonymy"/> where he treated it within ''[Verrucaria](/source/Verrucaria)'' as a group of "doubtful species" characterized by a cobwebby, {{lichengloss|floccose}} to somewhat spongy [thallus](/source/thallus) (or basal felt).<ref name="Acharius 1810"/> The name ''Inoderma'' was published at genus rank by [Samuel Frederick Gray](/source/Samuel_Frederick_Gray) in 1821. In Gray's treatment of ''Inoderma'' (attributed to Acharius) in 1821, the genus was diagnosed as a lichen with a soft, tow-like thallus that is closely attached to the [substrate](/source/substrate_(biology)) and may be spongy or thin and cobwebby. He also placed weight on the form of the [fruiting bodies](/source/fruiting_bodies), describing them as very small and nearly spherical, with the fertile tissue sitting low in the thallus and surrounded by a two-layered wall: an outer, thick black layer that splits above into a nipple-like opening ("mouth"), and an inner, very thin membranous layer enclosing the central spore-bearing mass.<ref name="Gray 1821"/>

Gray included two species, ''Inoderma epigea'' and ''I.&nbsp;byssacea'', and for each he pointed back to earlier placements under ''Sphaeria'' (Persoon) and ''Verrucaria'' (Acharius). He described ''I.&nbsp;epigea'' as forming a thin, uneven, pale yellowish thallus with sunken, globular fruiting bodies and a prominent dark opening, occurring "on muddy ground", while ''I.&nbsp;byssacea'' was said to have a dirty-white, cobwebby, somewhat powdery thallus and similarly small, half-sunken fruiting bodies with a black interior, growing "on the trunks of trees".<ref name="Gray 1821"/> In subsequent literature, the same group was also treated under other names (for example as ''Verrucaria'' [section](/source/section_(botany)) ''Inoderma'', or under the genera ''Thrombium'' and ''Phaeothrombis''), which are now regarded as [synonyms](/source/synonym_(taxonomy)) of ''Inoderma''.<ref name="Species Fungorum synonymy"/>

It was resurrected for use in 2015 for a small group of species with the following features: elevated, white [pruinose](/source/pruinose) [pycnidia](/source/pycnidia), immersed to adnate white pruinose [apothecia](/source/apothecia), and a weakly gelatinized [hymenium](/source/hymenium). ''[Inoderma byssaceum](/source/Inoderma_byssaceum)'' was assigned as the [type species](/source/type_species) for the genus.<ref name="Frisch et al. 2015"/> In 2024, [Gintaras Kantvilas](/source/Gintaras_Kantvilas) reported ''Inoderma'' from Australasia for the first time and recognised two regional species: ''I.&nbsp;applanatum'' (described as new) and a new combination ''I.&nbsp;platygraphellum''. Species in the genus are separated using a combination of often subtle differences in apothecial and pycnidial [morphology](/source/morphology_(biology)), ascospore size and septation, and thallus secondary chemistry.<ref name="Kantvilas 2024"/>

==Description==

''Inoderma'' is a genus of lichens that typically forms broad, pale, whitish to light olive-grey patches on its substrate. These patches (the thallus) can be continuous but often develop a network of fine cracks or appear as tiny, powdery {{lichengloss|granules}}. The surface is usually not covered by a protective "skin" ({{lichengloss|cortex}}) and can feel slightly soft or powdery. The lichen's green partner cells (the {{lichengloss|photobiont}}) belong to ''[Trentepohlia](/source/Trentepohlia_(alga))'', a genus of [green algae](/source/green_algae).<ref name="Cannon et al. 2020"/>

Some ''Inoderma'' species produce apothecia—small, often rounded, and slightly raised structures where spores are formed. These may lie flush with the lichen's surface or sit just above it, and they sometimes carry a thin to thick white powdery coating ({{lichengloss|pruina}}). The boundary between the apothecium and the main lichen body (the {{lichengloss|true exciple}}) is not clearly defined. Inside the apothecium, the spore-producing tissue (the hymenium) is colourless to pale yellowish-brown, with tiny pale crystals in its upper layer (the {{lichengloss|epithecium}}). Beneath this, the {{lichengloss|hypothecium}} is made of tangled fungal filaments within a jelly-like matrix, ranging in colour from pale to dark brown. Thin, thread-like structures called {{lichengloss|paraphysoids}} run through this layer, and their tips do not widen or darken. The [asci](/source/ascus), which are the spore-containing "sacs", follow the ''Arthonia''-type structure.<ref name="Cannon et al. 2020"/> The hymenium [stains](/source/staining) blue in iodine (KI+), but the asci lack KI+ (blue) structures in the {{lichengloss|tholus}}.<ref name="Kantvilas 2024"/> The spores are typically elongated, sometimes slightly egg-shaped (cylindric-{{lichengloss|obovoid}} or {{lichengloss|soleiform}}), and divided into two to four compartments by internal walls ([septa](/source/septum)). They remain colourless and do not narrow at the dividing lines.<ref name="Cannon et al. 2020"/>

In addition to apothecia, ''Inoderma'' may also form [conidiomata](/source/conidiomata)—tiny, elevated, spore-producing bumps called pycnidia. These pycnidia have dark brown to black walls and are often dusted with a thick layer of white powder. They release small, rod-shaped spores known as [conidia](/source/conidia).<ref name="Cannon et al. 2020"/>

From a chemical perspective, ''Inoderma'' species may contain substances such as [lepraric acid](/source/lepraric_acid) and [confluentic acid](/source/confluentic_acid), along with some compounds not yet fully identified ("byssaceum unknowns"). When tested with chemicals, the dark brown pigments in the apothecia and pycnidia turn greenish-black in the K spot test and slowly shift to an orange-brown colour when treated with [nitric acid](/source/nitric_acid). These reactions, along with the lichen's distinct physical features and internal structures, help distinguish ''Inoderma'' from related genera.<ref name="Cannon et al. 2020"/>

==Habitat and distribution==

Most species of ''Inoderma'' are [corticolous](/source/corticolous_lichen) crustose lichens that grow on the bark of old trees, and they are typically associated with long-undisturbed woodland, including [old-growth forest](/source/old-growth_forest) and other sites with veteran trees.<ref name="Frisch et al. 2015"/><ref name="Kantvilas 2024"/> In Europe, ''I.&nbsp;byssaceum'' is strongly linked with old oaks (''[Quercus](/source/Quercus)'') in locally humid climates, while the very rare ''I.&nbsp;sorediatum'' occurs in deep bark crevices of large trees such as ''[Quercus robur](/source/Quercus_robur)'' and ''[Fraxinus excelsior](/source/Fraxinus_excelsior)''.<ref name="Frisch et al. 2015"/><ref name="Ertz et al. 2018"/> ''Inoderma subabietinum'' is another bark species of oceanic districts, recorded mainly on old oaks but also on other trees and woody substrates in sheltered, semi-shaded situations.<ref name="Frisch et al. 2015"/><ref name="Coppins & James 1979"/> In the Southern Hemisphere, ''I.&nbsp;platygraphellum'' occurs on the dry, fissured bark of very old trees in cool temperate rainforest and old-growth wet [eucalypt](/source/eucalypt) forest, whereas ''I.&nbsp;applanatum'' is largely confined to coastal swamp woodlands in which it grows on the papery bark of ''[Melaleuca ericifolia](/source/Melaleuca_ericifolia)'' and, more rarely, on other bark and dead wood.<ref name="Kantvilas 2024"/> The only known [tropical](/source/tropical) member of the genus, ''I.&nbsp;afromontanum'', grows on large-tree bark in [afromontane](/source/afromontane) rainforest in Uganda.<ref name="Frisch et al. 2015"/>

The genus has a mostly temperate distribution, with species recorded from the Northern Hemisphere, Australasia and tropical East Africa.<ref name="Kantvilas 2024"/> ''Inoderma byssaceum'' is widespread across the temperate Northern Hemisphere, with documented occurrences in Europe, north-eastern North America and parts of eastern Asia, while ''I.&nbsp;nipponicum'' is known from Japan.<ref name="Frisch et al. 2015"/> ''Inoderma subabietinum'' is confined to western Europe and adjacent Atlantic islands (including Great Britain and Ireland, parts of France and the [Azores](/source/Azores), [Madeira](/source/Madeira) and [Canary Islands](/source/Canary_Islands)).<ref name="Frisch et al. 2015"/><ref name="Coppins & James 1979"/> ''Inoderma sorediatum'' is known only from its [type locality](/source/type_locality_(biology)) in north-eastern Poland.<ref name="Ertz et al. 2018"/> Australasia holds two species: ''I.&nbsp;applanatum'' is known from Tasmania and coastal Victoria, while ''I.&nbsp;platygraphellum'' occurs in New Zealand and has also been recorded from [Tasmania](/source/Tasmania), [Victoria](/source/Victoria_(state)) and [New South Wales](/source/New_South_Wales).<ref name="Kantvilas 2024"/> Several members of the genus appear sensitive to habitat continuity, and ''I.&nbsp;byssaceum'' has declined in parts of Europe, where it is treated as threatened or rare and used locally as an [indicator](/source/bioindicator) of well-preserved oak forests.<ref name="Frisch et al. 2015"/><ref name="Ertz 2024"/>

==Species==

{{Asof|2026|1}}, [Species Fungorum](/source/Species_Fungorum) (in the [Catalogue of Life](/source/Catalogue_of_Life)) accepts six species of ''Inoderma'';<ref name="CoL"/> a 2024 revision treated seven species worldwide, including two recorded from Australasia.<ref name="Kantvilas 2024"/>

*''[Inoderma afromontanum](/source/Inoderma_afromontanum)'' {{au|Frisch & G.Thor (2015)}}<ref name="Frisch et al. 2015"/> – Uganda
*''[Inoderma applanatum](/source/Inoderma_applanatum)'' {{au|Kantvilas (2024)}}<ref name="Kantvilas 2024"/>
*''[Inoderma byssaceum](/source/Inoderma_byssaceum)'' {{au|(Weigel) Gray (1821)}}
*''[Inoderma nipponicum](/source/Inoderma_nipponicum)'' {{au|Frisch, Y.Ohmura & G.Thor (2015)}}<ref name="Frisch et al. 2015"/> – Japan
*''[Inoderma platygraphellum](/source/Inoderma_platygraphellum)'' {{au|(Nyl.) Kantvilas (2024)}}<ref name="Kantvilas 2024"/>
*''[Inoderma sorediatum](/source/Inoderma_sorediatum)'' {{au|Ertz, Łubek & Kukwa (2018)}}<ref name="Ertz et al. 2018"/> – Poland
*''[Inoderma subabietinum](/source/Inoderma_subabietinum)'' {{au|(Coppins & P.James) Ertz & Frisch (2015)}} – Europe

The taxon ''Inoderma epigaeum'' {{au|(Pers.) Gray (1821)}} is now classified in the genus ''[Thrombium](/source/Thrombium)'' as ''[Thrombium epigaeum](/source/Thrombium_epigaeum)''.<ref name="IF: Inoderma epigaeum"/>

The name ''Inoderma'' has also been used for an unrelated, non-lichenised genus introduced by Berkeley in 1881 for gasteroid fungi ([Mesophelliaceae](/source/Mesophelliaceae), Basidiomycota),<ref name="Berkeley 1881"/> but this ''Inoderma'' {{au|Berk.}} is an illegitimate later [homonym](/source/homonym_(biology)) of the lichen genus ''Inoderma'' {{au|(Ach.) Gray (1821)}},<ref name="IF: Inoderma Berk."/> and is treated in modern databases under ''[Mesophellia](/source/Mesophellia)''.  The name ''Inoderma arenarium'' belongs to that basidiomycete usage and has been listed as a [synonym](/source/synonym_(taxonomy)) under ''Mesophellia arenaria'' in subsequent treatments;<ref name="De Toni 1888"/> it is therefore excluded from the species list here.

==References==
{{Reflist|refs=

<ref name="Acharius 1810">{{cite book |last=Acharius |first=Erik |year=1810 |title=Lichenographia Universalis. Lichenographia Universalis |location=Gottingen |publisher=Apud Iust. Frid. Danckwerts |page=294 |language=la |url=https://www.biodiversitylibrary.org/page/44219570}}</ref>

<ref name="Berkeley 1881">{{cite journal |last=Berkeley |first=M.J. |year=1881 |title=Australian fungi - II |journal=Journal of the Linnean Society. Botany |volume=18 |pages=383–389}}</ref>

<ref name="Cannon et al. 2020">{{cite book |last1=Cannon |first1=P. |last2=Ertz |first2=D. |last3=Frisch |first3=A. |last4=Aptroot |first4=A. |last5=Chambers |first5=S. |last6=Coppins |first6=B. |last7=Sanderson |first7=N. |last8=Simkin |first8=J. |last9=Wolselsey |first9=P. |year=2020 |title=Arthoniales: Arthoniaceae, including the genera ''Arthonia'', ''Arthothelium'', ''Briancoppinsia'', ''Bryostigma'', ''Coniocarpon'', ''Diarthonis'', ''Inoderma'', ''Naevia'', ''Pachnolepia'', ''Reichlingia'', ''Snippocia'', ''Sporodophoron'', ''Synarthonia'' and ''Tylophoron'' |series=Revisions of British and Irish Lichens |volume=1 |pages=34–35 |doi=10.34885/173 |doi-access=free}}</ref>

<ref name="CoL">{{Catalogue of Life |id=54HP |title=''Inoderma'' |access-date=8 January 2026}}</ref>

<ref name="Coppins & James 1979">{{cite journal |last1=Coppins |first1=B.J. |last2=James |first2=P.W. |year=1979 |title=New or interesting British lichens IV |journal=The Lichenologist |volume=11 |issue=2 |pages=139–179 |doi=10.1017/S0024282979000190}}</ref>

<ref name="De Toni 1888">{{cite book|last=De Toni |first=J.B. |editor-last=Saccardo |editor-first=P.A. |year=1888 |title=Sylloge fungorum omnium hucusque cognitorum. Vol. VII. Pars I |trans-title=Sylloge of all fungi known up to now. Vol. 7, part 1 |language=la |location=Patavii |publisher=Sumptibus auctoris; typis seminarii |page=57 |url=https://archive.org/download/syllogefungorum07sacc/syllogefungorum07sacc.pdf}}</ref>

<ref name="Ertz et al. 2018">{{cite journal |last1=Ertz |first1=Damien |last2=Sanderson |first2=Neil |last3=Łubek |first3=Anna |last4=Kukwa |first4=Martin |title=Two new species of Arthoniaceae from old-growth European forests, ''Arthonia thoriana'' and ''Inoderma sorediatum'', and a new genus for ''Schismatomma niveum'' |journal=The Lichenologist |volume=50 |issue=2 |year=2018 |doi=10.1017/s0024282917000688 |pages=161–172}}</ref>

<ref name="Ertz 2024">{{cite journal |last=Ertz |first=D. |year=2024 |title=Quatre espèces de lichens et deux espèces de champignons lichénicoles nouvelles pour la Belgique, et d'autres espèces intéressantes pour le pays |trans-title=Four species of lichens and two species of lichenicolous fungi new to Belgium, and other species of interest to the country |journal=Dumortiera |volume=124 |pages=28–33 |language=fr |url=https://www.jjh.cz/upload/38902.pdf}} {{Open access}}</ref>

<ref name="Frisch et al. 2015">{{cite journal |last1=Frisch |first1=Andreas |last2=Ohmura |first2=Yoshihito |last3=Ertz | first3=Damien |last4=Thor |first4=Göran |title=''Inoderma'' and related genera in Arthoniaceae with elevated white pruinose pycnidia or sporodochia |journal=The Lichenologist |volume=47 |issue=4 |year=2015 |doi=10.1017/s0024282915000201 |pages=233–256}}</ref>

<ref name="Gray 1821">{{cite book |last=Gray |first=Samuel Frederick |year=1821 |title=A Natural Arrangement of British Plants |volume=1 |location=London |publisher=Baldwin, Craddock, and Joy |page=498 |url=https://www.biodiversitylibrary.org/page/30087200}}</ref>

<ref name="IF: Inoderma Berk.">{{cite web |title=Record Details: ''Inoderma'' Berk., J. Linn. Soc., Bot. 18: 386 (1881) |url=https://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=19174 |publisher=[Index Fungorum](/source/Index_Fungorum) |access-date=21 January 2026}}</ref>

<ref name="IF: Inoderma epigaeum">{{cite web |title=Record Details: ''Inoderma epigaeum'' (Pers.) Gray [as 'epigaea'], Nat. Arr. Brit. Pl. (London) 1: 498 (1821) |url=https://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=387094 |publisher=[Index Fungorum](/source/Index_Fungorum) |access-date=8 January 2026}}</ref>

<ref name="Kantvilas 2024">{{cite journal |last=Kantvilas |first=G. |year=2024 |title=Tasmanian additions to the genus ''Inoderma'' (Arthoniaceae) |journal=Swainsona |volume=38 |issue=6 |pages=161–170}}</ref>

<ref name="Species Fungorum synonymy">{{cite web |title=Synonymy: ''Inoderma'' (Ach.) Gray, Nat. Arr. Brit. Pl. (London) 1: 498 (1821) |url=http://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=2492 |publisher=[Species Fungorum](/source/Species_Fungorum) |access-date=21 May 2022}}</ref>

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}}

{{Taxonbar|from=Q102178606}}

Category:Arthoniaceae
Category:Arthoniomycetes genera
Category:Lichen genera
Category:Taxa described in 1810
Category:Taxa named by Erik Acharius

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Adapted from the Wikipedia article [Inoderma](https://en.wikipedia.org/wiki/Inoderma) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Inoderma?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.