{{Short description|Species of lichen}} {{Use dmy dates|date=November 2025}} {{Use Oxford spelling|date= November 2015}} {{Speciesbox | image = | image_caption = | taxon = Inoderma nipponicum | authority = Frisch, Y.Ohmura & G.Thor (2015) | mapframe = yes | mapframe-zoom = 4 | mapframe-coordinates = {{coord|35|16|N|136|15|E}} | mapframe-caption = Holotype: Hikone-city, Japan }}

'''''Inoderma nipponicum''''' is a species of corticolous (bark-dwelling) lichen in the family Arthoniaceae.<ref name="CoL_3PRV2"/> It was formally described in 2015 from specimens collected on the bark of a large tree at Hikone Castle on Honshu, Japan. The lichen is characterised by its pale olive-grey crusty thallus and numerous conspicuous dark pycnidia (asexual fruiting bodies) that protrude from the surface and are dusted with thick white {{lichengloss|pruina}}. It grows on deeply fissured bark of both deciduous and coniferous trees in shady to semi-shady locations, and is known from Hokkaido and Honshu in Japan.

==Taxonomy==

''Inoderma nipponicum'' was described as new to science by Andreas Frisch, Yoshihito Ohmura and Göran Thor in 2015 as part of a revision resurrecting the genus ''Inoderma'' for species with elevated, white, frost-like ({{lichengloss|pruinose}}) asexual structures. The type specimen was collected on the trunk of a large Japanese bay tree (''Machilus thunbergii'') at Hikone Castle, Honshu, Japan (120&nbsp;m elevation), and the name is a straightforward reference to its Japanese origin.<ref name="Frisch et al. 2015"/>

==Description==

The thallus (lichen body) forms pale olive-grey patches that are fissured to fissured-areolate and lack a true outer skin ({{lichengloss|ecorticate}}), giving a matt, faintly felty or scurfy surface; a loose, thin necrotic layer often overlies the {{lichengloss|algal layer}}. The {{lichengloss|photobiont}} is a {{lichengloss|trentepohlioid}} green alga (''Printzina lagenifera''); cells are mostly 9–19 × 5–14&nbsp;micrometres (μm), and calcium oxalate crystals were not seen in the type material.<ref name="Frisch et al. 2015"/>

Sexual fruiting bodies (apothecia) were sparse and under-developed in the type material. When present they are small rounded {{lichengloss|discs}}, 0.4–0.6&nbsp;mm in diameter, set level with the thallus and covered in a thin white {{lichengloss|pruina}} (a frost-like powder). Internally the tissues and spore-bearing layer match the ''Arthonia''-type; ascospores are hyaline, narrowly {{lichengloss|obovate}}, typically 3–4-septate (rarely 2) and measure about 13–16 × 3–4&nbsp;μm.<ref name="Frisch et al. 2015"/>

Asexual fruiting bodies (pycnidia) are numerous and conspicuous: dark brown to black cups 0.25–0.50&nbsp;mm across that protrude strongly or sit with a constricted base on the thallus, their rims and shoulders dusted with thick white pruina. The pore is entire to ragged, and the interior shows a bowl-shaped cavity; the wall is strongly {{lichengloss|carbonised}} at the sides. {{lichengloss|Conidiogenous}} cells are 9–11 × 1.5–3.0&nbsp;μm and produce {{lichengloss|bacilliform}} conidia that are often slightly curved, with dimensions averaging around 4.9 × 1.3&nbsp;μm.<ref name="Frisch et al. 2015"/>

Chemically, the species contains lepraric acid. In routine spot tests the thallus and the white pruina turn K+ (lemon yellow), a diagnostic reaction for this compound, and are C−, KC−, Pd−; the thallus hyphae are I− but KI+ (pale blue).<ref name="Frisch et al. 2015"/>

===Similar species===

Within ''Inoderma'', ''I.&nbsp;nipponicum'' is most similar to ''I.&nbsp;subabietinum'' but differs consistently in lacking confluentic acid and in pycnidial traits: older pycnidia do not develop outwardly reflexed rims and carry a fine, mealy pruina rather than a coarse, granular one; its asexual spores (conidia) are often very slightly curved. Sterile material of ''I.&nbsp;byssaceum'' can appear similar, but that species has a K− thallus and pycnidia (no yellow reaction in the standard K test) and conidia that are a bit shorter and not weakly curved.<ref name="Frisch et al. 2015"/>

==Habitat and distribution==

''Inoderma nipponicum'' occurs below about 500&nbsp;m elevation in shady to semi-shady situations. It grows mainly on deeply fissured or flaky bark of both deciduous and coniferous hosts, including ''Acer buergerianum'', ''Machilus thunbergii'', ''Picea'' sp., ''Pinus densiflora'' and ''Torreya nucifera''; a small saxicolous collection was also made on rain-shadowed castle walls at Hikone. The species appears tolerant of drier conditions and of urban air, occurring in parkland as well as in old-growth forest. Confirmed records are from Japan (Hokkaidō and Honshū).<ref name="Frisch et al. 2015"/>

==References== {{Reflist|refs=

<ref name="CoL_3PRV2">{{Catalogue of Life |id=3PRV2 |title=''Inoderma nipponicum'' Frisch, Y. Ohmura & G. Thor |access-date=9 November 2025}}</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>

}}

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Category:Arthoniaceae Category:Lichen species Category:Lichens described in 2015 Category:Lichens of Japan Category:Taxa named by Andreas Frisch Category:Taxa named by Göran Thor