{{Short description|Species of lichen-forming fungus}} {{Use dmy dates|date=November 2025}} {{Use Australian English|date=November 2025}} {{Speciesbox | image = | image_caption = | taxon = Fuscidea ramboldioides | authority = Kantvilas (2001) | mapframe = yes | mapframe-zoom = 6 | mapframe-coordinates = {{coord|42|13|S|148|18|E}} | mapframe-caption = Holotype: Summit of Mount Freycinet, Tasmania }}

'''''Fuscidea ramboldioides''''' is a species of saxicolous (rock-dwelling) crustose lichen in the family Fuscideaceae.<ref name="CoL_6JSGW"/> First described from Mount Freycinet in Tasmania in 2001, it has since been recorded from mainland Australia, including New South Wales and Western Australia. The lichen forms extensive greyish-brown crusts on granite rocks that can reach nearly a metre wide. It is readily confused with the common ''Ramboldia petraeoides'', which inspired its scientific name, though the two species differ in their internal chemistry and ascospore structure.

==Taxonomy==

''Fuscidea ramboldioides'' was described as a new species by Gintaras Kantvilas from material collected on the summit of Mt Freycinet in eastern Tasmania. The type specimen was gathered in November 1999 from east-facing granite boulders at about 615&nbsp;m elevation, with an earlier collection from the same mountain cited as additional material. In describing the species, Kantvilas compared it with the superficially similar ''Fuscidea mollis'' and ''F.&nbsp;austera'', both of which also contain divaricatic acid but differ in having smaller apothecia and shorter, more broadly ellipsoid spores. He also distinguished it from ''F.&nbsp;cyathoides'' var. ''japonica'', which has consistently bean-shaped or dumbbell-shaped ascospores with a marked constriction.<ref name="Kantvilas 2001"/>

The species can be confused in the field with the very common Tasmanian lichen ''Ramboldia petraeoides'', with which it often occurs. Both have brown, crustose thalli, but those of ''Ramboldia'' are usually darker, less scurfy and less cracked, and its apothecia are flatter, glossy and dark brown. Chemically and anatomically the two are quite different: ''Ramboldia petraeoides'' produces norstictic acid and has narrowly ellipsoid, {{lichengloss|simple}}, hyaline ascospores, whereas ''F.&nbsp;ramboldioides'' has large, 1-septate, brown, oblong-ellipsoid spores and contains divaricatic acid. The specific epithet ''ramboldioides'' alludes to this superficial resemblance to ''Ramboldia petraeoides''.<ref name="Kantvilas 2001"/>

==Description==

''Fuscidea ramboldioides'' is a crustose, rock-dwelling lichen that forms extensive but discontinuous patches from a few centimetres across to nearly 1&nbsp;m wide. The thallus is markedly {{lichengloss|rimose}}-{{lichengloss|areolate}}, meaning it is cracked into small, tile-like units, and has a rather abraded, scurfy surface. It is pale to dingy greyish brown and 120–150&nbsp;μm thick. The {{lichengloss|prothallus}}, a marginal zone of bare fungal tissue, is poorly developed and at most appears as a narrow blackish band about 0.3&nbsp;mm wide. The internal medulla does not react with iodine (I–), and the photosynthetic partner ({{lichengloss|photobiont}}) consists of more or less rounded to oblong algal cells 10–16&nbsp;μm wide.<ref name="Kantvilas 2001"/>

The fruiting bodies (apothecia) are scattered over the thallus, {{lichengloss|lecideine}} in form (with a black {{lichengloss|disc}} and margin of fungal tissue only) and {{lichengloss|sessile}}. They are constricted at the base, 0.2–0.5&nbsp;mm wide and 240–260&nbsp;μm thick, usually roundish but sometimes deformed or contorted. The disc is flat and black, while the margin is thick, rolled inwards when young, and either the same colour as the disc or somewhat paler and brownish; the margin persists into maturity. In vertical section the {{lichengloss|exciple}} is 40–70&nbsp;μm thick at the sides, dark brown at the outer edge, and its pigment turns somewhat olive-brown in potassium hydroxide solution (K). The {{lichengloss|hypothecium}} beneath the hymenium is colourless, 40–80&nbsp;μm thick and densely filled with oil droplets 2–5&nbsp;μm wide. The hymenium itself is colourless, 60–70&nbsp;μm thick, capped by a dark brown {{lichengloss|epihymenium|epihymenial}} layer 10–20&nbsp;μm thick. The paraphyses are simple or occasionally forked filaments 2–2.5&nbsp;μm thick with swollen, brown-pigmented tips 3–4.5&nbsp;μm thick. The asci are 8-spored, ellipsoid to pear-shaped and measure 40–55 × 15–22&nbsp;μm.<ref name="Kantvilas 2001"/>

The ascospores are a key diagnostic feature of ''F.&nbsp;ramboldioides''. They are relatively large for the genus, usually oblong-ellipsoid with abruptly rounded ends, sometimes bean-shaped and only very rarely showing a slight constriction in the middle. They measure 9–15 × 4–8&nbsp;μm (based on 60 spores measured). When young they are hyaline and simple, but at maturity they are typically pale brown and have a single septum, and in old specimens they become roughened and ornamented. Asexual structures are scarce: pycnidia are very inconspicuous, immersed in the thallus, and apparently rare; the conidia are ellipsoid, 3.5–4 × 2&nbsp;μm. Spot tests on the medulla are negative (K−, KC−, C−, Pd−), but under ultraviolet light the lichen shows a faint white fluorescence, indicating the presence of the secondary metabolite (lichen product) divaricatic acid.<ref name="Kantvilas 2001"/>

==Habitat and distribution==

At the time of its original publication, ''Fuscidea ramboldioides'' was known only from Mt Freycinet on the east coast of Tasmania, where it is very abundant at the summit. There, the lichen grows on Devonian granite, either on vertical, exposed rock faces or in sheltered, moist overhangs. It is usually associated with a rich assemblage of mostly unidentified, rock-dwelling (saxicolous) crustose lichens. Kantvilas considered it likely to be more widespread but previously overlooked.<ref name="Kantvilas 2001"/> The lichen was later recorded from New South Wales and Western Australia. Mainland material generally shows a darker, thinner thallus and correspondingly thinner apothecia.<ref name="Kantvilas 2004"/>

The type locality is a low coastal mountain that receives relatively low annual rainfall, around 700&nbsp;mm, but is strongly influenced by sea mist and low cloud. These conditions appear to provide enough moisture to support a lichen funga more typical of the wetter western parts of Tasmania, including species of ''Bunodophoron'' and ''Cladonia murrayi''. Within this setting ''F.&nbsp;ramboldioides'' is abundant at the summit but absent from the lower slopes, which instead carry a lichen funga characteristic of drier, low-rainfall environments.<ref name="Kantvilas 2001"/>

==References== {{Reflist|refs=

<ref name="CoL_6JSGW">{{Catalogue of Life |id=6JSGW |title=''Fuscidea ramboldioides'' Kantvilas |access-date=21 November 2025}}</ref>

<ref name="Kantvilas 2001">{{cite book |last=Kantvilas |first=Gintaras |year=2001 |chapter=The lichen family Fuscidaceae in Tasmania |title=Lichenological Contributions in Honour of Jack Elix |editor-last1=McCarthy |editor-first1=P.M. |editor-last2=Kantvilas |editor-first2=G. |editor-last3=Louwhoff |editor-first3=S.H.J.J. |series=Bibliotheca Lichenologica |volume=78 |publisher=J. Cramer |location=Berlin/Stuttgart |pages=169–192}}</ref>

<ref name="Kantvilas 2004">{{cite book |last=Kantvilas |first=Gintaras |chapter=Fuscidaceae |editor-last1=McCarthy |editor-first1=Patrick M. |editor-last2=Mallett |editor-first2=Katie |title=Flora of Australia. Lichens 4 |volume=56A |year=2004 |publisher=Australian Biological Resources Study & CSIRO Publishing |location=Collingwood VIC |isbn=978-0-643-09056-9 |page=181}}</ref>

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Category:Umbilicariales Category:Lichen species Category:Lichens described in 2001 Category:Lichens of Australia Category:Taxa named by Gintaras Kantvilas