{{Short description|Species of lichen-forming fungus}} {{Use dmy dates|date=January 2026}} {{Use Oxford spelling|date=January 2026}} {{Speciesbox | image = | image_caption = | taxon = Gyalectidium flabellatum | authority = [[Sérus.]] (2001) | mapframe = yes | mapframe-zoom = 4 | mapframe-coordinates = {{coord|5|54|S|145|20|E}} | mapframe-caption = [[type locality (biology)|Type locality]]: [[Brahman, Papua New Guinea|Brahman Missio]]n, Papua New Guinea }}

'''''Gyalectidium flabellatum''''' is a species of [[lichen]]-forming [[fungus]] in the family [[Gomphillaceae]].<ref name="CoL_3HNNT"/> It is a [[foliicolous lichen|leaf-dwelling lichen]] known from Papua New Guinea and [[Queensland]], Australia, where it grows in [[lowland]] to [[montane]] forests. The species is distinguished by its characteristic fan-shaped reproductive structures that are broadest around the middle rather than at the base, a feature that separates it from other members of the genus with similarly crystalline [[thalli]].

==Taxonomy== ''Gyalectidium flabellatum'' was [[species description|described]] as a new species in 2001 by [[Emmanuël Sérusiaux]]. The [[type (biology)|type]] was collected from the south side of [[Ramu]] River in [[Brahman, Papua New Guinea|Brahman Mission]] ([[Madang Province]], Papua New Guinea), at an elevation of 100&nbsp;m. It is distinguished by the characteristic form of its {{lichengloss|hyphophores}} ([[asexual reproduction|asexual reproductive]] structures): when well developed, the scales are {{lichengloss|flabelliform}} (fan-shaped) and typically reach their greatest breadth around the middle rather than at the base.<ref name="Ferraro et al. 2001"/>

==Description== The [[thallus]] forms patches about 1–3 mm across that are angular-rounded to almost {{lichengloss|lobulate}}-{{lichengloss|crenate}} (with small lobes and scalloped edges). The thallus is composed of small, blister-like segments ({{lichengloss|areolate}}-{{lichengloss|bullate}}) and is heavily covered with a continuous layer of crystals, giving it a silvery to whitish-grey appearance. Thin greenish thallus parts may be present at the edges.<ref name="Ferraro et al. 2001"/>

Hyphophores occur at the thallus edges or close to it. Their scales are well developed but can be difficult to see, emerging from a low bulge and lying horizontally. The scales are broadly fan-shaped and have a slightly dentate upper margin. They are typically broadest around mid-height, and measure about 0.1–0.2&nbsp;mm long and 0.2–0.3&nbsp;mm broad. Its colour is whitish translucent to bluish grey. [[Apothecia]] are angular-rounded, about 0.2–0.3&nbsp;mm in diameter, with a pale yellowish-brown to greyish {{lichengloss|disc}} that can be thinly pruinose, and a prominent whitish margin. [[Ascospore]]s are [[ellipsoid]], with dimensions of 30–45 × 10–17&nbsp;[[μm]]. [[Pycnidia]] were not reported.<ref name="Ferraro et al. 2001"/>

==Habitat and distribution== ''Gyalectidium flabellatum'' was initially reported from two localities: one along the northern coast of Papua New Guinea and one in [[Queensland]], Australia. In Papua New Guinea it occurred together with ''[[Gyalectidium caucasicum]]'' and ''[[Gyalectidium verruculosum|G.&nbsp;verruculosum]]'', while in Queensland it was found with ''[[Gyalectidium australe|G.&nbsp;australe]]'' and ''[[Gyalectidium verruculosum|G.&nbsp;verruculosum]]''.<ref name="Ferraro et al. 2001"/>

==References== <references>

<ref name="CoL_3HNNT">{{Catalogue of Life |id=3HNNT |title=''Gyalectidium flabellatum'' Sérus. |access-date=27 January 2026}}</ref>

<ref name="Ferraro et al. 2001">{{cite journal |last1=Ferraro |first1=Lidia I. |last2=Lücking |first2=Robert |last3=Sérusiaux |first3=Emmanuël |year=2001 |title=A world monograph of the lichen genus ''Gyalectidium'' (Gomphillaceae) |journal=Botanical Journal of the Linnean Society |volume=137 |issue=3 |pages=311–345 |doi=10.1111/j.1095-8339.2001.tb01126.x |doi-access=free}}</ref>

</references>

{{Taxonbar|from=Q21270993}}

[[Category:Gyalectidium|flabellatum]] [[Category:Lichen species]] [[Category:Lichens described in 2001]] [[Category:Lichens of Australia]] [[Category:Lichens of New Guinea]] [[Category:Taxa named by Emmanuël Sérusiaux]]