{{Short description|Species of lichen-forming fungus}} {{Use dmy dates|date=February 2026}} {{Use Oxford spelling|date=February 2026}} {{Speciesbox | image = | image_caption = | taxon = Gyalectidium membranaceum | authority = [[Emmanuël Sérusiaux|Sérusiaux]] & [[Robert Lücking|Lücking]] (2001) | mapframe = yes | mapframe-zoom = 4 | mapframe-coordinates = | mapframe-caption = [[Holotype]]: Spain, Canary Islands, La Palma, Los Tilos (west of Las Lomados, south of Los Sauces), 800–850 m }}

'''''Gyalectidium membranaceum''''' is a species of [[lichen]]-forming [[fungus]] in the family [[Gomphillaceae]].<ref name="CoL_3HNP4"/> It is a tiny, [[foliicolous]] (leaf-dwelling) lichen known only from [[cloud forest]] on the island of [[La Palma]] in the [[Canary Islands]]. The species is distinguished by its unusual bluish, membrane-like reproductive structures, and no sexual fruiting bodies have been observed.

==Taxonomy== ''Gyalectidium membranaceum'' was [[species description|described]] as a new species in 2001 by [[Emmanuël Sérusiaux]] and [[Robert Lücking]]. In the original account, it was characterized by its thin, meagre [[thallus]] and by {{lichengloss|hyphophores}} (asexual reproductive structures) reduced to a bluish, membrane-like layer that covers a mass of [[conidia]]l spores (diahyphae).<ref name="Ferraro et al. 2001"/>

The species was compared with ''[[Gyalectidium imperfectum]]'', which also has hyphophores reduced to adnate spots. ''G.&nbsp;membranaceum'' differs by having much thinner, more membrane-like hyphophores and a thallus that is distinctly cracked into small patches ({{lichengloss|areolate}}) rather than finely warty ({{lichengloss|verrucose}}). The authors suggested that the membranaceous layer together with the diahyphal mass functions as a single dispersal unit, since many thalli have strongly scalloped ({{lichengloss|crenate}}) margins where these structures appear to have been removed as a whole.<ref name="Ferraro et al. 2001"/>

==Description== The thallus forms very small, rounded to crenate, rather ill-developed patches about 0.05–0.1&nbsp;mm in diameter. It is indistinctly areolate, with a whitish, flattened crystalline cluster at the centre surrounded by a thin greenish-grey marginal zone.<ref name="Ferraro et al. 2001"/>

The hyphophores are located at the thallus margins but lack the scale-like covering typical of the genus. Instead, each is reduced to a small spot of spore-producing tissue (the diahyphal mass), covered by a thin, pale bluish-grey membrane about 0.07–0.1&nbsp;mm in diameter. [[Apothecia]] and [[pycnidia]] have not been reported for this species.<ref name="Ferraro et al. 2001"/>

==Habitat and distribution== ''Gyalectidium membranaceum'' is known only from the island of [[La Palma]] (Canary Islands). The [[type locality (biology)|type locality]] was described as a remnant of evergreen, subtropical [[cloud forest]], and the species was reported as very rare there, found on only a few leaves.<ref name="Ferraro et al. 2001"/>

In that locality it was observed as a pioneer on young leaves of [[Lauraceae]], occurring together with ''[[Gyalectidium colchicum]]''.<ref name="Ferraro et al. 2001"/>

==References== <references>

<ref name="CoL_3HNP4">{{Catalogue of Life |id=3HNP4 |title=''Gyalectidium membranaceum'' Sérus. & Lücking |access-date=23 February 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=Q21271021}}

[[Category:Gyalectidium|membranaceum]] [[Category:Lichen species]] [[Category:Lichens described in 2001]] [[Category:Lichens of Macaronesia]] [[Category:Taxa named by Emmanuël Sérusiaux]] [[Category:Taxa named by Robert Lücking]]