{{Short description|Species of lichen-forming fungus}} {{Use mdy dates|date=January 2026}} {{Use American English|date=January 2026}} {{Speciesbox | image = | image_caption = | taxon = Gyalectidium denticulatum | authority = [[Robert Lücking|Lücking]] (2001) | mapframe = yes | mapframe-zoom = 4 | mapframe-coordinates = {{coord|9|47|N|83|51|W}} | mapframe-caption = [[type locality (biology)|Type locality]]: Orosi Valley, Costa Rica }}

'''''Gyalectidium denticulatum''''' is a species of [[lichen]]-forming [[fungus]] in the family [[Gomphillaceae]].<ref name="CoL_3HNNQ"/> It is a [[foliicolous lichen|leaf-dwelling lichen]] known from Central and South America, including Costa Rica, Brazil, and Argentina. The species is distinguished by its distinctive reproductive structures, which form small crater-like depressions surrounded by a ring of tooth-like segments, a feature that separates it from the similar-looking ''[[Gyalectidium caucasicum]]''.

==Taxonomy== ''Gyalectidium denticulatum'' was [[species description|described]] as a new species in 2001 by [[Robert Lücking]]. In the original treatment it was emphasized that, without close inspection, the species could easily be mistaken for the widespread ''[[Gyalectidium caucasicum]]'' because the [[thallus]] looks the same. It was separated from that species by its highly derived {{lichengloss|hyphophores}}, which are immersed in the thallus and form small crater-like depressions with a ring of tooth-like segments around a green diahyphal mass.<ref name="Ferraro et al. 2001"/>

==Description== The thallus forms rounded patches about 2–5&nbsp;mm across. It is {{lichengloss|areolate}}-{{lichengloss|bullate}} to marginally {{lichengloss|rugose}} because it is strongly encrusted with a continuous layer of crystals, giving it a silvery-grey appearance.<ref name="Ferraro et al. 2001"/>

Hyphophores are produced on the thallus surface and are immersed into it, appearing as small, rounded depressions about 0.15–0.2&nbsp;mm in diameter. Around each depression, the hyphophore "scale" is split into narrowly triangular to bristle-like segments that are arranged in a circle and point inward toward the centre; the segments are about 0.05–0.1&nbsp;mm long and 10–15&nbsp;[[μm]] broad. The segments are whitish, while the exposed diahyphal mass is green. [[Apothecia]] and [[pycnidia]] have not been reported for this species.<ref name="Ferraro et al. 2001"/>

==Habitat and distribution== As of its original publication, ''G.&nbsp;denticulatum'' known only from the [[type (biology)|type]] collection in Costa Rica ([[Cartago Province]], Orosi Valley). It was collected on leaves of trees along a road, so it was found in relatively [[disturbance (ecology)|disturbed]] vegetation rather than deep forest [[understory]]. The authors noted that ''[[Gyalectidium laciniatum]]'' was collected in the same gathering.<ref name="Ferraro et al. 2001"/> As of 2024, ''G.&nbsp;denticulatum'' was one of 13 ''[[Gyalectidium]]'' species that had been documented from Costa Rica.<ref name="Mardones et al. 2024"/> It has also been reported from Argentina<ref name="García et al. 2025"/> and Brazil.<ref name="dos Santos et al. 2016"/>

==References== <references>

<ref name="CoL_3HNNQ">{{Catalogue of Life |id=3HNNQ |title=''Gyalectidium denticulatum'' Lücking |access-date=January 27, 2026}}</ref>

<ref name="dos Santos et al. 2016">{{cite journal |last1=dos Santos |first1=Viviane Monique |last2=Lücking |first2=Robert |last3=da Silva Cáceres |first3=Marcela Eugenia |year=2016 |title=Liquens foliícolas (Ascomycota) em Brejos de Altitude: novos registros para o Nordeste e para o Brasil |journal=Iheringia, Série Botânica |volume=71 |issue=3 |pages=368–376 |url=https://isb.emnuvens.com.br/iheringia/article/view/593}} {{open access}}</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>

<ref name="García et al. 2025">{{cite journal |last1=García |first1=Renato A. |last2=Filippini |first2=Edith R. |last3=Díaz Dominguez |first3=Raúl |title=Diversity and distribution of lichen taxa in Argentina |journal=Darwiniana |series=Nueva Serie |volume=13 |issue=2 |year=2025 |doi=10.14522/darwiniana.2025.132.1262 |pages=308–347 |doi-access=free}}</ref>

<ref name="Mardones et al. 2024">{{cite journal |last1=Mardones |first1=Melissa |last2=Umañan Tenorio |first2=Loengrin |last3=Granados Montero |first3=María del Milagro |last4=Mata Hidalgo |first4=Milagro |last5=Ruiz-Boyer |first5=Armando |last6=Piepenbring |first6=Meike |last7=Minter |first7=David |last8=Coto-López |first8=Cristofer |last9=Carranza Velásquez |first9=Julieta |year=2024 |title=The first annotated checklist of Costa Rican fungi |journal=Funga Latina |volume=2 |doi=10.5281/ZENODO.14165034 |page=15 |url=https://www.researchgate.net/publication/385858963}}</ref>

</references>

{{Taxonbar|from=Q17387954}}

[[Category:Gyalectidium|denticulatum]] [[Category:Lichen species]] [[Category:Lichens described in 2001]] [[Category:Lichens of Argentina]] [[Category:Lichens of Brazil]] [[Category:Lichens of Central America]] [[Category:Taxa named by Robert Lücking]]