Gymnographopsis
{{Short description|Genus of lichens}}
{{Use dmy dates|date=June 2025}}
{{Use Oxford spelling|date=June 2025}}
{{Automatic taxobox
| image =
| image_caption =
| taxon = Gymnographopsis
| authority = C.W.Dodge (1967)
| type_species = Gymnographopsis chilena
| type_species_authority = C.W.Dodge (1967)
| subdivision_ranks = Species
| subdivision = G. cerei
}}
Gymnographopsis is a genus of lichen-forming fungi in the family Graphidaceae. It was circumscribed by American lichenologist Carroll William Dodge in 1967, with Gymnographopsis chilena assigned as the type species. These lichens form dull grey-olive to yellow-brown crusts on tree bark and are characterized by straight to weakly curved fruiting bodies whose sides appear brown-black and whose openings expose {{lichengloss|disc}}-like surfaces. The genus has a pantropical distribution, growing on shaded tree trunks and lower branches in evergreen forests, where their intolerance of heavy disturbance makes them useful indicators of long-standing, moist woodland habitats.
Description
Gymnographopsis forms a dull grey-olive to yellow-brown crust (thallus) that lacks a true {{lichengloss|cortex}} and is often dusted with minute beige crystals. The ascomata are straight to weakly curved {{lichengloss|lirellae}} (0.2–1.5 mm long) whose lips soon open to expose the disc; their flanks may appear brown-black but are only partly {{lichengloss|carbonised}}. A light brown {{lichengloss|excipulum}} overhangs the clear hymenium, which is free of {{lichengloss|inspersion}} and lined with short, smooth {{lichengloss|periphysoids}}. The Graphis-type asci usually contain eight hyaline ascospores that become conspicuously muriform—divided by numerous transverse and a few longitudinal septa—yet remain iodine-negative (I–); spore sizes in most species fall between 20 × 7 μm and 40 × 12 μm, though extremes occur. Chemistry is modest: norstictic acid is frequent, with stictic-series depsidones or no detectable metabolites in other taxa.
The genus is set apart from superficially similar script lichens by the coexistence of partly carbonised lirellae, smooth periphysoids, an inspersion-free hymenium and small, I– muriform spores. In Carbacanthographis the excipulum is completely carbonised; Acanthothecis and Anomomorpha have spiny ({{lichengloss|spinulose}}) or iodine-positive elements; and Gyphis has significantly larger spores. A diagnostic additional feature in several species, such as G. corticicola, is a rectangular {{lichengloss|perispore}} that folds at the poles when mounted in potassium hydroxide.
Ecology
Gymnographopsis is pantropical, ranging from the lowland Amazon basin and West-Central African rainforests to Indochina, New Guinea and north-eastern Australia. All known species are corticolous, occupying shaded trunks and lower branches in evergreen forests; their intolerance of heavy disturbance makes them handy indicators of long-standing, moist woodland.
Work in Mexico's seasonally dry forests uncovered the corticolous G. corticicola, the first Northern-Hemisphere record for the genus and its smallest-spored member (about 12 × 5 μm). Molecular data place the taxon within subfamily Redonographoideae and suggest further undiscovered diversity across Mesoamerica.
Species
- Gymnographopsis cerei {{small|Follmann (1968)}}
- Gymnographopsis chilena {{small|C.W.Dodge (1967)}}
- Gymnographopsis corticicola {{small|R.Miranda, Herrera-Camp. & Lücking (2020)}}
- Gymnographopsis follmannii {{small|C.W.Dodge (1967)}}
- Gymnographopsis koreaiensis {{small|(Sipman) Lücking & Sipman (2021)}}
- Gymnographopsis latispora {{small|Egea & Torrente (1996)}}
References
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