Gymnographopsis
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 -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 that lacks a true and is often dusted with minute beige crystals. The ascomata are straight to weakly curved whose lips soon open to expose the disc; their flanks may appear brown-black but are only partly. A light brown overhangs the clear hymenium, which is free of and lined with short, smooth. 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 ; 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 or iodine-positive elements; and Gyphis has significantly larger spores. A diagnostic additional feature in several species, such as G. corticicola, is a rectangular 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. Molecular data place the taxon within subfamily Redonographoideae and suggest further undiscovered diversity across Mesoamerica.