Platythecium Verrucoareolatum

''Platythecium'' is a genus of lichen-forming fungi in the family Graphidaceae. It comprises 25 species. Described in 2002 by the German lichenologist Bettina Staiger, these bark-dwelling lichens are found in humid, shaded forests across tropical and warm temperate regions worldwide. They are characterized by their flattened, plate-like fruiting structures with completely blackened walls and are sensitive to forest disturbance, making their presence an indicator of long-established woodland conditions.

Taxonomy

The genus was circumscribed in 2002 by the German lichenologist Bettina Staiger in her 2002 monographic treatment of the family Graphidaceae. '' Platythecium grammitis'' was assigned as the type species.

Description

''Platythecium'' produces a smooth, pale grey-green to yellow-olive crust (thallus) that embeds directly in the bark and lacks a true . Its fruit bodies are short to elongate whose slate-black walls are completely ; the narrow slit is usually covered at first by a thin thalline veil that later breaks to reveal a flat, often faintly white- disc. Beneath the margin a colourless to pale brown lines a clear, non- hymenium traversed by smooth paraphyses. Eight hyaline ascospores develop in each ''Graphis''-type ascus; they become conspicuously —divided by many transverse and a few longitudinal septa—but remain iodine-negative (I–) and generally measure 25–60 × 8–15 Î¼m. Most species are chemically inert or contain only low amounts of stictic acid-series depsidones, a contrast to many anthraquinone-rich script lichens.

The flattened, plate-like lirellae and pale excipulum distinguish ''Platythecium'' from superficially similar genera. In '' Glyphis'' and ''Hemithecium'' the discs stay narrow and the walls alone form the exposed edge, whereas ''Platygramme'' displays broader shields with a persistent thalline rim, and ''Kalbographa'' is set apart by its vivid orange to brick-red produced by anthraquinones.

Ecology

The genus is pantropical to warm-temperate in distribtion, occurring on shaded boles and large branches in mature evergreen forests from Amazonia and West-Central Africa to Southeast Asia, northern Australia and the Atlantic Plain of North America. All species are corticolous and appear sensitive to prolonged canopy opening: they decline sharply after logging or edge creation, so their presence is a convenient field signal of long-established, humid woodland conditions.

Species

, Species Fungorum (in the Catalogue of Life) accept 25 species of ''Platythecium''.
*'' Platythecium acutisporum''
*'' Platythecium albolabiatum''
*'' Platythecium allosporellum''
*'' Platythecium annonacea''
*'' Platythecium biseptatum''
*'' Platythecium commiscens''
*'' Platythecium cristobalense''
*'' Platythecium dimorphodes''
*'' Platythecium floridanum''
*'' Platythecium grammitis''
*'' Platythecium hypoleptum''
*'' Platythecium inspersum''
*'' Platythecium intortula''
*'' Platythecium leiogramma''
*'' Platythecium maximum''
*'' Platythecium nothofagi''
*'' Platythecium pertenellum''
*''Platythecium pyrrhochroum''
*'' Platythecium serpentinellum''
*'' Platythecium seychellense''
*'' Platythecium sphaerosporellum''
*'' Platythecium sripadakandense'' – Sri Lanka
*'' Platythecium streimannii''
*'' Platythecium suberythrellum''
*'' Platythecium verrucoareolatum''

References

{{Taxonbar, from=Q7202856

Graphidaceae
Lichen genera
Graphidales genera
Taxa described in 2002
Taxa named by Bettina Staiger