Sarcographa Dendroides

''Sarcographa'' is a genus of lichen-forming fungi in the family Graphidaceae. Established in 1825 by the French botanist Antoine Laurent Apollinaire Fée, the genus contains 22 species that are recognised by their distinctive star-shaped colonies of radiating, script-like fruiting structures with black borders. These bark-dwelling lichens are found in humid tropical and warm temperate forests worldwide and serve as indicators of undisturbed woodland, as they quickly decline when forest canopy is opened or disturbed.

Taxonomy

The genus was circumscribed by the French botanist Antoine Laurent Apollinaire Fée in 1825. In his original description, Fée characterised the genus by its labyrinthine fruiting bodies () that are sunken into a fleshy support structure, with the disc initially covered by a powdery substance () and containing an elongated, branched nucleus with irregular striations. He initially described three species: '' S. cinchonarium'' (the type species) from the bark of cinchona trees, '' S. tigrina'' with its yellowish, thick, and uneven thallus, and '' S. cascarillae'' distinguished by its pale yellowish, membranous, thick, and somewhat uneven thallus. Fée noted that the lirellae are partially embedded in a fleshy, whitish, rather thick support structure that serves as a kind of universal receptacle, and emphasised that this support structure often becomes bifurcated at the extremities of the lirellae.

Description

''Sarcographa'' develops a thin, chalk-white to pale grey crust (thallus) that sits flush with the bark and lacks a true . Its most conspicuous feature is a star-shaped colony of radiating : each slit is 0.5–3 mm long, commonly curved, and bordered by a completely (blackened) rim that makes the pattern stand out black against the thallus. A colourless to pale brown lines the interior, while the hymenium is usually clear and non-. The '' Graphis''-type asci contain eight hyaline (colourless and translucent) ascospores that become prominently —divided by numerous transverse and a few longitudinal septa—remain iodine-negative (I–) and typically measure 30–70 × 8–16 Î¼m. Chemically, most species produce stictic acid or norstictic acid (occasionally together with trace protocetraric-series depsidones) which can impart a yellow-brown tinge to the disc surface.

The rosette of radiating lirellae, together with the fully carbonised margins and large I– muriform spores, separates ''Sarcographa'' from superficially similar script lichens. In ''Graphis'' and '' Glyphis'' the lirellae are scattered rather than arranged in a star-burst; '' Redingeria'' and '' Reimnitzia'' share black rims but lack the distinctive radial pattern; whereas ''Kalbographa'' differs by its bright orange anthraquinone . A closely allied genus, '' Sarcographina'', also forms rosettes, but its smaller spores react I+ (violet) and the hymenium is densely inspersed—features absent from ''Sarcographa''.

Ecology

''Sarcographa'' has a pantropical to warm-temperate distribution. All known species are corticolous, favouring smooth, shaded bark in humid evergreen forests from lowland Amazonia and West-Central Africa to Southeast Asia, northern Australia and the Gulf–Atlantic Coastal Plain of North America. Several species (e.g., ''S. colombiana'') also colonise mangrove stems just above the high-tide mark, displaying a tolerance of intermittent salt spray. Because the genus declines quickly after canopy opening or repeated burning, its presence is a useful field indicator of long-standing, moisture-rich woodland habitat.

Species

, Species Fungorum (in the Catalogue of Life) accepts 22 species of ''Sarcographa''.
* '' Sarcographa astroidea''
* '' Sarcographa atlantica''
* '' Sarcographa cinchonarum''
* '' Sarcographa colliculosa''
* '' Sarcographa dendroides''
* '' Sarcographa fenicis''
* '' Sarcographa fissurinoides''
* '' Sarcographa glyphiza''
* '' Sarcographa heteroclita''
* '' Sarcographa intricans''
* '' Sarcographa kirtoniana''
* '' Sarcographa labyrinthica''
* '' Sarcographa macrohydrina''
* '' Sarcographa maculata''
* '' Sarcographa medusulina''
* '' Sarcographa megistocarpa''
* '' Sarcographa nagalandica''
* '' Sarcographa oculata''
* '' Sarcographa praslinensis''
* '' Sarcographa ramificans''
* '' Sarcographa subglobosa''
* '' Sarcographa subtricosa''
* '' Sarcographa verrucosa''

References

{{Taxonbar , from1=Q7423591 , from2=Q107289249

Graphidaceae
Lichen genera
Graphidales genera
Taxa named by Antoine Laurent Apollinaire Fée
Taxa described in 1825