Allographa chamelensis


Allographa chamelensis is a species of script lichen in the family Graphidaceae. Originally described in 2014 as Graphis chamelensis from the Chamela-Cuixmala Biosphere Reserve in Jalisco, Mexico, this bark-dwelling lichen forms a pale greenish-grey crust in seasonally tropical dry forests. The species is characterised by its prominent, often partly branched, slit-like fruiting bodies with black lips, ascospores divided by 7–10 cross-walls, and the presence of norstictic acid.

Taxonomy

Allographa chamelensis was described as new to science in 2014 by the lichenologists Alejandrina Bárcenas-Peña and Robert Lücking. The holotype was collected in the Chamela-Cuixmala Biosphere Reserve at the Chamela Biological Station, near the Hornitos stream, in a transition between seasonally tropical dry forest and semideciduous arroyo forest, growing on bark. Lücking and Klaus Kalb reclassified the taxon in the segregate genus Allographa in 2018.
In the original, the species was distinguished from the similar Graphis emersa by its longer, partly branched lirellae, and from G. conferta by its norstictic acid chemistry. In the accompanying remarks it is compared again with G. emersa, and with G. conferta.

Description

The lichen grows on bark and forms a continuous, smooth, pale greenish-gray crust about 0.5–1.0 cm across and about 40–80 μm thick, without a visible. In section, the thallus has a thick, upper, an irregular, and conspicuous clusters of calcium oxalate crystals.
The apothecia are and, often partly branched and prominent, with a basal-to-lateral thalline margin; the is concealed. The are black and entire, and the is completely . The hymenium is clear. Ascospores are colorless and oblong, produced 4–8 per ascus, transversely 7–10-septate, and measure about 25–35 × 7–10 μm. Thin-layer chromatography detects norstictic acid, with a K spot test yielding yellow that turns red.

Habitat and distribution

Allographa chamelensis is known from low elevations in Jalisco, Mexico, in and around the Chamela Biological Station within the Chamela-Cuixmala Biosphere Reserve. The type collection came from the same transitional vegetation reported for G. bungartzii, but from a different host tree, Forchhammeria pallida.
Additional specimens were collected nearby – about from the type locality – at about elevation in seasonally tropical dry forest, on bark of Forchhammeria pallida, Bursera heteresthes, and Guettarda elliptica. The original description notes that, despite occurring on more host trees than G. bungartzii, it appears to be more localized and may depend on more specific microclimate conditions.