Type locality: Argentina, Neuquen Province, 15 km south of Alumine along Río Alumine, on rocks, xx m, 29.ix.1985, T. H. Nash 24083 (ASU - holotype; BAFC - isotype).

Description: Lichen. Thallus foliose, adnate, yellow-green but darkening to olive-black in the older lobes, to 3 cm in diameter. Lobes irregular, 1.0-2.0 mm wide, becoming laterally imbricate, + contiguous, rotund at the apices. Upper surface plane to + ndulating and wrinkled, dull to slightly shiny; pustulate-sorediate, pustules laminal, forming on ridges in older lobes, erument, forming granular soredia; medulla white. Lower surface black with a narrow, naked, brown rim, sparsely rhizinate, rhizines short, simple or tufted at the apices, concolorous with the lower surface. Apothecia not seen. Pycnidia common, black, black, punctiform, immersed; conidia weakly bifusiform, 5-7 x 1-1.5 µm (Elix & Johnston 1988: 393).

Photobiont: Trebouxia.

Chemistry: Cortex K-; medulla K-, C-, P-; containing usnic acid, diffractaic acid (major), 4-0-demethylbarbatic acid (minor), barbatic acid (trace), unknowns (trace) (Elix & Johnston 1988: 393).

Ecology: Saxicolous.

Molecular data: Genbank

Distribution: Known only from the type locality.

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