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This is a LifeDesk for the lichen genus Psora Hoffm. (Psoraceae, Lecanorales, Ascomycetes).

The genus consists of c. 30 species growing on soil and rock, often on calciferous substrates in open habitats. It is cosmopolitan but most common in arid zones and with a centre of diversity in western North America.

The genus was formerly often included in the genus Lecidea Ach. as a section comprising the squamulose species. The current narrow circumscription of Psora was established by Timdal (1984), based on the squamulose thallus, asci with amyloid tube in the tholus, anthraquinones in the epithecium, calcium oxalate in the hypothecium, immersed, laminal pycnidia, and acrogenous, bacilliform pycnoconidia.

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    <i>Psora rubiformella</i>, Japan, collection Kashiwadani, Lich. Minus Cognitae Exsicc. 338 (O-L-151788)
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