Squamules: up to 8 mm wide, rounded, adnate and dispersed to adjacent or partly imbricate, weakly concave to weakly or strongly convex; upper surface: gray to olivaceous brown, dull, epruinose or partly to entirely pruinose, strongly fissured; margin: concolorous with upper side or white, straight, entire or crenulate; upper cortex: up to 140 μm thick, composed of thin-walled hyphae with round lumina, containing crystals of lichen substances and calcium oxalate; medulla: containing calcium oxalate; lower cortex: absent or poorly developed; lower surface: white to pale brown; Apothecia: up to 2 mm diam., marginal, immarginate even when young, black, epruinose or white pruinose; ascospores: 10-17 x 6-8 μm; Pycnidia: laminal, immersed; conidia: bacilliform, 5-7 x 1 μm; Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow; medulla K-, C-, KC-, P-; Secondary metabolites: atranorin, sometimes trace of norstictic acid.
The species is recognized by the olivaceous brown, isodiametrical squamules, marginal, black apothecia and the thallus chemistry of atranorin (sometimes with traces of norstictic acid). Psora crenata differs in having pink to red squamules containing norstictic acid (in North America; several other chemical strains occur elsewhere but never containing atranorin).
Psora cerebriformis has a wide distribution in the arid areas in western North America. The recorded altitudes range from 470 to 2590 m.
The species is terricolous, occurring in open, arid habitats.
Psora crenta.
