Psora testacea Hoffm.

     Squamulous thallus formed of squamules arranged in small rosettes 3-5 cm in diameter, squamules 1-3 mm, flat then convex with a slightly lobulated and uptourned margin. Upper surface slightly pruinose, olive-grey in dry weather, olive-green in wet weather, lighter margin; lower surface paler. Biatorine marginal apothecia generally present, sessile, simple or grouped, 1-3 mm in diameter, convex disc, rust-red, orange, margin barely visible and insignificant. Clavicle asci with 8 spores. Ascospores simple, hyaline, elliptical, 10-14 x 5-7 µm. Photobiont: chlorococcoid. Thallus: K+/- yellow, C-, K-, KC-, P-; apothecia: K+ purple. Thermophilic, Mediterranean and subcontinental species, mainly found in mossy crevices in dry limestone rocks.