Fuscidea praeruptorum (Du Riest & H. Magn.) V. Wirth & Vezda
Lecidea praeruptorum Du Rietz & H. Magn.
Thallus crustose, rough and irregular, areolate, ochraceous pale to cream, brownish at the end, often well limited by a blackish hypothallus, covered with rounded or tubercular soralia which can cover the whole center of the thallus by union, ocher-cream in dry weather ocher-greenish in wet weather. Apothecia very rare, sessile, 0.5-1 mm in diameter, disc somewhat convex, blackish, margin thin. Kidney-shaped spores, 9.5-12 x 3-4 µm. Soralies: C + red, K-, KC + red, P + yellow. Rare species occurring on sheltered faces or on overhangs of vertical acid rocks, in particular slate shales. See Ropalospora hibernica which is P-.
N.B. Species probably going unnoticed if chemical tests are not carried out.