Lecidella scabra (Taylor) Hertel & Leuckert

    Thallus crustose, more or less thin, granulose-verrucose, coarse becoming rimose to areolate, grey-greenish, yellow-greenish with paler sections with soralia, yellow-greenish, blue-greenish, sometimes concolourous to the thallus, potentially confluent or forming small piles; when abraded, the thallus becomes paler and whitish, prothallus grey, more or less distinct. Apothecia sometimes scarce (usually the more soredia, the less apothecia), sessile, discs slightly convex, often convoluted, sometimes sub-gyrose, black, exciple brown-black, becoming excluded. Ascospores simple, ellipsoid, 10-15 x 6-8 µm. Photobiont: chlorococcoid. Cortex : C-, K+ yellow, Pd- ; Soredia : C+ orange, K+ yellow. Not especially maritime, but common on dusty siliceous rocks of the foreshore, notably car parks, nutrient-rich rocks around harbours, and also inland in ancient quarries of stones and old walls, seldom on ground between the rocks, more rarely on soil protection textiles placed at the base of the dunes to limit erosion: Lecidella scabra forme sur textile de protection des sols, also on wood by the sea: Lecidella scabra forme lignicole.

_ Beware of non-fertile specimens of Lecania erysibe which are blastidized and which come on more alkaline substrates (negative color reactions)