Lepra aspergilla

Thallus rather thin to moderately thick, even, sometimes ± fissured or cracked-areolate; prothallus indistinct, marginal, often paler; upper surface pale or dark grey; soralia ± evenly scattered, to 1 mm diam., white,punctiform, flat or somewhat convex, rounded; isidia very rare, small, cylindrical. Apothecia unknown. Thallus C–, K+ dirty yellow-brown, KC+ yellow-red, Pd+ orange-rust red, UV– (fumarprotocetraric (major), succinprotocetraric (major) and ± protocetraric acids). 

Characterised by the small, pale, punctiform soralia and succinprotocetraric acid in concentration above or equal to fumarprotocetraric acid. The soralia in L. amara are KC+ violet and taste bitter; those in Varicellaria lactea are C+ red; L. excludens is K+ red and mild-tasting; specimens on lignum in relict Scottish pine woodlands previously referred here are L. borealis. See also L. leucosora.