Lepra amara  

Like Lepra albescens, but the thallus is often smaller, less well-zoned at the margin, the soralia typically smaller, sometimes punctiform, 0.5-1.5 mm diam., discrete or occasionally contiguous, rather regularly scattered over the thallus and with an extremely bitter taste due to picrolichenic acid.
Anamorph: no information available.
Teleomorph: ascomata apothecia, very rare. Asci 1-spored. Ascospores 130-150 × 40-50 μm.
Chemistry: soralia and medulla C–, K–, KC+ violet, Pd± red, UV– (picrolichenic, ± protocetraric acids).