Lepra melanochlora

Thallus rather thick, grey to dark grey, ± rimose with abundant crowded coarse ± cylindrical isidia-like papillae, 2–3 mm tall × 0.5–2 mm broad, rarely branched, with blunt, flattened pale apices, often abraded exposing a white medulla which may form a few granular soredia. Fertile warts rare, arising from papillae, later expanding to 2– 3.5 mm diam.; apothecia often poorly developed, 1-5 per papilla; disc 1.5–2 mm diam., black, whitish pruinose, flat or convex, irregular, surrounded by a curved, wrinkled thalline exciple. Asci 1-spored. Ascospores 180–250 (–300) × 70–130 (– 200) μm; wall ca 22 μm thick, smooth, unzoned. Conidia 4–5 × 0.5–1 μm, cylindrical. Thallus C–, K+ yellow-red, KC+ magenta-violet (fleeting), Pd+ orange-red, UV– (picrolichenic and protocetraric acids). 

Like L. amara and L. pulvinata, it has a characteristic very bitter taste and KC+ magenta-violet thallus; it is separated by the distinctive gross peg-like pale-tipped papillae. The KC reaction is fleeting and best observed on squashes of thallus or papillae on filter paper.