Menegazzia pulchra

Detailed description

Thallus firmly attached, forming regular or irregular, complete or partial rosettes, to 15 cm diam., sometimes coalescing and then covering extensive areas of substrate, corticolous. Lobes numerous, radiating, 3-5(-6) mm wide, remaining distinct to centre of thallus, irregularly branched, laterals few, contiguous throughout entire length, becoming compressed and distorted centrally, rarely overlapping, margins sinuous-contorted, entire or occasionally notched, ± thinly blackened, especially centrally, hollow, lower side of internal cavity pale, apices ± suffused-brownish. Upper surface mostly convex, uniformly pale grey, here and there irregularly white-maculate, smooth or subrugose, shining, without isidia or soredia. Perforations frequent, median, mostly on main lobes, 1-1.5 mm diam., ± elevated, becoming low-conical or truncate, rounded or becoming distorted with age. Apothecia frequent, rather widely scattered, rarely 2-3-contiguous, elevated, ± pedicellate, ± turbinate, to 5 mm tall and to 4 mm diam., margins thick, persistent, entire, becoming ± striate-crenulate with age, inflexed, elevated, disc concave to ± plane, dark brown, usually ± bright orange-pruinose, pedicel and margins also ± densely coated in bright orange-red pruina. Epithecium ± red-brown, surface with numerous to few, irregular or ± rectangular orange-brown crystals. Asci 8-spored 130 × 60 µm. Ascospores ellipsoid, 35-43 × 20-23 µm, wall 3.5 µm thick.

Chemistry: Atranorin (cortex), norstictic acid [K+ red(crystals), Pd+ orange] and an unidentified orange pigment (K+ purple); apothecial margins K+ purple → black.