Psoroma caliginosum Stirt.
Lectotype: New Zealand. Near Wellington. J. Buchanan 45, GLAM!
Thallus squamulose, very closely attached to substrate, in ± rounded or closely spreading patches, 2-10 cm diam., on a fine, black, minutely fibrous, closely attached prothallus which may extend 2-4 mm beyond margins of squamules. Squamules very closely appressed, flattened, smooth, lobate-crenate, rounded and scattered at margins, becoming rosette-shaped 1-2 mm wide, coalescing into a closely attached, ± imbricate mosaic centrally, apices and margins of squamules slightly thickened, ± whitish pubescent, pubescence very short, minute, appearing "frosted", pale greenish, yellow-green to brownish or pale glaucous, matt or ± shining, paler at margins, glossy, smooth. Cephalodia large, lobate-crenate, to 3 mm diam., flattened, placodioid, smooth to ridged-striate, pale blue-grey or blackened to bluish-brown, ± frequent at margins, laminal or marginal on squamules or growing directly on hyphae of prothallus, often concolorous with thallus when dry, with a faint blue-black cast. Apothecia sessile, closely attached to squamules or projecting above, ± central, sparse to numerous, round to irregular, 0.2-1.0 mm diam., margins thick, inrolled, striate-crenate, concolorous with thallus, disc matt, plane, dark brown or black, occasionally with small thalline lobules centrally or disc ± obliterated by concentric rings of thalline tissue, epruinose. Ascospores large, (12-)17-24 × (9-)12-14 µm.
N: S: St: Ch: A: C: Throughout, widely distributed in mainly lowland and coastal habitats, s.l. to 1500 m, on trees and shrubs rarely on rocks in damp, shaded habitats.
Australasian
