Psoroma asperellum Nyl.
Pannaria imbricata Nyl., Syn. Meth. Lich. 2: 31 (1863).
Pannaria imbricata. Lectotype: Van Diemen's Land (Tasmania), Circular Head, ex Herb. Hooker. Sine leg., H-NYL 31277!
Thallus small, squamulose, epiphytic on mosses in scattered colonies, to 3 cm diam., or on bark to 5 cm diam., squamules ascendent from an occasionally present, fine, black prothallus. Squamules small, delicate 0.3-0.8 mm wide, rounded, incised, minutely lobulate, rather loosely developed, not forming a tight crust, ascendent, pale greenish-grey to bright lettuce-green when wet, pale whitish-grey on storage, surface smooth, matt, not pruinose at margins, dispersed to crowded-imbricate. Cephalodia ± frequent, pale grey-blue, laminal and marginal, flattened, placodioid or minutely lobed, squamulose. Lower surface white, ± corticate, rhizines few or absent. Apothecia sessile, ± frequent, round, disc pale yellow-orange to pale red-brown, conspicuous, 0.5-1.5 mm diam., plane to subconvex, matt, continuous, eperforate, not gyrose-etched or pruinose, margins crenulate to minutely subsquamulose, overlying a thin, entire, pale proper margin. Ascospores ellipsoid-fusiform, 12-25 × 8-10 µm.
N: South Auckland (Rotorua), Wellington. S: Nelson to Fiordland, west of the Main Divide, on the east coast in South Canterbury and Southland. Characteristically over-growing mosses in damp, humid sites in lowland, mainly coastal forest, rarely on soil inland.
Australasian (also in South Africa)
P. asperellum is a rather variable species characterised by its squamulose thallus, (the squamules on moss conspicuously scattered and discrete, those on bark ± imbricate and rosette-forming), the blue-grey squamulose cephalodia and the conspicuous fruits with squamulose margins. The type (ex Herb. Hampe, H-NYL 30818-19) from the Cape of Good Hope is exceedingly fragmentary, but seems to be closely similar to the material of Pannaria imbricata from Tasmania. For the present the two taxa are combined as P. asperellum.
