Psoroma athroophyllum Stirt.
Lectotype: New Zealand. Near Wellington. J. Buchanan 45, GLAM!
Thallus squamulose, in neat rosettes, to 5 cm diam., or spreading irregularly, 10-15 cm diam., very closely attached to substrate, small foliose-lobate at margins. Lobes short to medium, 5-12 mm long and 1-4 mm wide, incised, margins becoming phyllidiate, on a visible prothallus, densely squamulose-phyllidiate centrally, often forming a diffract-areolate crust. Phyllidia very small, finely raised, fragile, ascending, dorsiventral or lobulate-subcoralloid, naked or white- tomentose on lower surface, densely imbricate. Upper surface smooth, matt, sometimes shining, without tomentum, lettuce-green when wet, pale green or grey-green when dry becoming uniformly yellow-brown on storage. Cephalodia laminal or marginal, sparse, pale blue-grey, flattened or globose-granular to placodioid or rosette-shaped. Lower surface dark brown to black centrally, buff or brown at margins, ± densely rhizinate with a narrow, naked, marginal zone. Rhizines black or pale greyish, squarrose, to 3 mm long, rarely to 5 mm long, often projecting beyond lobe margins as a byssoid prothallus. Apothecia 1-3 mm diam., round to irregular, ± central, disc pale yellow-brown to red- brown or brown-black, undulate, matt, epruinose, thalline margin, squamulose, squamules often spreading onto disc, disc not gyrose-etched or contorted, margins crenate-striate or ± entire. Ascospores mainly subglobose, 13-15-12-14 µm or ellipsoid and halonate 12-20 × 10-14 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.
Endemic
A somewhat variable species whose relationship to P. coralloideum has yet to be definitely settled. There is considerable variation in the number and position of phyllidia throughout the range of the species, from a few phyllidia at margins only, to a dense covering over the whole thallus. Lobes may be narrow and ± discrete on a visible prothallus, or wide and covered with phyllidia with the prothallus difficult to detect.
