Buellia griseovirens (Turner & Borrer ex Sm.) Almb.
Variolaria griseovirens Turner et Borrer ex Sm. in Sm. et Sowerby, Engl. Bot. 34: t. 2400 (1812).
Thallus pale grey, very thin, continuous or lacking, sometimes minutely cracked, sorediate, prothallus black, or lacking. Soralia numerous, seldom confluent, often forming a mosaic to 2 mm diam., soredia farinose, less than 0.01 mm diam., greenish-grey in freshly gathered material, pale yellowish-grey on storage, ± delimited in circular, plane or subconvex soralia. Apothecia rare (not seen in New Zealand material) sessile, plane at first with a prominent proper margin, becoming convex and immarginate. Epithecium dark brown. Hymenium colourless 110-120 µm tall. Hypothecium dark brown. Asci clavate, 110 × 15 µm. Ascospores pseudomuriform, ellipsoid (13-)15-28 × 7-13 µm.
S: Canterbury, Hanmer State Forest, on Betula bark. First collected by P.M. Jørgensen (Bergen) in September 1981 during IAL excursion to New Zealand. It is probable that this overlooked species is more widely distributed on stands of Betula throughout New Zealand.
Cosmopolitan
