Trapelia corticola
Description : Thallus olive-green, effuse, 2–5 cm diam., of inconspicuous, ±scattered areolae, to subcontinuous or microphylline. Soralia prominent, scattered, 0.1–0.2(–0.5) mm diam., convex, pale greenish to whitish, soredia farinose, white. Apothecia scattered, rather rare, rounded, solitary, 0.05–0.1(–0.2) mm diam., convex, pale red-brown, epruinose, exciple very thin, paler than disc. Hymenium hyaline, I+ yellowish, 55–60 μm; epithecium pale brownish, Paraphyses rather scanty, irregularly branched, 0.8–1.0 μm diam. Hypothecium colourless to pale straw-yellow, 44–55 μm thick. Asci clavate with broadly acute apices, 45–60 × 12–15 μm. Ascospores biseriate, ellipsoidal, hyaline, 11–14 × 5–6.5 μm.
Chemistry : soralia K−, C+ red, Pd−; containing gyrophoric acid.
S: Canterbury (Hawdon River), Otago (Hina Hina State Forest near Owaka); Southland (Waituna Lagoon). On dry, decorticated and/or rotting wood at base of silver beech and mountain beech, and on old burned logs in grassland. First collected in New Zealand by Dr Leif Tibell 10232 (UPS). Known also from Great Britain, Europe; Canary Is, Azores, Turkey, North America and Chile (Coppins & James 1984; Purvis et al. 1992; Tønsberg 1992; Nimis 1993; Santesson 1993; Goward et al. 1994b; Esslinger & Egan 1995; John 1996; Diederich & Sérusiaux 2000; Scholz 2000; Llimona & Hladun 2001; Coppins 2002b; Nimis & Martellos 2003; Santesson et al. 2004).
Cosmopolitan
Illustrations : Coppins & James (1984: 242, fig. 1F; 255, fig. 2A, B).
Trapelia corticola is characterised by the spreading, olive-green thallus and the scattered, white, convex soralia. It is probably more widepsread on dryish rotting wood than the present records indicate.
