Lecanora argentata
≡Parmelia subfusca f. ("η") argentata Ach., Methodus: 169 (1803).
Description : Thallus continuous, yellowish to greenish white, or greyish smooth at margins, uneven to subverrucose centrally, without pruina or soredia, delimited by a ±prominent grey-white or whitish prothallus. Apothecia sessile, 0.4–1 mm diam., scattered or crowded centrally; thalline exciple persistent, concolorus with thallus, smooth to ±verrucose or crenulate; discs reddish or dark red-brown to bright red-brown, epruinose. Amphithecium with large crystals (pulicaris-type not dissolving in K); epithecium reddish brown not dissolving in K, without crystals (glabrata -type), 10–15 μm thick. Paraphyses c. 2 μm thick, simple, dense, apices capitate to 4 μm thick . Hymenium colourless, 55–70 μm tall. Hypothecium colourless. Asci clavate 40–55 × 10–14 μm. Ascospores ellipsoidal, 10.5–15.5 × 5.5–8.5 μm, the wall 0.5 μm thick.
Chemistry : Thallus and apothecial margin K+ yellow, C−, KC−, Pd+ yellow; containing atranorin and gangaleoidin as major compounds with chloroatranorin, 4-dechlorogangaleoidin and norgangaleoidin as minor compounds (Lumbsch 1994).
N: Northland (Little Barrier I., Waiwera) to Auckland (Mt Albert Research Station). In coastal forest (Metrosideros) and on a planted specimen of Nothofagus. Known from Great Britain, Europe, Scandinavia and North America (Brodo 1984a; Hawksworth & Dalby 1992; Nimis 1993; Santesson 1993; Ibáñez & Burgaz 1998; Scholz 2000; Nimis & Martellos 2003; Santesson et al. 2004) and in the Southern Hemisphere from eastern Australia, South Africa, Argentina, Chile, Paraguay and Uruguay (Lumbsch 1994: 68; Guderley 1999: 178; McCarthy 2003c, 2006; Lumbsch & Elix 2004; Ryan et al. 2004b: 194–195).
Cosmopolitan
Illustrations : Wirth (1987: 227; 1995b: 467, 478); Lumbsch (1994: 65, fig. 51D–F); Guderley (1999: 175, figs 13E, F); Dobson (2000: 188; 2005: 215); Ryan et al. (2004b: 195, fig. 24).
Lecanora argentata is recognised by: the corticolous habit; the clear, red-brown epithecium; large crystals in the amphithecium; and products of the gangaleoidin chemosyndrome. It occurs in high-light habitats with species of Buellia, Flavoparmelia, Pertusaria and Parmotrema.
