Lecanora expallens
Description : Thallus effuse, granular–scurfy, pale yellow-green, abundantly sorediate, spreading in irregular patches, 2–5(–10) cm diam. Apothecia crowded to sparse or absent, in small groups of 6–8(–12) when present, solitary to crowded, 0.2–0.5(–0.8) mm diam., disc plane to subconvex, yellow to yellowish fawn, matt to slightly waxy, epruinose, margins thin to thick, warty, sorediate, concolorous with thallus. Epithecium pale yellowish to brownish, granular, granules dissolving in K. Hymenium colourless, 35–55 μm tall. Hypothecium colourless, 90–129(–140) μm thick. Ascospores broadly ellipsoidal, 9–15 × 3–6(–9) μm.
Chemistry : Soralia and apothecial margins K+ yellow, C+ orange, Pd−; containing usnic acid, zeorin, thiophanic acid and two unidentified xanthones (Śliwa & Wetmore 2000: 480).
N: Northland (Whangarei). Auckland (Victoria Park, Domain). South Auckland (Huntly, Te Kuiti). On bark and decorticated wood of both native and introduced trees. Probably more widespread in urban environments, but still very much under-collected (Galloway et al. 2001: 31). Known also from Great Britain, Scandinavia, Europe, and North America (Purvis et al. 1992; Tønsberg 1992b; Nimis 1993; Santesson 1993; Filson 1996; Scholz 1999; Śliwa & Wetmore 2000; Coppins 2002b; Nimis & Martellos 2003; Ryan et al. 2004b: 216–217; Santesson et al. 2004).
Cosmopolitan
Illustrations : Dobson (1992: 175; 2000: 193; 2005: 222); Wirth (1995b: 474); van Herk & Aptroot (1999: 545, fig. 1D).
Lecanora expallens is characterised by: the corticolous habit; the effuse, granular–scurfy, abundantly sorediate, pale yellow-green thallus, which is C+ orange (thiophanic acid). Apothecia may be present or absent. When present, the disc is waxy yellow, epruinose, the thalline margin thin to thick, verruculose, sorediate and concolorous with the thallus.
