Psilolechia lucida
≡Lichen lucidus Ach., Lichenogr. suec. prodr.: 39 (1799) ["1798"].
Description : Thallus bright yellow-green, spreading in irregular patches, often quite extensive, 5–15(–20) cm diam., leprose-granular, to 0.5 mm thick; continuous, cracked or granular-areolate, the areolae 0.1–0.3 mm diam. Goniocysts discrete in leprose forms, less or not discernible in areolate forms, ±globose, 18–30(–40) μm diam., often ±oblong in forms with Stichococcus; hyphae and algal cells inspersed with yellowish granular crystals. Photobiont Stichococcus (in NZ collections). Apothecia (often lacking), convex to ±globose, 0.1–0.3 mm diam., rarely tuberculate and to 0.5 mm diam., yellow-green or yellow-orange at maturity. Hymenium c. 25 μm high, colourless, I+ yellow; epithecium c. 5 μm thick, yellow, encrusted with minute crystals. Asci 20 × 5.5 μm. Ascospores ellipsoidal, 4–5 × 1.5–2 μm.
Chemistry : Thallus and apothecia K−, C−, KC−, Pd−, UV+ orange; containing rhizocarpic acid and zeorin.
S: Canterbury (Woolshed Hill), Otago (Mt Cargill, Swampy Spur track, Black Gully Blue Mts). On small stones, overhanging clay banks, along walking tracks in somewhat shaded situations. Probably more widespread than present records indicate. Widely distributed in the Northern Hemisphere (Coppins & Purvis 1987; Tønsberg 1992; Nimis & Martellos 2003) and known from Australia and Tasmania, southern Chile, and Charcot I., Antarctica (Rambold 1989; Convey et al. 2000; McCarthy 2003c, 2006).
Cosmopolitan
Illustrations : Brightman & Nicholson (1966: 79, fig. 2); Moberg & Holmåsen (1982: 124); Hafellner (1984: 306, fig. 51); Phillips (1987: 166 – as Lecidea lucida); Wirth (1987: 399); Hertel & Rambold (1988: 295, fig. 5); Dobson (1992: 285; 2000: 328; 2005: 372); Purvis (2000: 45); Brodo et al. (2001: pl. 721).
Psilolechia lucida is characterised by: the terricolous/saxicolous habit; its bright, chartreuse, yellow-green, leprose-granular thallus (UV+ orange); and the yellow, immarginate, convex apothecia, often sunk in thalline granules.
