Flora of New Zealand Series

Description : Thallus verrucose to dispersed, cryptothalline of scattered areolae, in patches to 8 cm diam., very thin (to 0.2 mm thick). Prothallus greyish, visible between areolae. Upper surface areolate, areolae angular, grey-white or sometimes rusty-oxydated, plane, roughened, 0.5–1 mm diam. Medulla I+ violet. Apothecia rounded to irregular through mutual pressure, sometimes scattered, mainly rather crowded, (0.1–)0.5–1.2(–2) mm diam., overmature fruits sometimes secondarily producing additional, small, apothecia. Disc convex to plane to subconvex, black, matt, epruinose. Margins distinctly raised, to 0.05 mm thick, rarely becoming occluded, concolorous with disc, matt. Hypothecium pale-brown to brown, 100–250 μm thick, subhymenial layer pale-green (5–)10–12 μm thick. Hymenium 40–50 μm tall, colourless to greenish, I+ blue; epithecium dark-green to black, 9–12 μm thick. Asci 30–40 × 7–8 μm; tholus 4–9 μm thick. Ascospores oblong (6.5–)7.5–8.5(–10) × 2.5–3 μm. Pycnidia immersed. Conidia (11–)13.5–16 × 1 μm.

Chemistry : Thallus and medulla K−, C−, KC−, Pd−; exciple C+ orange-red; containing confluentic acid (medulla) and 2'- O -methylanziaic acid (C+ orange-red in excipulum) (Schwab 1986: 322; Hertel 1995: 158).

S: Canterbury (Foggy Peak, Torlesse Ra., Porter's Pass, Lynn Stream Mt Peel), Otago (Ben Nevis, Hector Mts, Pulpit Rock, Silver Peaks, Maungatua). On subalpine to alpine rocks in exposed fellfield and on outcrops (Hertel 1989b: 220). Still rather poorly collected in New Zealand. Known also from alpine areas of Great Britain (Jersey, Scotland, Orkney, Shetland), central Europe, Scandinavia, Svalbard, Iceland, Greenland, artic Canada, Alaska, Arizona, Novaya Zemlya, Siberia (Hertel 1977b, 1981, 1991; Schwab 1986; Nimis 1993, Santesson 1993; Hertel & Andreev 2003; Hertel & Printzen 2004) and mountains in Australia (Rambold 1989; McCarthy 2003c, 2006) and in Tierra del Fuego (Hertel 1997).

Bipolar

Lecidea diducens is characterised by: the saxicolous habit; the roughened, grey-white, areolate, somewhat poorly developed thallus; the crowded, well-developed apothecia with distinctly raised, thickened margins enclosing a plane to concave, black, epruinose disc; the small, oblong ascospores and the C+ orange- red colour of the exciple (2'- O -methylanzaic acid).