Flora of New Zealand Series

≡Lecidea petraea var. fuscoatra f. grandis Flörke in J.C.G.U.G.G.A.E.A.F. von Flotow, Flora 11: 690 (1828).

Description : Flora (1985: 505).

Chemistry : Thallus K+ yellow, C+ red, KC+ pink-purple (fading fast); containing gyrophoric acid, ±stictic acid.

S: Canterbury (Waimakariri riverbed, Hakataramea Valley), Otago (Lake Ohau, Old Man Ra., Poolburn Reservoir, Gem Lake, Umbrella Mts, Maungatua), Southland (Manapouri). On exposed, dry, sunny rocks from s.l. to 1000 m, on both schist and greywacke, and on vertical to overhanging surfaces with Lecanora cavicola (Galloway 2002b). Known also from Europe, Scandinavia, Svalbard, Greenland, the Ukraine, North America, Chile, South Orkney Is, South Shetland Is, and Antarctica (Lynge 1932, 1936; Thomson 1968a, 1979; Feuerer 1978; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; Hansen 1995; Wirth 1995a, 1995b; Kondratyuk et al. 1996a; Elvebakk & Hertel 1997; Galloway & Quilhot 1999; Scholz 2000; Hafellner & Türk 2001; Øvstedal & Lewis Smith 2001; Feuerer & Timdal 2004; Santesson et al. 2004; Søchting et al. 2004).

Bipolar

Illustrations : Feuerer (1978: 88); Hansen (1982: 29, fig. 18; 1995: 112); Foucard (1990: 243, pl. 278); Wirth (1995a: 535, pl. 55F; 1995b: 805F).

Rhizocarpon grande is characterised by: the areolate, spreading to orbicular thallus on a prominent black prothallus; areolae dispersed, convex, smooth, ashy brown to grey-white tinged violet (C+ red, KC+ pink-purple); apothecia scattered, angular to rounded, black, thinly marginate; a red-brown to brown-black epithecium (K+ red); 8-spored asci; and dark-brown, muriform ascospores, 24–46 × 11–16 μm; and gyrophoric and ±stictic acids in the medulla. Rhizocarpon grande is very closely related to R. eupetraeum (q.v.), from which it differs only in chemistry. Its separation from R. eupetraeum is discussed above under R. eupetraeum.