Arthonia lapidicola
≡Lecidea lapidicola Taylor in J.T. Mackay, Fl. hibern. 2: 124 (1869).
Description : Thallus evanescent, scurfy, granular, whitish, grey or ±fawnish, in irregular patches, often not readily distinguished from limestone substratum. Apothecia scattered, solitary or 1–3-together, 0.1–0.3(–0.5) mm diam., subimmersed to plane or subconvex, rounded, immarginate, disc black, matt or slightly shining, epruinose. Epithecium to 20 μm thick, red-brown above greenish below. Hymenium colourless or pale greenish above, 35–55 μm tall. Hypothecium red-brown. Ascospores soleiform, colourless, 1-septate, end cell broader, 13–18(–19) × 4–7 μm.
S: Southland (Castle Rock). On limestone. Known also from Scandinavia, Great Britain, Europe and North America (Coppins 1992a; Nimis 1993; Nimis & Martellos 2003), the South Orkney Is (Øvstedal & Lewis Smith 2000), and the South Shetland Is (Søchting et al. 2004: 615).
Bipolar
Illustrations : Foucard (1990: pl. 17); Dobson (2005: 67).
Arthonia lapidicola is characterised by: the saxicolous habit (limestone rocks); scattered, black apothecia, 0.1–0.3 mm diam.; and colourless, soleiform, 1-septate ascospores, 13–19 × 4–7 μm.
