Porpidia skottsbergiana
Description : Thallus grey-white to pale ochraceous, areolate, without soredia, in irregular patches to 3 cm diam. Medulla I−. Apothecia black, sessile, constricted at base, 1.5–2.5 mm diam., disc plane, matt, epruinose; proper exciple, persistent, thin to thick, concolorous with disc. Epithecium blue-green to greenish black. Hymenium colourless, 65–80 μm tall. Hypothecium brownish to red-brown. Excipular tissue colourless centrally, pigmented greenish in outer parts, of very wide hyphae, 6–8 μm diam. Ascospores ellipsoidal, 11.5–13.5 × 4.5–6.5 μm.
Chemistry : Thallus K+ pale yellow or −, C− KC−, Pd−; containing unidentified triterpenoids.
C: Known also from South Georgia and South Orkney Is (Hertel 1984b; Øvstedal & Lewis Smith 2001; Søchting et al. 2004).
Austral
Illustration : Hertel (1984b: 497, pl. 6).
Porpidia skottsbergiana is characterised by: the saxicolous habit; the pale greyish to ochraceous, areolate thallus; sessile black apothecia with a prominent, concolorous raised proper margin; very wide excipular hyphae; a brownish to red-brown hypothecium; ellipsoidal ascospores, 11.5–13.5 × 4.5–6.5 μm; and a depauperate secondary chemistry of unidentified triterpenoid(s).
