Acarospora nodulosa
≡Parmelia nodulosa Dufour in E. Fries, Lich. Eur. Ref.: 185 (1831).
Description : Thallus squamulose-areolate, the areolae scattered or contiguous, markedly swollen-verrucose, 1–3 mm diam., pale olivaceous to green-brown, densely white-pruinose in scattered, glistening patches; lower surface pale-buff. Apothecia immersed, 1–3 per areola, 1–1.5 mm diam., disc grey-black to brown, deeply urceolate, ±pruinose, thalline margin prominent, raised, concolorous with thallus or white-pruinose. Hymenium 100–110 μm tall. Ascospores c. 100 per ascus, subglobose to broadly ellipsoidal, 5–7 × 3.5–5 μm.
Chemistry : TLC−, all reactions negative.
S: Otago (Flat Top Hill, Teviot Valley). Spreading over and consolidating bare soil in depleted, arid grassland with scattered Thymus vulgaris, and on sloping rock surfaces of disused railway cutting (on schist). Associating with Placopsis subparellina, Xanthoparmelia molliuscula and X. semiviridis. Known also from Spain, Italy, Arabia, North America and Australia (Magnusson 1929; Filson & Rogers 1979; Esslinger & Egan 1995; Eldridge 1996; St. Clair 1999; McCarthy 2003c; Nimis & Martellos 2003).
Cosmopolitan
Illustrations : Ozenda & Clauzade (1970: 514, fig. 428); Filson & Rogers (1979: 50, fig. 10A – as Acarospora ferdinandii); St. Clair (1999: 28).
Acarospora nodulosa is characterised by: the terricolous habit; the swollen, verrucose, squamulose-areolate thallus, the surface olivaceous to pale green-brown with scattered glistening patches of white pruina; immersed apothecia, 1–3 per areola, with a brown, or grey-black and pruinose disc, and raised, often white-pruinose thalline margins; and subglobose ascospores, 5–7 × 3.5–5 μm.
