Digitothyrea rotundata
≡Thyrea rotundata Büdel, Henssen & Wessels in A. Henssen, B. Büdel & D. Wessels, Mycotaxon 22: 191 (1985).
Description : Thallus rosette-shaped, 4–12 mm diam., and tall, branched into flattened lobes, blackish, rigid, brittle and easily fragmented when dry, dark olive-green to olive brown, pliable, flabby, translucent when moist, attached by a central, irregular, pale brownish or fawnish umbilicus to 1 mm diam., of anticlinally arranged hyphae. Lobes somewhat congested and folded, suberect to erect, 1–4 mm long, 1–1.5 mm wide, sparsely branched, rounded at tips the margins slightly thickened–ridged below. Upper and lower surfaces smooth at margins, roughened–granular centrally. Photobiont cells yellow-brown, 8–10(–12) × 4–6 μm, arranged in packets of 2–8 (usually 4), each cell penetrated by a haustorium. Apothecia and pycnidia not seen.
Chemistry : TLC−, all reactions negative.
S: Canterbury (Rangitata Gorge, Lake Benmore). Along water-seepage channels on dry, sunny, steeply sloping to vertical rock faces. Known also from Morocco, Namibia and South Africa (Henssen et al. 1985; Moreno & Egea 1992a, 1992b).
Southern xeric
Illustrations : Henssen et al. (1985: 172, fig. 11; 174, figs 12, 13; 184, figs 37–39; 186, fig. 41 – as Thyrea rotundata); Moreno & Egea (1992b: 219, fig. 3, 1–3, 7–9; 222, fig. 5, 2–6; 224, fig. 6, 1–4).
Digitothyrea rotundata is characterised by: the saxicolous habit; the rosette-forming, black or dark olive-green thallus, attached to substratum by a central, irregular umbilicus; and the folded, congested lobes, suberect to erect, sparsely branched, with rounded apices.
