Poeltidea perusta
≡Lecidea perusta Nyl. in J. Crombie, J. Bot. 13: 334 (1875).
Description : Thallus irregularly spreading, 1–5 (–8) cm diam., areolate; areolae angular, brown, ±plane, 0.5–1.5 mm diam., surface smooth, shining. Prothallus black, visible between areolae and at margins. Apothecia angular to rounded, crowded to scattered, 0.5–2 mm diam., immersed to sessile; disc plane, dark-brown to black, immarginate, epruinose. Exciple not developed. Epithecium brown, 15–18 μm thick, with a gelatinous layer above, 15–30 μm thick. Hymenium colourless, 100–120 μm tall. Hypothecium colourless. Asci 90–95 × 50 μm. Ascospores ellipsoidal, at first colourless becoming greenish brown to dark-brown at maturity, 27–39 × 14–17 μm. Pycnidia immersed. Conidia cylindrical, 4–6 × 1–1.5 μm.
Chemistry : TLC−, all reactions negative.
S: Canterbury (Craigieburn Ra., Mt Hutt, Mt Peel), Otago (Harris Saddle), Southland (Key Summit). On subalpine to alpine rocks, often in exposed habitats, 800–1650 m. Known also from Kerguelen, Prince Edward I., the Falkland Is, Chile, Argentina, South Georgia, the South Orkney Is, the South Shetland Is, and SE Australia (Hertel 1984b, 1987b, 1989b, 2001 [see p. 123 (fig. 9) for a distribution map of the species]; Rambold 1989; Øvstedal & Gremmen 2001; Øvstedal & Lewis Smith 2001; McCarthy 2003c, 2006; Søchting et al. 2004).
Austral
Illustration : Rambold (1989: 276, fig. 28).
Poeltidea perusta is characterised by: the saxicolous habit; its brownish, glossy thallus; immersed apothecia and relatively large, halonate ascospores that become greenish brown at maturity. Fertile areolae are characteristically elevated above sterile areolae, and are surrounded by a thalline collar that is intermediate between strictly "aspicilioid" and "lecanoroid" types (Rambold 1989: 276).
