Psora crystallifera
≡Lecidea crystallifera Taylor, Lond. J. Bot. 6: 148 (1847).
≡Eremastrella crystallifera (Taylor) Gotth.Schneid., Biblthca Lichenol. 13: 76 (1980) ["1979"].
Description : Thallus squamulose, spreading in crowded, congested clumps or lines and appearing somewhat caespitose, (0.2–)0.5–1.5(–3) cm diam. Squamules round to angular or polygonal, (2–)3–7(–9) mm diam., plane to shallowly concave or subfaveolate, yellow-brown to dark-brown, with or without a fine, white, crystalline pruina; margins thickened, slightly raised, cracked, densely white-pruinose and contrasting with surface of squamules. Cortex of "Kegelrindentyp" (Timdal 1984b: 527, fig. 1F; Lumbsche & Kothe 1993), splitting reticulately in older parts of thallus or cracking into translucent, pyramid-like polygons or papillae and appearing like a mass of crystals; attached to soil by spreading rhizomorphs when well developed. Photobiont layer discontinuous. Apothecia rare to common, convex to plane, marginal or laminal, rounded to spreading, 1–2 mm diam., with a distinct, undulate, slightly raised, coal-black proper margin; disc plane, matt, black, epruinose, minutely striate-cracked to subpapillate or roughened. Epithecium dark-green to greenish brown, dense, unchanged in K, 10– 20 μm thick. Hymenium colourless, 65–100 μm tall. Hypothecium pale red-brown. Paraphyses thin-walled, 2–3 μm diam., simple to sparingly branched towards apices, very strongly conglutinated, apices slightly swollen, to 5 μm diam. Asci clavate, 48–60 × 12– 16 μm. Ascospores ellipsoidal, apices rounded or pointed, 13–16.5(–18.5) × 6.5–8.5 μm.
Chemistry : TLC−, all reactions negative.
S: Otago (Poolburn Reservoir). On wind-blown soil in narrow joints of rock tors near ground, probably more widespread on arid, preferably alkaline soils. Along with Aspicilia calcarea and Psora decipiens, it is a good indicator of soils that are high in carbonate (Eldridge 2001: 126). Known also from arid areas in Australia and South Africa (Vogel 1955; Filson & Rogers 1979; Schneider 1980; Timdal 1984b; Almborn 1987: 412 fig. 12 [map of known distribution]; Lumbsch & Kothe 1993; Eldridge 2001; McCarthy 2003c, 2006).
Southern xeric
Illustrations : Vogel (1955: 105, fig. 14; 108, fig. 15 – as Eremastrella tobleri); Filson & Rogers (1979: 70, fig. 15C – as Lecidea crystallifera); and Schneider (1980: 77, fig. 7); Timdal (1984b: 527, fig. 1F); Lumbsch & Kothe (1993: 22, fig. 1F; 23, fig. 2A, B; 25, fig. 3F; 26, fig. 4A, B; 27, fig. 5A,B; 28, fig. 6F; 29, fig. 7F); Eldridge & Tozer (1997: 39, fig. 4.18); Belnap et al. (2001a: 6, figs 18, 19) – all as Eremastrella crystallifera.
Psora crystallifera is characterised by: the terricolous/saxicolous habit; crowded, thick, rounded to polygonal squamules, with a yellow-brown to dark-brown, often white-pruinose upper surface, the cortex splitting with age into pyramid-like polygons and appearing coarsely crystalline (×10 lens); marginal, black apothecia, 1–2 mm diam.; and ellipsoidal ascospores, 13–16.5(–18.5) × 6.5–8.5 μm.
