Lepraria lobificans
Description : Thallus leprose, usually diffuse forming a thick, powdery crust and without marginal lobes, but when eroded the medulla often develops into a leprose membrane with delimited sublobes, of a mass of powdery, convex granules of variable shape and size, up to 0.5 mm diam., with projecting hyphae sometimes forming a weft on the surface; bright greenish grey to whitish grey (especially when eroded), rarely bluish green. Medulla white, often conspicuous. Hyphae of thallus 1.5–5 μm diam., anastomosing, sparsely septate, colourless. Photobiont green, trebouxioid, cells spherical, to 21 μm diam.
Chemistry : Thallus K− or + yellow, C−, KC− or + yellow, Pd+ orange; containing atranorin, zeorin and stictic acid, ±constictic acid, cryptostictic, connorstictic and constictic acids and an unidentified fatty acid (Lohtander 1994: 229; Egan et al. 2002: 7).
N: S: In dry, sheltered habitats in generally deep shade, forming thick, leprose, glaucous-grey crusts on the underhanging faces of old, inclined beech trees, tree-fern trunks or the undersides of large branches. It is the most widespread of all species of Lepraria, occurring throughout Europe, Scandinavia, Asia, Africa, North America, Australia and Tasmania (Kantvilas & James 1991; Laundon 1992: 330; Lohtander 1994; Kukwa 2002a; McCarthy 2003c, 2006; Nimis & Martellos 2003; Santesson et al. 2004; Tønsberg 2004b). Throughout its known range it is most common at low altitudes, colonising a variety of substrata, shaded bark, mosses (it is known to invade mosses in plant pots in warm greenhouses in Europe), calcareous rock, acid rocks and soil. It is also tolerant of both heavy metal and atmospheric pollution (Laundon 1992).
Cosmopolitan
Illustrations : Tønsberg (1992b: 202, fig. 67); Dobson (2000: 212; 2005: 243); Brodo et al. (2001: 397, pl. 445).
Lepraria lobificans is characterised by: the corticolous habit; the greenish grey thallus and white medulla; and the Pd+ orange reaction indicating the presence of stictic acid.
