Leptogium burgessii
≡Lichen burgessii L., Systema naturae ed. 13: 807 (1774).
Description : Thallus orbicular to spreading or in small clumps, 1–3(–4) cm diam., not swelling much when wet, dark-grey or blue-grey when wet, olive-greenish, pale-greyish blue to reddish brown when dry, pliable and rather springy when wet, extremely fragile when dry. Lobes small, 1–2(–4) mm diam., crowded, somewhat imbricate, crenulate or lacerate. Margins entire, occasionally inrolled, slightly thickened, wavy, crisped, becoming sparsely to densely phyllidiate. Upper surface smooth, not plicate–wrinkled, here and there phyllidiate. Phyllidia flattened–lobulate, not coralloid, 0.2–0.5 mm tall, concolorous with thallus or ±red-brown. Lower surface concolorous with upper surface at margins, paler to ±creamish centrally, white-tomentose, tomental hairs short, 25–50 μm, cells spherical. Apothecia pedicellate, numerous, (0.1–)0.5–1.5(–2) mm diam., concave at first, becoming plane, disc shallowly concave to plane, orange-brown to red-brown, thalline exciple crowded with projecting lobules, concolorous with thallus or ±browned. Ascospores ellipsoidal to broadly fusiform, apices pointed, submuriform with 3–4 transverse septa and 1–2 longitudinal septa, (20–)22.5–25 × 7.5–10 μm.
N: Northland (Three Kings Is to Waiwera), Wellington (Manawatu River). S: Otago (Wakari Dunedin, Taieri Beach, Coutts Gully Road). Among bryophytes and other lichens on bark in lowland and coastal habitats between latitudes 34º10's and 46º04's (map in Galloway 1999: 328, fig. 5). Still very poorly understood and collected in New Zealand. It is known from the eastern United States, Mexico, Ecuador, West Indies, Macaronesia, western Europe (to SW Norway) East Africa, South Africa, southern India and Thailand (Jørgensen 1997a; Bjelland 2001; Wolseley et al. 2002), but is absent from Australia (Verdon 1992a; Filson 1996; McCarthy 2003c, 2006; Jørgensen & Nash 2004).
Cosmopolitan
Illustrations : Phillips (1987: 175); Swinscow & Krog (1988: 133, fig. 65); Jørgensen et al. (1994a: 282, fig. 10); Dobson (2005: 248).
Leptogium burgessii is characterised by: the corticolous habit; the presence of phyllidia on both margins and upper surface; a smooth upper surface; a short white tomentum on the lower surface; and projecting lobules on the margins of the apothecia.
