Physcia erumpens
Description : Thallus orbicular to irregularly spreading, 1–3(–5) cm diam., closely attached from margins to centre. Lobes rather narrow, 0.5–1.5(–2) mm wide, 2–3(–10) mm long, subdichotomously to irregularly branched, discrete, adjacent to subimbricate at apices, complex-imbricate centrally, plane to convex or somewhat crumpled. Margins entire, shallowly notched or incised to ±wavy, or with small secondary lobules, apices rounded to irregularly scalloped or incised, slightly thickened–ridged below. Upper surface pale greenish white when moist, off-white to white when dry, matt, smooth, minutely white-maculate (×10 lens) in older parts, epruinose, sorediate. Soralia laminal, rounded to irregular, (0.2–)0.5–1(–1.5) mm diam., often confluent and eroding large areas and exposing white medulla, distinctively crateriform, margins often conspicuous and flaring back from exposed medulla and accumulated soredia; soredia coarsely granular, pale greenish to white. Lower surface smooth, matt to slightly glossy in parts, greyish to red-brown to black, rhizinate. Rhizines sparse to numerous, simple, with a squarrose tuft at tip, 0.2–0.5(–0.8) mm long, grey to brown-black. Apothecia sparse to occasional, solitary to 2–3-together, sessile, constricted at base, rounded, 0.5–1(–2) mm diam.; thalline exciple prominent, persistent, swollen, smooth to crenulate–striate; dissolving here and there into soredia in older fuits, concolorous with thallus; disc subconcave to plane, pale to dark red-brown to ±blackened, with or without pruina. Epithecium olive-brown to dark-brown, 10–12.5 μm thick. Hymenium 85–100 μm tall, colourless. Hypothecium opaque, densely interwoven, pale yellowish or brownish. Ascospores brown, broadly ellipsoidal, Pachysporaria -type, (20–)22–25(–28) × 7.5–10 μm.
Chemistry : Upper cortex and medulla K+ yellow; containing atranorin and zeorin and several unidentified triterpenoids.
K: (Raoul I.). N: Northland (Waitiki Stream to Warkworth), South Auckland (Whale I.), Wellington (Kapiti I.). S: Marlborough (d'Urville I). St: (Port Pegasus). On coastal vegetation (maritime scrub, mangroves, trees in coastal forest) and rocks (both maritime and in coastal grasslands) and in parks and farmland on introduced trees, s.l. to 100 m. First described from East Africa (Moberg 1986b) it was subsequently recorded from Madagascar (Aptroot 1988), the Philippines (Aptroot & Sipman 1989), South America (Moberg 1990; Scutari 1995b; Marcao et al. 1996; Galloway & Quilhot 1999; Calvelo & Liberatore 2001), Portugal, the Azores, Macaronesia and Italy (Moberg 1989; Nimis 1993; Nimis & Martellos 2003), the Sonoran Desert and Baja California in North America (Moberg 1997, 2002b) and South Africa (Moberg 2004b).
Cosmopolitan
Illustration : Swinscow & Krog (1988: 227, fig. 110).
Physcia erumpens is characterised by: the corticolous habit; convex lobes; the black lower surface; crateriform to capitate laminal soralia.
