Flora of New Zealand Series

≡Lecanora tribacia Ach., Lichenogr. universalis: 415 (1810).

Description : Thallus orbicular, stellate-radiating, thalli often confluent (0.5–)1–2(–4) cm diam., closely attached centrally, more loosely attached to somewhat ascending at margins. Lobes very narrow, 0.1–0.5(–1) mm wide, 1–2(–4) mm long, dichotomously to irregularly branched, densely imbricate centrally, shallowly convex; margins crenate, apices crenulate–incised, noticeably curled under. Upper surface pale-grey to grey-white, matt to minutely crystalline and here and there glistening and minutely white-maculate (×10 lens). Lower surface corticate, whitish to pale-brownish, rhizinate, sorediate. Rhizines common to sparse, mainly at margins, white to pale-buff, simple, to 1 mm long. Soralia mainly apical, also marginal, irregular, coarsely granular or coralloid eroding lower surface of lobe apices ["sorediigenous parasidia" of Scutari (1990b)]. Soredia granular grey-white to greenish. Apothecia and pycnidia not seen in New Zealand material.

Chemistry : Cortex K+ yellow; medulla K−; containing atranorin.

N: Gisborne (Mt Taitai). S: Canterbury (Hurunui River, Lowry Peaks Ra., Christchurch, Rangitata Gorge, Burke's Pass), Otago (Arrowtown, Poolburn, Hawkdun Ra., The Remarkables, Garvie Mts, Alexandra Lookout, Roxburgh, Dunedin, Waipahi). Southland (Invercargill Cemetery). Occuring on tops and vertical sides of sunny rocks (schist and greywacke), in dry rock overhangs, occasionally growing near sea level on bitumen footpaths, and on concrete posts, and collected once from a polished granite grave headstone. Still very poorly collected. Known also from Great Britain, Scandinavia, Europe, North and South America, North, East and South Africa, Turkey, the Ukraine, India, Asia, Japan, the Pacific and Australia (Awasthi 1960; Thomson 1963; Poelt 1974; Kashiwadani 1975; Moberg 1986, 1990, 1997, 2001, 2002b, 2002g, 2004b; Scutari 1990b, 1995b; Purvis et al. 1992; Nimis 1993; Elix & Kantvilas 1995; Esslinger & Egan 1995; Egea 1996; John 1996; Kondratyuk et al. 1996a; Marcano et al. 1996; Esslinger 1997; Elix & McCarthy 1998; Galloway & Quilhot 1999; Scholz 2000; Diederich & Sérusiaux 2000; Hafellner & Türk 2001; Llimona & Hladun 2001; Calvelo & Liberatore 2001; Coppins 2002b; Kurokawa 2003; McCarthy 2003c, 2006; Nimis & Martellos 2003; Santesson et al. 2004).

Cosmopolitan

Illustrations : Moberg (1986b: 861, fig. 21); Dobson (2000: 306; 2005: 342).

Physcia tribacia is characterised by: the saxicolous habit; the small narrow lobes (1–2 mm wide); the shining upper surface; the crenulate lobe tips; the terminal soralia developed at the lobe tips and eroding the tip and the lower surface. Physcia callosa, the name given in the Flora (Galloway 1985a: 393) to specimens of P. tribacia, refers to a Califonian species (Thomson 1963: 91–92), which is not present in New Zealand.