Flora of New Zealand Series

≡Verrucaria polytropa Hoffm., Dtschl. Fl.: 196 (1796).

=Lecidea acerviformis Js. Murray, Trans. Roy. Soc. N. Z. Bot. 2: 66 (1963).

Lecidea acerviformis. Antarctica. Victoria Land, Cape Hallett, 72º25's, 170º55'E, "Crater Hill, Hallett Base", 488 m, 11–12.i.1958, Croll, Fitzgerald, McKellar, Harrington (WELT L-84 – holotype). See also Hertel (1983: 446).

Description : Flora (1985: 217).

Chemistry : Usnic and rangiformic acids and zeorin.

N: Gisborne (Mt Hikurangi). S: Nelson (Ruby Lake) to Southland (Invercargill). St: Throughout, on alpine to high-alpine rocks (schists and greywacke – to 3550 m on the exposed Middle Peak of Mt Haast), on flat, exposed rock surfaces, on pebbles in fellfield, and on vertical sides and roofs of overhangs and caves where it may become hummocky–pulvinate. It is most common east of the Main Divide, especially on sunny, exposed schist surfaces, as well as in shaded overhangs in the Central Otago Mountains. The presence of usnic acid as a photoprotective compound in this species allows it to survive comfortably in areas of high UV radiation (see Bjerke & Dahl 2002). It also commonly occurs on old weathered, rusted iron gates, railings (especially around headstones in graveyards), abandoned metal fluming, wheels, pipes and dredge buckets, on weathered lignum (including tops of tanalised posts in both rural and urban environments, where it often forms conspicuous, radiating, yellow-green patterns interspersed with bands of golden Candelariella), and old, abandoned farm and industrial machinery, and on flaking painted surfaces where the paint is rich in iron oxide. It is quite common in urban environments on old painted surfaces of wooden railings, on stonework of bridges [e.g. the impressive stone bridge over the Leith at Woodhaugh Gardens in George Street, Dunedin, supports a vigorous growth of L. polytropa], on concrete coping and kerbing along fencelines where the surfaces are washed periodically by leached iron slats from metal railings and/ or fence-wires (see also Brightman & Seaward 1977: 284; Gilbert 2000). On man-made substrata it commonly associates with Candelariella vitellina, Physcia adscendens, P. caesia. Along with Carbonea vorticosa, it was recorded from a height of 7400 m in the Himalaya, the highest known altitude for lichens (Hertel 1977a, 1988a). L. polytropa is a characteristic species in the alliance Umbilicarion cylindricae Frey (James et al. 1977: 374). Known also from Great Britain, Europe, Scandinavia, the Arctic, Asia, North and South America, Australia, South Georgia, South Orkney Is, South Shetland Is and the Antarctic Peninsula (Purvis et al. 1992; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; Scholz 2000; Brodo et al. 2001; Øvstedal & Lewis Smith 2001; Coppins 2002b; McCarthy 2003c, 2006; Nimis & Martellos 2003; Lumbsch & Elix 2004; Martínez & Aragón 2004; Ryan et al. 2004b: 256–257; Santesson et al. 2004; Søchting et al. 2004).

Bipolar

Illustrations : Ozenda & Clauzade (1970: 580, fig. 479); Moberg & Holmåsen (1982: 114); Wirth (1987: 241; 1995b: 455); Dobson (1992: 172; 2000: 198; 2005: 228); Hansen (1995: 95); Malcolm & Galloway (1997: 69, 100); St. Clair (1999: 101); Gilbert (2000: pl. 10A); Malcolm & Malcolm (2000: 129); Brodo et al. (2001: 387, pl. 432); Printzen (2001: 385, fig. 2E; 396, fig. 5D); Flora of Australia56A (2004: xiv, pl. 14); Pope (2005: 52).

Lecanora polytropa is characterised by: the saxicolous/lignicolous habit; the clusters of yellow to tan apothecia with greenish yellow thalline margins, and the virtual absence of thallus. The related species L. stenotropa Nyl., said to be present in New Zealand (Lumbsch & Elix 2004: 50), is morphologically indistiguishable from L. polytropa, but has narrower ascospores (8–12 × 3–4 μm – those of L. polytropa are 9–15 × 4.5–7 μm), isorangiformic as main metabolite. In the Northern Hemisphere, L. polytropa is commonly parasitised by several lichenicolous fungi including * Carbonea aggregantula (Müll.Arg.) Diederich & Triebel, * C. supersparsa (Nyl.) Hertel, * Cercidospora epipolytropa (Mudd) Arnold, and * Muellerella pygmaea var. athallina (Müll.Arg.) Triebel (Hawksworth 1983a; Triebel 1989; Alstrup & Hawksworth 1990; Obermayer 1993; Hafellner 2000; Hafellner & Obermayer 2001), all of which should be sought in New Zealand populations, which commonly show signs of parasitism by lichenicolous fungi.