Flora of New Zealand Series

≡Verrucaria swartzii Ach., K. Vetensk.-Akad. Nya Handl.: 185 (1794).

Description : Thallus in spreading rosettes, 0.5–2.5(–3) cm diam., continuous to somewhat effuse at margins, cracked–areolate centrally, often becoming clumped–caespitose to subfruticose, uneven or wrinkled, white, grey-white to grey-brown, surface smooth to roughened, strongly C+ yellow-orange (containing sordidone). Prothallus white, byssoid, C+ yellow-orange. Apothecia clustered centrally, (0.1–)0.5–1(–1.5) mm diam., immersed at first becoming sessile and soon distinctively convex, strongly constricted at base, or often at the tips of subfruticose stalks, rounded to angular, separated by deep cracks, or conglomerate, the apothecia rather easily detached from thallus, thalline margin narrow, very slightly raised, entire, flexuous, at length becoming excluded, concolorous with thallus or darker; disc convex, often strongly so, yellow-brown to brown-black, shining, densely grey-pruinose appearing bluish (C+ yellow). Epithecium colourless to olive-greenish, inspersed with granules. Hymenium 60–85 μm tall; paraphyses simple, 2–2.5 μm wide, apices slightly thickened. Ascospores ellipsoidal, (9–)10–12(–14) × 5–6(–7) μm.

Chemistry : Thallus: C+ yellow or orange, KC+orange; apothecial margins C+ yellow or orange, KC+ orange, PD−; apothecial discs C+ yellow or orange, KC+ orange; containing sordidone, thiophanic acid, roccellic acid and atranorin (Leuckert & Poelt 1989). Lumbsch & Elix (2004: 58) give the chemistry as atranorin (major), roccellic acid (major), sordidone (major), chloroatranorin (minor) and eugenitol (minor).

S: Otago (Old Man Ra., Manorburn, Poolburn Reservoir, Teviot River near Lake Onslow, Rock & Pillar Ra.). Beneath overhanging surfaces and on roofs and steeply sloping sides of underhangs and dry caves of high-alpine rocks especially of schist tors, often occurring with Caloplaca lutea, Lecanora cavicola, L. polytropa, L. rupicola pale greenish forms of Protoparmelia badia, Ramalina fimbriata, Rhizocarpon geographicum and R. grande (Galloway 2002b). Known also from upland Britain (Hawksworth & Dalby 1992) high mountains of Europe including Sardinia (Nimis & Poelt 1987; Leuckert & Poelt 1989; Wirth 1987, 1995b; Nimis 1993; Nimis & Martellos 2003), Scandinavia (Creveld 1981; Foucard 1990, 2001; Santesson 1993; Santesson et al. 2004), North America (Nash et al. 1998; McCune 1998; Ryan et al. 2004b: 274) and from alpine habitats in SE Australia and Tasmania (Lumbsch & Elix 2004). Still very poorly known and collected in New Zealand.

Bipolar

Illustrations : Wirth (1987: 247; 1995a: 487); Leuckert & Poelt (1989: 127, pl. 2; 136, fig. 2); Poelt (1989: 68, fig. 1; 69, fig. 2; 70, fig. 3); Hansen (1995: 97 – as Lecanora subradiosa); Flora of Australia56A (2004: xv, pl. 18).

Lecanora swartzii is characterised by: the saxicolous habit (underhangs and roofs of small caverns); rosette-forming to spreading whitish thalli that are immediately and strongly C+ yellow-orange; the distinctly convex apothecia that are grey-pruinose. It is distinguished from L. rupicola by the C+ yellow-orange reaction (sordidone) of the thallus (L. rupicola has sordidone only in the apothecial discs). This lichen is characteristic of dry, shaded caves or underhangs and is not found in exposed, sunny situations where L. rupicola mainly occurs. The development of small, fruticose forms of L. swartzii from the predominantly crustose form is discussed in detail in Poelt (1989) and commented on by Lumbsch & Feige (1994).