Flora of New Zealand Series

≡Lichen athroocarpus Ach. [" L. athrocarpus "], Lichenogr. suec. prodr.: 77 (1799) ["1798"].

Description : Thallus small to very large (1–10 cm diam.), irregularly spreading, thin to moderately thick, distinctly and regularly areolate, yellow-brown to dark grey-brown, olive-brown to ±blackened, ±glossy. Areolae angular, subconcave, plane to subconvex, separated by deep cracks. Medulla I+ dark violet–blue. Prothallus black to grey-black, visible between areolae and at margins. Apothecia rounded to angular, ±immersed, aspicilioid, scattered to crowded, to 1.8 mm diam., but frequently smaller; disc dark-grey to black, matt, sometimes weakly pruinose, plane to concave; margins thin, persistent, raised or flat. Hypothecium colourless to pale brownish or brown, to 200 μm thick. Hymenium 70–125 μm tall, colourless, I+ yellow to bluish; epithecium 10–20 μm thick, brown-black to greenish brown. Ascospores 13–24 × 6–9.5(–12) μm.

Chemistry : Cortex K−, C−, Pd−; medulla K−, C−, Pd−; containing confluentic and 2'- O- methylperlatolic acids [The chemistry is variable – see Rambold (1989: 241) for discussion of three known chemodemes].

N: Wellington (Tongariro National Park). S: Canterbury (Torlesse Ra., Mt Peel, Kirkliston Ra.). Otago (Old Man Ra., Lake Onslow, Rock & Pillar Ra., Flagstaff, near Dunedin). On siliceous, often iron-containing and weathered basaltic, schistose and greywacke rocks, alpine to high-alpine, 650 –1700 m in exposed habitats. Known also from Great Britain, Europe, Scandinavia, Asia, North America, South Africa, Australia and Antarctica (Hertel 1977a, 1991; Rambold 1989; Santesson 1993; Nimis 1993; Esslinger & Egan 1995; Øvstedal & Lewis Smith 2001; Coppins 2002b; McCarthy 2003c, 2006; Nimis & Martellos 2003; Kainz 2004a; Obermayer 2004; Santesson et al. 2004).

Bipolar

Exsiccati : Hertel (1985a: No. 156 – as Porpidia athroocarpa).

Illustrations : Wirth (1995a: 771; 772); Lumbsch et al. (2001a: 32).

Immersaria athroocarpa is characterised by: the saxicolous habit; the constantly immersed, black apothecia; and glossy brown areolae with a ±concave surface and a rather thick epinecral layer (Rambold 1989: 241). In the field it is rather similar to small forms of Lecidea fuscoatrula, but is distinguished from this taxon, and from L. atromorio, by differences in chemistry, colour of the hypothecium, and iodine reactions of the asci.