Lecanora subimmergens
Description : Thallus crustose, uniform, closely attached, thin, smooth, continuous to areolate, yellow-grey to greenish or greenish grey, without pruina, often slightly glossy. Apothecia immersed at first, becoming sessile, 0.3–1.2 mm diam., disc pale to dark red-brown, sometimes also reddish orange, epruinose. Thalline margin concolorous with thallus, thickened, smooth, ±verrucose to crenulate. Amphithecium with large crystals, not dissolving in K (pulicaris -type). Epithecium 10–15 μm tall, orange-brown, the pigment not dissolving in K, without crystals (glabrata -type). Hymenium colourless 70–85 μm tall. Asci club-shaped, 65–75 × 10–16 μm. Ascospores ellipsoidal, 10.5–14.4 × 5.5–7.5 μm.
Chemistry : Thallus and apothecial margins K+ yellow, C−, KC−, Pd+ yellow-orange; containing atranorin and zeorin (major), chloroatranorin, four unidentified fatty acids and unidentified triperpenoid (minor).
N: Northland (Great Barrier I.). On coastal rock. Known also from Japan, North, Central and South America and Australia (Brodo 1984a; Miyawaki 1988; Lumbsch 1994; Guderley 1999, 2000; McCarthy 2003c, 2006; Lumbsch & Elix 2004; Ryan et al. 2004b: 270–271).
Cosmopolitan
Illustrations : Brodo (1984a: 72, fig. 1; 73, fig. 8); Lumbsch (1994: 138, fig. 69C–F); Guderley (1999: 144, fig. 2F; 148, fig. 4A, B; 233, fig. 24A, B).
Lecanora subimmergens is characterised by: the saxicolous habit; a continuous greenish thallus; small, crowded, red-brown, argentata -type apothecia; and atranorin and zeorin as major medullary compounds. Two subspecies are recognised, ssp. subimmersa with a wide distribution, and ssp. ramboldii Lumbsch & Elix, from eastern Australia, Papua New Guinea, Martinique and Brasil (Lumbsch et al. 1994a; Guderley 1999: 236–237; Lumbsch & Elix 2004: 56–57). Recently, Guderley (2000) proposed the conservation of L. subimmergens over the earlier name L. argillaceofusca Müll.Arg.
