Diplotomma chlorophaeum
≡Lecidea chlorophaea Hepp ex Leight., Lich. Fl. Gr. Brit. ed. 3: 348 (1879).
Description : Thallus thick, white to ochraceous, regularly cracked or warted to thin and pale-grey, areolate or disappearing, ±determinate, without a marginal prothallus. Apothecia 0.2–0.6 mm diam., disc plane to convex, epruinose. Thalline exciple spurious, disappearing, proper exciple indistinct. Epithecium brown. Hymenium (80–)105–115 μm high. Hypothecium brown. Asci 40–80 × 13–20 μm. Ascospores 3-septate to submuriform, 14.5–27.5 × 7–12.5 μm.
Chemistry : Medulla K+ yellow→red, C−, KC+ red, Pd+ orange; containing norstictic acid.
S: Otago (Horse Ra.). First collected from this site by J.S. Thomson in 1934. Known also from Great Britain, Europe, Scandinavia, and North America (Purvis et al. 1992; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; Scholz 2000; Nimis & Martellos 2003; Santesson et al. 2004). Occurring throughout its range on slightly base-rich, often maritime rocks, on small pebbles or on brick and sandy mortar.
Cosmopolitan
Diplotomma chlorophaeum is characterised by: the saxicolous habit; the absence of laminal soredia; and the K+ yellow→red reaction (norstictic acid).
