Erioderma glaucescens
Peltidea glaucescens Taylor, Hook. Lond. J. Bot. 6: 183 (1847).
Thallus foliose, dorsiventral, 1-3(-7) cm diam., rosette-forming to irregularly spreading, lobes 0.5-1.5 cm diam., margins entire, often ascending and strongly inrolled, exposing white lower surface, naked and slightly thickened, to irregularly rhizinate. Upper surface dark slate-blue when wet, pale olive-greyish when dry, smooth or shallowly wrinkled, undulate, glabrous and ± shining in small patches, ± continuously tomentose, tomentum arachnoid to dense and thick and rather shaggy, whitish or grey-white or olivaceous, soredia absent. Lower surface white, never yellow or brownish, arachnoid, continuous, felted, hyphae in veins, very shallowly ridged or uneven or ± faintly bullate. Rhizines short, 0.1-0.8 mm long, black, in small, dense, squarrose tufts, scattered, marginal, rarely laminal, inconspicuous, often absent, rarely pale greyish or whitish, rarely as a thin marginal fringe. Medulla white. Photobiont in chains, cells ± globose, thick-walled 7-10 µm diam., Scytonema. Apothecia marginal, subpedicellate 0.5-2.0(-6.0) mm diam., plane at first becoming convex-glomerulate with age, marginate, margins entire slightly raised, persistent, concolorous with disc or paler, glabrous, exciple smooth to verrucose-scabrid, pale flesh-coloured or whitish, minutely white-pubescent to densely tomentose-hirsute, disc red-brown to dark brown or black, concave, plane or convex, smooth or furrowed-glomerulate or ± gyrose-contorted with small secondary apothecia developing centrally, glabrous or minutely white-pruinose, pruina delicate, pubescent. Hymenium colourless, 60-70 µm tall. Hypothecium pale orange-brown or red-brown 70-80 µm thick. Paraphyses straight, dense, simple 3-4 µm diam., apices multiseptate, rounded, projecting from surface of disc, tips free. Asci 8-spored, broadly to narrowly clavate, ascospores uniseriate or biseriate, rounded to oval (8.3-) 10.2-12(-14) × 6.8-8.3 µm, wall 1.5 µm thick, not warted, colourless. Chemistry: cf. Pannarin + two unidentified UV+ pale grey spots.
N: Throughout. S: Nelson, Westland, Canterbury (Boyle River). Found in similar habitats to E. sorediatum with which it is often sympatric. Mainly a twig species but will also colonise bark.
Pantropical
E. glaucescens (Keuck loc. cit., pp. 136-137) is related to the South American species E. chilense Mont., but has smaller spores and a white lower surface that is never sulphur-yellow or brownish. In earlier accounts of New Zealand lichens it was called E. velligerum Tuck., which is a synonym of E. chilense. The New Zealand material is not quite comparable to E. glaucescens sens. str. , and may yet be shown to be an independent species.
