Megalaria obludens (Nyl.) Fryday & Lendemer
Lichenologist 42: 599. (2010)

Basionym: Lecidea obludens Nyl., Lich. Fueg. Patag.: 12 (1888).ŚCatillaria obludens (Nyl.) Zahlbr., Catalogus Lichenum Universalis 4: 21 (1926).
Synonym: Megalaria imshaugii Fryday, Bibliotheca Lichenologica 88: 136. 2004.

Thallus effuse, variable, typically pale to lead-grey, 0.25-0.4 mm thick, cracked-areolate; areoles 0.7-1.0 mm across, ▒flat. Photobiont chlorococcoid, cells globose, 10-15 Ám diam.
Apothecia black, lecideine, orbicular, sessile, flat when young but soon becoming convex, 0.7-1.2 mm diam., margin persistent, even in strongly convex apothecia, 0.06-0.08 mm wide. Excipulum of radiating hyphae with enlarged cells (8.5-15 Ám diam.), with dark blue pigment on outer walls of the hyphae, continuous under hypothecium. Hypothecium 35 Ám thick, dark blue (K+ blue, N+ red), composed of randomly arranged hyphae. Hymenium hyaline, 100-120 Ám; epihymenial zone dark blue-green (K+ blue, N+ red), 30-35 Ám thick; subhymenium ▒hyaline, 45-50 Ám. Paraphyses simple, readily separating, 2.0-2.5 Ám thick, apices swollen to 5.0 Ám with dark blue pigmented cap. Asci cylindrical, 80-85 x 15-17 Ám, Bacidia-type. Ascospores hyaline, 1-septate, 12-16(-18) x 6-7(-8) Ám.
Conidiomata not observed.

Chemistry: no substances detected by TLC.

Distribution: Common on siliceous rocks on Campbell Island and also occurs on the Auckland Islands and South America (Isla Bucket and the Falkland Islands).

Notes: Species associated with Megalaria obludens on Campbell Island include Fuscidea subasbolodes, Pannaria dichroa, Pertusaria sp., Placopsis sp., and Rimularia psephota.

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Thallus and apothecia