Megalospora disjuncta
Description : Thallus yellowish grey of roundish or irregular granules (0.3–0.5 mm diam.) on a thin or evanescent continuous layer, granules often inflated and bursting apically producing soredia (20–50 μm diam.). Apothecia 1–3 mm diam., disc plane, brown, glossy epruinose; margins very prominent, pale-brown, epruinose, matt. Epithecium diffuse orange-brown, to 20 μm thick. Hymenium to 160 μm tall, I−, ascus tips weakly I+ purple. Exciple pale or yellowish, with aggregates of fine crystals (c. 1 μm diam.) in upper part of ectal exciple, K+ yellow. Ascospores 1 per ascus, 1-septate, straight, atrorubicans -type, 100–145 × 30–45 μm, epispore smooth.
Chemistry : K−, C−, KC+ yellow, Pd−; containing usnic acid and zeorin.
N: South Auckland (Te Aroha). S: Nelson (Kaihoka). On old exposed rotting tree stumps at Te Aroha at 100 m, and on exposed, damp maritime rocks within the spray zone at Kaihoka; both specimens collected by the late John Bartlett in 1982 (Sipman 1986b: 560). Still very poorly collected in New Zealand. Known also in Australia from Nothofagus moorei -dominated rainforests in Queensland and northern New South Wales where it grows in understorey shrubs such as Trochocarpa and Vesselowskya (Kantvilas 1994d: 359; McCarthy 2003c, 2006).
Australasian
Megalospora disjuncta is characterised by: the lignicolous/saxicolous habit; the coarsely granular, yellowish thallus; apothecia with red-brown, epruinose discs; large, solitary, 1-septate ascospores of atrorubicans -type (100–145 × 30–45 μm) ; and usnic acid and zeorin as major chemical compounds.
