Flora of New Zealand Series

Holotype: New Zealand. Nelson, Brook Stream track, on siliceous rocks in shaded lowland mixed Nothofagus– podocarp forest, 160 m, 12.v.1993, W. Malcolm 800 – CHR 470258l. Isotypes – BM, CANB, DUKE, ESS, GZU, H, HO, M, PRM, TSB, UPS, VBI, Herb. K. Kalb, Herb. A. Vězda.

Description : Thallus crustose, minutely farinose to warty, matt or glossy, with or without a marginal whitish to dark-green prothallus. Apothecia rounded, 0.5–0.8 mm diam., 0.2–0.5 mm tall, sessile, strongly constricted at base; disc plane to convex, black, matt, epruinose, with a narrow, white, byssoid margin disappearing with age. Hymenium 60–70 μm tall, colourless, often with numerous scattered, inspersed granules; epithecium brown. Hypothecium dark-purple. Asci clavate, 8-spored. Ascospores ellipsoidal, one apex more obtuse than the other, transversely (3–) 5-septate, halonate, 15–18 × 4.5 μm.

S: Nelson. On siliceous rocks and tanalised, worked timber in lowland, humid, forest habitats. It also colonises aluminium name tags (see Malcolm & Malcolm 2001: 20).

Endemic

Illustrations : Malcolm & Vězda (1995a: 359, fig. 1); Malcolm & Galloway (1997: 153, 170, 177); Malcolm & Malcolm (2000: 32, 111; 2001: 20).

Exsiccati : Vězda (1995d: No. 201).

Byssoloma adspersum is characterised by: the saxicolous/lignicolous habit; the minutely farinose to warty thallus; plane to convex, black, matt apothecia with a narrow, white byssoid margin (disappearing with age); and (3–)5-septate, halonate ascospores, 15–18 × 4.5 μm.