Flora of New Zealand Series

≡Dimerella fuscescens Vězda & Malcolm, Australas. Lichenol. 41: 35 (1997).

Holotype: New Zealand. South Island. Nelson, York Valley, 41º18.2's, 173º16.5'E, 200 m, on leaves of Alectryon excelsus in disturbed lowland rainforest, 11.xi.1993, W. Malcolm 1275 – CHR 489338. Isotypes – Herb. W. Malcolm; Herb. A. Vězda.

Description : Thallus crustose, foliicolous (epiphyllous to hypophyllous), continuous, forming blotches on leaves to 1 cm diam., pale brownish yellow to brown, smooth, glossy, 10–12 μm thick, without a marginal prothallus. Apothecia abundant, rounded, 0.2–0.28 mm diam., 0.1 mm tall, broadly attached but somewhat constricted at base, plane, disc pale-brown to brick-red, the margins slightly to strongly raised. Exciple 25–30 μm thick, plectenchymatous, hyaline, thinly covered towards margins with photobiont-containing tissue. Hymenium 60–70 μm tall, hyaline. Paraphyses 1.5 μm diam., terminal cell clavate to subglobose, 3–4 μm diam. Asci thin-walled, cylindrical. Ascospores uniseriate, fusiform-ellipsoidal, 7–9 × 1.8–2 μm.

S: Nelson (York Valley, Cable Bay). On leaves of Alectryon excelsus and Beilschmiedia tawa in disturbed lowland rainforest. Still very poorly collected.

Endemic

Illustrations : Vězda & Malcolm (1997: 38, figs 4–5 – as Dimerella fuscescens).

Coenogonium fuscescens is characterised by: the foliicolous habit (epiphyllous and hypophyllous); the brownish, blotchy thallus without a marginal prothallus; the brownish apothecia; the plectenchymatous exciple with a thin, thalline covering.