FAGACEAE. Nothofagus fusca: Otago, Routeburn Valley, 450 m.

Hymenophore subpileate when umbonate-sessile, or resupinate, probably perennial, woody coriaceous, loosely attached, forming irregularly orbicular colonies 2-10 mm diameter, or merging to form linear areas 2-3 x 1-2.5 cm; pilei reduced to thickened upper edges of specimens growing vertically, naked, black, longitudinally striate, 1-1.5 mm thick; hymenial surface pallid ferruginous, or cinnamon, not creviced, even; margin usually abrupt, sometimes thinning out, crenate, concolorous, free. Context ferruginous, black next the substratum, 0.3-1 mm thick, of mainly erect hyphae embedding scattered setae and numerous large crystals; skeletal hyphae 3-4 µm diameter, walls to 1 µm thick, golden brown; generative hyphae 2.5-3 µm diameter, walls 0.2 µm thick, hyaline. Setal layer occupying the entire fructification, of numerous overlapping rows of setae sometimes arranged in irregular strata; setae subulate, some projecting to 60 µm, 65-95 x 9-12 µm, walls naked or encrusted, ferruginous, lumena narrow. Hymenial layer to 35 p deep, a close palisade of basidia and paraphyses. Basidia subclavate, 14-22 x 3.5-4 µm, bearing 2-4 spores; sterigmata slightly arcuate, slender, to 6 µm long. Paraphyses cylindrical, 8-15 x 2.5-3 µm. Spores suballantoid, 5-6.5 x 2-2.5 µm, walls smooth, hyaline, 0.1 µm thick.

DISTRIBUTION: North America, West Indies, New Zealand.

HABITAT: Living trunks associated with a pocket rot.

The collection listed agrees with authentic specimens examined in Kew herbarium as to macrofeatures and size, the shape and distribution of setae, and size and shape of spores. It differs in that specimens were collected on dead wood of an axe blaze on a living trunk, whereas North American plants grow upon bark of living trunks.
The species is difficult to place within a key; for fructifications, although often resupinate, are not uncommonly umbonate-sessile with the upper margin (of those growing on upright trunks) thickened into a black glabrous pileus. The context is composed of erect hyphae embedding setae arranged in overlapping rows, sometimes in strata; and, as setae are present throughout the fructification a context, present in most pileate species, is wanting. The plant therefore belongs to Section III, and has been treated as a stratose species with rudimentary pilei. Scattered through the context are numerous coarse crystals, or cavities in which they once were present. Projecting setae are usually encrusted with crystals, and sometimes enmeshed in hyphal sheaths.

TYPE LOCALITY: South Carolina, U.S.A.

Type: Lignicolous Fungi; Description: Basidiomata perennial, subpileate or resupinate, leathery-woody, loosely attached to the substrate and forming irregularly circular colonies 2–10 mm in diameter or merging to form linear areas 20–30 × 10–25 mm. Pilei reduced to thickened (1–1.5 mm) upper edges of basidioma growing vertically. Pileus surface glabrous, concentrically striate, black. Pore surface even, reddish brown to cinnamon brown, margin crenate, concolorous. Context reddish brown, black adjacent to the substratum, 0.3–1 mm thick. Setae in numerous overlapping rows, subulate, naked or encrusted, reddish brown, 65–95 × 9–12 μm. Basidiospores suballantoid, 5–7 × 2–3 μm, smooth, hyaline.

Distribution: Otago Lakes.; 1st Record: Cunningham (1957: as Hymenochaete corticolor).

Significance: The cause of pocket rot in a damaged living trunk of Nothofagus fusca (Cunningham 1957).; Host(s): Nothofagus fusca.