Flora of New Zealand Series

≡Omphalodiscus subaprinus var. durietzii (Frey) Llano, Monogr. Lich. Fam. Umbilicariaceae: 102 (1950).

Holotype: New Zealand. Otago, Mt Pisgah summit rocks 1615 m, 30.i.1935, J.S.Thomson T1898 – G. Isotypes – CHR 160026, 160028, OTA 029676.

Description : Thallus orbicular, monophyllous, 1–3(–5) cm diam., margins entire, to irregular crenulate, incised, torn or notched, occasionally with projecting rhizinomorphs. Upper surface undulate, smooth to shallowly dimpled towards margins, occasionally with small holes or tears, folded or with radiating wrinkles over umbilicus, reddish-brown when wet, pale- to dark-grey, grey-brown or blackened when dry, whitish or paler over umbilicus, minutely roughened, velvety at or near margins, coarsely granular-crystalline centrally, scabrid-areolate in parts (×10 lens), and with marked wrinkles or cracks between apothecia. Lower surface smooth, sooty black to dark-grey, minutely to coarsely scabrid-areolate. Umbilicus 2–5 mm diam. Rhizinomorphs occasional to frequent, often in dense patches, pale-grey to black, 1–3 mm long, 0.1 mm diam., cylindrical, rarely flattened, simple to squarrosely branched, with minute, lateral, knob-like black thalloconidia. Apothecia sessile to subimmersed, solitary and widely scattered to closely compressed or deformed in small groups or lines, rounded, occasionally somewhat irregular to distorted through mutual pressure, (0.1–)0.5–1.5(–2) mm diam., larger apothecia from a collar of thalline tissue, commonly surrounded by radiating cracks or puckers; disc very shallowly concave to flat, matt, roughened to smooth, epruinose, coal-black, rarely minutely papillate or with a small, central sterile plug, very occasionally also irregularly fissured, without gyrae; margins thin, slightly raised above surface of disc, glossy black, entire to shallowly scalloped (not irregularly crenate as in U. subaprina). Epithecium dense brown-black, 8–15 μm thick. Hymenium pale yellow-brown to colourless, 70–90 μm tall. Paraphyses slender, 1–2 μm thick, apices yellow-brown, swollen to 5 μm diam. Hypothecium 100–300 μm thick, opaque, dense brown-black. Asci broadly clavate, 50–55 × 25–30 μm. Ascospores colourless, broadly ellipsoidal (8.5–)10–13.5(–15) × 6–8.5(–9) μm. Pycnidia frequent, scattered, black, punctiform, 0.1–0.2 mm diam. Conidia bacillar, 3–4 × 1 μm.

Chemistry : Not tested.

S: Westland (Mt Haast), Canterbury (Two Thumbs Ra., Kea Point Mt Cook, Hopkins Valley, Mt St Mary, Grampian Mtns, Kirkliston Ra.), Otago (Lake Ohau, Mt Brewster Haast Pass, Treble Cone, Whitbourn Valley, Rockburn Valley, Kea Basin Mt Earnslaw, The Remarkables, N Dunstan Mts, Kurow, St Marys Ra., Mt Pisgah, Kakanui Mts, Rock & Pillar Ra., Gem Lake Umbrella Mts). On exposed alpine to high-alpine rocks and moraine boulders, 915–2955 m.

Endemic

Illustration : Frey (1949: 463, fig. 16).

Umbilicaria durietzii is characterised by: the saxicolous habit; the orbicular, monophyllous thallus; the black to dark-grey, scabrid-areolate lower surface; cylindrical to flattened rhizinomorphs in patches on the lower surface and occasionally projecting at margins; subimmersed apothecia, surrounded by radiating cracks or puckers and with blacks discs (0.5–2 mm diam.) that are papillate or irregularly fissured but not gyrose; broadly ellipsoidal ascospores, (8.5–)10–13.5(–15) × 6–9 μm.