Flora of New Zealand Series

≡Placopsis parellina var. carnea f. subcribellans I.M.Lamb, Lilloa 13: 254 (1947).

Description : Thallus closely attached, mainly orbicular, (1–)2–5(–8) cm diam., forming solitary, neat rosettes or coalescing to form larger patches; margins continuous, scalloped, flat, not swollen, former of contiguous to overlapping, flabellate lobes, 1–3 mm diam., separated by narrow (rarely gaping) cracks, radiating from margins to near centre, sometimes areolate in a neat mosaic at centre. Prothallus absent. Upper surface pale olive-greenish when wet, whitish or creamish when dry, suffused brownish at margins, smooth, glossy (resembling polished ivory), continuous to incised with radiating, narrow cracks, flat to subconvex, isidiate, without maculae, pruina, pseudocyphellae or soredia. Isidia subglobose to flattened, 0.05–0.2 mm diam., developing along cracks in thallus, often widely scattered and rather sparse, eroding and leaving small pits, commonly seen scattered on rock adjacent to parent thallus. Cephalodia mainly central, sometimes in concentric circles or arcs, shallowly hemispherical, orbicular, 1–8(–10) mm diam., plicate-furrowed to radially cracked, dark purple-blue when wet pale brown-pink to red-brown when dry, matt, epruinose, sometimes secondarily colonised by isidia and small thalli. Apothecia sparse, often absent, sessile, constricted at base, solitary or in small groups (2–4), rounded to subangular through mutual pressure, 0.5–1(–1.5) mm diam. Thalline margin prominent, swollen at first and obscuring disc, entire, smooth, glossy, concolorous with thallus. Proper margin visible in mature fruits as a thin, entire to subcrenulate, pale yellow-brown, slightly elevated rim to disc. Disc concave to plane, pale-pinkish, red-brown to rusty brown, smooth at first, becoming roughened-papillate to cracked, with or without a fine, white pruina. Epithecium red-brown, granular, 25–40 μm thick. Hymenium colourless to pale yellow-brown, 190–210(–240) μm tall. Hypothecium opaque, pale-brownish, 150–200 μm thick. Ascospores uniseriate in ascus, oval–ellipsoidal, 15–21(–24) × (8.5–) 9–12 μm. Pycnidia not common, immersed in thalline verrucae towards thallus margins, ostiole depressed-punctiform, concolorous with thallus. Conidia thread-like, curved, 21–24 × 1 μm.

Chemistry : Thallus K−, C+ red, KC−, Pd−; containing gyrophoric acid.

S: Otago (Routeburn Track, between The Divide and Lake Howden; Purakanui Falls Catlins), Southland (Pahia Point, Dusky Sound, Resolution I., Goose Cove). A: (Beacon Point). C: (summit ridge of Beeman Hill). On coastal rocks to subalpine rocks in tussock grassland. Known also from heavily glaciated, high-rainfall areas of western Patagonia (Galloway 2002d: 101).

Austral

Placopsis subcribellans is distinguished from P. cribellans by its broader, thicker, less-divided lobes, the glossy upper surface resembling polished ivory, the much more sparse isidia which are commonly along narrow cracks or folds in the thallus, the higher hymenium, and the larger ascospores.