Placopsis stenophylla
≡Lecanora stenophylla Hue, Ann. Mycol. 12: 523 (1914).
Description : Thallus closely attached, orbicular to spreading, generally in neat rosettes, solitary to coalescing, 2–5(–8) cm diam., margins ±continuous, without a prothallus. Lobes contiguous to overlapping, flabellate, 1–3 mm wide, separated by narrow to sometimes gaping cracks developing from margins to centre, apices entire to subcrenulate, centrally areolate, areolae angular, 0.1–1(–1.5) mm diam., shallowly convex to plane, separated by narrow cracks. Upper surface pale-olivaceous or greenish white when wet, grey-white or pale-pinkish to brownish or in places rusty orange when dry, sometimes noticeably suffused brownish or olive at margins, smooth, matt, flat to shallowly convex between cracks, rarely ±glebose-warted, occasionally pseudocyphellate, without isidia, maculae, pruina or soredia. Pseudocyphellae, widely scattered to absent, white, minute, punctiform to minutely urceolate (×10 lens). Cephalodia orbicular, hemispherical, 1–3(–5) mm diam., plicate-folded becoming radially cracked, developed centrally in young thalli, in ±concentric arcs in larger thalli, dark purplish blue when wet, rust-brown or orange when dry. Apothecia scattered to crowded, central or in ±concentric arcs between centre and margins, sessile, constricted at base, rounded to subangular through mutual pressure, 0.5–1.5 (–2) mm diam. Thalline margin prominent, thick, smooth, entire, concolorous with thallus. Proper margin pale yellow-pink, roughened-verrucose, raised above disc and thalline margin as a narrow, elevated rim. Disc shallowly concave to plane, matt, smooth, dull brown-pink or pale to dark red-brown, with or without a fine, white pruina. Epithecium pale yellow-brown, 25–30 μm thick. Hymenium colourless, (120–)150–220(–270) μm tall. Hypothecium opaque, pale pinkish brown, 150–220 μm thick. Ascospores uniseriate in ascus, colourless, oval–ellipsoidal, (14–) 16–22(–24) × (7.5–)9–12(–13.5) μm. Pycnidia common, dispersed evenly over thallus from apices to centre, immersed in thalline verrucae, ostiole depressed-punctiform, concolorous with thallus or brownish, exuding a reddish gel when moist. Conidia thread-like, curved to straight, 20–24 × 1 μm.
Chemistry : Thallus K−, C+ red, KC−, Pd−; containing gyrophoric (major) and lecanoric (minor) acids (Hertel & Leuckert 1969).
S: Canterbury (Hooker Valley, Avoca Station Lake Ohau). On rocks in grassland. Known also from Chile [Chiloé to Tierra del Fuego] (Lamb 1947; Galloway 2002d).
Austral
Illustrations : Lamb (1947: pl. III, fig. 8 – as Placopsis patagonica; pl. V, figs 16, 17; pl. IX, fig. 30 – as Placopsis parellina var. carnea; pl. XII, fig. 37 – as Placopsis terricola); Hertel (1969a: 119, fig. 3A – as "Placopsis gelida var. carnea Räs".
Placopsis stenophylla is characterised by: closely attached, rather thin, spathulate lobe ends separated by deep cracks running from central parts to periphery, central parts areolate, with scattered, white, punctiform to urceolate pseudocyphellae (×10 lens), but without isidia, pruina or soredia; cephalodia that are hemispherical, orbicular, delicately plicate-folded, commonly separated by narrow to wide, radiating cracks; prominent, sessile apothecia, with a thick, entire, thalline margin and a brownish to red-brown, epruinose disc; ascospores are oval–ellipsoidal, (14–)16–22(–24) × (7.5–)9–12(–13.5) μm.
