Flora of New Zealand Series

≡Lecanora rhodophthalma Müll.Arg., Flora 62: 164 (1879).

Holotype: New Zealand. Westland, sine loco, 1879, ex Herb. F. v. Mueller – G.

Description : Thallus 0.5–3(–6) cm diam., closely attached to substratum, orbicular to irregularly spreading, developing initially from minute, flattened squamules, tartareous, 0.15–0.25 mm thick; margins continuous to delicately scalloped or notched, and separated by narrow cracks, to occasionally minutely lobulate, swollen to flattened, to slightly inrolled, without a projecting prothallus. Upper surface pale-green to lettuce-green or slightly olivaceous to grey-green when wet, pale-greyish to whitish, grey-white or greenish white when dry, without any traces of pink, smooth to irregularly and minutely lumpy or hummocky (×10 lens), or of crowded, overlapping or overgrowing minute, swollen squamules, here and there separated by minute, irregular cracks, to ±areolate centrally with angular areolae separated by very narrow to gaping cracks (cracks open when thallus dries and shrinks; in the moist state thalli have a ±continuous surface); with small spots or patches of glistening, white pruina, 0.05–0.3 mm diam., scattered to coalescing, developed on thalline hummocks or more generally in a zone towards the thallus margins, best seen in dry thalli; isidia, soredia and pseudocyphellae absent. Cephalodia widely scattered, often best developed and largest centrally, round to irregular, (1)2–5(–9) mm diam., sessile and ±flush with thallus surface at first, becoming shallowly convex and projecting slightly above thallus, flattened, continuous, to minutely wrinkled to plicate-radiate, the delicate narrow folds and ridges separated by shallow to occasionally widely gaping cracks, purplish to dark blue-black when moist, pale brownish pink when dry, without any surface pruina; older cephalodia at centre often recolonised by spreading, flattened thalline squamules. Apothecia developed towards centre of thallus, widely scattered to crowded, solitary to 2–5-together, subimmersed at first to sessile and constricted at base, (0.5–)1–2(–3) mm diam., often noticeably raised above surface of thallus, round to irregular-contorted through mutual pressure, young apothecia at first hemispherical, pale-whitish, with a minute apical pore, later as the disc expands thalline margin persisting as a narrow, to thick, continuous to minutely crenulate collar at base of disc, concolorous with thallus, sometimes with spots of white pruina; proper margin entire, prominent, raised, 0.1–0.15 mm thick, concolorous with disc or paler; disc vivid candy-pink or reddish pink, convex, appearing immarginate and translucent when moist, becoming opaque and commonly obscured by a thick, white pruina when dry, shrinking when dry and becoming deeply urceolate to plane, sometimes obscured by a plug of white-pruinose tissue, continuous, or becoming deeply cracked. Epithecium pale olive-brown, 35–50 μm thick. Hymenium colourless to very pale pinkish, 200–250 um tall. Paraphyses slender, 1.5 μm thick, apices slightly swollen, submoniliform, occasionally branched, to 3–4 μm diam. Hypothecium colourless, densely opaque, to 250 μm thick. Asci cylindrical, with a short, narrow foot, 112–145(–150) × 16.5–20 μm. Ascospores uniseriate in ascus, filling entire ascus except for the narrow foot, colourless to pale-pinkish, broadly ellipsoidal, contents granular (20–)22–26(–28.5) × 10–13 μm. Pycnidia red-brown to brown-black, widely scattered to crowded in a submarginal zone, in minute, hemispherical swellings, 0.05–0.1 mm diam., apical ostiole punctiform-depressed. Conidia filiform, curved, 15–18 × 0.5 μm.

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

N: Wellington (Haurangi Forest Park). S: Nelson (Mt Arthur, Flora Saddle, Cape Foulwind, E of Springs Junction, W of Inangahua Junction) Westland (Yorkey Creek, Fox Glacier, Callery Gorge, Hercules Creek), Marlborough (Titirangi Bay Road, Ship Cove, Resolution Bay). Otago (Matukituki Valley, Howden Hut, Leith Valley Dunedin). On streamside rocks and rock outcrops in subalpine bogs on damp cuttings and roadside banks and alongside walking tracks in forest, in riverbed gravels and in consolidated glacial drift. Associating with the lichens: Gyalidea lecanorina, Lecidella schistiseda, Placopsis clavifera, P. elixii, P. hertelii, P. illita, P. perrugosa, P. polycarpa, P. pruinosa, P. salazina, Polyblastia cruenta, Stereocaulon colensoi, S. corticatulum

Endemic

Illustration : Lamb (1947: pl. XII, fig. 38).

Placopsis rhodophthalma is characterised by: rosette-forming thalli, pale grey-white or greenish white upper surface with scattered, glistening, white spots of pruina, often noticeable on marginal lobes; cephalodia, closely appressed, not projecting much above cortex, often separated by small cracks, delicately wrinkled, plicate-radiating, flattened; prominent apothecia with thick, smooth, swollen margins and sometimes fissured discs, when wet the disc is a vivid candy-pink, immediately noticeable among mosaics of other species, when dry the disc becomes pale, opaque and markedly white-pruinose; ascospores broadly ellipsoidal, contents granular, (20–)22–26(–28.5) × 10–13 μm.