Flora of New Zealand Series

≡Squamaria rhodocarpa Nyl. Annls Sci. nat. Bot. sér. 4, 15: 376 (1861).

≡Lecanora rhodocarpa (Nyl.) Nyl., Bot. J. Linn. Soc. 9: 251 (1866).

≡Placodium rhodocarpum (Nyl.) Müll.Arg., Bull. Herb. Boissier2, App. 1: 46 (1894).

≡Placopsis parellina var. rhodocarpa (Nyl.) I.M. Lamb, Res. Norweg. Sci. Exped Tristan da Cunha 1937–38, 3: 3 (1940

Description : Thallus closely attached, small, placodioid to irregularly spreading, 1–2.5(–6) cm diam., margins minutely lobulate or crenulate, irregularly lumpy or papillate centrally, often of congested to overlapping small, crenulate squamules, 0.5–1 mm diam., sometimes coalescing to form a continuous to areolate thallus. Prothallus absent. Upper surface pale- to dark-green when wet, pale grey-green or whitish or pale-olive when dry, smooth, matt, with here and there small, rounded, capitate greenish soralia, 0.2–1 mm diam., or sometimes confluent and eroding larger areas, soredia fresh lettuce-green when moist (contrasting with thallus), pale grey-green when dry, farinose, without isidia, maculae, pruina or pseudocyphellae. Cephalodia scattered, ±immersed in thalline squamules, dark bluish purple when wet, olive-brown to yellow-brown when dry, somewhat flattened, rosette-shaped, 0.5–1(–1.5) mm diam., smooth or slightly wrinkled, without surface cracks or pruina. Apothecia sessile, constricted at base, solitary or 2–4-together and then subirregular through mutual pressure, 1–2(–2.5) mm diam. Thalline margin thick, entire, smooth or glossy, obscuring disc at first, concolorous with thallus or paler. Proper margin persistent in mature fruits, minutely crenulate–irregular, slightly raised above and paler than disc. Disc subconcave to plane, matt, smooth, yellow-brown, pale or dark red-brown, with or without a fine whitish pruina. Epithecium yellow-brown, 20–22.5 μm thick. Hymenium colourless, 150–175 μm tall. Hypothecium densely interwoven, pale-yellowish, 150–170 μm thick. Ascospores uniseriate in ascus, broadly ellipsoidal, 22.5–25(–27.5) × 8–10(–12.5) μm. Pycnidia not seen.

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

N: Northland. S: Canterbury (Hanmer, Cass, Woolshed Hill), Otago (Haast Pass, Makarora, Routeburn Valley, Survey Flat Dart Valley, Black Gully, Blue Mts), Southland (Cascade Creek). On stones and pebbles, alongside streams and tracks in damp, shady, forest environments. Known also from Bolivia and Chile (Lamb 1947; Galloway 2002d).

Austral

Illustration : Lamb (1947: pl. VIII, fig. 27 – holotype of Squamaria rhodocarpa (H) as Placopsis parellina).

Placopsis rhodocarpa is characterised by: a pale to dark-greenish to whitish, rather thin, placodioid thallus; small, scattered, pustulate capitate, greenish soralia with lettuce-green, farinose soredia; flat pink (purple-blue when moist), delicately wrinked–folded cephalodia without cracks or pruina; sessile, thick-margined Ochrolechia -like apothecia with matt, smooth, yellow-brown, pale or dark red-brown discs, with or without a fine whitish pruina.; and ascospores 22–27 × 8–10 μm.