Flora of New Zealand Series

Lectotype: New Zealand. Near Wellington, 1874, J. Buchanan 46/74 – BM [fide Galloway (1985a: 472)]. Isolectotype – WELT.

Description : Flora (1985: 471).

Chemistry : TLC−, all reactions negative.

N: Wellington (Wellington) S: Nelson (Denniston Plateau), Westland (Ngatau Valley), Canterbury (Nina Valley, Arthur's Pass, Cass), Otago (Forgotten River, Lake Wilkie Catlins), Southland (Stuart Mts, Caswell Sound). St: (Sylvan Cove Port Pegasus). A: (Carnley Harbour, Enderby I.). Throughout, mainly W of the Main Divide in South I., in Nothofagus forest on bark and wood and among mosses on tree trunks and on twigs in damp, semi-shaded habitats. Known also from Argentina (Keuck 1977) and SE Australia (McCarthy 2003c, 2006).

Austral

Illustrations : Keuck (1977: 115, fig. 17; pl. 183.).

Psoroma contextum is characterised by: the corticolous habit: the squamulose thallus developing on a rather thin, black, scattered to somewhat eroded prothallus; thalline squamules 1–3 m diam., flattened, lobate-crenate, surface waxy, smooth, pressed together and separated by fine black lines like a jigsaw puzzle, rarely imbricate at margins, becoming minutely lobulate and subimbricate centrally, margins not "frosted"; rather rare, simple, globose to glomerulate cephalodia developed below squamules and projecting from margins of squamules; apothecia projecting above squamules, 1–2 mm diam., margins waxy, crenate-striate, the disc red-brown often darkening centrally, and rarely with a few scattered thalline lobules; and ellipsoidal ascospores, 18–24 × 12–17 μm. This taxon is closely similar to P. pholidotoides (q.v.) and may in fact prove to be conspecific with it. More work is needed on this and other taxa in the P. implexum group.