Flora of New Zealand Series

≡Thelotrema megalophthalmum Müll.Arg., Flora 65: 500 (1882).

Description : Thallus olivaceous-greyish to dull greenish brown, ±continuous or with small cracks, or wrinkles, spreading in indeterminate patches on rock 1–5(–10) cm diam. Apothecia erumpent, 2–3 mm diam., margins, ragged, torn, obscuring disc when young, concolorous with thallus above, pale whitish below; disc ±plane, matt, smooth or subpapillate, dark-brown or yellow-brown, epruinose. Epithecium of fused tips of paraphyses, bluish or purple in Lugol's I. Ascospores large, fabiform, submuriform, 30–45(–60) × 8–13(–18) μm, with 9–13(–16) transverse septa, mostly extending continuously across the width of the spore, and 0–4 longitudinal septa.

Chemistry : Medulla K+ yellow-red, C−, KC+ red, Pd+ yellow; containing stictic (major), and constictic (tr.), substictic (tr.), peristictic (tr.), ±cryptostictic (tr.), ±norstictic (tr.) and "±methylstictic acids.

N: Wellington (Rimutaka Ra., Butterfly Creek). S: Nelson (Brook Stream); Marlborough (Mt Stokes, Lookout Peak, Mt Maude d'Urville I.); Otago (near Kinloch, Lake Wakatipu), Southland (Fiordland, between Lakes Thomson and Hankinson). On damp, streamside siliceous rocks, rarely on tree roots and occasional to frequent on small pebbles and rocks amongst mosses on the forest floor in shaded habitats. It is widespread in Central New Zealand, and also on the forest floor in stands of Nothofagus fusca, although easily overlooked. Originally described on material collected by Hartmann from bark at Toowoomba in Queensland (Müller Argoviensis 1882; Filson 1986: 293), it is known also from Queensland and New South Wales (Kantvilas & Vězda 2000; McCarthy 2003c, 2006). Earlier Tasmanian records of this taxon (Jarman & Kantvilas 1995; Kantvilas 1995; Filson 1996) refer to C. lamelliferus (Kantvilas & Vězda 2000: 340).

Australasian

Illustrations : Malcolm et al. (1995b: 17, 18); Seaward et al. (1998: 464, fig. 1; 465, fig. 2; 466, figs 3, 4); Kantvilas & Vězda (2000: 340, fig. 6); Malcolm & Malcolm (2000: 74, 105); Lumbsch et al. (2001a: 38; 2004a: 13).

Exsiccati : Vězda (1995b: No. 181).

Chroodiscus megalophthalmus is characterised by: large (2–4 mm diam.), erumpent apothecia bursting through the olivaceous, crustose thallus; dark-brown apothecial discs; large, fabiform, muriform ascospores (30–60 × 8–18 μm), the transverse septa extending ±continuously across width of the spore; and compounds of the stictic acid aggregate.