Flora of New Zealand Series

*P. concentricum Ertz, Diederich & Wedin in D. Ertz, C. Christnach, M. Wedin & P. Diederich, Biblthca Lichenol. 91: 34 (2005).

Holotype: New Zealand. South I. Nelson, NW of Maruia Springs, E of Springs Junction along Rough Creek Walk, 750 m, mature Nothofagus fusca forest, on rotten log, on Pseudocyphellaria homoeophylla, 1990, M. Wedin 2710 (UPS). Isotypes – to be distributed in R. Santesson, Fungi Lich. Exs.

Description : Lichenicolous. Ascomata on upper surface of host thallus, solitary, more rarely in groups of 2–4, rounded, always flattened, at first immersed in host thallus and detected by dark-brown, circular necrotic areas of thallus, then bursting through host cortex in more or less concentric rings, with remnants of host cortex present between them, when older, remnants of host cortex almost disappearing, 1–5 mm diam.; galls inconspicuous from the outside, but visible in section; surface with irregularly lirellate openings; visibly damaging the host thallus as the ascomata are surrounded by dark-brown rings. Stroma multilocular, 150–200 μm thick; sterile stromatic tissue dark-brown to black, K+ olivaceous-brown, N+ reddish brown, generally well-developed between, above and below loculi. Hymenium hyaline to pale-brown, I+ blue, quickly turning red, 95–105 μm tall. Subhymenium hyaline to pale-brown, 10–14 μm thick. Paraphyses richly branched, anastomosing, 1–2 μm thick, not enlarged apically. Asci clavate to subcylindrical, 4-spored, 65–80 × 14–19 μm. Ascospores hyaline, 3-septate, not or only very slightly constricted at septa, the end cells sometimes longer than central ones, 21–28.5 × 5–6.5 μm; perispore distinct, hyaline, 2–2.5 μm thick, with brown, granular pigment when over-mature. Pycnidia not seen.

N: Known only from the type collection.

Endemic

Host : Pseudocyphellaria homoeophylla.

Illustrations : Ertz et al. (2005: 34, fig. 14; 35, fig. 15).

* Plectocarpon concentricum is characterised by: the large, black, flattened ascomata, bursting through the host cortex in concentric rings, not inducing externally visible galls; and by 4-spored asci. * Perigrapha nitida (q.v.) differs in having very glossy ascomata sprinkled with numerous, small depressions, a K+ deep-greyish to bluish green, sterile stromatic tissue and a different host (Pseudocyphellaria glabra).