Plectocarpon tibellii
Holotype: New Zealand. South I., Canterbury. Mt Peel, lower part of Deer Spur Track, 43º54's, 171º14'E, 420 m, in mixed stand with Pseudopanax–Myrsine and Leptospermum dominating, on trunk of Kunzea ericoides, on Pseudocyphellaria rubella, 21.x.1980, L. Tibell 9235 (UPS).
Description : Lichenicolous. Ascomata on upper surface of host thallus, solitary, rarely in groups of 2 or 3, black, rounded, flattened at first, becoming strongly convex, 0.4–1.5 mm diam.; galls inconspicuous, but visible in section; surface uneven, completely warted, but sometimes lirellate at margins, each wart (190–290 μm diam.) corresponding to vertical projections of sterile tissue surrounded by hymenium, which is often hidden and appears as slit-like openings between contiguous warts; central depression on warts rarely present; remnant of host cortex sometimes persistent in mature ascomata; not visibly damaging host. Stroma multilocular, 200–250 μm thick; sterile stromatic tissue dark-brown, K+ olivaceous-brown, N+ reddish brown, generally well-developed between and below the hymenium. Hymenium hyaline, I+ blue, quickly turning red, 115–140 μm tall. Subhymenium hyaline to pale-brown, 10–15 μm thick. Paraphyses branched, anastomosing, 1.5–2.5 μm thick, not swollen apically. Asci subcylindrical to clavate, 4–6-spored, 80–90 × 14–17 μm. Ascospores hyaline, (2–)3-septate, not or only very slightly constricted at septa, end cells not distinctly longer than central cells, (15.5–)17–21(–24) × (6–) 6.5–7.5(–8) μm; perispore distinct, hyaline, 1–1.5 μm thick, becoming brown and granular in over-mature ascospores. Pycnidia not seen.
N: Known only from the type collection.
Endemic
Host : Pseudocyphellaria rubella.
Illustrations : Ertz et al. (2005: 107, figs 86, 87; 108, fig. 88).
* Plectocarpon tibellii is characterised by: the strongly convex, warted ascomata; the absence of visible galls; the particularly broad ascospores; and Pseudocyphellaria rubella as host.
