Flora of New Zealand Series

Description : Lichenicolous, parasitic on thalli (rarely on thalline margin of host apothecia) of various species of Heterodermia. Apothecia arising superficially (not developing below and bursting through host cortex) in clusters, to 3.5 mm diam., and containing up to 15(–38) ascomata, causing the surrounding host tissue to become discoloured and brownish; clusters characteristically elliptical, with the long axis of the clusters and most individual ascomata parallel with the host lobes. Ascomata black, epruinose, 200–300(–420) μm long, 125–160(–200) μm wide and to 150 μm tall, simple or occasionally shortly 1–2-furcate, straight or slightly curved, the disc slit-like or at length gaping. Exciple well-developed, entire, dark-brown to blackish brown sometimes tinged reddish, K− or K+ brownish or olivaceous (never bright-green or red-brown). Hymenium colourless, (40–)45–65(–70) μm tall, I+ blue; epithecium absent. Hypothecium pale-brownish, K− or + slightly olivaceous. Paraphyses branched, 1–2 μm thick. Asci broadly clavate, (30–)32–40(–45) × 11–16 μm, with I+ blue ring around apex of ocular chamber. Ascospores colourless, 3(–4–5)-septate, upper 2(3 or 4) cells somewhat more swollen than lower cells, 12.5–17(–19) × (3.5–)4–5.5 μm, apices obtuse, sometimes with a thin perispore to 1 μm thick, mature ascospores becoming brown through deposition of minute pigment granules on perispore. Pycnidia sometimes present around outside of ascomatal clusters, immersed in host tissue, dark-brown to black, 40–60 μm diam., wall tissue dark-brown, K−. Conidia bacillar, 3.5–5 × 0.5–0.7 μm.

N: Northland (Russell), South Auckland (Mt Maunganui). On Heterodermia growing on coastal rocks. Known also from Africa, Mauritius, India, Japan, Hawai'i, Puerto Rico, Colombia and Louisiana in the United States (Coppins & Kondratyuk 1998: 12–13; Etayo 2002: 89), with several specimens being collected in the 18th century by Archibald Menzies (Galloway 1995b).

Cosmopolitan

Host : Heterodermia obscurata. Elsewhere in its range on H. albicans, H. leucomela, H. speciosa (Coppins & Kondratyuk 1998: 12–13).

Illustration : Coppins & Kondratyuk (1998: 10, fig. 1A, B; 11, fig. 2A, B).

* Opegrapha trassii is characterised by: the lichenicolous habit; clusters of black ascomata on Heterodermia as host; 2, 4, 6, or 8-spored asci with 4–6 ascospores being most commonly encountered; and ascospores 3(–4–5)-septate, 12.5–17.5(–19) × (3.5–)4–5.5 μm.