Arthonia maculiformis
Holotype: New Zealand. Wellington, Tongariro National Park, vicinity of Whakapapa Village, along Whakapapanui Stream, on Pseudocyphellaria glabra, 39º11's, 175°32'E, 1990, M. Wedin 2298 – UPS. Isotypes – AK, BM, GZU.
Description : Lichenicolous, causing extensive areas of discoloured, darkened tissue on host lichens Apothecia evenly distributed in central parts of infected areas, dark-brown to black, irregular to ±rounded, fleck-like, flattened, c. 0.1–0.5 mm diam., insection 35–45 μm tall. Epithecium 5–11 μm thick, strongly pigmented, dark-brown, greenish black in K. Hymenium 20–35 m tall, I+ red, K/I+ blue. Hypothecium 5–11 m thick, colourless. Paraphysoids 0.5–1.5 μm diam., branching and extending periclinally above asci, to 2.5 μm diam., brown-walled strongly brown-pigmented. Asci pyriform to subglobose, 15.5–25.5 × 13.5–16.5 μm, no amyloid apical ring in K/I, 8-spored. Ascospores 1-septate, soleiform, constricted at septum, oblong-ovate, colourless at first with a thin perispore (c. 0.5 m thick), soon becoming brown and verrucose; perispore I+ red, 13–16.5 × 5–6.5 μm.
N: Wellington (Whakapapa Village, Tararua Ra.). On usnic-acid-containing species of Pseudocyphellaria in northern beech forests.
Endemic
Hosts : Pseudocyphellaria glabra, P. homoeophylla.
Illustrations : Wedin & Hafellner (1998: 66, fig. 2D; 74, fig. 5A).
* Arthonia maculiformis is characterised by: the lichenicolous habit (on species of Pseudocyphellaria as host); scattered, dark-brown to black, irregular, rounded, fleck-like apothecia, 0.1–0.5 mm diam.; and 1-septate, soleiform ascospores, colourless at first but soon becoming brown and warted, 13–16.5 × 5–6.5 μm. It is readily distinguished from A. pseudocyphellariae by the colour of the apothecia, black or brown-black in A. maculiformis, and bright red (K+ violet) in A. pseudocyphellariae.
