Arthonia fuscopurpurea
≡*Celidium fuscopurpureum Tul., Annls Sci. nat. Bot. sér. 3, 17: 121 (1852).
Description : Lichenicolous. Apothecia (0.2–)0.5–1.5(–2) mm diam., red-brown to brown-black, often surrounded by a ring of damaged, chlorotic host tissue, rounded, plane to convex. Epithecium orange to red-brown, K+ dull brown. Hymenium to 30 μm tall, pale orange-brown, I+ red. Hypothecium to 100 μm thick, pale brown-orange, "mottled red-brown. Paraphysoids 1.5–2.5 μm diam. Asci clavate, 35–45 × 10–14 μm. Ascospores 9–15 × 3–5 μm, 1-septate, ovoid to oblong-ovoid, upper cell shorter and broader than lower.
N: S: Throughout on lichens on trees and shrubs. Also in Great Britain, Europe, the Canary Is, Iceland, the Faeroes, Greenland, and South Orkney Is (Hawksworth 1983a; Alstrup & Hawksworth 1990; Kondratyuk & Galloway 1994; Martínez & Hafellner 1998; Øvstedal & Lewis Smith 2001), where it occurs on the hosts: Lecania racovitzae, species of Peltigera, Solorina and Psoroma hypnorum.
Bipolar
Hosts : Pseudocyphellaria dissimilis, P. poculifera, P. rufovirescens (Kondratyuk & Galloway 1994, 1995). See also Vouaux (1914a: 161).
Illustration : Hawksworth (1983a: 37, fig. 10).
* Arthonia fuscopurpurea is characterised by: the lichenicolous habit (on species of Pseudocyphellaria); red-brown to brown-black apothecia often surrounded by a ring of damaged, chlorotic host tissue; and ovoid to oblong-ovoid, 1-septate ascospores, the upper cell shorter and broader than the lower cell, 9–15 × 3–5 μm.
