TYPE. GERMANY. Near Heidelberg. On trunk of an old Castanea vesca. Zwackh s.n. (Körber 1860).
Life form. Lichenized fungus
Description.Thallus crustose, areolate; areoles scattered to contiguous, convex, 80–160 (–250) µm diam.; surface greenish white or whitish grey, sometimes tinged grey-brown or olivaceous, occasionally (when on charred lignum) dark brown, sometimes thinly white-pruinose; in section with a distinct algal-free cortex visible. Photobiont chlorococcoid alga; cells 4–7 µm diam. Ascomata biatorine apothecia, rare, (0.8-)1.2-3.0 mm diam.; disk dark brown to brown-black, matt, convex to subglobose, often tuberculate and to 0.8 mm diam. Exciple poorly developed and much reflexed; epithecium dark brown, K+ pigment dissapearing, sometimes also K+ faintly violet; hymenium 30–40 µm high, hyaline or with yellowish brown vertical streaks; hypothecium pale, tinged pale yellowish brown, K–, N–. Paraphyses numerous, sparingly branched but more richly branched in the epithecium, 0.8–1 µm diam., tips widening to ~2 µm. Asci 23–, 35 × 10–12 µm; ascospores (9–) 11–15 (–24) × 2–3.5 µm, fusiform, cylindric-fusiform or ovoid-cylindrical, ± slightly curved, 0 or 1(-3)-septate. Conidiomata pycnidia, usually frequent, immersed but often emergent, grey-brown, sometimes whitish around the ostiole; wall pale olivaceous or brownish, K+ violet; of two types: (a) 100–200 µm diam., often widely gaping, with mesoconidia 3.5–4.5 × 1.3–1.7 (–2) µm, ± cylindrical or slightly wider at the proximal end; (b) 23–40 µm diam., with microconidia (4–) 4.5–6 (–6.5) µm in length, narrowly cylindrical.
Chemistry. Spot tests negative; unidentified substance detected by TLC.
Substrate and habitat. Lignicolous on decorticate logs in old forests
Distribution. Europe and eastern North America west to Ozark highlands; in North Carolina found in the Blue Ridge ecoregion.
Literature
Cannon, P., Orange, A., Aptroot, A., Sanderson, N., Coppins, B. & Simkin, J. (2022). Lecanorales: Pilocarpaceae, including the genera Aquacidia, Byssoloma, Fellhanera, Fellhaneropsis, Leimonis and Micarea. Revisions of British and Irish Lichens27: 1-48.
Körber, G.W. (1860) Parerga lichenologica. Ergänzungen zum Systema lichenum Germaniae. 2: 97-192 (original description as Biatora elachista).
Tsurykau, A. & Czarnota, P. (2014) Three lichen species of Micarea (Pilocarpaceae) new to Belarus. Acta Mycologica49(2): 249-253.