A curstose lichen with a supperficial rough thallus and rounded and delimited soralia and thallus Pd+ red. Resembles Lepra aspergilla, but confined to old lignum in old growth native pinewoods in the Scottish Highlands. Pertusaria pupillaris, also has a Pd+ red spot test, and can occur in the same habitat, but ith thallus is ± immersed in the lignum.
Thallus thin to thick, pale grey to pale green-grey, continuous, often fissured; prothallus indistinct; soralia mostly delimited, rounded, convex, rarely excavate, to 1.5 (–3) mm diam., occasionally fused; soredia white, coarse. Apothecia rare, developing within soralia, disciform, single-pored; disc pale pink, to ca 0.7 mm diam. Ascospores 6 per ascus, 18–20 × 10–14 um; Thallus C–, K+ brownish, Pd+ red (fumarprotocetraric, protocetraric and succinprotocetraric (trace) acids).
Pertusaria pupillaris, from similar habitats, is ± immersed in bark and lacks succinprotocetraric acid. Lepra amara has KC+ violet soralia and a very bitter taste.
On old Pine lignum, in Caledonian Pine forest
Rare, Scottish Highlands
Confined to well lit dead wood in native pinewoods, where it may be vulnerable to overgrowth and shading by coarse vegetation if grazing levels are greatly reduced.
Britain: Notable & International Responsibility species
Scotland: Priority Taxon for Biodiversity in Scotland
Cannon, P., Kukwa, M., Coppins, B., Fletcher, A., Sanderson, N. & Simkin, J. (2021). Pertusariales: Ochrolechiaceae, including the genera Lepra, Ochrolechia and Varicellaria. Revisions of British and Irish Lichens 5: 1-17. Link
Text by Neil A. Sanderson, based on Cannon et al (2021)