Lecanora symmicta

Thallus of dispersed granules to irregularly areolate, often forming discrete patches but sometimes almost leprose, very variable in colour, typically pale yellow-green, sometimes white or green-grey; prothallus inconspicuous. Apothecia 0.3–0.8 (–1) mm diam., dispersed to aggregated, sessile, scarcely constricted below; the margin poorly developed, entire and soon excluded or perhaps missing altogether, often devoid of algal cells and composed of radiating narrow hyphae; disc variable in colour, cream to pink, pale orange or brown, flat to strongly convex; epithecium colourless or yellow-brown to olivaceous, interspersed with yellow-brown granules dissolving in K; hymenium 40–60 µm tall; paraphyses 2–2.5 µm diam., branched and anastomosed, the apices 2.5–3.5 µm diam., not or slightly thickened. Ascospores 9–12 (–14) × 4–5 (–6) µm. Conidia 18–25 × 0.5–1 µm, thread-like to curved. Thallus C± orange, K–, KC± weakly yellow, Pd–, UV+ dull orange (usnic acid, zeorin, arthothelin, ± thiophanic acid, up to three other xanthones).

The central species of the L. symmicta group, and thus a candidate for segregation into the genus Zeora Fr. (Ivanovich et al., in prep.). L. aitema, formerly often included within this species, is primarily separated by the darker apothecial discs and is always C–. At least some C– Lecanora symmicta thalli still show the K/UV (wet)+ bright yellow-green fluorescence test for xanthones. See also L. confusa, L. strobilina, L. subintricata.

A related unnamed species with 3-septate ascospores occurs on Juniper in the Speyside native pinewoods of the Scottish Highlands. In addition, material with brighter yellow thallus and dark disks has been found on wind pruned prostate montane Heather stems in the Cairngorms, Chestnut lignum on paling fences in ski runs in the same habitat and on Heather stems on an acid coastal dune system in Dorset (Lecanora “black symmicta”): thallus areolate, yellowish, C + O, K –, Pd – UV –; epithecium blue-green, K –, brown granules dissolving in K; ascus K/I + blue Lecanora type; spores simple, 10 – 12.5 x 4.5 – 5µm.