Micarea lignaria
Thallus of scattered to confluent, ± globose, whitish, grey-green or bluish grey, glossy or matt areoles 80-300 µm diam., sometimes ± immersed; photobiont cells 4-7 μm diam.
Anamorph: conidiomata pycnidia, ± immersed; walls green (K–) in upper parts: (a) ca 100 µm diam., with macroconidia 16-22 × ca 1 μm, curved, 3- to 7-septate; (b) ca 100 µm diam., with mesoconidia 4-7 × 1.5-2 μm, ± cylindrical to obovoid; (c) 40-50 µm diam., with microconidia 5-7 × ca 0.8 μm, narrowly cylindrical; only (c) is common.
Teleomorph: ascomata apothecia, 150-600 (-900) µm diam., black or blue-black, immarginate, convex to ± globose, rarely with a stalk to 1 mm tall. True exciple ± distinct in young apothecia but soon reflexed, brownish in outer parts. Hymenium 50-75 μm tall, hyaline or the upper and sometimes lower part olivaceous to blue-green, K–, rarely with a few scattered, minute violaceous (K+ green) granules. Hypothecium pale blue-green or olivaceous, K–, the central part often ± hyaline or pale brownish. Interascal tissue of paraphyses 1.5-2 μm diam., numerous, simple or sparingly branched above; apices often ± swollen and coated in green or greenish brown pigment. Asci 45-50 × 11-19 μm, clavate, 8-spored. Ascospores 16-36 (-38) × 4-6 (-7) μm, fusiform to cylindric-fusiform, straight or slightly curved, the apex rounded and the base acute, (3-) 4- to 7-septate, hyaline, fairly thin-walled, smooth, without an epispore, gelatinous sheath or appendages.
Chemistry: thallus C–, K–, KC-, Pd+ red (argopsin); apothecial sections C–.
Assessed by Woods & Coppins (2012) as of Least Concern.
Micarea cinerea and M. peliocarpa differ in having Pd– thalli and C+ red apothecial sections (gyrophoric acid). Catillaria contristans (which may be referable to Micarea) has a Pd–, C– thallus and 1-septate ascospores. Protomicarea limosa has a similar Pd+ red thallus, but aseptate ascospores. Rare morphs of M. lignaria with stalked apothecia resemble Pilophorus strumaticus, which differs in having cephalodia, aseptate ascospores and a Pd– or faintly yellowish thallus. Often confused with Bilimbia lobulata and B. sabuletorum, which grow in calcareous or base-rich habitats.
Widespread and common, especially in upland districts. Throughout the British Isles. BLS map here.
On various acidic substrata, often over mosses and plant debris.