Micarea farinosa
Micarea farinosa is a species of saxicolous lichen in the family Pilocarpaceae. It forms light green, powdery patches on rocks and soil in sheltered woodland spots like tree bases and dry rock overhangs. Originally discovered in Welsh woodland in 2008, it has since been found across western Europe and as far away as South Korea.
Taxonomy
Micarea farinosa was described as new to science by Brian J. Coppins and André Aptroot in 2008. The holotype was collected in Wales from sheltered shale fragments at the base of a tree in old woodland. It was distinguished from the similar M. lithinella by its powdery thallus, smaller apothecia, and smaller, simple spores; pale-fruited Micarea myriocarpa can look similar in the field, but has a more scurfy granular thallus, typically narrower and often 1-septate spores, and a reddish to orange-brown.Description
The thallus is light green and distinctly, i.e., made of tiny mealy granules. Microscopically these granules are, small spherical packets of the alga and fungal hyphae, 12–18 micrometres in diameter. The outer hyphae are colourless and the algal cells are 4–7 μm across.Apothecia are very small, usually 0.15–0.3 mm across, pale orange to orange-brown, and convex to nearly spherical; they are . The apothecial rim tissue is poorly developed and colourless; the ascospore-bearing layer is 24–30 μm high, with a colourless upper surface and a clear lower layer. The supporting threads are scanty, branched, 1–1.5 μm wide, with a few stouter threads up to 3 μm. Asci measure 27–30 × 7–10 μm and contain simple, colourless spores that are ovoid to oblong-ellipsoid, 5–7.5 × 2–3.4 μm. No asexual fruiting bodies have been seen, and thin-layer chromatography detected no lichen products.