Micarea meridionalis van den Boom, Brand, Coppins & Sérus.
Lichenologist (in press) MB 811050, 2016.
Distribution: C- Laz (van den Boom & al. 2016). S - Cal (van den Boom & al. 2016).
Description: Thallus crustose, episubstratic, effuse, granular, of ecorticate, 0.04-0.1 mm wide, subglobose to irregularly flattened, greenish, greenish grey, brownish grey or pale brown, matt to slightly shiny, up to 20 μm thick areoles which usually coalesce forming a continuous crust or scattered patches; granules soredia-like, mostly thinly coated by gelatinous algae, rarely forming loose, 10-14 μm wide goniocysts. Apothecia micareoid, slightly to moderately convex, beige or pale to dark brownish grey, immersed to semi-immersed amongst the granules and thus seemingly marginate when young, 0.1-0.3(-0.35) mm across, scattered or confluent into tuberculate aggregates, without a distinct proper margin. Proper exciple poorly developed, sometimes distinct in young apothecia and up to 10 μm wide laterally; epithecium olive-green, K+ violet, N+ red; hymenium colourless with pale greyish brown spots, 40-50 μm high, K+ violet, N+ red; paraphyses richly branched, c. 1.2 μm thick, the apical cells up to 1.5 μm wide, not pigmented; hypothecium colourless. Asci 8-spored, clavate, the I+ blue tholus with a wide, intensely I+ dark blue tube structure that expands towards the top, without a pale axial body. Ascospores 1(-3)-septate, hyaline, ellipsoid, 8-9.4 x 3.4-4 μm. Macropycnidia very rare, c. 50 μm across, colourless except at the grey top, producing 1-septate, slightly curved macroconidia measuring 15-17 x 1.1-1.3 μm. Mesopycnidia frequent, immersed, 50-70 μm across, colourless, producing bacilliform to fusiform mesoconidia measuring 5.8-6.7 x 1-1.2 μm. Photobiont micareoid, the cells, 4-6 μm wide, clustered in compact masses Spot tests: K-, C-, KC-, P-, UV-. Chemistry: thallus and apothecia with micareic acid; Sedifolia-grey pigment in epithecium.
Note: a recently described corticolous species belonging to the M. prasina-complex, with a southern distribution in Europe; it is known from several stations in Portugal, where it grows in ruderal and even dusty situations such as along waysides and in urban parks; the Italian samples are from Pinus along the coast in Calabria, from the Botanical Garden of Rome, and from an open woodland at the periphery of Rome on Quercus suber. Ecological values are tentative. For further details see van den Boom & al. (2016).