Placidium subrufescens (Breuss) Breuss

Ann. naturhist. Mus. Wien, Ser. B, Bot. Zool., 98, suppl.: 39, 1996. Basionym: Catapyrenium subrufescens Breuss - Sauteria, 1: 225, 1986
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Distribution:
Description: Thallus squamulose, pale to medium brown, dull to somewhat shiny, the squamules up to 6 mm broad, 0.3-0.45 mm thick, contiguous or slightly overlapping, rounded to mostly undulate, concave to flattened, smooth, with an up-turned edge. Lower surface pale, attached by colourless, 4-6 μm thick rhizohyphae. Upper cortex paraplectenchymatous 40-95 μm thick of 5-17 μm wide cells, with a thin epinecral layer; medulla white, 63-200 μm thick, prosoplectenchymatous, with elongated cells; lower cortex clearly delimited from the medulla, 25-87 μm thick, with irregularly arranged, rounded to angular cells. Perithecia frequent, laminal, pyriform, immersed in the squamules, up to 0.5 mm wide, without involucrellum. Exciple pale throughout; paraphyses absent, substituted by periphyses; hymenium K/I+ blue. Asci 8-spored, cylindrical, thin-walled, non-amyloid and without an ocular chamber. Ascospores 1-celled, hyaline, ellipsoid, thin-walled, uniseriately arranged in the asci, (9-)12-15(-17) x 5-7 μm. Pycnidia marginal, small and poorly evident. Conidia bacilliform, 3-7 x 1-1.5 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a mainly Mediterranean to Mediterranean-montane, often coastal species growing on calciferous soil and fissures of calcareous rocks, known from Macaronesia, the Iberian Peninsula and Greece; to be looked for in Italy.
Growth form: Squamulose
Substrata: rocks, soil, terricolous mosses, and plant debris
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

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Predictive model