Acarospora melaplaca (Nyl.) Arnold

Verh. zool.-bot. Ges. Wien, 30: 98, 1881 (1880). Basionym: Lecanora melaplaca Nyl. - Flora, 62: 204, 1879
Description: Thallus crustose-placodioid, episubstratic, areolate, the areoles brown-black, often faintly grey-pruinose, flat, the central ones 0.2-0.8 x 0.2-0.6 mm, the peripheral ones elongated and radiating, 1-2 x 0.3-0.5 mm, becoming narrower at tips. Cortex 9-12 μm thick, the uppermost layer dark brown, the rest colourless; algal layer continuous; medulla white, of densely intricate hyphae. Apothecia lecanorine, 0.2-0.4 mm across, 1-3 per areole, more or less raised, with a black, epruinose, concave to flat, rugose disc, and a thick but weakly prominent, often radially sulcate thalline margin concolorous with thallus. Epithecium brownish, 15-20 μm high; hymenium colourless, (65-)80-100 μm high; paraphyses more or less branched and anastomosing, 1.5-2 μm thick at base, the apical cells capitate, 3-4.5 μm wide; hypothecium brownish yellow. Asci c. 200-spored, the apical dome K/I-. Ascospores 1-celled, hyaline, ellipsoid, (2-)3-4 x c. 1.5 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a silicicolous species described from Switzerland and also reported from Austria (Tyrol), whose ecology and distribution need further study. To be looked for in the Italian Alps.
Growth form: Crustose placodiomorph
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

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Altitudinal distribution:


Predictive model

Magnusson A. H. (1935) Acarosporaceae, Thelocarpaceae. - In: Rabenhorst G. L.: Kryptogamen-Flora von Deutschland, Österreich, und der Schweiz-. 2nd- IX. Die Flechten. Abt. 5- 1. Gebr. Borntraeger. Leipzig, pp. 1-318. – Public Domain