Acarospora oligospora (Nyl.) Arnold

Flora, 53: 469, 1870. Basionym: Lecanora oligospora Nyl. - Bot. Not.: 162, 1853.
Synonyms: Acarospora glebosa (Flot.) Körb.
Distribution: N - VG (Castello 2002, Martellos & Castello 2004), Ven, TAA, Lomb, Piem (Isocrono & Ferrarese 2008), Emil (Fariselli & al. 2020). C - Tosc. S - Camp (Aprile & al. 2002), Bas (Nimis & Tretiach 1999).
Description: Thallus crustose, epilithic, areolate-verrucose, forming small patches to 2 cm across. Areoles convex, 0.3-1.5 mm wide, 0.3-0.5 mm thick, dispersed or in small groups, brown, dull, smooth, epruinose. Cortex paraplectenchymatous, 10-15(-40) µm thick; algal layer continuous, filling most of the areoles; medulla white. Apothecia one per areole, regularly round, 0.3-1 µm across, with a dark brown disc and a usually evident thalline margin. Epithecium reddish brown; hymenium colourless, 80-150 µm tall; paraphyses 1-2 µm thick at base, slightly expanded at apex; hypothecium colourless. Asci (16-)24-32-spored, clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, ellipsoid, 9-13(-16) x 5-9 µm. Photobiont chlorococcoid. Spot tests: all negative. Chemistry: no lichen substances.
Note: a holarctic-temperate species found on basic siliceous rocks (e.g. calciferous sandstone and schist), usually on pebbles, but also on walls, roofing tiles, etc., below the subalpine belt; probably overlooked in Italy, but certainly not common.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Pioneer species

Commonnes-rarity: (info)

Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: extremely rare
Submediterranean belt: very rare
Padanian area: extremely rare
Humid submediterranean belt: very rare
Humid mediterranean belt: very rare
Dry mediterranean belt: absent


pH of the substrata:

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Solar irradiation:

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Aridity:

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Eutrophication:

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Poleotolerance:

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Altitudinal distribution:

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P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (29919)
2001/12/08


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