Acarospora versicolor Bagl. & Carestia

Comm. Soc. Critt. Ital., 1, 5: 440, 1864.
Synonyms: Acarospora cineracea (Nyl.) Hue; Acarospora miskolensis H. Magn.
Distribution: N - TAA, Lomb (Nascimbene 2006), Piem (Isocrono & al. 2003), Lig. C - Sar (Knudsen & al. 2015). S - Camp (Jatta 1909-1911), Pugl (Jatta 1909-1911), Si (Grillo 1998, Poli & al. 1998).
Description: Thallus crustose, episubstratic, areolate, the areoles 0.5-1(-2) mm wide, 0.3-0.5 mm thick, usually flat, smooth, dispersed or contiguous, grey to brown, partially bluish white-pruinose, the margins most often brown. Epicortex thin or lacking; cortex 20-40 µm thick, the cells mostly 3-4 µm wide; algal layer continuous; medulla white, up to 0.3 µm thick, I-. Apothecia lecanorine, immersed, 0.1-0.4 mm across, with a black, concave disc, and a thin thalline margin. Proper exciple prosoplectenchymatous, I-, forming a black excipular ring around the disc; epithecium brown; hymenium colourless, 100-120 µm high, hemiamyloid, I+ blue rapidly turning red-brown, K/I+ blue; paraphyses 1.5-2 µm thick at mid-level, the apical cells hardly swollen or sometimes up to 4-5 µm wide; hypothecium thin, colourless. Asci 100-200-spored, cylindrical to narrowly clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, ellipsoid, 3-5 x 1.5-2 µm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on basic siliceous rocks in the Mediterranean belt, but also on walls in Alpine villages, and on thin soil layers, probably more widespread in Tyrrhenian Italy and in dry-warm Alpine valleys below the montane belt. For further details see Knudsen & al. (2015).
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)

Commonnes-rarity: (info)

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

pH of the substrata:


Solar irradiation:








Altitudinal distribution:


Predictive model
Herbarium samples

P.L. Nimis CC BY-SA 4.0
TSB 23310

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