Acarospora admissa (Nyl.) Kullh.

Not. Sällsk. Fauna Fl. Fenn. Förh., Ny Ser. ,11: 272, 1871 (1870). Basionym: Lecanora admissa Nyl. - Flora, 50: 370, 1867
Synonyms: Acarospora discreta (Ach.) Th.Fr.; Acarospora durietzii H.Magn.
Distribution: N - TAA (Knudsen & Kocourková 2020).
Description: Thallus crustose, episubstratic, areolate, pale chestnut brown to dark brown or black, the areoles of various colours, often pale brown and the margin of elevated apothecia dark brown (or vice-versa), sometimes shiny, usually smooth but occasionally rugulose, forming up to 5 cm wide patches. Areoles flat to convex, usually dispersed, sometimes clustered, 0.2-1.5 mm wide, 300-600 μm thick, broadly attached. Epicortex 10-20(-40) μm thick; cortex 25-45(-60) μm thick, of 3-5 μm wide, round to irregularly shaped cells; algal layer 50-100 μm thick, continuous; medulla 100-400 μm thick, of thin walled, 2-4 μm thick, intricate hyphae. Apothecia cryptolecanorine, 1-5 per areole, 0.2–1 mm across, at first immersed and punctiform, later becoming elevated and with an expanded, rough, sometimes umbonate, dark brown, epruinose disc, the margin formed from the parathecium (sometimes with some algae) with a thin thalline remnant around the base of elevated apothecia. Proper exciple 20-40 μm thick in immersed apothecia, expanding to 50-100 μm in elevated apothecia, K/I-; epithecium brownish, c. 10 μm high; hymenium colourless, 90-120 μm high, K/I+ blue slowly turning red (hemiamyloid), paraphyses coherent, (1-)1.5(-2) μm thick at mid-level, the apical cells up to 4 μm wide; subhymenium 10-35 μm high, K/I+ blue; hypothecium 10-30 μm high. Asci 100-200-spored, clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, narrowly ellipsoid, 3-4(-5) x (1-)1.5(-2.5) μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a pioneer, probably circumboreal species found on granite, sandstone and schist, often occurring in species-poor stands.
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: very rare
Submediterranean belt: very rare
Padanian area: absent
Humid submediterranean belt: absent
Humid mediterranean belt: absent
Dry mediterranean belt: absent

pH of the substrata:


Solar irradiation:








Altitudinal distribution:


Predictive model

J. Kocourková
Lectotype of Lecanora admissa Nyl., leg. J. P. Norrlin (H-Nyl 27455). - Bar: 1 mm