Acarospora insolata H. Magn.

Göteb. Vetensk.-och Vitter.-Handl., ser. 4, 28, 2: 112, 1924.
Distribution: N - Ven, Piem (LD -1549228), Emil (Fariselli & al. 2020). C - Tosc, Sar (Rizzi & al. 2011). S - Bas (Nimis & Tretiach 1999).
Description: Thallus crustose, episubstratic areolate, medium brown, shiny, forming small patches, usually developing on the thalli of other crustose lichens. Areoles angular or rounded, slightly convex, 0.4-1.5(-3) x 0.3-2.4 mm, finely subdivided into smaller units by a dense network of fissures, dispersed or aggregated into small groups amongst the areoles of the host; lower surface black, visible along the margins. Cortex 20-30(-50) μm thick, overlain with a to 15 μm thick amorphous layer, the cortical cells 2-3 μm wide; algal layer continuous; medulla white, without crystals. Apothecia lecanorine, 0,2-0,4 mm across, immersed in the areoles, (2-)5-12 per areole, often confluent and poorly developed, round to elongate, with an initially concave, then flat, reddish brown disc, and a more or less prominent, sometimes indistinct thalline margin. Proper exciple thin, poorly developed; epithecium brown; hymenium colourless, 50-60(-80) μm high, I+ blue; paraphyses stout, 2-2.5 μm thick at base, the apical cells to c. 3 μm wide. Asci c. 100-spored, clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, broadly ellipsoid, 3-5 x 2-3.5 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on inclined faces of siliceous rocks wetted by rain. Probably more widespread in the mountains, especially in the Alps. The species does not belong to Acarospora s.str. (Westberg & 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)
paras Immersaria and Rhizocarpon spp.

Commonnes-rarity: (info)

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

pH of the substrata:


Solar irradiation:








Altitudinal distribution:


Predictive model
Herbarium samples

P.L. Nimis CC BY-SA 4.0
TSB 29925

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

P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (29925)
on the host, Aspicilia sp.