LICHALP

Acarospora hostilis H. Magn.

Lichenised. Poorly known taxon.

Substrate: siliceous rocks,

Altitudinal range: from the subalpine belt (potential vegetation: open, taiga-like forests dominated by Larix decidua and/or Pinus cembra and Rhododendron) to the alpine belt (potential vegetation: treeless Alpine grasslands and tundras, to the lower limit of perennial snow and the equilibrium line of glaciers)

Note: a species resembling in habitus A. veronensis, with a thallus consisting of dispersed, red-brown, irregular, flattened areoles (not reacting with K, C, Pd) with incised to sublobate margins and a pale underside, a thin thalline cortex of small cells, immersed, contiguous to fusing apothecia (0.2-0.4 mm in diam.), a more than 100 µm tall hymenium, and asci with more than 100, broadly ellipsoid ascospores (2-3.5 × 1.5 μm); on siliceous boulders, often invading the thallus of other crustose lichens; described from the treeline ecotone in Northern Italy and only known from the Alps; the study of the type material could prove that this a synonym for another species.