LICHALP

Thelidium impressum (Müll. Arg.) Zschacke

Syn.: Sagedia impressa Müll. Arg.

Lichenised.

Substrate: calciferous rocks

Altitudinal range: from the submediterranean/colline belt (potential vegetation: mixed deciduous forests dominated by Quercus and Carpinus) 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 of the Th. pyrenophorum-group resembling Verrucaria dufourii, but perithecia smaller (to 0.3 mm in diam.) with involucrellum reaching down about half of the perithecium, and with ellipsoid, 1-septate ascospores (to 12 µm long); on inclined surfaces of compact calcareous rocks in upland areas.