Verrucaria viridula (Schrad.) Ach.

Syn.: Amphoridium leightonii (A. Massal.) Arnold, Amphoridium viridulum (Schrad.) Servít, Endocarpon viridulum Schrad., Verrucaria griseorubens Mig., Verrucaria leightonii A. Massal. non Hepp, Verrucaria obductilis (Nyl.) Zschacke, Verrucaria polygonia Körb.
Lichenised.
Substrate: calciferous rocks, siliceous rocks
Altitudinal range: from the mesomediterranean belt (potential vegetation: evergreen broad-leaved forests dominated by Quercus ilex) to the montane belt (potential vegetation: deciduous forests dominated by Fagus sylvatica and closed coniferous forests with Picea abies)
Note: an early coloniser of calciferous substrata, most common on small pebbles, also in urban areas (e.g. on roofing tiles); easily mistaken for V. macrostoma; widespread throughout the Alps.
Austria: Vorarlberg; Tirol; Salzburg; Kärnten; Steiermark; Oberösterreich; Niederösterreich (incl. Wien); Germany: Schwaben; Switzerland: Bern; Graubünden; Luzern; Schwyz; Uri; France: Alpes-de-Haute-Provence; Haute-Alpes; Alpes-Maritimes; Drôme; Savoie; Haute-Savoie; Vaucluse; Italy: Friuli; Veneto; Trentino Alto Adige; Lombardia; Piemonte; Liguria;