Verrucaria aquatilis Mudd

Syn.: Bachmannia maurula (Müll. Arg.) Zschacke, Verrucaria maurula Müll. Arg., Verrucaria retecta Zschacke; incl. Verrucaria vitricola Nyl.
Lichenised.
Substrate:
Altitudinal range: from the submediterranean/colline belt (potential vegetation: mixed deciduous forests dominated by Quercus and Carpinus) to the subalpine belt (potential vegetation: open, taiga-like forests dominated by Larix decidua and/or Pinus cembra and Rhododendron)
Note: distinguished from other freshwater species by the thin blackish thallus and the very small, broadly ellipsoid ascospores, this lichen grows on siliceous or calcareous rocks submerged in cold creeks; probably more widespread in the Alps, but overlooked, like many amphibious lichens.
Austria: Tirol; Salzburg; Kärnten; Steiermark; Niederösterreich (incl. Wien); France: Alpes-de-Haute-Provence; Haute-Alpes; Alpes-Maritimes; Haute-Savoie; Italy: Veneto; Trentino Alto Adige;