Polyblastia epomphala (Nyl.) Zschacke

Syn.: Thelidium epomphalum (Nyl.) Zahlbr., Verrucaria epomphala Nyl.
Lichenised.
Substrate: siliceous rocks
Altitudinal distribution: subalpine belt (potential vegetation: open, taiga-like forests dominated by Larix decidua and/or Pinus cembra and Rhododendron)
Note: a species with a thin, whitish thallus and ascomata immersed in thalline warts, with an apical involucrellum and a pale ascomatal wall, ascospores submuriform, resembling those of P. sepulta; based on a type from Romania on temporarily submerged calcareous stones; the only record from the Alps (France), however, is on siliceous rocks.
France: Isère;