Verrucaria diaphragmata Zschacke

Lichenised. Poorly known taxon.
Substrate: 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, epilithic, grey, continuous thallus, hemispherically protruding, black, ascomata (c. 0.2 mm in diam.) with a rough surface, an involucrellum tightly adpressed to the perithecial wall and reaching down to the base, and ellipsoid, simple ascospores (20-22 × 9-10 μm); on small (calcareous?) stones in the shade of closed subalpine forests; only known from the type locality in the Eastern Alps (Switzerland).
Switzerland: Graubünden;