Thelidium obscurum (Garov.) Zschacke
Syn.: Involucrothele obscura (Garov.) Servít, Verrucaria olivacea Fr. var. obscura Garov.
Lichenised. Poorly known taxon.
Substrate: calciferous rocks
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: a species with a blackish thallus, entirely immersed perithecia, and 1-septate ascospores (to c. 30 µm long); on sheltered calcareous rocks, with a few records only from the Western and Southern Alps.
France: Haute-Alpes; Var; Italy: Lombardia;