Physcia tribacia (Ach.) Nyl.

Physcia tribacia is similar to P. dimidiata but lacks crystalline pruina on the lobes. It might also be confused with P. dubia, which is reliably identifiable microscopically based on the anatomic structure of the lower cortex. P. tribacioides is also similar, distinguished by laminal soralia, not yet confirmed in the Czech Republic.

The species grows on trees with higher bark pH and on basic siliceous rocks. Generally, it is a heliophilic and thermophilic species with suboceanic distribution and cosmopolitan distribution range. In Europe, it is scattered to rare in the warmer parts of the continent. In the Czech Republic, P. tribacia is rare and there are reliable recent records only from slightly calcareous granodiorite rocks in the Middle Vltava region. There it grows on exposed but humid microhabitats near the water level of the Slapy water reservoir. Historical records are also few, mostly from rock substrates in warmer areas.

Ascomycota → Lecanoromycetes → Caliciales → Physciaceae → Physcia