Leptogium teretiusculum (Wallr.) Arnold

A tiny, grey-brown to black cyanolichen with short cylindrical lobes, sliced deep into the thin coralloid protuberances, making the thallus look shrubby. The species is linked to moss communities of calcareous and basic siliceous rocks, calcareous soils and tree bark. Its saxicolous and terricolous occurrence is restricted to several localities scattered across the Czech Republic. Leptogium teretiusculum occurs also epiphytically, mainly at bases and roots of old trees with subneutral bark, such as Fraxinus excelsior and Acer pseudoplatanus, often growing on basic subsoil. The lichen prefers open habitats. At lower elevation, it represents a typical species of rocky forest steppes, open oak forests and scree forests. However, it is seldomly reported epiphytic at lower elevations (e.g. in valleys of the Dyje and Berounka rivers). In suitable habitats, such as corries in the Šumava Mts, the species may occur up to the elevation of 1000 m.

Individuals growing on bryophytes covering rocks or soils usually have less compact and more branched thalli, if compared to the epiphytic ones. Thus, they may resemble young thalli of Polychidium muscicola which may rarely occur in similar habitats.

Ascomycota → Lecanoromycetes → Peltigerales → Collemataceae → Leptogium