ASCOMYCOTA | LECANOROMYCETES > TRAPELIALES > Trapeliaceae

Genus Placynthiella, meaning 'diminutive of Placynthium' from the form of the thallus

Common name:            Stiff Tar-spot Lichen

Synonyms:                    Lecidea fuliginea, Lecidea icmalea

Habitat:                         Varied

Substrata:                     Stumps, weathered timber etc., otherwise as text               

Growth form:                Primarily lignicolous, but also terricolous and saxicolous) 

Thallus:                  Crustose

Apothecia:                    Lecideine, often absent

BLS identity rating:        Graded 2/5 (visual identification possible with care)

Thallus often spreading, composed of closely packed or sometimes scattered, minute coralloid isidia-like granules, up to 0.2mm dia; red-brown to black-brown, shining; apothecia, very often absent, otherwise usually scattered, rarely crowded or confluent, 0.2-0.6mm dia; disc concolourous, but usually with a distinct, often slightly paler exciple; pycnidia not seen.

Placynthiella icmalea is a common and widespread species most frequently found on the top of stumps, bark or wood of fallen trees, tree roots, weathered timber such as the tops of fence posts, railings or, as in the example below, on an old bench seat; also commonly forming extensive crusts on soil in acid heathlands - a primary coloniser after burning; and on shaded silicious rocks.