Lichen on sandstone for ID please

[Adam Cheeseman]

Any ideas what this is growing on York Sandstone in west London.




Cheers,

Adam

[AlanS]

Hi Adam

This is Rinodina oleae, formerly and better known as R. gennarii (the name in the current 'Dobson').

It is a common species on urban sandstone walls, but easily overlooked because of its small size and is, I am finding myself, a photographic challenge.

Until recently, the view was that R. oleae and R. gennarii were separate species, R. oleae on bark and R. gennarii on stonework. However, apart from habitat, there seems to be no difference between them and, quite often, species that normally grow on stone can grow on wood and bark, especially when the substrate is impregnated with rock or cement dust. If regarded as a single species, as in the new BLS lichen flora, the correct name is R. oleae.

[A similar species is Lecania erysibe, common on walls and concrete - it has less clustered apothecia with thinner, less conspicuous margns.]

Alan