A crustose lichen that forms grey, thick, granular or warted thalli that may be surrounded by a grey prothallus. The apothecia have strongly convex, black discs, that, if scraped, show the red medulla beneath.
Cortex: C-, K+ yellow. Medulla: K+ red, UV-
In Scotland, Mycoblastus sanguinarius occurs mainly in the upland areas of the northern, central and western Highlands where it grows on hard siliceous rocks, over mosses or direct on both bark or wood of deciduous trees such as birch. BLS distribution map
scottishlichens.co.uk 