Description: This crustose lichen consists of creamy-brown thallus of plate-like squamules (like cracked mud) with tiny, scattered, reddish discs which are mostly immersed. It occurs as barely visible streaks on acid rocks such as sandstone so has to be carefully searched for. It is particularly attracted to metal rich substrates. In churchyards, for example, it will grow at the base of old iron railings at the junction of the metal and the stone. It varies considerably with substrate, especially in the colour of the squamules. It is relatively common in suitable habitats throughout Ireland.

Key Identification Features:

• The thallus forms little fragmented red-brown to cream mosaics only a centimetre or so long of tile-like squamules with several small discs per squamule
• It is distinguished from Acarospora fuscata (which turns C + red and K-) by the C- and K+ red reaction.

Original text submitted by Simon Davey

Distribution Map from NBN: Myriospora smaragdula at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Myriospora smaragdula at iNaturalist World Species Observations database.