A crustose species with a thallus that is dull brown to black cracked into neat areoles. The surface is matt with numerous black dots.
In Scotland, Hydropunctaria maura can be found in particular on exposed shores where it creates a distinctive black zone on rock around the high-water mark. BLS distribution map
Hydropunctaria maura is often found alongside Caloplaca marina and Caloplaca thallincola.
scottishlichens.co.uk 