Verrucariaceae Verrucaria fusconigrescens Growth type crustose Chemical results negative Can be frequent on siliceous coastal rocks above HWM, sometimes also found some distance inland. Perithecia +/- half-immersed, apex projecting with +/- inconspicuous ostiole. Well-developed areolate brown thallus with a darker prothallus, sometimes locally pruinose. Spores (17-)19-24(-26) x (6.5-)8-10(-11) µm. Microscope photograph below. Similar: Verrucaria nigrescens occurs on calcareous rocks

Microscope photograph

Verrucaria fusconigrescens
Studland beach, Dorset. March 2013