Verrucariaceae Verrucaria ochrostoma Growth type crustose. BLS conservation evaluation: DD NR Chemical results negative Widespread on limestone, mortar and plaster but overlooked until recently Superficial thallus composed of pale grey to grey-brown, more/less convex and mostly crowded areoles that form a cracked crust. Perithecia are immersed in the thallus, one in each areole with only the blackish-brown apex visible, involucrellum absent. Spores 16-26 x 9-13 µm, sometimes developing a septum. Microscope photograph below.

Microscope photograph

Verrucaria ochrostoma
Wimborne Minster, Dorset. March 2017