Description: Known only from collections made from Counties Clare and Fermanagh, V. polysticta originates from the disbanded V. glaucina aggregate which has also cast adrift V. fuscella and V. canella. V. polysticta grows on calcareous rock and has clearly demarcated areoles (islands of thallus) growing from a black prothallus, and discs (perithecia) arising from between the units not from the middle of them. From above, the thallus appears broken up with black, interconnecting lines.

Key Identification Features:

• Not initially parasitic on Aspicilia calcarea; more resembling V. fuscella
• Prothallus black, perithecia growing from between the mosaic pieces which appear connected by dark lines made by a thin, black, felt-tipped pen.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Verrucaria polysticta at iNaturalist World Species Observations database.