Description: This rare endemic could be confused only with P. albescens var. corallina (described elsewhere). The thallus is made of columnar warts concealing two to five discs bursting only at the tips to produce soralia. Spot tests negative. It has been collected from mosses overgrowing rock and the bark of trees such as rowan. In Ireland, it is known only from two sites in County Kerry.

Key Identification Features:

• Like P. albescens but with thallus of columnar warts on tree mosses
• Warts break only at the tips to produce soralia.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Pertusaria polythecia at iNaturalist World Species Observations database.