Description: Like some members of Verrucaria, for example, V. baldensis, this species forms ‘burrows’ or pits in limestone. The lichen hunter is compelled to dig them out with the edge of a razor blade and squash the contents between a cover slip placed on a microscope slide. The thallus is barely visible as a stain. The spherical discs (perithecia) immersed in the rock have their tops freed from the side of the pit by a narrow crack (hand lens). The disc is not reinforced above by a thick outer layer (involucrellum). The spores are muriform and colourless 25-50 x 12-25&

371;m, 8/ascus). On hard, well-lit limestone, or damp walls. Northern and western Ireland.

Key Identification Features:

• Dots the surface of hard limestone with pits so must be dug out
• Spores muriform, with 10-36 cells present.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Polyblastia albida at iNaturalist World Species Observations database.