Description: This rare and inconspicuous crustose epiphyte has a mostly grey-white scurfy thallus and small, dense, brown-black discs (to 0.6mm diam.). Making a squash of the disc is beset with problems due to the presence of insoluble granules, so doing this often cracks the slide. The long, narrow spores (50-100 x 2&

371;m) soon fragment into numerous pieces. Look for it growing in bark fissures on old trees (especially oaks) in sheltered areas of old estate parklands and old woodlands. Scarce: north-eastern Ireland, but also County Mayo.

Key Identification Features:

• Scurfy thallus with small black discs; spores break with pressure into rounded or cuboid fragments; mounting the disc in K can crack microscope slide
• A rare bark fissure lichen of ancient woodland or parkland trees.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Bactrospora corticola at iNaturalist World Species Observations database.