Description: This is a common species of man-made, calcareous habitats such as cemetery headstones as well as on hard, natural limestone. The thallus is immersed and virtually invisible. The small clustered or scattered discs (to 0.75mm diam.) are very characteristic, with a pie-crust, or indented appearance to the margin, hence the specific name: crenulata. On calcareous monuments, the little cogwheel-like discs can be found by searching between the larger orange, brown or grey crusts. The species is frequent in Ireland.

Key Identification Features:

• The indented margin to the discs separates this species from members of the equally common Lecanora ‘dispersa’ complex in which rock-inhabiting forms have an entire disc margin
• Generally the disc margin is white and the centre of the disc beige-brown. The species is faithful to limestone habitats.

Original text submitted by Simon Davey

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

iNaturalist: Myriolecis crenulata at iNaturalist World Species Observations database.