Description: This is a crustose lichen of the seashore occurring below the orange zone of lichens, the one which colours the lowest edge of the sea cliffs. The thallus is thin and translucent, coloured watery olive green or brown (only in well-illuminated sites). It lacks the ridges of several of its companion species in this habitat. The tidy, hemispherical discs (perithecia) with ellipsoid spores 8–10µm long on average, may occur alongside tiny dots (pycnidia) in a film-like matrix which occurs patchily between or among many of its shade-loving relatives. In Ireland, the species is occasional to frequent.

Key Identification Features:

• Thin olive green thallus, prominent perithecia without ridges or Pleiades-like clusters of embedded black dots (punctae), though pycnidia do occur but only as scattered dots
• Shore rocks often with V. mucosa in shady fissures and crevices; never extensive only a centimetre or two of thallus at most.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Verrucaria halizoa at iNaturalist World Species Observations database.