Verrucaria halizoa

A species of rocky shores in the west of Britain, where it grows in crevices and shaded rocks  in the mid-littoral, often with V. mucosa and V. striatula. The thallus is superficial and thin, usually and uncracked pale olive-green, translucent when wet. The perithecia are conical-hemispherical.

Listed by Alan Orange in Flora of Glamorgan (Wade et al, 1994).