Description: This is a species of damp, sheltered limestone rock. The thallus is unlike most species of Staurothele in that it is superficial (epilithic), ivory or creamy-green or grey, with the spherical discs (perithecia) neatly immersed in pits in the rock. Within the disc the algae will be seen to be shortly oblong or as wide as they are long. A key feature of this species is the spores, which are dark brown at maturity and in groups of four or occasionally five per spore sac (ascus). It is uncommon on damp limestone except in the Burren, County Clare.

Key Identification Features:

• Thallus: epilithic, green; perithecia in pits
• Spores 4/ascus, brown, 40–60µm long; disc algae: barely oblong; on damp limestone (but never wet with seepage water).

Original text submitted by Vince J. Giavarini

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

iNaturalist: Staurothele rupifraga at iNaturalist World Species Observations database.