Description: C. undulatum is a rare ‘jelly’ lichen of exposed limestone rocks. In general appearance it resembles C. cristatum (large, dark thallus and channelled lobes with wavy margins). Discs are numerous often crowded with exciple, level with, or lower than, that of the disc. The spores are three-septate and fusiform-ellipsoid. Forms with globose or granular isidia belong to the var. granulosum. In Ireland, it is only known from the Burren, though there are earlier records from stone walls in Connemara, County Galway.

Key Identification Features:

• Like C. cristatum (described elsewhere) but with three-septate spores, concave lobes and exciple never above the level of the disc
• On the hard limestones of exposed ridges.

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Lathagrium undulatum var. undulatum at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Lathagrium undulatum var. undulatum at iNaturalist World Species Observations database.