Description: This is a species primarily of acid streams and rivers. On upland streams the scaly, reddish-brown thallus with warty or knotted isidia and occasional brown discs forms neat rosettes (1-3cm wide) on rocks and midstream boulders above the submerged zone. There is nothing else like it on wet rocks or by streams so it is unlikely to be confused with other species. Siliceous upland areas; throughout Ireland.

Key Identification Features:

• Rosettes of reddish-brown overlapping lobes with coarse isidia
• On mossy boulder tops and ledges; in and by streams or rivers.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Massalongia carnosa at iNaturalist World Species Observations database.