Description: Often confused in the past with Megalaria pulverea, M. tuberculosa has a thick, soft, pale green or grey finely granular thallus disintegrating to form yellow-grey or blue-grey soralia. Spot tests K+ pale yellow, Pd-. Discs are unknown from Irish material. Most lookalike species test Pd+ red. It grows on oak and ash, especially in sheltered, long-established, well-illuminated woodland sites.

Key Identification Features:

• Thallus thick, soft, finely green-grey granular, eroding to form soralia blue-grey or yellow-grey in colour
• Forming distinct patches; K+ pale yellow, Pd-.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Megalospora tuberculosa at iNaturalist World Species Observations database.