Description: A very rare, granite-loving species celebrating the Irish lady lichenologist Matilda Knowles when first described in 1956 as L. matildae. This lichen is unusual in that it has a thallus without a cortex (major visible top layer). Instead, a black prothallus dominates. The flat black, sometimes pore-like discs (<0.4mm diam.) have brown outer rims C+ faintly reddish. The epithecium is brown throughout with no coloured granules. In Ireland, it was collected from the Lagnaquilla Mountains, County Wicklow. Not in Britain.

Key Identification Features:

• Thallus without a cortex; prothallus black bearing small, flat black discs with C+ faintly reddish outer rim (exciple); epithecium brown throughout
• On granite, tightly bound to the crevices between the crystals; test exciple in the field with C.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Lecidea confluentula at iNaturalist World Species Observations database.