Description: This shy, neutral- to basic-barked, tree-trunk ‘bottom dweller’, with a thin grey thallus, draws the attention of the searcher by its subtle speckling of white spots (pycnidia) and few discs (lirellae). Lecanactis subabietina also boasts white pycnidia but they are chalkier, very prominent (‘in your face’) and always on acid-barked trees. The related Lecanactis abietina has thinner, neat upright pycnidia that react C+ red; this is also an acid-bark species. In Ireland, O. vermicellifera is scattered but grows most commonly on the dry sheltered bark of sycamore and ash.

Key Identification Features:

• Grey thallus with a sprinkling of tiny, white pycnidia (C-) towards the bottom of trees with basic bark
• The discs are slits, but these are often absent.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Opegrapha vermicellifera at iNaturalist World Species Observations database.