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(Map updated: 11 August 2009)

This aquatic, crustose lichen is a familiar sight on permanently submerged bedrock, boulders or stones in streams, rivers and loughs. The thin, blackish thallus is sprinkled with low, cone-like projections: the spherical discs (perithecia). Examination of the spores show them to be small (about 9 x 6/7ųm), simple (without partitions) and broadly ellipsoid. The similar V. rheitrophila is black-flecked, the freckles lying like bits of shrapnel in the body of the thallus. Thinly scattered in Ireland.

Key characteristics

• Thin, blackish thallus, cone-shaped perithecia and small, broadly ellipsoid spores
• In the submerged zone of streams and rivers.

Original text submitted by Vince J. Giavarini