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(Map updated: 11 August 2009)

This aquatic Verrucaria has a brown, cracked thallus, prominent discs (perithecia) forming convex projections and large spores (27 x 11.5ųm) with a perispore (a feint halo around the spore). It is a species of shaded streams and shallow ravines. In my experience it is a species of siliceous rocks, slates especially. In Ireland, the species is only known from one site in Connemara, County Galway and from County Leitrim. It is probably under-recorded.

Key characteristics

• Thallus brown, cracked with conspicuous and prominent perithecia containing large spores, each surrounded by a perispore
• It grows on smooth, sheltered siliceous rocks by fast-flowing streams and along shaded lake margins.

Original text submitted by Vince J. Giavarini