Bacidia adastra, a new sorediate lichen species from Western Europe

Bacidia adastra Sparrius & Aptroot is newly described from the Netherlands, Belgium, England and Germany. It is related to Bacidia arnoldiana s. lat. and differs from Bacidia caligans, B. neosquamulosa and B. viridescens by thallus structure and pigmentation of the excipulum and epithecium. It usually grows on acid or neutral, eutrophicated bark. It is characterized by the remarkable, pale green, thick, leprose thallus, the pale apothecia with aeruginose or dark brown flecks in the epihymenium and excipulum, and the hyaline hymenium and hypothecium. (C) 2003 The British Lichen Society. Published by Elsevier Ltd. All rights reserved.