Abstract
The charcoalified fragment of the dorsiventrally organized, internally stratified presumed green algal lichen Chlorolichenomycites salopensis from the Lower Devonian Lochkovian strata in the Welsh Borderland carries bacterial colonies on the upper surface, i.e. the cortex, and actinobacterial filaments in the medulla underneath the photobiont layer. Moreover relatively thin hyphae of presumed endolichenic fungi were found. As in extant lichens, which are best regarded as consortia with an unknown number of participants, this internally stratified, fossil thallus fragment of a presumed green algal lichen harbours a diverse microbial community.