Abundant and diverse bioerosion trace fossils in the Lower Devonian of the Rade de Brest, France, were produced by boring ctenostomate bryozoans, polychaete annelids and algae. Two unidentifiable traces of encrusting sclerobionts are also considered. Two new taxa are described: Pinaceocladichnus cristatus ichnosp. nov. and Ichnogutta erectus ichnogen. et ichnosp. nov. Both are attributed to the work of boring bryozoans. Sedimentary condensation during intervals of sea-level rise seems to have had an important influence in promoting infestation by organisms, the activities of which are now preserved as trace fossils. A zonation of bioerosion trace fossils within the offshore zone, in the Lower Devonian of the Armorican Massif, is also suggested.