Earliest rhynchonelliform brachiopod parasite from the Late Ordovician of northern Estonia (Baltica)

•Earliest rhynchonelliform brachiopod parasites appear in the Sandbian.•Burrinjuckia clitambonitofilia ichnosp. nov. was a kleptoparasite.•B. clitambonitofilia ichnosp. nov. damaged brachiopod mantle.•B. clitambonitofilia ichnosp. nov. occurs in C. squamatus.

A new parasite trace fossil, Burrinjuckia clitambonitofilia ichnosp. nov., is described from the ventral mantle cavity of the Sandbian (Late Ordovician) brachiopod Clitambonites squamatus. This is the earliest record of a parasite associated with a rhynchonelliform brachiopod. The parasite that produced Burrinjuckia clitambonitofilia caused damage to the ventral mantle of C. squamatus, used brachiopod resources for building its mineralized domicile, and likely stole food from the host's inhalant currents. Predation pressure and the need for easily exploited food resources (i.e., brachiopod-created nutrient flow) may have been the primary driving forces behind the evolution of brachiopod parasites.