The mesolophe, a new lophophore type for chonetacean brachiopods

Abstract
Following a summary of previous lophophore reconstructions for the chonetaceans, we describe an unusual pyritized structure within the calcite infill of an exceptionally preserved shell of Archeochonetes primigenius (Twenhofel) from the Late Ordovician (Ashgill) of Anticosti Island, Quebec, Canada. The brachial valve interior of most Lower Devonian to Permian chonetaceans shows the development of three depressed deepened areas (gutters) in the valve floor. The disposition of these gutters coincides remarkably with the shape of the pyritized structure, which we postulate as a new type of lophophore the mesolophe.