Fish remains from the Middle Devonian (Late Eifelian) were found in three limestone quarries in the Elm Point and Winnipegosis formations, near Lake Manitoba, south-central Manitoba. The arthrodire material represents a taxon previously unknown from Manitoba. Eastmanosteus lundarensis sp. nov., is described based on an articulated, nearly complete cranial roof and incomplete cranial roof, a suborbital plate and thoracic shield fragments. E. lundarensis is the oldest representative of the genus, and is the first record of the genus in Canada. E. lundarensis is most similar to the other North American and European Eastmanosteus species rather than the two Australasian Eastmanosteus species and Golshanichthys.