The fossil ship-timber beetle Cratoatractocerus grimaldii gen. et sp.n. is described from the Lower Cretaceous of Brazil. The new taxon is placed within Atractocerinae. It is distinguished from all modern genera of the subfamily by a M+Cu fork in the hind wing venation. Cratoatractocerus grimaldii is the oldest known representative of Lymexylidae and considered as the most basal member of Atractocerinae. This fossil proves that this subfamily appeared at least by the Early Cretaceous.