Arcantipsocus courvillei n. gen., n. sp. is described from the Cretaceous amber of Archingeay (France). It is placed within the suborder Psocomorpha, and in the Mesozoic extinct family Arcantipsocidae n. fam. characterized by 14-segmented antenna; legs with tarsi 3-segmented; forewing setose with evanescent veins; pterostigma dark, thickened and setose; M 2-branched; areola postica free; nodulus present; hind wing with M bifurcated, without basi-radial cell; claws with a preapical tooth. A cladistic phylogeny for Psocomorpha is given including the new fossil taxon. The discovery of this new taxon demonstrates the necessity of a deep phylogenetic redefinition of the currently admitted major subdivisions of this suborder.