A new pleurosternid turtle from the Upper Jurassic of the Central West of Portugal is described. Pleurosternids are abundant in the European and American Upper Jurassic and Lower Cretaceous fossil record. Despite this, at present, there is no reference to any genus of pleurosternids before the upper Tithonian in Europe. Selenemys lusitanica, gen. et sp. nov., represented by several specimens from the upper Kimmeridgian of the Lusitanian Basin (Portugal), constitutes the most ancient generic attribution to a pleurosternid turtle in Europe. A cladistic analysis shows that Selenemys is more closely related to the European Lower Cretaceous pleurosternids than to the Jurassic North American representatives of this group. This is interpreted as a vicariant biogeographical distribution of the group on both sides of the North Atlantic during the Uppermost Jurassic, in contrast to that observed in other groups of reptiles.