A new fossil taxon assigned to the family Pseudoziidae, Osonacarcinus n. gen. is recorded from outcrops of Lutetian age of regions of the Barcelona and Girona provinces (Catalonia). The new taxon is compared with distinct present and fossil genera assigned to the family, mainly with all the species of the genus Euryozius. The current pseudoziid fossil genera are known from United States, Hungary, Italy and New Zealand. This is the first record of a pseudoziid crab in the Iberian Peninsula.
