Duerosuchus piscator is a middle Eocene eusuchian known only from Corrales del Vino (Zamora, Spain). The species was defined based on an incomplete skull, partial lower jaws and two vertebrae from a single individual, and several osteoderms referred to other specimens. A detailed study of these remains allows us to question the attribution of all these remains to the same form. Just the cranial remains are considered as indisputably attributable to it; the validity of this species being supported. The present study provides a detailed description and an amended diagnosis for Duerosuchus piscator, which is included for the first time in a phylogenetic analysis in order to establish its systematic position within Crocodylia. As a result of this study, the Eocene crocodyliform paleobiodiversity in the Duero Basin is recognized as comprising a notosuchian (Iberosuchus macrodon), as well as three crocodylians, each belonging to a clade: the alligatoroid Diplocynodon tormis, a crocodyloid traditionally attributed to the genus Asiatosuchus, and Duerosuchus piscator, which is here identified as a planocraniid, up to now unrecognized in the Iberian fossil record.