Lonchidiidae Herman, 1977, represents one of the most diverse and controversial families of Hybodontiformes, the sister group of Neoselachii (i.e., modern sharks, skates, and rays). It was initially erected as a monogeneric family including only Lonchidion Estes, 1964, a genus of small euryhaline hybodonts from the Mesozoic. Recently, Cappetta (2012) recognized up to eight genera within the family: Baharyodon, Diplolonchidion, Vectiselachos, Hylaeobatis, Isanodus, Parvodus,Lissodus, andLonchidion, although the content of the family is still under discussion (see, e.g., Rees, 2008; Khamha et al., 2016). Major discrepancies concern the phylogenetic relationships between Lonchidion and Lissodus and the taxonomic status of the latter. Thus, based on the general similarity of their teeth,Duffin (1985, 2001) considered Lonchidion as a junior synonym of Lissodus. Subsequently, Rees and Underwood (2002) restored Lonchidion as a valid genus, closely related to Lissodus, within the family Lonchidiidae (togetherwith Vectiselachos, Parvodus, andHylaeobatis). This interpretation has been followed by several authors (e.g., Fischer, 2008; Cappetta, 2012; Johns et al., 2014). In contrast, Rees (2008) considered Lonchidion and Lissodus not so closely related to each other, excluding Lissodus from Lonchidiidae. The majority of Lonchidion species has been described on the basis of disarticulated teeth, and complete or partial articulated skeletons have been known only recently from juvenile specimens, assigned to Lonchidion sp., from the inland lacustrine Konservat- Lagerst¿atten outcrop of Las Hoyas (Lower Cretaceous, Spain) (Soler-Gij on et al., 2016). Currently, the stratigraphic distribution of the ranges from the Middle-Upper Triassic (Fischer et al., 2011; Johns et al., 2014) to the Upper Cretaceous (Estes, 1964). In the present study, we describe a new species assigned to Lonchidiidae, Lonchidion derenzii, sp. nov., based on distinctive isolated teeth from the Upper Triassic (Carnian) of Spain, representing the earliest well-documented occurrence of the genus in Europe.