Revision of so-called Pomatoschistus (Gobiiformes, Teleostei) from the late Eocene and early Oligocene

Abstract

The Gobiiformes (Teleostei) are among the most speciose groups of vertebrates, and are found in all aquatic habitats. Identification of extant gobiiform species is primarily based on soft-tissue characters, and their diversity and phenotypic variability often makes species determination difficult. Fossils normally lack soft-tissue features, and secure assignment of fossil Gobiiformes at family and genus levels can be extremely problematical. "Pomatoschistus bleicheri (Sauvage)" from the lower Oligocene of Rouffach (France) and "Pomatoschistus(?) cf. bleicheri (Sauvage)" from the upper Eocene of the Isle of Wight (England) exemplify these difficulties. These finds are of special interest, because they may represent the oldest fossil skeleton-based members of the Gobiidae + Oxudercidae (gobiiforms with five branchiostegals; hereafter 5brG). Reexamination of the type material of those two species now reveals the presence of a premaxilla with a postmaxillary process, which precludes assignment of these fossils to the genus Pomatoschistus. Indeed, they do not even belong to the 5brG because they display six branchiostegals. We conclude that the fossils from France and England both belong to Paralates Sauvage. Differences in the shape of the frontal bones and the numbers of caudal fin rays allow us to assign the French material to Pa. bleicheri Sauvage and the English specimens to Pa. chapelcorneri n. sp. Thus the oldest currently known 5brG species based on articulated skeletons is Gobius jarosi Pikryl and Reichenbacher, 2017 from the lower Miocene.