A new species of black drum (Acanthuriformes: Sciaenidae: Pogonias Lacépède, 1802) from the Upper Miocene of Argentina

Abstract

Pogonias blettleri sp. nov., a new species of black drum (Acanthuriformes, Sciaenidae) from the marine Upper Miocene Paraná Formation, which crops out in the Province of Entre Ríos, Argentina, is described. The holotype specimen comprises a large and nearly complete skull articulated with the anterior vertebral column and associated with fragmentary remains of the pectoral and pelvic girdles, as well as a complete pectoral fin. Morphological and phylogenetic analyses including several Western Atlantic sciaenid taxa confirm the assignment of the fossil specimen to the genus Pogonias Lacépède, 1802, as the sister taxon to the clade of Pogonias cromis + Pogonias courbina. The erection of a new species is based on the presence of a combination of primitive and derived characters, such as: the sub-triangular dorsal outline of the anterior neurocranium, with the lateral borders of frontals delimiting an isosceles triangle; the cavernous frontals with wide bridge-like bony struts; a conspicuous dorsal protuberance of frontals; a crescent-shaped preoperculum, with a smooth posterior margin and a strongly thickened anteroventral edge; and a robust and craniocaudally wide hyomandibula, with a strongly ossified anterior expansion. The palaeoenvironmental reconstruction of the upper levels of the Paraná Formation suggests that P. blettleri sp. nov. inhabited brackish and shallow waters in estuarine environments, particularly in areas near large river run-offs. The known palaeontological content from this unit includes potential prey of the black drum, suggesting that P. blettleri sp. nov. likely fed on annelids, crabs, molluscs, and small fish, similar to its extant counterparts.