A new pycnodontiform fish from the Early Cretaceous of Las Hoyas (Cuenca, Spain)

Abstract

Abstract Stenamara mia is a new genus and species of a rare pycnodontiform fish from the Barremian, early Cretaceous, lacustrine beds of Las Hoyas, province of Cuenca, Spain. It was previously considered Eomesodon sp., but a number of characters clearly separates it from the genus Eomesodon: lack of prognathism; absence of nuchal plates; presence of a parietal process and of only two rows of teeth in the prearticular; and peltate pattern of ossification and distribution of scales, that is, scales are present only before the level of the unpaired fins, and are complete only in the ventralmost abdominal area. The unique combination of these and other characters, plus the following autopomorphies, diagnoses the new taxon: presence of a strongly curved dorsal prominence that results in an ovoid shape of the contour of the body; body deeper than long, with maximum body height near 125% of standard length; and narrow, high cloaca formed by only two differentiated scales, the posterior one considerably longer than the anterior one. Stenamara mia nov. gen. nov. sp. is considered a primitive Pycnodontidae, pending a cladistic analysis to determine precisely its phylogenetic relationships.