Scombroclupea javieri sp. nov., an enigmatic Cenomanian clupeomorph fish (Teleostei, Clupeomorpha) from the marine deposits of the Cintalapa Formation, Ocozocoautla, Chiapas, southeastern Mexico

Scombroclupea javieri sp. nov. is erected based on the description of well-preserved specimens collected in the lower Cenomanian marine outcrop at the El Chango quarry, near Ocozocoautla de Espinosa, Chiapas State, southeastern Mexico. This new species shows the distinctive feature of the superorder Clupeomorpha, the presence of the abdominal scute series, as well as the diagnostic characters of Scombroclupea, as the lack of the dorsal scutes and the presence of two supramaxillae, the comb-like dentition in the maxilla, the horizontal laminae in the anterior caudal vertebrae, the flat epineurals and epipleural in caudal region of the trunk, and the finlets present along the anal fin, and differs from the other three nominal species of this genus in meristic data of the fins and vertebrae. Scombroclupea was previously thought as an incertae sedis members of the order Clupeiformes; however, S. javieri displays two primitive features never recorded before in this clupeomorph order and commonly observed in the order Ellimmichthyiformes, this new species has a large beryciform foramen piercing the anterior ceratohyal and its parietal bones are sutured to each other. The review of specimens of S. occidentalis and S. macrophthalma confirms that these species share the presence of a large beryciform foramen in the anterior ceratohyal. These characters make it difficult to include Scombroclupea as a member of any of the orders Clupeiformes and Ellimmichthyiformes. This record of Scombroclupea, the oldest in America and the second in Mexico, widens the geographical Cenomanian distribution of the genus along the Tethys Sea, from Middle East to southern North America. (C) 2020 Elsevier Ltd. All rights reserved.