Osteology of the Southern Ocean daggertooth (Anotopterus vorax) and status of the Anotopterus genus in the Aulopiformes order

Abstract

The skeletal structure of the Southern Ocean daggertooth (Anotopterus vorax) has been studied for the first time. It generally corresponds to the A. pharao skeleton, as it has been previously described. The discrepancies pertain to the authors’ other various data on both the details of the structures of branchial arches, maxillae, cranium, and axial skeleton and the traits of the Anotopterus genus, which have not been described earlier. They include the availability of a considerable number of bony ribs (epineurals and epicentrals) attached to the neurocranium bones (epiotic, intercalar, and exooccipital) and some elongated and discontinuous lateral keel bones located on both sides of the central keel bone. Cladistic analysis has been performed with the finding that the A. vorax is united with the A. pharao and the Polymerichthys fossil genus into one clade, which takes an intermediate status between the representatives of the Alepisauridae and Paralepididae families. The assumption has been made about the necessity for the restitution of the family status of Anotopteridae.