A reappraisal of the pectoral skeleton of lantern sharks (Elasmobranchii: Squaliformes: Etmopteridae).

The morphology of the articular region of the pectoral girdle and associated basals in Etmopteridae is revised in light of new evidence provided by taxa unavailable for previous studies. Such studies considered that etmopterids plesiomorphically had a single pectoral articular condyle, and only Etmopterus had two separate ones. Our reanalysis indicates that the possession of two separate condyles, one for the articulation of the propterygium and the second for the meso- and metapterygium, is the most widespread condition in this group. However, the presence of two separate articular condyles is not recovered as a synapomorphy for Etmopteridae. Previous studies also proposed that etmopterids lack a hook-like process on the anteroproximal margin of the anteriormost pectoral basal. We document that the hook-like process is plesiomorphically present in Etmopteridae, thus corroborating the hypothesis of closer relationships between this family and the other squaliforms that also share this process, namely Centrophoridae, Dalatiidae, Oxynotidae, and Somniosidae.