Multiple Nuclear Gene Phylogeny of Trichiuroidea (Teleostei, Acanthomorpha) Supports Recognition of the Family Lepidocybiidae

ABSTRACT

The Trichiuroidea, commonly known as snake mackerels and cutlassfishes, constitute an important component of marine pelagic and demersal fish assemblages. Members of this superfamily exhibit a wide spectrum of body shapes from fusiform to elongate and are currently classified into two families (Gempylidae and Trichiuridae), comprising 26 genera and 73 species. In this study, a new and comprehensive multiple nuclear gene dataset of the Trichiuroidea and their allies was constructed to evaluate the monophyly of trichiuroid families, relationships within the superfamily and the monophyly of constituent genera. Our phylogenetic analyses support the monophyly of the Trichiuroidea and Trichiuridae, but also support the non‐monophyly of Gempylidae with respect to Lepidocybium . The monotypic genus Lepidocybium has been an independent lineage for c.a. 62.1–65.1 million years. To adhere the principle of phylogenetic classification, we propose a new family Lepidocybiidae (elevated from formal subfamily of Gempylidae). Lepidocybiidae can be distinguished from Gempylidae and Trichiuridae by a combination of characters, including median caudal keels flanked by two smaller keels, a strongly tortuous lateral line, inward‐curving conical teeth, a pale porous reticulation around the scales, fewer vertebrae (31–32) and a relatively long, posteriorly expanded, leaf‐like dorsal postcleithrum. In addition, Lepidocybiidae differ from Trichiuridae in possessing finlets and two pairs of nostrils rather than a single pair. Within the Trichiuroidea, all currently recognized genera are recovered as monophyletic except Trichiurus .