Abstract

The Stomiiformes are among the most abundant and ecologically important groups of deep-sea fishes. Despite this importance, our understanding of their evolutionary history is limited. Morphological work advanced our understanding of stomiiform relationships, but subsequent analyses using DNA sequence data have suggested alternative hypotheses and consistently questioned the monophyly of some or all stomiiform families. To assess the limits and relationships of the Stomiiformes and its currently recognized families (Gonostomatidae, Phosichthyidae, Sternoptychidae, and Stomiidae), we conducted a simultaneous analysis of 88 morphological characters and 409 mitochondrial and nuclear loci to resolve the relationships within this order. Here we present our results and a monophyletic classification that recognizes 3 families (Gonostomatidae, Sternoptychidae, and Stomiidae). This taxonomy places the Phosichthyidae into the synonymy of the Stomiidae and transfers Triplophos from the Gonostomatidae to the Stomiidae. These changes to the Stomiidae result in the family now being one of the 10 largest families of fishes and the largest deep-sea or open-ocean family of fishes (344 species). This revised phylogeny of the Stomiiformes based on the combination of anatomical and genomic data will allow subsequent researchers to explore phylogenetic scenarios for the Stomiiformes in a comprehensive framework.