Molecular phylogenetic analysis of the squid family Histioteuthidae (Mollusca, Cephalopoda)

Abstract

Histioteuthid squids are an important part of marine food webs, being abundant in the diets of many predators. Although they represent a substantial biomass in the deep sea, their systematics are not fully understood; damaged (especially ex-gut-content) and paralarval specimens are difficult to identify morphologically, since most morphological characters presently used to distinguish species involve external photophore patterns. The purpose of this study was to test a morphological hypothesis for the division of the family Histioteuthidae into species groups using two mitochondrial genes (cytochrome c oxidase subunit I [COI] and 16S rRNA). Both the Bayesian and maximum-likelihood analyses supported the division of this family into six genera (formalising previously hypothesised species groups): Calliteuthis, Fragariateuthisgen. nov. Histioteuthis, Histiothauma, Naviagen. nov., andStigmatoteuthis. Barcode Index Numbers based on COI and 16S rRNA were used to distinguish 17 currently accepted species, and revealed up to nine additional species, including potentially new, unnamed species. A DNA barcode reference library of sequences generated in this study is available on the Barcode of Life Data Systems (BOLD), which can be used to confirm identifications or identify damaged specimens, such as those from gut contents. This study is the largest, most complete phylogenetic analysis of this family to date