Mitogenomic sequences and evidence from unique gene rearrangements corroborate evolutionary relationships of myctophiformes (Neoteleostei)

Jan Y Poulsen, Ingvar Byrkjedal, Endre Willassen, David Rees, Hirohiko Takeshima, Takashi P Satoh, Gento Shinohara, Mutsumi Nishida, Masaki Miya

A skewed assemblage of two epi-, meso- and bathypelagic fish families makes up the order Myctophiformes - the blackchins Neoscopelidae and the lanternfishes Myctophidae. The six rare neoscopelids show few morphological specializations whereas the divergent myctophids have evolved into about 250 species, of which many show massive abundances and wide distributions. In fact, Myctophidae is by far the most abundant fish family in the world, with plausible estimates of more than half of the oceans combined fish biomass. Myctophids possess a unique communication system of species-specific photophore patterns and traditional intrafamilial classification has been established to reflect arrangements of photophores. Myctophids present the most diverse array of larval body forms found in fishes although this attribute has both corroborated and confounded phylogenetic hypotheses based on adult morphology. No molecular phylogeny is available for Myctophiformes, despite their importance within all ocean trophic cycles, open-ocean speciation and as an important part of neoteleost divergence. This study attempts to resolve major myctophiform phylogenies from both mitogenomic sequences and corroborating evidence in the form of unique mitochondrial gene order rearrangements.