Evidence for a close phylogenetic relationship between the teleost orders Tetraodontiformes and Lophiiformes based on an analysis of soft anatomy
Recent phylogenetic studies based on comparisons of DNA sequences have shown that Lophiiformes (anglerfishes) and Tetraodontiformes (puffers, triggerfishes and sunfishes) were closely related, whereas no morpho-anatomical work has assessed this point. Dissections of 80 fresh specimens belonging to 49 species of 29 acanthomorph families, coupled with analyses of the literature indicate the existence of shared soft anatomy characters between Lophiiformes and Tetraodontiformes. Among acanthomorphs, anglerfishes, puffers, ocean sunfish and triggerfishes are peculiar in possessing: i) a reduced gill opening; ii) rounded and anteriorly disposed kidneys; iii) a compact thyroid included in a blood sinus; iv) an abbreviated spinal cord; v) an asymmetric liver; and vi) clusters of supramedullary neurons in the rostral part of the spinal cord. The sharing of these unusual characteristics by these two groups might be synapomorphies supporting a close relationship between Lophiiformes and Tetraodontiformes. The present study shows both the importance of comparative anatomy and the utility of confronting morpho-anatomical and molecular results.