Comparative Mitogenomic Analysis of Two Snake Eels Reveals Irregular Gene Rearrangement and Phylogenetic Implications of Ophichthidae.

The family Ophichthidae has the largest number and the most various species (about 359 valid species) in the order Anguilliformes worldwide. Both morphological and molecular characteristics have been used to assess their taxonomic status. However, due to the ambiguous morphological features, molecular data such as mitochondrial DNA sequences have been implemented for the correct identification and classification of these fishes. In this study, the gene arrangement and structure characteristics of two Ophichthidae mitochondrial genomes were investigated for the first time. The total mitogenome lengths of and were 17,759 bp and 17,856 bp, respectively. Comparing with the ancestral mitochondrial gene order, the irregular gene rearrangement happened between and tRNA-Pro (P) genes with another similar control region emerging between tRNA-Thr (T) and genes, which could be explained by the tandem duplication and random loss (TDRL) model appropriately. ML phylogenetic tree demonstrated that the family Ophichthidae was monophyletic origin, but genus might be polyphyletic because of the confused cluster relationships among different species.