Comparative Analysis of Complete Mitogenomes of Two Oxyurichthys Gobies and Their Phylogenetic Implication.

Oxyurichthys is a genus of goby that is widespread in the tropical Indo-West Pacific region. Oxyurichthys species are usually found in estuarine and coastal marine habitats. In Southeast Asia, they are commercial fishes and often collected by trawling to serve the market's demand. The mitogenome serves as a good marker for investigating the systematics and evolution of fishes, but the mitogenome of Oxyurichthys species remains unknown. In this study, mitogenomes of two Oxyurichthys gobies, O. ophthalmonema and O. microlepis, were characterized and compared. The sizes of the mitogenomes were 16,504 bp and 16,506 bp for O. ophthalmonema and O. microlepis, respectively. Mitogenomes of these two species were similar in gene content and structure. Both included 37 genes and a control region. The two Oxyurichthys mitogenomes shared similar gene features and base composition with other recorded gobies. Typical conserved blocks (CSB-1, CSB-2, CSB-3 and CSB-D) were found in the control region of both species. Phylogenetic analyses based on concatenation of 13 protein-coding genes and 2 rRNAs revealed that the two Oxyurichthys species clustered together and were sister to species of the genera Sicydium, Sicyopterus and Stiphodon. The findings of the present study support previous evolutionary studies of gobies using other molecular markers.