Four complete mitochondrial genomes of the genera Candidia, Opsariichthys, and Zacco (Cypriniformes: Cyprinidae).

Members of Candidia, Nipponcrysis, Parazacco, Opsariichthys, and Zacco are a group of East Asian freshwater fishes, and these five genera form a monophyletic group within the subfamily Oxygastrinae (Cypriniformes: Cyprinidae). In this study, we first determined complete mitogenomes of Candidia pingtungensis, Opsariichthys acutipinnis, O. chengtui, and Zacco acanthogenys. The four mitogenomes with the length of 16 611-16 615 bp displayed the same patterns in gene arrangements and the use of start and stop codons for protein-coding genes. Our phylogeny divided Candidia, Nipponcrysis, Parazacco, Opsariichthys, and Zacco into two major groups that the former three genera consisted of a group and the latter two genera formed another group. The phylogeny also revealed that C. pingtungensis was nested within Nipponcrysis. Our findings indicate that the taxonomy status of Candidia and Nipponcrysis is still needed to be confirmed.