New insights on molecular systematics of opsariichthines based on cytochrome b sequencing

Species or sub-species including Parazacco spilurus fasciatus , Candidia barbatus , Zacco temminckii , Zacco sieboldii , Zacco platypus , Zacco macrolepis , Zacco pachycephalus , some undetermined Zacco taxa formerly misidentified as Chinese Z. platypus and Opsariichthys uncirostris were sampled, and their mitochondrial cytochrome b genes were sequenced. In the phylogenetic analysis, the genus Parazacco forms the basal taxon for the remaining members of the opsariichthine fishes, which can be divided into two major groups. The first group includes species with one longitudinal stripe on the flanks and contains Z. temminckii , Z. sieboldii and C. barbatus with sequence divergences of 12·7–16·5%. The second group has species with 10 cross bars on the body and includes O. uncirostris , Z. macrolepis , Z. platypus , Z. pachycephalus and five undetermined Zacco spp. (A–E) lineages. The estimated divergence times of mtDNA lineages within the nominal species of Z. pachycephalus and C. barbatus are >2 million years ago. According to geological evidence, this predates the earliest possible time for their arrival in Taiwan Island and indicates that the population differentiations might have been taken place in mainland China before their subsequent dispersal to Taiwan.