Abstract
The intraspecific mitochondrial DNA (mtDNA) phylogeny of a Japanese brackish water goby, Mimizu-haze (Luciogobius guttatus) (Perciformes: Gobiidae), was inferred from partial nucleotide sequences of the mitochondrial 12S and 16S rRNA genes (1, 053 bp). The resultant mtDNA tree showed two major intraspecific lineages, and suggested that there were two cryptic species in the goby. One of the major lineage also showed two haplotype groups, one being distributed on the northeastern Japan and another on southwestern Japan and Ryukyu Islands. The mtDNA divergence between the two haplotype groups suggested that those mtDNA groups have been isolated for about one million years.
