Complete mitochondrial genomes of Korean lamprey (Lethenteron morii) and American brook lamprey (L. appendix).

The complete mitogenomes of two lampreys with complex taxonomic histories, the Korean lamprey (Lethenteron morii) and the American brook lamprey (L. appendix) were determined. Three-nt length difference between two genomes occurred on tRNA-Ser2 and control region 2. Except for 3 indel sites, there are 58 variable sites between two genomes which occurred on 11 of the 13 protein-coding genes (aside from COX3 and ND3) and 2 of rRNAs, tRNAs, control regions and intergenic regions. Among these sites, 15 sites are non-synonymous substitution sites occurred on 8 protein-coding genes including COX1-COX2, ND1-ND2, ND4-ND6 and ATPase6. Control region 1 contains 4 consecutive 39-nt repetitive strings and a 26-nt repetitive string in control region 2 is repeated 3.8 times in both lampreys. The observed level of similarity between nucleotide sequences (99.62%) implies the Korean lamprey and American brook lamprey are very close relatives and should be assigned into the same taxonomic genus.