Complete mitochondrial genomes of paired species northern brook lamprey (Ichthyomyzon fossor) and silver lamprey (I. unicuspis).

The complete mitogenomes of paired species northern brook lamprey (Ichthyomyzon fossor) and silver lamprey (I. unicuspis) is reported. The two mitogenomes show a 13 bp length difference on the tRNA-Gly and two control regions. The gene order and contents are conserved in the two lampreys and identical to the lamprey mitogenomes published. Except for three indel polymorphic sites, there are 27 SNP sites which are all synonymous substitution sites and occurred on 9 protein-coding genes, two rRNAs and one tRNA. The control region1 contains six consecutive 39-nt repetitive strings in both lampreys. A 7-nt repetitive string in the control region2 is repeated 3 and 5 times in northern brook lamprey and silver lamprey, respectively. The observed level of similarity between nucleotide sequences (99.74%) is consistent with the hypothesis that northern brook lamprey and silver lamprey represent two ecotypes of one species.