Phylogeny of the lamprey genus Lampetra inferred from mitochondrial cytochrome b and ND3 gene sequences

Mitochrondrial DNA analysis resolved many previously unanswered questions concerning the phylogeny of the lamprey genus Lampetra (comprising the subgenera Entosphenus, Lethenteron, and Lampetra). A total of 735 base pairs were sequenced from the cytochrome b and NADH dehydrogenase subunit 3 (ND3) genes in 11 lamprey species. With the exception of L. (E.) hubbsi from California, species of the Entosphenus subgenus formed a tight-knit clade that was very distinct from the other two subgenera. Lampetra hubbsi clustered with species of the Lampetra subgenus from the west coast of North America (L. ayresii and L. richardsoni) whereas species of the Lampetra subgenus from Atlantic drainages, namely the North American L . aepyptera and European L. fluviatilis, formed a third cluster. A fourth cluster included two species from the Lethenteron subgenus (L. japonica and L. appendix). Inclusion of published data from a third Lethenteron species, L. zanandreai, showed it to group with the L. (L.) fluviatilis lineage rather than with the other two Lethenteron species. Within each subgenus, members of paired and satellite species were closely related to one another (e.g., L. japonica and L. appendix) or were genetically indistinguishable (e.g., L. ayresii and L. richardsoni). Using rates of molecular evolution estimated in other fish taxa, these genetically indistinguishable species diverged less than 70 000 years ago.