A mitochondrial multigene approach contributing to the systematics of the brook and river lampreys and the phylogenetic position of Eudontomyzon mariae

The evolution of nonparasitic brook lamprey forms and their relationship to the morphological similar parasitic river lampreys are long-standing questions in lamprey research. The present study examines the utility of 11 mitochondrial gene segments ( a total of 3800 base pairs) to discriminate the closely related members of the European species pair Lampetra fluviatilis and Lampetra planeri. The intent was to identify fast-evolving genes in the mtDNA that might allow a discrimination of pair members. Therefore, the noncoding regions as the fastest evolving gene segments of animal mtDNA were also included. The results revealed that in all investigated loci, L. fluviatilis and L. planeri were genetically indistinguishable, indicating either a very recent divergence event or ongoing gene flow between both species. The position of the Ukrainian brook lamprey, Eudontomyzon mariae, and the phylogentic relationships within the Lampetrini was inferred from partial cytochrome b by adding available sequences from GenBank to the data set. Eudontomyzon mariae formed a monophyletic cluster with Lampetra aegyptera and the European species pair. A reintegration of E. mariae in the genus Lampetra is therefore recommended.