A revised taxonomy and estimate of species diversity for western North American Lampetra

Abstract

Lampreys are an ancient lineage of jawless fish for which the relationships among some lineages are uncertain. We addressed these information gaps for Lampetra species with a focus on western North America. Phylogenetic analysis using all publicly available sequences of two mitochondrial genes—cyt b and COI—supported designation of western North American Lampetra as a distinct genus from Lampetra in Europe, Asia, and eastern North America. Species delimitation analysis of cyt b sequences identified seven species, only three of which are currently recognized. Lampetra ayresii and L. richardsoni, regarded as separate under the “paired species concept,” were not genetically distinct; we recommend synonymizing L. richardsoni with L. ayresii because the latter has precedence, yet continuing to recognize each ecotype using its current common name. Other than the widespread L. ayresii clade, all other species exhibited limited ranges often restricted to one or two locations. Within headwaters of the Willamette River, L. ayresii demonstrated strong genetic structure and lack of gene flow among subbasins, indicating that the subbasin scale may represent an appropriate management unit. However, the appropriate management scale in other areas may differ based on evolutionary histories and gene flow. Subsequent work is needed across western North America to better delineate the ranges of the aforementioned species and to evaluate whether other unrecognized taxa in this lineage may be present.