Recognition of the lamprey genus Occidentis as distinct from Lampetra: Comment on Hughes et al., 2024 as distinct from Lampetra Bonnaterre, 1788

Abstract

Lamprey molecular phylogenies to date have relied on mitochondrial (mt) DNA sequence data, and there has long been recognition that a robust molecular phylogeny of this ancient group of vertebrates - with relatively few phylogenetically informative morphological characters - will require the use of a wider range of genes, particularly nuclear genes (e.g., Lang et al. 2009; Potter et al. 2015; Docker and Hume 2019). Hughes et al. (2025) performed this long awaited phylogenomic analysis to assess phylogenetic relationships of lampreys, and estimated divergence time and diversification rates among lamprey clades. They examined 355 exons among 81 specimens representing 36 recognized and one undescribed (Lethenteron sp. “N”) extant lamprey species. The latter has recently been identified as Lethenteron mitsukurii (Hatta, 1901) by Sakai et al. (2025). To assess phylogenetic relationships, Hughes et al. (2025) estimated a maximum likelihood tree using concatenated exon sequences, and a multi-species coalescence tree using one gene tree per specimen. In agreement with previous studies using mt DNA (Docker et al. 1999; Lang et al. 2009; Brownstein and Near 2023; Carim et al. 2023), the authors observed a strongly supported clade representing species of: 1) Lampetra Bonnaterre, 1788 from Eurasia (and possibly eastern North America; see discussion below); 2) Lampetra from western North America; and 3) Eudontomyzon Regan, 1911 (Figure 1). Because the presence of Eudontomyzon rendered Lampetra polyphyletic, Hughes et al. (2025) recommended reassigning all members of Eudontomyzon to Lampetra.

Citation

Carim, Kellie J.; Renaud, Claude B.; Young, Michael K.; Docker, Margaret F. 2025. Recognition of the lamprey genus Occidentis as distinct from Lampetra: Comment on Hughes et al., 2024 as distinct from Lampetra Bonnaterre, 1788. ZooTaxa. 5692(2): 393-399.