A complete mitochondrial genome-based phylogeny of gooseneck barnacles confirms the sister group relationship between the eastern Pacific Pollicipes elegans and the eastern Atlantic P. pollicipes

Gooseneck barnacles are a fascinating group of crustaceans, and their taxonomic classification has attracted the attention of several specialists, including Charles Darwin, who was the first to note the close relationship between two species of gooseneck barnacles found on the eastern coasts of the Pacific, Pollicipes elegans, and the Atlantic, P. pollicipes. A third species from the eastern Pacific, P. polymerus, is believed to have diverged earlier from this group. Here, we used short-read sequences from GenBank to assemble the first complete mitochondrial genome of P. elegans. This genome was then used to assess the relationships of cirripede species from the superorder Thoracicalcarea through a complete mitochondrial genome-based phylogenetic analysis. Our findings revealed that both P. elegans and P. pollicipes clustered together in a well-supported discrete clade, reinforcing the close relationship between them. On the other hand, P. polymerus emerged as a basal branch within the Pollicipes lineage, indicating its earlier divergence from the group. Further efforts should aim to sequence the complete mitogenomes of other species within the order Pollicipedomorpha. Such endeavors will enable a more comprehensive phylogenetic analysis of this group, whose classification continues to be a subject of debate.