Species boundaries, host associations, and possible host shifts in the turtle barnacle genus Platylepas

The barnacle genus Platylepas contains obligate epibionts of marine vertebrates, but the taxonomic status and evolutionary history of the sea-snake specialist, P. ophiophila, have remained unclear. Here, we reassess species boundaries and host associations in Platylepas using shell-morphological comparisons and sequence data from mitochondrial COI and nuclear H3 genes from specimens collected from sea turtles, sea snakes, and a dugong. Our results show that P. ophiophila is a valid species, phylogenetically and morphologically distinct from the widespread turtle barnacles P. decorata and P. hexastylos. Furthermore, we report the first record of P. ophiophila from a sirenian host (Dugong dugo