Range extensions of Pacific bone-eating worms (Annelida, Siboglinidae, Osedax)

Abstract

First described in 2004 off California, Osedax worms are now known from many of the world's oceans, ranging from 10 to over 4000 m in depth. Currently, little is known about species ranges, since most descriptions are from single localities. In this study, we used new sampling in the north-eastern Pacific and available GenBank data from off Japan and Brazil to report expanded ranges for five species: Osedax frankpressi, O. knutei, O. packardorum, O. roseus and O. talkovici. We also provided additional DNA sequences from previously reported localities for two species: Osedax priapus and O. randyi. To assess the distribution of each species, we used cytochrome c oxidase subunit I (COI) sequences to generate haplotype networks and assess connectivity amongst localities where sampling permitted. Osedax frankpressi, O. packardorum, O. priapus, O. roseus and O. talkovici all had one or more dominant COI haplotypes shared by individuals at multiple localities, suggesting high connectivity throughout some or all of their ranges. Low ΦST values amongst populations for O. packardorum, O. roseus and O. talkovici confirmed high levels of gene flow throughout their known ranges. High ΦST values for O. frankpressi between the eastern Pacific and the Brazilian Atlantic showed little gene flow, reflected by the haplotype network, which had distinct Pacific and Atlantic haplotype clusters. This study greatly expands the ranges and provides insights into the phylogeography for these nine species.