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.

Postembryonic development and male paedomorphosis in Osedax (Siboglinidae, Annelida)

“… Westheide (1987) further argued that natural selection in this habitat might be so harsh that it precludes “middle-sized” body forms, leaving progenesis as the only viable evolutionary “shortcut” for colonizing such selective habitats. The spatially- and temporally limited environment of bony substrates colonized by Osedax also appears highly selective, demanding precision in timing, navigation, and motility of small body forms, as well as in fertilization and dispersal strategies ( Rouse et al, 2008 ; Berman et al, 2023 ). In all studied Osedax species, eggs are fertilized before leaving the female oviduct, with internal fertilization likely being essential for ensuring high fertilization rates and successful dispersal and colonization of offspring.…”

New Species of Osedax (Siboglinidae: Annelida) from New Zealand and the Gulf of Mexico

“…Depth has been hypothesized to contribute in part to high species richness of Osedax in Monterey Bay Canyon (Rouse et al 2018;Vrijenhoek et al 2009). Many species of Osedax have been found across a range of depths while some are known from only a single record (Berman et al 2023;Rouse et al 2018). Osedax estcourti n. sp.…”

“…has a distinct demarcation between the palps and the trunk, O. docricketts does not, and the ovisac and oviduct are distinctive on O. bozoi. Osedax docricketts is suspected to be a cryptic species complex (Berman et al 2023;Rouse et al 2018) and the minimum interspecific distance between the two species was 13.7% based on sequence EU267676, an individual of Osedax docricketts from Monterey Bay (Table 3). (Eilertsen et al 2020).…”

New occurrences of the bone-eating worm Osedax from Late Cretaceous marine reptiles and implications for its biogeography and diversification

“…Concentrated research efforts in specific regions have resulted in the recognition of numerous species, with 18 species described from the Monterey Submarine Canyon alone [3]. There are currently 29 described species of Osedax [4] (World Register of Marine Species; https://marinespecies.org), forming a globally distributed marine clade that includes occurrences in the Atlantic, Indian, Pacific and Southern oceans, extending from 73.6°N in the Arctic [5] to 65.1°S in the Antarctic Peninsula [6] (Global Biodiversity Information Facility; https://www.gbif.org). The depth range of Osedax is also extensive, with living individuals discovered on vertebrate remains at depths of between 21 m [6] and 4208 m [7], showing its ability to adapt to a wide variety of marine environments, as long as there is bone and sufficient levels of oxygen present in those environments [8].…”