Polychaetes distributed across oceans—examples of widely recorded species from abyssal depths of the Atlantic and Pacific Oceans

Abstract

Distributional ranges of selected deep-sea annelids are examined in an integrative approach using genetic markers (COI, 18S) and morphology. The source material comes from various deep-sea expeditions to the Pacific and Atlantic Oceans realized between 1998 and 2015. Selection criteria for the eventual target species are a reliably documented widespread distribution in the deep-sea, and the presence in sufficient numbers of specimens in our source material. Specimens from museum collections are also incorporated. Species studied are Sigambra magnuncus, Bathyglycinde profunda and B. sibogana, Progoniada regularis, P. cf. regularis, and Spiophanes cf. longisetus, plus three newly described species: Octomagelona borowskii sp. nov., Spiophanes australis sp. nov., and Spiophanes pacificus sp. nov. Illustrated descriptions are provided and the morphological distinction to congeners discussed. Genetic diversity is highest in most frequently found species, also reflected by the large numbers of genetically divergent haplotypes. The majority of haplotypes are singletons. Pan-oceanic distribution is observed for Progoniada regularis, Bathyglycinde profunda and Sigambra magnuncus, but even species restricted to a single ocean have distributions spanning hundreds or even thousands of kilometres. Our data suggest multiple and possibly ongoing dispersal and genetic exchange between oceans, most cogent for Sigambra magnuncus.