Diversity of Orbiniella (Orbiniidae, Annelida) in the North Atlantic and the Arctic.

In this work, the diversity of the genus Orbiniella in the Nordic Seas and the North Atlantic waters south of Iceland is studied based on the analyses of molecular markers (mitochondrial COI, 16S rDNA and nuclear ITS2) and morphological characters. Our results showed the presence of at least five genetic lineages in the studied material which could also be morphologically identified by their segmental annulation patterns, the number and the shape of acicular spines, and the length and the shape of pygidial lobes. The species name Orbiniellapetersenae is assigned to one of the lineages restricting its geographical and vertical distribution to the deep-sea areas north of Iceland and Jan Mayen, and three lineages are described as new species (i.e., Orbiniellagriegi Meca & Budaeva, sp. nov., Orbiniellamayhemi Meca & Budaeva, sp. nov., and Orbiniellaparapari Meca & Budaeva, sp. nov.) elevating the number of known species in the genus to 25. Three deep-sea species of Orbiniella in our study are reported only north of the Greenland-Iceland-Scotland Ridge, one deep-sea species found south of the ridge. A single shallow-water species is distributed along the ridge and on the Norwegian shelf.