The biodiversity and biogeography of the free-living nematode genera Desmodora and Desmodorella (family Desmodoridae) at both sides of the Scotia Arc

Samples taken at two stations in the northern and southern parts of the Scotia Arc, at depths of 277 and 307 m, respectively, were analysed for metazoan meiofauna with special attention to the nematodes. Identification to species level was performed for two closely related subdominant nematode genera (Desmodora and Desmodorella) in samples from the two Scotia Arc stations and in other available samples from adjacent areas (Magellan Region, Drake Passage, Weddell Sea). Seven Desmodora species and three Desmodorella species were found, of which, respectively five and two species are new to science. The Scotia Arc stations show relatively high densities and average diversity on meiofauna and nematode level compared to adjacent areas. The distribution patterns of the various Desmodora and Desmodorella species suggest the Scotia Arc as a shallow bridge and a possible exchange route for meiofauna between the Antarctic and South America, especially since these species seem to be constrained by water depth.