The family of Argestidae Por, 1986 belongs to the benthic living harpacticoid copepods. They are primarily found in deep-sea samples and show a worldwide distribution. 50% of all Argestidae detected in deep-sea material belong to Mesocletodes Sars, 1909. Within this genus, members of the Mesocletodes abyssicola group are distinctly separated from the remaining congeners of Mesocletodes: strong cuticular processes on cephalothorax and/or telson and extremely elongated furcal rami are interpreted as apomorphic to the M. abyssicola group. The combination of their conspicuous morphological features, their comparatively large body size (ca. 1mm) and their cylindrical formed body allows fast recognition in samples of metazoan meiobenthos. Moreover, compared with other harpacticoid species, a fairly high number of specimens per species is found for the M. abyssicola group in sampled material from remote deep-sea regions. For these reasons, they are considered as an ideal taxon to investigate distribution patterns for deep-sea Harpacticoida at species level. For instance, Mesocletodes robustus Por, 1964, which was described from a fjord in Norway, was found in deep-sea samples of the Southeast Atlantic (campaign DIVA), Southern Ocean (campaign ANDEEP), the equatorial Pacific (campaign NODINAUT) and even in the eastern Mediterranean Sea in depths of 180m only. In conjunction with data on benthic deep-sea organisms, collated during the Workshop on Cosmopolitan Deep-Sea Species in December 2008 (Wilhelmshaven, Germany), these findings lead to the assumption that geographic barriers like undersea ridges or continental masses do not prevent the dispersal of meiobenthic deep-sea organisms.