Antarctic arthropods (mites and springtails) have been the subject of numerous studies. However, by far, the most diverse and numerically dominant fauna in Antarctica are the limno-terrestrial microfauna (tardigrades, rotifers and nematodes). Although they have been the focus of several studies, there remains uncertainty of the actual number of species in Antarctica. Inadequate sampling and conserved morphology are the main cause of misclassification of species and underestimation of this diversity. Most species' distributional records are dominated by proximity to research stations or limited opportunistic collections, and therefore, an absence of records for a species may also be a consequence of the limitations of sampling. Limitations in fundamental knowledge of how many species are present and how widespread they are prevents any meaningful analyses that have been applied more generally to the arthropods within Antarctica, such as exploring ancient origins (at least pre-last glacial maximum) and tracking colonisation routes from glacial refugia. In this review, we list published species names and where possible the distribution of microfaunal (tardigrade, rotifer and nematode) species reported for Antarctica. Our current state of knowledge of Antarctic records (south of 60°S) includes 28 bdelloid rotifers, 66 monogonont rotifers, 59 tardigrades and 68 nematodes. In the light of the difficulties in working with microfauna across such geographical scales, we emphasise the need for molecular markers to help understand the 'true levels' of diversity and suggest future directions for Antarctic biodiversity assessment and species discovery.
Tardigrada, Rotifera, Nematoda, DNA barcoding, Antarctic Conservation Biogeographic Regions (ACBR)