New Records of Marine Tardigrades (Arthotardigrada) from the Iberian Peninsula: Biogeographical Implications

Biogeography patterns of marine tardigrades are poorly studied. Many species of marine tardigrades are considered endemic, but this high number may be an artifact resulting from skewed knowledge about marine tardigrade diversity in different regions of the world. On the other hand, some species of marine tardigrades are considered cosmopolitan. Most of these were described many years ago. Unfortunately, these early descriptions are very incomplete and omit many characteristics with diagnostically relevant value, thus, resulting in many types of these records of these species worldwide. The objective of this study is to report, for the first time, the presence of three species of marine tardigrades in the Atlantic shores of the Iberian Peninsula. These three species were previously described from other regions of the world and the biogeographic consequences of their presence on the study area are discussed. These records provide valuable insights about the biogeography of marine tardigrades in this region.