Invasion of terrestrial enchytraeids into two postglacial tundras: North-eastern Greenland and the Arctic Archipelago of Canada (Enchytraeidae, Oligochaeta)

The aim was to study the invasion of terrestrial enchytraeids into the two postglacial tundras, North-eastern Greenland and the Arctic Archipelago of Canada. The majority of species recorded have a wide distribution in the Northern Hemisphere and the species diversity is considerably lower than that of potential source regions indicating either strong selection or varied dispersal ability. It appears that the Archipelago is influenced mainly from North America and North-eastern Greenland from Europe while the specialized fauna of the ancient Beringian tundra is of minor importance. The two alternative scenarios: (a) survival of a prepleistocene fauna in protected refugia within the area or (b) a postglacial re-invasion from outside are discussed, but the available data do not discriminate between these two possibilities. A total of 24 terrestrial enchytraeid taxa are recorded of which 22 are identified to the species level. Bryodrilus archipelagicus and Hemifridericia bivesiculata are described as new to science and Henlea groenlandica Černosvitov is revalidated. We hesitate to conclude that the new taxa described are endemic.