Eighteen new enchytraeid species (Enchytraeidae, Annelida) from Alaska: Faunistic and taxonomic results of the 2001 expedition

In this paper, the enchytraeid species recovered from 90 samples collected from Prudhoe Bay to Prince William Sound during an Alaskan expedition in 2001 are presented, as well as the species previously collected in Alaska by Torben R. Christensen. A total of 53 species were identified. Thus, together with the previously described and validated species, the enchytraeid fauna of Alaska now consists of 70 species. Eighteen species are new to science: Achaeta vagile sp. nov., Bryodrilus bidiverticulatus sp. nov., B. paraboralis sp. nov., B. polydiverticulatus sp. nov., B. varisetosus sp. nov., Cernosvitoviella diverticulata sp. nov., Cognettia circula sp. nov., Euenchytraeus alaskanus sp. nov., Enchytraeus extraglandulosus sp. nov., Fridericia alaskana sp. nov., F. diverticulafera sp. nov., F. incompleta sp. nov., Henlea rosetta sp. nov., H. semidiverticulata sp. nov., Mesenchytraeus alaskanus sp. nov., M. franciscanoides sp. nov., M. multidiverticulatus sp. nov. and M. synspermathecus sp. nov. Further 35 species are recorded and most of them are redescribed and illustrated, based on fresh material. Mesenchytraeus grandis (Eisen 1904) is considered a junior synonym of M. harrimani (1904). Our results show that the enchytraeid fauna of Alaska is similar to that of Siberia with many common or morphologically highly similar species, which is probably due to the former connection provided by the Bering Land Bridge during the last ice age. At the same time, similar to Siberia, characteristic endemic species can also be found here. In general, large enchytraeids are common in Alaska. Since earthworms are absent, it can be assumed that the more frost-tolerant enchytraeids have largely taken over their role in decomposition.