Taxonomic diversity and abundance of enchytraeids (Annelida, Clitellata, Enchytraeida) in the Northern Palaearctic. 1. Asian part.

Background: Enchytraeids, or potworms, are tiny oligochaetes that are distributed worldwide in many terrestrial, freshwater and marine ecosystems. Despite their key role in the functioning of ecosystems, the diversity and abundance of Enchytraeidae are rarely studied due to the laborious process of species identification. The present study addresses this gap and sheds some light on the distribution and abundance of enchytraeids in the lands of the Northern Palearctic. The provided dataset constitutes the latest and comprehensive field sampling of enchytraeid assemblages across the Asiatic part of the Northern Palearctic, encompassing an original set of soil samples systematically collected throughout the region from 2019 to 2022. New information: The dataset includes occurrences from 131 georeferenced sites, encompassing 39 species and 7,074 records. This represents the first dataset providing species-specific information about the distribution and abundance of terrestrial enchytraeids across an extensive geographic area covering the Asian sector of the Northern Palaearctic. The compiled dataset is the key for exploring and understanding local and regional enchytraeid diversity. It may also serve as a valuable resource for monitoring and conserving the entire soil biodiversity.

Enchytraeidae (Annelida: Oligochaeta) from Eastern Dagestan, Russia, with the description of a new species.

The first ever list of terrestrial enchytraeids of Eastern Dagestan includes 12 species belonging to five genera. Several species from studied localities may be assigned as undescribed, therefore additional comprehensive research of enchytraeid fauna from Eastern Dagestan is required. A new enchytraeid species of the genus Fridericia Michaelsen, 1889, Fridericia samurai sp. nov., is described from Eastern Dagestan, Russia. It clearly differs from other species of the genus by short and simple oesophageal appendages, not subdivided spermathecal diverticula, and the absence of spermathecal ectal glands and clitellum on ventral side.

A history of study and new records of terrestrial enchytraeids (Annelida, Clitellata, Enchytraeidae) from the Russian Far East.

A list of terrestrial enchytraeids of the Russian Far East is compiled based on literature and extensive field data collected by the authors in 2019. A database has been created consisting of geographic coordinates, habitat type, species, and data source. For some species collected by the authors, barcoding using COI, 16s, and 12s rRNA genes has been performed. In total, there are at least 62 species of enchytraeids belonging to 12 genera. Seven species (Achaeta macroampullacea, Cognettia sphagnetorum, Enchytraeus dichaetus, Fridericia cusanica, Globulidrilus riparius, Marionina southerni, Mesenchytraeus gigachaetus) are reported in the Russian Far East for the first time. Cognettia sphagnetorum and F. cusanica are most probably introduced. Taxonomic and biogeographical remarks on some of the species found and differences from the original descriptions are provided. Some of the specimens may be undescribed species, but this requires a more in-depth examination. The Russian Far East, especially its southeastern part, is of great interest as a possible location for new species of enchytraeids.