Species richness of Enchytraeidae (Enchytraeidae: Clitellata: Annelida) in the center and east of northern Palaearctic

The role of enchytraeids (Enchytraeidae: Clitellata: Annelida) in sois is hard to underestimate. However, there is little knowledge of their spatial distribution and species richness both globally and regionally. In this paper, we aim to analyze the preliminary patterns of species richness spatial distribution across Central and Eastern sectors of the Northern Palearctic, specifically in Eastern Europe, Siberia, the Russian Far East, Central Asia, and Mongolia. The analysis is based on the mapping of 79 species occurrence records and interpolating species richness from 322 sampling points across the study region. Only own material was used for the analysis due to potential methodological inconsistencies with earlier data. The highest interpolated species richness of enchytraeids, was observed in the temperate coniferous and broadleaf and mixed forests of European Russia, seaside sectors of the North Caucasus (both the Black and the Caspian seas), the south of West Siberia, and the Russian Far East, up to 16 species per location. Temperate natural grasslands and deserts were characterized by low interpolated enchytraeid species richness ranging between one and two species. Species richness in the sampling locations within the Arctic did not differ from that in boreal forests pointing to the important role of Enchytraeidae in the total Clitellata diversity at higher latitudes. In the future, broader species distribution modelling with involving literature data, molecular-based taxonomic identification results and habitat abiotic parameters data will help in discovering mechanisms standing behind the revealed enchytraeid species richness spatial patterns in the Palaearctic. • We studied enchytraeid species richness in Northern Palaearctic. • Highest species richness was associated with temperate forests. • Grasslands and deserts had low interpolated enchytraeid species richness.