New data on rotifers (Rotifera) from European waterbodies

Background Rotifers (Rotifera) are microscopic pseudocoelomate animals that represent one of the key components of plankton, periphyton and benthos communities in aquatic ecosystems. As members of the zooplankton, they play an important role as primary consumers of phyto- and bacterioplankton, serve as a food source for fish larvae and act as indicators of water quality. Although rotifers have been studied in Europe for over three centuries, they remain an important subject of zoological research, as their ecological characteristics and biodiversity in several European countries are still insufficiently understood. This is particularly true for bdelloid rotifers, whose study is complicated by the impossibility of reliable identification in fixed material. The availability of georeferenced data on rotifer occurrences, coupled with environmental parameters, is of great importance for such studies, yet such data on the GBIF platform are not complete for many aquatic rotifer species. New information We present new georeferenced data on rotifers in all major types of European freshwater and brackish inland waterbodies: lotic (rivers, streams, brooks, waterfalls, canals), lentic (lakes, ponds, swamps, bogs, marshes, puddles, cryoconite holes and other temporary waterbodies) and transitional (estuaries). The littoral zone of the Black Sea and the southern coast of the English Channel (La Manche) are represented as marine habitats in this dataset. Twenty-five protected areas were surveyed during this study. The survey was conducted from 1976 to 2021. In total, we added to GBIF 4,862 new occurrences of Phylum Rotifera, including the classes Eurotatoria (subclasses Monogononta and Bdelloidea) and Pararotatoria. The dataset substantially expands the information on the distribution of still inadequately studied bdelloid rotifers (Bdelloidea) available through GBIF (1,514 new occurrences are added). We focused our study on aquatic communities that have received less attention than planktonic ones, such as periphytic, benthic and psammic rotifers and commensals on aquatic invertebrates. We also added new data on rotifers in waterfalls (6 species), temporary waterbodies (153 taxa of species rank) and tree hollows (5 species). Three species amongst those recorded are new to the fauna of Ukraine: Lecane elsa Hauer, 1931, Lindia pallida Harring & Myers, 1922, Paradicranophorus aculeatus (Neizvestnova-Zhadina, 1935).