New records of water mites (Acari: Hydrachnidia) from Sri Lanka with description of four new species and some remarks of relationships

New records of water mites (Acari: Hydrachnidia) from the standing waters of Sri Lanka are presented. Fifteen species have been registrated, among them four species, i.e. Piona srilankana (Pionidae), Neumania edytae (Unionicolidae), Krendowskia (Krendowskiella) srilankana (Krendowskiidae), and Mideopsis ewelinae (Mideopsidae) are described as new to science. DNA was extracted from 18 water mite specimens and DNA barcodes are given for the first time for nine species.