 In the decades following the erection of "Pelomyxa", researchers assigned numerous new species to it.However, in the last quarter of the 20th century, investigators reduced the genus to a single species, "Pelomyxa palustris", which was understood to be a highly changeable organism with a complex life cycle, whose various phases had been mistaken for separate species.All described species were relegated to the status of synonyms, or moved to the unrelated genus "Chaos".