We have encountered at least twelve species (shown below) in our investigations of the Cobalt, Ontario area lakes and Lake Sentani, Indonesia. Many of these have dramatic morphological variations, or phenotypic differences (strains). We consider them ecophenotypes as they change their gross morphology depending upon the environmental conditions in which they are found.
Some researchers consider each variant a new species ("splitters"), while on the other extreme there are those who consider all arcellaceans as belonging to the same species ("lumpers"). We take the moderate approach. If one species is seen to change with respect to the environment, then it and all its variants are placed in one species.
