Those are not generic names Jenny. They are species names and you are right about all 3 looking very different. The habrosus look like tiny versions of a paleatus but the other two have very different looks. This is the 3 we are talking about.
One of my habrosus
A hastatus group
A pymaeus swimming behind a Heterandria formosa
One of my habrosus

A hastatus group

A pymaeus swimming behind a Heterandria formosa
