Watersipora arcuata is very similar to W. subtorquata and they are often confused with each other. They are physically indentical except for their apertures. W. arcuata has a concave lower edge of its aperture while W. subtorquata has a convex lower edge (Cohen, 2005)
Watersipora edmondsoni has been previously included in a previously unclear "Watersipora subtorquata complex." DNA testing has concluded that it is a separate species. W. edmondsoni has a more quadrate zooid shape. It is known to exist in Hawaii and its morphology resembles specimens collected in Indonesia (Geller, 2008).
Watersipora new sp.
A new species of Watersipora has been designated, but not yet named, resulting from an extensive sampling and DNA testing study. Watersipora new sp. co-inhabits a several locations in California with Watersipora subtorquata (Geller, 2008).
Watersipora subovoidea has been previously included in a previously unclear "Watersipora subtorquata complex." DNA testing has concluded that it is a separate species. Known locations of W. subovoidea include Florida, Brazil, and Australia (Geller, 2008).