Several other varieties and forms of S. carolinense are not considered taxonomically distinct nowadays:

They are taxonomically distinct from the true moles, which they resemble due to convergence.

But these are generally also not considered to be taxonomically distinct today:

It is taxonomically distinct from "true frogs" from the family Ranidae.

They are not usually considered taxonomically distinct:

Nearly a century later, phylogenetic analyses vindicated Murrill's original placement, as it has shown to be a taxonomically distinct appropriate genus.

Two other orders of decapodiform cephalopods are also called squid, although they are taxonomically distinct from Teuthida and differ recognizably in their gross anatomical features.

In addition to this and the junior synonyms cited above, two varieties of S. aviculare have been named, but they are not considered taxonomically distinct anymore:

Scottish authorities currently do not regard Scottish ferox to be taxonomically distinct from Salmo trutta.

Similarly, the proposed subspecies abrawayae is apparently based on individual variation occurring in adults and not taxonomically distinct either.