Nevertheless, it is well recognized that the Plymouth red-bellied turtle extends the range of the northern red-bellied cooter by 30-40 percent.

Current thinking is that they are not a full subspecies and that they belong in synonymy under Pseudemys rubriventris or northern red-bellied cooter.

The current range of the red-bellied cooter includes a colony in Massachusetts which was previously a separate species (Pseudemys rubriventris bangsii) as well as the coastal areas of New Jersey, Pennsylvania, Delaware, Maryland, Virginia and North Carolina.