Captured this BBC news story link because it says:
Formal delineation of dolphin species is notoriously tricky.
Whenever people complain about the poor parallels between genes and memes, this is something I often point out, that despite appearances, even species (of anything) are not nearly as well defined as our more obvious daily experience suggests. The distinctions can be woolly, and quite dependent on the context for making the distinction.
Memetic speciation is no less precise than genetic speciation.
[Post Note : In fact scientifically speaking there are no such things as “fish” even. It’s only a conventional class of other classes – bony fish, cartilagenous fish and jawless fish. The classes of class “fish”, have less in common than these constituent classes have with other excluded classes.]