I would suggest that there is no really good definition of species. (At least, I heard that over 50 years ago; it's gotten worse.) "Species" is not a property of an individual (or even a group); I suggested calling assuming so, the Cladistic Fallacy. It is a result of our classification methods.
Of course, to make things worse, the real world doesn't give clear boundaries among what we might like to call species. Things are even more complicated with plants and bacteria.
I sadly recognize these facts... it just galls the precision machinist in me.