Typically they’ll draw a species boundary if two individuals from the two distributions can not create a sustainably procreating line of descendants. So either

Typically they’ll draw a species boundary if two individuals from the two distributions can not create a sustainably procreating line of descendants. So either they can’t have kids, or their kids can’t have kids. There are probably other rubrics but that’s the one I’m familiar with. In this case I think I read that this animal has a different chromosome count than its siblings? Which would make reproduction basically impossible