Well, if biologists could ever get around to actually coming up with an international standard of measurement to determine precisely and mathematically what, exactly, a species is, we could probably answer that question.
Cute, but my guess is that they were close enough to being fruit flies that only an idiot or someone with a political point to make would try to call them another species.
I'm not a biologist, but this is my understanding of it:
First off, species are groups of organisms (this is really basic, but I don't want to leave anything out).
For species that are not gendered: (like bacteria, and lots of other stuff)
Every asexually-reproducing organism with DNA distinct from another organism could theoretically be put in a different group. For bacteria, "species" seem to be categories of convenience. It has much more meaning for organisms that are male or female.
For species that contain male and female genders: (animals, maybe plants... like I said, I'm not a biologist)
If two fertile members of a species f---, the resulting offspring should be another fertile member of that species. Obviously, some animals are not fertile (birth defects, etc. can prevent a woman from bearing children or a man from producing proper sperm). But in general, Fertile Male + Fertile Female --> One or More Fertile Offspring of the Same Species.
This is why common dogs are considered to be a single species, even though there are many "pure" breeds (because two dogs can almost always produce a mutt, even if they are from different "breeds")
Likewise, horses and donkeys are considered different species, because the offspring of a horse and donkey is a mule, which is infertile. If mules could make mule babies, then horses and donkeys would be considered to be in the same species--in fact, instead of horses on one side and donkeys on the other, we would have a continuum between the two. Some animals would be 80% horse, 20% donkey, some would be 50/50, etc. They would not be considered separate species.
This is an objective test for whether or not two animals are in the same species (and hence an objective definition for what a species is). In fact, if Intelligent Design theorists are correct, and God designed all animals, then of course there would be such a thing as species. If animals cannot evolve between species, then God would have had to create all species. Species would be put here by God. So it makes no sense for an ID person to attack evolutionists on the grounds that species are not distinct! If species are not in fact distinct, that is not evidence for intelligent design! In fact, if you look at the Hebrew Bible, Jews are specifically commanded not to mix species. Mules are an abomination--even clothing made from multiple fibers is banned (cotton + rayon --> DEMONIC). So from a creationist viewpoint, attacking the idea that species follow solid boundaries, is absurd.
The idea behind speciation is that through evolution, one species (one group of animals capable of mating with each other) would break into two separate groups. Separated somehow, the two groups would evolve separately until they became unable to produce fertile children from f---ing each other. It doesn't always require separation, as far as I know, but that is the simplest way to get there. (but it does usually take many, many years to happen, so it's not something that can generally be observed in the lab under a normal time-frame)
Species can be more complex, though. For instance, there are a bunch of arctic birds that are considered to be within the same species, even though not all members of the species can mate and produce fertile offspring with all others. There are multiple sub-species, and while all subspecies are sexually compatible with at least one other sub-species, not all sub-species are compatible with all other sub-species. Classifying animals as belonging to a species can indeed be somewhat messy, but that is evidence for evolution, not evidence for design! If God designed everything and nothing evolved, species would be easy to tell apart and would be absolute!
Already done. A species is a population whose members will will not breed with individuals of another population.