[quote=@DarkwolfX37]
<Snipped quote by DarkwolfX37>

And before you even, we specifically discussed unicorn anatomy in the context of how they evolved. One of us thought there was a bone in the horn and one didn't, don't remember which of us had which position. 
[/quote]

There's no problem with that. It only makes sense that all four subsets arose from one group. But I don't know that they can be considered separate species because their phenotypes are different, but it seems to be a random aspect of the genome due to the fact that they can reproduce and the offspring will be any of the 3/4.