How would I best express this in English?

I’m new to English writing and, unfortunately, I cannot even find words to describe the problem properly (I guess there would be a special name for this issue).
I wrote a sentence "[…] the assessment of alpha-diversity only requires the distinction between, but not the identification of species" but I am not sure whether this is clear and correct or it would be preferable to wrap the "what it is not"-part (I want to highlight what it is not about, however just slightly ;D) in em dashes. I’m also not sure about the necessity of the "but". But then, should lots of dashes even be used in scientific writing?
So, what’s the most appropriate version?

1. […] requires the distinction between, but not the identification of species
2. […] requires the distinction between—but not the identification of—species
3. […] requires the distinction between—not the identification of—species