No source, but iirc the scientists applied a colored dot on the ants head. When they saw themselves in the mirror the started trying to remove it from their heads.
There are parasitic mites that attach themselves to ants and they look like a colored dot (usually red).
I think the ant “thinking” that the dot was a mite is a much more plausible explanation than the that the ant is some how conscious with its cluster of like 3 and a half neurons
So the ant (allegedly -- I'm eagerly awaiting that source!) saw a dot on the ant in the mirror, and tried to remove the dot on its own forehead. The key point: that looks an awful lot like the identification of the self with the reflected image.
The issue you brought up about the mite is a bit orthogonal to this point. I can give you that the ant was concerned about the possibility of having a mite, and the point still remains that the ant thought it was on its own head only on basis of a reflected image of itself. (Compare to the alternative behavior: the ant tries to get the mite off the reflected image, never making any attempt to remove it from itself.)
