Reason
Many users, especially those who live in countries where "opossum" and "possum" are interchangable, don't actually know the difference between the two, or sometimes that there even is one. Having them aliased to didelphid, and phalangeriform respectively may hint that they are different, but it often goes unnoticed. This leads to a constant tag project. The scientific names have their own pros and cons, but the common name might help users more if it has some context. I suggest adding a continent to the tag to potentially help and clear up confusion. Another potential suggestion is adding visual context, however there are exceptions with a couple of species, it would make a smaller tag project. If you have other suggestions, please share.
Examples:
opossum_(americas)
possum_(australia)
Or,
didelphid_(americas)
phalangeriform_(australia)
opossum_(bare_tail)
possum_(furry_tail)
Updated