For when bestiality doesn't make sense, e.g. human-alien or human-humanoid debauchery.

I thought that was already a tag. Oh, I'm thinking of interracial.
Anyway, interspecies seems a legit tag.

There's xenophile, but interspecies sounds better. Though if people start using it on completely human-looking characters minus blue skin/horns/whatever, Touhou, or other cases of MUH CANON, we might as well kill the tag now before the cancer starts.

What exactly constitutes "MUH CANON?"

Elves, demon girls, kanmusu and the admiral, Takatsuki Ichika, everything from Touhou, take your pick. How far the defintion of interspecies will go needs to be addressed, or people will take the definition extremely literally and include half the site just because it's not canon-human with canon-human.

If we want to draw the line at monster girl for "humanoid" characters, it would go a long way in stopping the eventual mess.

Hillside_Moose said:

If we want to draw the line at monster girl for "humanoid" characters, it would go a long way in stopping the eventual mess.

That would be a rather thin line between bestiality and "normal" sex. Can't be too human and can't be too inhuman?
I would need some examples.

Seems like bestiality would be interspecies too. I sense the wink and one_eye_closed madness returning...