I've had past experience with these at camp. I never got to hold one until I went to the Bronx Zoo. So that was a real treat. While researching these I was reminded that these were mind boggling little bastards ( no harm meant, quite the opposite ).
And why do you ask? Well this is why my dear friends. They're polytypic. What does it mean?
WARNING!: Trying to understand the following will result in a major headache.
The White Admiral or Red-spotted Purple (Limenitis arthemis) is a polytypic species of North American brush-footed butterfly, common throughout much of the eastern United States. L. a. astyanax has red spots on its underside and the top of the wings are notable for their iridescent blue markings. L. a. arthemis on the other hand has a large white band traversing both the forewings and hindwings.
The Red-spotted Purple is a mimic of the poisonous Pipevine Swallowtail (Battus philenor) and is typically found in open woodlands and along forest edges.
Are you screaming from the pain yet? :P Yeah this is mind boggling because I don't have the slightest clue what polytypic means and Wiki doesn't give a decent definition.
I'll have to look for one and edit this post with updated info. I'm just guessing that this is another form of the White Admiral and they named it as subspecies. The Bronx Zoo has it listed as Limenitis astyanax instead of Limenitis a. astyanax.
They're making people think they're separate species!! Oh blasphemy! :P And they fooled me too because I had forgotten about all of this.
But it's fascinating even if thinking on it too much makes your head hurt.
Rest of info here.