This seems to be the currently most accepted treatment. I think it still gets debated some though. There is also the name "gothica" that sometimes still pops up for yellow individuals in inland populations (versus "nitra for black). Generally the yellow form is much more common than the black, but one batch of eggs can produce both color forms, from either color of mother, from almost any location, and nitra is the older name.

However, I just checked the 'Butterflies of America' web site, and they aren't making any subspecies distinctions within the species now.

To me the biology and appearance of near coastal insects is fairly distinct from the single-brooded inland populations, even though the line between may be pretty fuzzy.

Todd Stout did an interesting little write up of the butterfly here:
http://www.utahlepsociety.org/pzelicaonnitra.html
And, there have been several other aticles on the subject.

I suppose the two best options here are 1) drop the subspecies altogether for all of them and go the route of 'Butterflies of America', or 2) this individual is subspecies nitra. I don't want to lump everything together without a concensus, so I'm going to go ahead and move this one.

Moved from Anise Swallowtail.