Synonyms and other taxonomic changes
ssp. gothica
Explanation of Names
There has been a lot of debate over the years as to whether the inland populations of P. zelicaon are different enough to consider as a distinct subspecies from "typical" zelicaon from closer to the Pacific. Also, it is debated, assuming there is a difference, just what the difference is, and where one population begins and the other ends.
The name "gothica" was long used for the inland (particularly Rocky Mountain region) populations, but it was shown that the black "nitra" is just a color form of the same thing, and the name "nitra" is the older name so takes priority over the name "gothica". Even though the name "gothica" was applied to the common yellow form, and the name "nitra was originally applied to the rare black form, the older name is the proper name.
Identification
A few qualitative distinctions of subspecies nitra from typical zelicaon that are more tendencies than absolute differences include the following: smaller size; somewhat more rounded wings; shorter tails; more extensive black coloring; body more "hairy"; black form more likely to occur; single-brooded as apposed to sometimes double or multiple-brooded. It has been suggested that most of these differences are the result of differing environments, and the question needs more study.