Limenitis

[The Arthurs]

Hi. I have been looking on-line lately about the relationships between the various species of Limenitis that live in North America. They seem to all be surprisingly closely related. I have found records of hybrids between all of the species that overlap; even between lorquini and archippus, and L. archippus X L. arthemis astyanax hybrids have been found forty-five times. There's a photograph on BugGuide of what appears to be a hybrid between L. weidemeyerii and L. archippus, which was taken in southeastern Arizona. It is like a weidemeyerii without the white median bands, and has relatively large dull orange postmedian spots on the hindwing. Apparently, by what I've read, lorquini and arthemis form a blend zone where they come together. With all this hybridization, it would seem that all the Limenitis, or at least archippus and arthemis, may be forms of one variable species. What has convinced scientists that this is not the case? 

Tiger swallowtails (Papilio? Pterourus?) also look very closely related and possibly like a single, variable species. For example, in J. Scott's Butterflies of North America, it says that most of the artificially induced hybrids between P. rutulus and P. glaucus produced adults. I have also read that glaucus, rutulus, and canadensis hybridize in the wild. Also, I recently caught a male rutulus here in Oakland, California that shows many traits of canadensis, such as relatively small size, narrow and restricted black borders on the hindwings and rounded, rather than long and pointed, forewings. What convinces scientists that all the tigers should be different species from one another? 

Besides that odd specimen, there are two forms or rutulus in Oakland. One is rather pale yellow, with narrow black stripes, the stub-tail just below the tail on the hindwing is rather long (not quite long enough to be multicaudatus), and there is very little orange on the underside. The other is brighter yellow with a very short stub-tail and has relatively extensive orange suffusion in the postmedian hindwing, as well as in the submarginal spots. In one extreme of this form that I caught, there was orange in the uppermost submarginal yellow spot on the upperside of the hindwing. Are these forms two different subspecies that meet in the Bay Area? 

Thanks. 

 -- Noah Arthur, Oakland, CA 

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