papilio vs. pterourus

[Michael Gochfeld]

I agree that most recent books are using the broad generic concept of 
Papilio (although I'm not sure this is conservative).

Interestingly the swallowtail-ologists are more likely to engage in 
generic splitting. For instance, Tyler, Brown and Wilson (Swallowtail 
Butterflies of North America) split (or retain) Pterourus and 
Heraclides as well.  It may be understandable when you have a book 
entirely on swallowtails, that you would be more inclined to split, 
rather than have a long monotonous list of Papilios. Others might simply 
call these subgenera. 

Regardless of your taxonomic philosophy or where you stand on splitting 
or lumping on any level, I suspect you would enjoy "A Note on 
Systematics and Philosophy" (page 26 of the aforementioned book), which 
includes: 

"they seem to be undergoing rapid diversification almost under our very 
noses."
"We have not yet discovered a uniformly applicable and objective way to 
deal with the fact that evolution is always underway and some lineages 
are in the middle of the process of speciation."
Butterflies "resist attempts to establish absolute and universal 
criteria for their classification, tending instead to be exuberant and 
mischievious proclaimers of the variability inherent in any dynamic and 
adapting natural system."

They have a lot more to say about the species level including the not 
very radical statement:  "Where two entities ...can be obtained by 
rearing the eggs from a single female, we do not hestiate to regard them 
as...the same species"  Whew---it's nice to agree on something. 

About molecular systematics they suggest that "this will only maintain, 
increase, or rearrange the present confusion and uncertainty."

Interestingly, I couldn't find their philosophy on the genera. 

M. Gochfeld