Papilio polyxenes, zelicaon, & ♀ ​polyxenes asterius × ♂ zelicaon Pupae Comparison (Pharate)

Comparison of the pharate pupae of the black swallowtail (Papilio polyxenes asterius), anise swallowtail (Papilio zelicaon) and a ♀ Papilio ​polyxenes asterius × ♂ Papilio zelicaon hybrid cross.

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The hybrid is almost here now. Just another day and it should be out. As of tonight it is pharate and the wing patterns can already be seen. We currently also have pharate zelicaon and a close to pharate polyxenes (the two parent species) for comparison, plus an actually pharate male and female polyxenes photo from a month ago (bottom center). All pupa shown are male except for the female polyxenes.

The main thing to compare here is the amount of yellow on the wings. It's the number one difference that separates zelicaon and polyxenes adults (and many other closely related western and eastern swallowtails) and thus the also main area of focus on the hybrid wing patterns as well. In zelicaon, the fore and hind wings of both males and females are predominantly yellow. In polyxenes, both males and females are predominantly black, but the male has a thin row of yellow on both fore and hind wings while the female is almost entirely black. See Papilio zelicaon and Papilio polyxenes asterius Side by Side Pictures for a visual.

On the developing pupae, the zelicaon very clearly has a large yellow portion on the hindwing while the male polyxenes only has a small strip of yellow spots. The hybrid, on the other hand appears to be a perfect intermediate, having the yellow portion of the zelicaon wing pattern but rather than a bright rich yellow, it is partially masked by black, turning it into a greyish yellow. The hybrid also has the marginal row of yellow spots, a trait shared by both parent species.

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​Authors
Alan Liang

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