Cabbage Tree Emperor Moth from Sierra Leone: Gynandromorph or Not???

Subject: Interesting bilateral gynandromorph
Location: Freetown, Sierra Leone
July 2, 2015 5:07 am
Spotted in Freetown, Sierra Leone at 9 am on July 2nd. Possibly a species of dactyloceras?
Signature: Jules

Bunaea alcinoe
Cabbage Tree Emperor Moth

Dear Jules,
We believe your moth is a Cabbage Tree Emperor Moth or Common Emperor Moth,
Bunaea alcinoe, a species of Giant Silkmoth found in many African countries that is pictured on African Moths, and we are really curious why you believe this is a bilateral gynandromorph.  It appears that half of the body is in brighter light than the other half which is in shadow, and we cannot really see the antennae in your image.  This species does not have pronounced sexual dimorphism, and a primary means of distinguishing the male from the female quickly is the antennae.  If we are missing something, please let us know why you believe this to be a bilateral gynandromorph, the scientific name for an hermaphrodite.  Please get back to us and let us know why you believe this is a gynandromorph  Though we don’t have any images of the adult moth on our site, we do have numerous images of the caterpillars, including this posting of a caterpillar from Sierra Leone.

Update:  July 9, 2015
Hi Daniel,
I believed the moth in question was a bilateral gynandromorph because it had one hairy antenna (the left one) and one not, and because the yellow ‘eye’ was only present on the left wing. Sorry about the low-quality photo – it was a quick cell phone snap!

Thanks for getting back to us Julian.  If you observed two different types of antennae, then this might be a gynandromorph, but that difference is not visible in the image you provided.  Male Giant Silkmoths have more developed, feathery antennae, while those of the female are much thinner.  Though the comparison is of a different species, you can see the antennae of the male Cecropia Moth compared to a female on the Prairie Haven site, after scrolling down.  You can also compare the male and female mating Polyphemus moths on our site, with the male being the individual on the right in the second image.  The yellow eyespot or oculi in your image is not a consideration.  Many Giant Silkmoths have oculi on the lower wings and the spots are generally hidden while the moth is resting.  When disturbed, the oculi are revealed, frequently startling a predator like a bird who may think it has disturbed a much larger predator.  The moth in your image is winking by only revealing one spot.  The spot on the other side is hidden by the upper wing.  We also have a nice image of a “winking” Polyphemus Moth on our site.  

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