Double-sex butterfly

This article was in the Guardian today, talking about a bilateral gynandromorph butterfly which emerged at the NHM's Sensational Butterflies exhibit last week. The individual is a Great Mormon, Papilio memnon, a polymorphic mimetic swallowtail (like my favourite Papilio dardanus) from South East Asia. The genetic control of the polymorphism by a supergene was demonstrated by Cyril Clarke and Philip Sheppard in the 1960's.

Photograph: Kevin Webb/Natural History Museum, via guardian.co.uk

I have talked about this before. This specimen is a bilateral gynandromorph - the two sides of its body are composed of cells of different sexes. Here, the left hand side is male, showing the characteristic male pattern of this species and the right hand side is female. The genitalia are likewise mismatched - one male clasper and one half of the female reproductive system.

This was how it looked this afternoon; rather tatty. When this butterfly dies (likely in the next week or so) we will examine it much more closely to examine this rare phenomenon. Watch this space!