deformed abdomen looks like chrysalis

[HarassedDad]

I've been sent a photo of a small tort - looks recently emerged. The top of the abdomen clearly has two rows of spines running down it, a pair to each segment, exactly like the chrysalis does. It looks like the body had grown into the inside of the spines and retained the shape. I've not seen any reference to this phenomenon anywhere. Weird mutation or is it a temporary thing in recently emerged imagos? (You can tell I'm not a breeder. I rarely see butterflies emerging)

[Neil Hulme]

It sounds from your description that the butterfly was unsuccessful in ridding itself of the entire pupal case, as it emerged and expanded. Occasionally this will leave one or two segments of the chrysalis attached as rings around the abdomen. I once saw an image depicting an extreme case, in which the part of the pupa enclosing the head-parts was still attached, despite the wings being fully inflated .... nasty!
BWs, Neil

[Roger Gibbons]

I saw something last year that is probably similar:

http://www.butterfliesoffrance.com/html ... mes_2Jul14_

It didn't seem to affect its movement, though.

[downland boy]

Continuing the theme of this thread, I have attached a couple of photos that may be of interest. The High Brown Fritillary was freshly emerged and the antennae retained remnants of pupa membrane which I gently tried to remove but they were stuck fast. The grass snake photo shows a more catastrophic outcome to skin shed failure whereby the old skin has failed to separate from the head and neck, thus preventing the creature from being able to feed.

[HarassedDad]

Having studied the photo with your comments in mind, I'm inclined to think you're right, it's the pupal case itself . In this case the pupa completely encloses the abdomen - no openings at all (along the top at least) It looks as if it simply didn't withdraw the abdomen before inflating the wings.
Thanks