I have seen that photo before.
One cannot tell from that photo whether the air bubbles are UNDER or OVER the pupal covering. Some aquatic organisms such as black flies harvest air bubbles from rocks and use the air to rise in the water column.
http://www.google.com/search?hl=en&c...bubble&spell=1
The question for me is whether the air is under the pupal skin which means it came from the pupa or whether the air is over the skin which means the pupa likely harvested it from underwater air bubble on plants and rocks.