I could see it being U. vulgaris but it would help if the flower were fully-developed. Do you have a photo of the main part of the plant?
A cold one that is not cold is scarcely a one at all. - SB
Could be U.australis. I agree with Mark though, a pic of a fully opened flower would help.
I hate to tell you, Jim, but that looks a lot like U. gibba to me.
Yup. Flower looks more like U.gibba now and traps definitely look like U.gibba. I'd say you've got U.gibba there.
I'm curious to know what it was supposed to be. I think you only told us what it wasn't, and I'm curious.
My U.Gibba, Aurea and stellaris all flower in the pond and it is never below the 50cm deep mark, so I guess they don't care if its shallow, in saying this they won't flower unless their in a dense mass in deep water, but as single plants they will all flower in 1-2cm water, so maybe the dense colony tricks the plant, or maybe they just need the support to flower?