Moved from Notonecta undulata.

Moved tentatively. Ordinarily, I like to get a good look at the key character(s) for a taxon. In this case, the interocular distances seem to be a good match. From what I can make out, the mesotrochanter seems angulate and not spinose.

Thanks for posting the extra photo. It's too bad the critter wasn't quite ready for its close-up!

This is either N. unifasciata]/i] or [i]N. spinosa. I'm leaning towards the former. It would be helpful if you had a clearer shot of the middle leg -- specifically, whether the base of the leg, the trochanter, is angulate or spinose. I can't quite make out which it is from your ventral photo.

Both of these species have a similar color pattern, including the "V" marking on the pronotum. This marking is lacking in N. undulata. Notonectids go on fly-about quite often and will wind up in the weirdest places. They tend to land on cars, as many aquatic insects will do.