Still water in woodland.
No interactions present.
Yes, very likely H. palustris with such a strong pattern, but I'd want to put it under a microscope to make sure it isn't incognitus.
John I would agree with that view on this. Wonder what you think of the other specimens identified as palustris.? the one on the left looks like Suphrodytes to me with its circular patches
Yes, could be. The convexity of the sides of the pronotum suggests it isn't Hydroporus. I'll leave it for you to put a new id.
The snag is, if you correct it, the picture will disappear from this thread and no one will know what we are talking about.
Lat/Lng: 54.57405, -1.04074
OS grid ref: NZ621202
Still water in woodland