I would have called that a coppernose cause of the roundness and dark color. But then, someone took a picture recently of an orangish coppernose and posted it. I still have trouble telling the different BG apart, it seems. Would have called the orangish one a pumpkinseed.
I've caught a lot of black gills under the trees in my fav cypress ponds. They are so black it comes off on your hands. The tannin from the annual bark shedding I suppose. I've thought of giving one a rinse under a light spray just to see what color it really was.