Here is what I have come to believe about this T. elegans/T. gibbosa issue:

Trametes gibbosa has been recently introduced into the US somehow( Wooden skids etc.?) Since it has similarities to T. elegans but is not in taxonomic keys for the US historically it keys out to T. elegans (closest thing to it in keys).

For a number of years the late, great Dr. Samuel Ristich was perplexed as to why T. elegans had suddenly been appearing in the Northeast when it was historically considered a more southerly species. Therefore what had been IDed as T. elegans at several NEMF forays and by clubs in the NE was probably T. gibbosa. Stay tuned, this will likely be clearer in the near future.

The description of Trametes gibbosa is copied from Ryvarden & Gilbertson :-)
I searched for DNA-proof that it really is the same as the european gibbosa, and found this abstract:
http://www.ingentaconnect.com/...
I suppose the reason why gibbosa hadn’t been reported earlier from North America, is only because the name elegans has been used instead.

This species(T gibbosa) have been reported quite commonly in North-america I found only one time(I am new mycologist of 15 years old.)

You could judge from the excellent mycoquebec.org(french on picture and description of T gibbosa.

What you call Trametes elegans looks exactly like the European Trametes gibbosa (through Asia to Japan, growing mainly on beech, but can occur on all kinds of hardwoods, and Picea too).
In my old book (-94) by Ryvarden & Gilbertson, it is said not to appear in North America.
But, as Walt points out, Trametes elegans was originally described from the tropics – New Guinea. It sounds less likely to find a species from the tropics in Ontario, more likely to find a Eurasian one. I think this species needs a check-out to find out what it really is.

Maybe not but one of the features for T. gibbosa is the layers of growth. Of more interest is T. elegans not being reported in Gilbertson North of New Jersey. It is now being found much farther north. When I learned this species from the late Wm. Bridge Cooke, he said it was subtropical!

Gilbertson and Ryvarden do not list Trametes gibbosa in their book on North American Polypores. Maybe it is a newer name for another species.