I doubt they'd introduce a new type. "Sylvan" means something with forests, too. Obviously it can't be a grass-type, but I'd be surprised if that's unrelated.
That is unrelated, its name is based on "Sylph," an air elemental, according to Bulbapedia. So it's a flying-type. Or it was made by Silph Co., one of the two.
Oops, that was talk page speculation. I need to stop talking. ;~;