A very promising cold hardy hybrid produced by B.Voss in Hamburg.
It is believed to have C.ichangensis and Poncirus as parents. Leaves are mostly monofoliate and that is why I think that the story is more complex, could be citrumeloxichangesnsis.
My plant is now more than 2 m high, planted in 2012, never protected, never damaged.
Dozens of rather large pear-sharpen fruits.

Skin is pleasantly lemon-like, although not strongly scented, albedo is moderately bitter, no poncirus taste or odor.
Around 20 large, ichangensis-like seeds.

Moderately juicy, less bitter than grapefruit, rather acid, but less than lemon.
Some fruity aftertaste is faintly present, but is is very different from poncirus.
Amazingly, at this stage the juice already contains a lot of sugar: 11.5° of Brix, approximately the same as commercial clementines.