Thank you very much!
In the Wikipedia list is a link to the "Airplane Engine Encyclopedia", both mention a 18 cylinder with 200hp, but do not name it.
This makes sense, the U.III was a two row Lambda-Lambda copy.
I have a book about the Steyr-Daimler-Puch AG in Austria from 1864 to 1918. There are nice pictures of the production of a license built Gnome with 11 cylinder, 160hp and 191kg. May be it is derived from the Oberursel Ur.III ? The text call then Gnome, but the look more like a Le Rhone with intake pipes and valve rocker on back side.
On of the aircrafts using this was the Aviatik 30.40 and 30.27. In the "Austro-Hingarian Army Arircraft" of WWI this engine is rated with 150hp.
Cheers,
Frank