Solution
W. F. von Holzhausen Akademische Schachblätter, 1901
5+2. Mate in 1
There is no apparent mate in 1. Anyway, it can be seen that White did play last (Black has no last move) so that Black has the move.
Black plays 0 ... Kxa7 / Kxc7 / Rxa7 and is mated by 1. b8=N / ba8=N / Rc8#.