Sir, The new “species” of butterfly created by hybridising two Heliconius butterflies is by no means the first known case of a hybrid acting as a new species.
In the book The Charm of Birds by Viscount Grey of Fallodon, Northumberland, the author reports how in 1917 a pinioned captive white-eyed (ferruginous) pochard in his collection (Aythya nyroca) sired two offspring with an unpinioned tufted duck (Aythya fuligula).
The free-flying offspring, a drake and a duck, then mated with each other, and gave rise to several generations consistently coloured like the original hybrids, and to his knowledge only mating with their own new kind at least up until 1927.
JAMES LEVY
London NW11