Istervaalan

Istervaalans were a species that had evolved from mountain goats on the planet Istervaal. The Tenth Doctor claimed of the species, "Evolution didn't take a funny old turn there". (PROSE: Ghosts of India)

Behind the scenes
The species is simply used for a gag in Ghosts of India, and the Doctor never actually names the species. Thus Istervaalan may only be a rather than a proper species name.