There is only a single mention of a Hedgehog in the whole of Fighting Fantasy canon is in Deathmoor where YOU may encounter "the skeleton of a small animal - perhaps a hedgehog".[1]
This implies that Hedgehogs exist in north-east Khul at least, but their wider distribution is unknown - it is possible that these small, unobtrusive creatures are widespread but are not mentioned because they rarely impact upon the lives of other inhabitants of Titan.
- For another possible Hedgehog in Fighting Fantasy (this time in Allansia), see Monotremes