Speco just means 'kind'. So while the name of a particular species would be an appropriate answer to this question, so would something more vague. For instance, you could certainly reply 'it's a gorilla', but you could also say 'it's some kind of primate', or 'it's a mammal', etc.
The word for 'species' is specio. (And the i in that word is not an affix, it's just part of the root.)