Do you have to have put the map together in order for the Loyalty Potion Totem to list Hydrus as an option? I was going to use mine and it isn't listed.

Hydrus is not really a color...? If you ever pound a pet that's Hydrus it will go back to it's original default color (common color). I'm not sure that it would be listed as such, but the good thing is at least the Map is fairly easy to put together. :)