In my science fiction universe I think I've already mentioned one of the species that occupies the outer rim planets: Arachnids. Rather than one species of spider Arachnids are a group of multiple species but all of which are giant spiders (the smallest of which being the size of a common housecat, the largest discovered being the size of a double decker bus). While not serving as main antagonists, but still serving as enemies with impact on the story is a cult who worship the giant spiders as gods. The cult is a mixture of different species including humans, Curabitur (mentioned before) and Usurha (bird-like people). I've struck a bit of a mental blank with the name though and I was wondering if someone could help me out.