You've got that wrong... absolutely wrong...O_O WUT? whats a Wurm? She is clearly a Dragonized lamia.
A wurm is a dragon with an elongated body and no hind legs, in other words a wurm is a serpent like the Quetzalcoatl, the Cuélebre or the Leviathan.
Serpents have nothing in common with nagas but for the long tail and they're closer to dragons (since they're a dragon subspecies) than nagas.
It's not a mispelling but an alternate spelling, Wurm is as accurate as either Wyrm or Worm are. The fact that people feels more comfortable with the term Wyrm it doesn't mean that it's the only proper term.I dunno why KK mispelled that
However it might be a good idea to change it to "Wyrm" in the final translated version since it will save you quite the controversy and intransigence once it's done.
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Speaking of serpents... I can't help but wonder if we will see more of this subspecies in the future...