The crystal fox we see on Crait in The Last Jedi trailer is a vulptex; A pack of them would be vulptices, and the name was developed by Pablo Hidalgo. Detailed today in Entertainment Weekly, the creatures will be both animatronic puppets and digital creations.
“They live within the burrows and within the tunnels beneath the planet,” [Creature shop head Neal] Scanlan says. “So there is a time where their ability to shine within the darkness, should provide a guiding light to our heroes.”