For this Cryptid File I wasn't really trying to design a Chupa that resembled any known species or looks realistic- I just blended together traits from sightings and mixed in a few touches of my own.
A lot of reports include wings or a gliding membrane, so I kinda mixed the two ideas and gave him a gliding skin supported by an elongated fourth finger, sort of like miniature pterodactyl wings.
Since they're sometimes described as being covered in short hairs, I gave mine some bristles- smaller spines that might be mistaken in the dark for hairs. Of course I kept the large spines- which can flash bioluminescence at night, since some eyewitnesses claim that the Chupacabras spines can "change color".
Like any good Chupa, mine has large eyes that are very sensitive to light. While this is a disadvantage during the day, it allows them to hunt at night and spot the bioluminescence of other Chupacabras.
As far as the mouth goes, I went for a very different concept. Usually Chupas are shown with big vampire fangs, but you can't really suck blood through teeth like that, so I came up with an alternative method.
This Chupacabra's fangs are more like those of a rattlesnake or spider. Supplied with venom glands, the Chupacabra injects a chemical agent that liquifies the prey's insides. Then, jabbing into the wound (or straight through the flesh if needed), the Chupacabra uses it's modified, straw-like tongue to suck up the blood and liquified organs, leaving it's victim as a meer husk, not much more than a skeleton with skin draped overtop.