Starting off with the least-known species. It is the only known goblinoid species known from Sansorna, a largely-unknown continent far to the West, which is notoriously hard to reach and only one expedition sent there having actually made it back so far. They have a number of unique traits like the whiskers (while all imps have a row of sensitive feathers under their eyes, they are not bristle-like), differing ear structure and foot scute pattern. The gliding membranes being bare on their undersides seems to be an adaption to life in mountain forests; the sailors reported the coast they anchored at had forested mountains nearby, where such half-feathered membranes would be useful to deal with the temperature differences between day and night.
There is very little known about their behaviour and culture, but reports said their vocalisations sounded like mocking laughter, but whether this is true or the imagination of panicked men is up to debate.