The Vnartia are a species, a civilization native to either the Alpha, Beta, or Gamma Quadrants. The Vnartia were present at Deep Space 9 for the trade negotiations in 2370. After Sisko finished tending to the arguing Klingon and Aresai ambassadors following the bombing of Garak's store, the Vnartia ambassador was extremely upset at having been put on hold. She told Sisko that, out of shame, he should cut off one of his right hands, only to be reminded that Humans do not regenerate limbs. (DS9 novel: Betrayal)

The Vnartia ambassador's line about Sisko cutting off "one" of his right hands perhaps indicates that they have more than two hands themselves. She was also said to have been "swollen purple with indignation". This could mean that the Vnartia have purple skin (or skin that changes color). However, it's also possible that the author was just being metaphorical.