Xelatian
From Memory Alpha, the free Star Trek reference
Xelatians are a humanoid species and members of the United Federation of Planets. The Xelatians were represented on the Federation Council by two ambassadors in 2285 during the crisis created by the alien Whale Probe.
Xelatians are distinguished in appearance by the metallic gold faceplate used to cover all portions of their face with only a small area for viewing where the eyes would ordinarily be. (Star Trek IV: The Voyage Home)
The name for this species comes from the FASA Star Trek IV Sourcebook Update book, however, this information has never been mentioned on-screen.
