Xelatian
Xelatians were a sentient, humanoid species, whose homeworld was a member of the United Federation of Planets by the late 23rd century. 

Xelatians were 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. 

In 2286, the Xelatians were represented by two ambassadors on the Federation Council. ()

Appendices

Background information 
The name of this species comes from FASA's Star Trek IV Sourcebook Update. While strictly a non-canon source, it is the only widely recognized source for names of most of the Star Trek IV aliens.

According to that source, the Xelatians were a race of s, possessing four-meter long tentacles for limbs instead of arms and legs. Xelatians communicate among themselves using telepathy and bio-luminescent pigmentation. To survive on land, they need environmental suits to trap moisture and circulate water through their gill slits. They also need anti-grav harnesses to move about on land. Xelatians wear masks because standard lighting is too bright for them. First contact with the Xelatians was made by the USS Audacious.

Their homeworld was called Xelata, which is the third planet in the Tau 56 system.

External link
 

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Species
Memory Alpha articles named from supplementary resources