Here are two Canon species that have not made an appearance yet that I am aware of. Kerelians where mentioned in the TNG Episode: “Lessons”, Kriosians appeared in both ST: ENT: “Precious Cargo” and ST: TNG: Perfect Mate. Enjoy!
Feel free to leave your comments or thoughts down below.
Based on references in TNG Mind’s Eye it was reveled that the Kriosians were subjects of the Klingon Empire.
Yes, they were Klingon subjects. In the episode of TNG The Perfect Mate [2368], they have gained their independence and re-unify with their Valtese cousins.
The Kriosians also appear in ENT “Precious Cargo”, where we get a glimpse at the Kriosian Kingdom prior to the Klingon conquest.