Does anyone know a book which features an alien race called the Q'thraaa? It's probably from the 1980s. I don't have any other information for it but it's driving me mad!
I thought of 2 possibilities based on similarities to the name you remember, one from the sound of the name, another based on the look of the name.
1. sound : The Pride of Chanur by C.J.Cherryh (1981) -- first book in the Chanur series. If you have a primarily auditory memory of the name, there are races called Tc'a and Kif, and lots of words with "kk" and "aah" sounds.
2. look : A Matter for Men by David Gerrold (1983) -- first book in the The War Against the Chtorr series. I have a more visual memory, which is why "Q'thraaa" reminded me of reading the word Chtorr as the name for the aliens, and the word Chtorran in descriptions.
3. Alternate spelling : Alien race known as the K'Thraa in Earth Invaded by Christopher Evans (1986) -- first book in The Hood's Army trilogy.