You missed out karate, TKD and TSD.
Sambo is in itself a mixed martial art.
I don't think Karate, TKD, or TSD are very well represented (at least compared to styles like BJJ, Muay Thai, Wrestling, and Boxing), regardless of whether or not they deserve to be. Certainly there are some talented fighters who have trained these styles in the past, or still do (Machida, Liddell, Bas, Cung Le, etc).
I guess you could call Sambo a mixed martial art. It evolved from Judo and folk wrestling. Though of all the styles of sambo, only combat sambo incorporates striking. The thing is, mixed martial arts implies the mixing of multiple styles. And sambo is considered to be a single style. But you are right.