so in summary of the mandrill situation in Australia:
*Melbourne Zoo -- all hybrids of mandrill X drill
*Adelaide Zoo -- were all pure mandrills but their breeding male is now a Melbourne hybrid (and females from Melbourne may have also been added previously?)
*Tasmania Zoo -- two retired animals, both pure mandrills (male certainly)
*Taronga Zoo -- were all pure mandrills (possibly derived from the direct import from Africa I mentioned earlier) but now all dead or mixed into the other zoos' populations.
It isn't really a big deal that they are all hybrids because they are only display animals. The only issue would be if individuals were sent overseas and mixed into groups of pure mandrills but that is unlikely to happen.
My understanding is that all breeding from the hybrid animals stopped, and only pure mandrills were bred, making all individulas in the region pure.