Were these kept in the exhibit with Indochinese box turtle, Vietnamese pond turtle, Tokay gecko, Pricklenape, and Phonsaly flying frog in the Cat/Reptile house (opposite the Malayan/Sumatran tiger indoor exhibits)?
On my three visits (once in July of last year, and then twice yesterday and the day before) I have missed these, when I did spend quite some time at their exhibit. On zootierliste they are listed in the former holdings, but the last proof of this species being present in the collection would be the yearbook in 2014 (or, well, your picture here, though judging by the description I believe they were unsigned?). However, they are still signed now, so I'm not sure what to think.