@Goura I had the same problem when I was there in April. Many of the bird species, the Lesser mousedeer (Bornean subspecies) and Prevost squirrel are also unsigned in that walkthrough. Which is a pity because it is one of the best enclosures in the zoo.
@Goura I suppose I would argue that ongoing changes should be matched by changes to signage. I've visited Jurong three times over a two year period and I did feel that as the species line up in, say, Jungle Jewels weakened the signage got worse as well, but I wouldn't really like to pass judgement.