Having looked again, I would agree with lintworm. The stripes on this seem to go right down to the belly, while on the Veiled I saw at Oregon they only went down ~two-thirds of the body. There's also the horn...
Is Meller's a rare species in captivity? I have only seen them at Madrid and Wroclaw.
I don't think they are as rare in North America as in Europe. I know that Saint Louis has them, and I believe that Lincoln Park Zoo in Chicago does as well, among other places. They are also part of the exotic pet trade.
There's almost certainly more in captivity in Europe than in USA. Same with most chameleon species (including the less frequent Madagascar species that are smuggled and therefore fundamentally problematic). As always there are far more kept privately than in zoos. It's not among the most common chameleon species in captivity, but it's not really a true rarity either.
Keep in mind that although zootierliste is an excellent resource for European zoos, it is not really that complete when it comes to things like reptiles (+amphibians+fish) with many entries that either are missing or outdated.
