The exporter has now ID'd them as Mylossoma duriventre. I can't seem to find much info on them, but they are getting more and more red and orange in their anal fins. They're also losing the single spot in the middle of the body, and their bars are visible, though fading somewhat from what they initially had.
Has anyone kept any Mylossoma with live plants? My red hooks will annihilate live plants (usually within hours), but so far the few small jungle vals I've put in with the Mylossoma have lasted ok with only a bit of nibbling.