I can't offer much help.
I currently have five of these in a 38g tank, but are no closer than you to a definative ID. Honestly I haven't tried all that hard either though. I bought mine as Orange-Fin Plecos though, not Red. Good to know they are from Columbia, should help narrow it down a bit.
This is as close as I can find in the
Cat-ELog, but for my fish it's not quite right. This fish actually looks more like a second group of "Orange-Fin Plecos" that I picked up in a different store.
There was a recent thread (can't remember who posted it though) that had photos much closer to my fish. I'll do a little digging through old posts tonight.