Here's info for the Rio Negro Pleco. This seems to be the species listed at LiveAquaria.
Peckoltia braueri • Loricariidae • Cat-eLog
I've never ordered from LiveAquaria so I really can't speak to how good or bad they might be. Shipping fish though in general can get expensive. Just something to keep in mind if you want a fish from the West Coast.
The one pleco I'd really love to have for my blackwater is L183
. I've seen them various places online, but just haven't gotten them yet.
I've also had red lizard whiptails
. Not really centerpiece fish, but I loved them and would like more someday.
Those aren't all your choices, just the ones I like best ;)