Attached are a few photos of a BN I have. I received about 8 from a friend who collected fish from South America (he colletcs c***lids, and he often imports them, and he gets some bristlenose as a bonus. Two of the fish I have are dark, almost black with distinct spots. The other 6 are similar to this guy, except the light and dark areas on the body are not consistent between fish. They all have the same spots, body shape and the same markings on the fins. I thought these 6 would be a common BN, but the black might be another species.
I sent you a pm, but I don't think there are more for sale, if that is what you are interested in, the plecos came along for the ride with his other SA fish........
I agree with Mike. Particulary, IF THEY ARE WILDCAUGHT, they are nearly 100% sure NOT to be A. sp(3), but some other Ancistrus species. There are 53 described species of Ancistrus, and many of them are pretty similar until you start looking at very fine details...
There's probably also another similar amount of currently undescribed species...
A capture location would at the very least help rule a few of them out...