As juveniles a few BNs look similar to L183, there are a few key distinguishing features of L183 that make them identifyable but it can still be quite difficult. The #1 feature is that L183 have more dorsal rays than other species of BN's. Also, as adults, L183 maintains the white bands while others that look similar as juveniles lose them as adults.
Photos of your plecs, even marginally good ones, can go a long way in providing a positive ID. When you get used to looking at them & know what to look at, BNs are pretty easy to ID (at least enough to place them in the Ancistrus family).