Baryancistrus demantoides

Baryancistrus demantoides
Hi Fin Green Phantom Pleco (L200a)
The colouration of this fish can only really be confused with Hemiancistrus subviridis. The key to tell these two apart is that the dorsal fin and the adipose fin are connected in this species, and separated in the Hemiancistrus species. 
On a more technical side, this is the keys to distinquish the fish from original species description: Baryancistrus demantoides can be distinguished from all other Loricariids except Baryancistrus niveatus, Parancistrus, and Spectracanthicus by having the dorsal and adipose fins connected by an expanded posterior section of the dorsal-fin membrane. Baryancistrus demantoides can be separated from the other species with connected dorsal fins by having a yellow-olive color with white or cream colored spots (vs. typically dark with white, gold, or no spots); from other Baryancistrus with the dorsal fins connected by having the spots only on the anterior portion on the body (vs. all over), from Parancistrus by not being dorsoventrally flattened, and from Spectracanthicus by having greater than 30 teeth per jaw ramus (vs. less than 25). There is one other described species of Baryancistrus (B. longipinnis) that has an expanded posterior membrane of the dorsal fin, but the membrane does not connect to the adipose fin as in B. demantoides and B. longipinnis lacks light spots.