Peckoltia ephippiata is distinguished from P. pankimpuju by its well developed color and eyes; from all other congeners by the absence of spots or bands in the dorsal fin; from all congeners except P. greedoi by having small, very faint spots on the head (vs. large spots, mottling, short lines, or thick dark areas, always much more intense than the weak spots in P. ephippiata; P. greedoi has a uniformly dark head, but the small faint spots of P. ephippiata can appear uniformly dark without closer inspection); from all congeners except P. furcata, P. greedoi, P. lujani, P. pankimpuju, and P. sabaji by having the dentaries meet at an angle greater than 90°; from P. greedoi and P. lujani by the absence of bands in the dorsal fin, rays light and membranes dark (vs. bands present), by having more teeth, 39-72 dentary, 41-73 premaxillary (vs. 16-39 dentary, 20-38 premaxillary in P. greedoi; and 20-37 dentary, 23-45 premaxillary in P. lujani:), by having slight keels on the lateral plates, particularly the median series (vs. keels absent), and by having platelets on the central region of the abdomen posterior to the pectoral girdle present (vs. platelets maximally present below pectoral girdle and in a narrow, lateral column just posterior to pectoral fin, and below pelvic girdle); and from P. lujani by having the pectoral-fin spine relaxed position angled dorsally, pointing at insertion of dorsal fin (vs. pectoral-fin spine angled only slightly dorsally, pointing maximally to dorsal insertion of caudal fin) and by the pectoral-fin spine reaching two or more plates of the ventral series beyond the pelvic base when adpressed ventral to pelvic fin (vs. less than one plate).

It can be diagnosed from Etsaputu by having greater than six evertible cheek odontodes, the largest of which extends posterior to the eye (vs. six or fewer, the largest not extending beyond the exposed portion of the opercle); from Hemiancistrus (except ‘H.’ landoni) and Ancistomus by having prominent dorsal saddles (vs. dark or light spots or entirely dark); and from all Hemiancistrus and Ancistomus by having bands in the caudal fin and no free spots (vs. bands absent or present with some free spots). It differs rom Peckoltichthys bachi by having small, faint spots on the head (vs. large dark spots or mottling); by having the eyes high on the head with the dorsal rim of the orbit higher than the interorbital space (vs. low on the head, dorsal rim of orbit lower than interorbital space), and by having small plates on the abdomen (vs. relatively large) (Ref. 99824).

Description: Dorsal fin ii,7; anal fin i,4; pectoral fin i,6; pelvic fin i,5 (Ref. 99824).