Parotocinclus variola can be distinguished from all other congeners from northeastern to southeastern Brazilian rivers in having the cheek canal plate elongated posteriorly on the ventral surface of head and contacting the cleithrum. It differs from P. collinsae (Essequibo River basin, Guiana) and P. halbothi (rio Trombetas basin, Brazil and Marowijne River, Suriname), by the presence of a triangular patch of dark pigmentation on the anterior portion of the

dorsal-fin membrane, by the absence of unicuspid accessory teeth on both the premaxilla and dentary, and by having a Y-shaped light mark on the snout . It can be separated from all other species of Parotocinclus from Amazon, Orinoco and the Guianas by possessing a pigmentation pattern consisting of conspicuous dark dots smaller than a pupil diameter, broadly distributed dorsally and ventrally. It further differs from P. eppleyi (Orinoco basin), P. longirostris, P. amazonensis (Amazon basin) and P. britskii (Orinoco and coastal drainages of the Guianas) by having the central abdominal plates arranged in a single series between the lateral abdominal plates, from the coracoid to the preanal plate and with a wide naked area at the pelvic-fin base (vs. arranged in two or more series between the lateral abdominal plates and without wide naked area at the pelvic-fin base). It can be further diagnosed from P. eppleyi, P. longirostris, and P. polyochrus by having a Y-shaped, light mark on the snout only (vs. Y-shaped, light mark present on both the snout and head). It can be further distinguished from its congeners in having more oral teeth: 38-46 premaxillary and 39- 46 dentary teeth (Ref. 100824).