Chauliocheilos saxatilis is distinguished from all species of the Loricariidae by its unique labial appendix at laterodorsal portion of lower lip, associated to the proximal region of insertion of the maxillary barbel, in females above 3.24 cm SL and in males above 3.0 cm SL, but always much more developed in males, in which the appendix is highly grooved and can be very elongated posteriorly, surpassing the anterior portion of pectoral girdle. It differs further from all members of Hypoptopomatinae by the possession of 2 additional series of lateral plates on the body, one between the dorsal and mid-dorsal series with 2 to 16 plates, and the other between the mid-ventral and ventral series with 2 to 11 plates. Additional characters useful to identify this species within Hypoptopomatinae include the high number of lateral plates, mainly in the mid-dorsal (25-39) and mid-ventral series (28-41), lack of iris operculum, and the insertion of dorsal-fin posterior in the body, with the anterior portion of compound supraneural plus first dorsal-fin proximal radial contacting the neural spine of eighth vertebra (Ref. 98819).