Hypostomus rhantos is described for a uniquely pigmented species of loricariid catfish from the upper Río Orinoco of Amazonas, Venezuela. Light gray to tan when alive, becoming tan when preserved. Body densely covered with tiny spots, head spots even smaller than body spots. Spots present on all fins, generally larger than spots on body, evenly distributed on rays, spines, and membranes. Caudal fin membranes light and spotted anteriorly, fading to dark wash posteriorly. Abdomen lighter than sides, with tiny spots. Occasionally with four dorsal saddles, first below anterior dorsal-fin rays, second below and slightly behind posterior dorsal-fin rays, third below and slightly anterior to adipose-fin spine, and fourth at base of caudal peduncle; all saddles angled anteriorly, saddles one and two combine and continue to base of pelvic fin, third and fourth terminating at middle of midventral plate row. Fin spines usually lighter than rest of body. Spots relatively larger in juveniles. Juveniles with fewer spots distally on all fins, lower half of caudal fin much darker. Head and nape forming arch from tip of snout to origin of dorsal fin. Body depth decreasing from origin of dorsal fin to dorsal procurrent caudal spines then increasing to caudal fin. A rounded ridge present from anterodorsal corner of orbit, running ventral to nares, and ending slightly anteroventral of anterior nare. Longitudinal ridge of raised bone and slightly larger odontodes present on pterotic-supracleithrum beginning at posterodorsal corner of orbit and contiguous with supraorbital ridge. Space between orbits concave such that supraorbital ridge higher than medial surface of head. Supraoccipital convex medially with slight crest (Ref. 58737).