This species can be distinguished from R. elongatus by the following: A 6 (vs. 7); pectoral-fn rays 11 (vs. 10); pelvic-fn rays 5 (vs. 9-10); upper caudal-fn rays 5 (vs. 4); caudal vertebrae 88 (vs. 77-80); end of dorsal-fn base anterior to middle of anal and caudal fns (vs. posterior), the distance between end of dorsal-fn base and caudal-fn base 20.7% SL and 144.7% HL (vs. 14.0-15.5% SL and 94.5-102.7% HL); anal-fn rays short [the frst ray very short, 0.7% HL (vs. 1.8-2.1% HL)]; lateral line through middle of body at pectoral-fn base, its height 50.3% (vs. higher than middle, 54.3-58.6%); lower jaw completely covered by upper jaw (vs. not covered by upper jaw); anterior tip of upper jaw projecting anteriorly beyond lower jaw when mouth open (vs. not projecting); mandible with a single irregular row (vs. 2 irregular rows), teeth larger and sharper than premaxillary teeth (vs. similar to premaxillary teeth) (Ref. 123098).