| Main Ref. | Menezes, N.A. and C.A.S. de Lucena, 1998 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks |
| Striking features | |
| Body shape lateral | elongated |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | |
| Type of scales | |
| Diagnosis |
This species is distinguished from R. molossus by having fewer branched anal-fin rays (41-43, versus 43-47). It differs from R. itupiranga by having more anal-fin rays (41-43, versus 38-41), fewer scale rows between lateral line and anal-fin origin (15-16, versus 18-19) and fewer scale rows around caudal peduncle(27-28, versus 30-31). |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | |
| Pored lateral line scales | 78 - 84 |
| Scales in lateral series | |
| Scale rows above lateral line | 23 - 26 |
| Scale rows below lateral line | 15 - 16 |
| Scales around caudal peduncle | 27 - 28 |
| Barbels | |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | 11 - 12 |
| on upper limb | 3 - 6 |
| total | 14 - 18 |
| Vertebrae | |
| preanal | |
| total | 37 - 40 |
| Attributes | |
| Fins number | |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | |
| Soft-rays total | 11 - 11 |
| Adipose fin | present |
| Attributes | more or less truncate; more or less normal |
| Fins number | |
| Spines total | 4 - 5 |
| Soft-rays total | 41 - 43 |
| Pectoral | Attributes |
| Spines | |
| Soft-rays 16 - 18 | |
| Pelvics | Attributes |
| Position | |
| Spines | |
| Soft-rays 8 - 8 |