| 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 |
Readily distinguished from the other two species of the genus by having more branched rays on the anal fin (43-47, versus 41-43 in R. ogilviei and 38-41 in R. itupiranga). Hooks are present on the anal fin of adult male specimens of R. itupiranga and in one adult male of R. ogilviei but have not been found in males of R. molossus of comparable sizes. |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | |
| Pored lateral line scales | 78 - 79 |
| Scales in lateral series | |
| Scale rows above lateral line | 22 - 28 |
| Scale rows below lateral line | 14 - 19 |
| Scales around caudal peduncle | 27 - 32 |
| Barbels | |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | 11 - 13 |
| on upper limb | 3 - 7 |
| total | 14 - 20 |
| Vertebrae | |
| preanal | |
| total | 40 - 40 |
| Attributes | |
| Fins number | 1 |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | |
| Soft-rays total | 11 - 11 |
| Adipose fin | present |
| Attributes |
| Fins number | |
| Spines total | 4 - 5 |
| Soft-rays total | 43 - 47 |
| Pectoral | Attributes |
| Spines | |
| Soft-rays 15 - 18 | |
| Pelvics | Attributes |
| Position | |
| Spines | |
| Soft-rays 8 - 8 |