| Main Ref. | Gomon, M.F. and F.J. Neira, 1998 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | other |
| Different appearance | always different morphology between mature adults |
| Different colors | |
| Remarks | Males with brood pouch; females with ovipositor (Ref. 205). |
| Striking features | |
| Body shape lateral | elongated |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | tube-like |
| Position of mouth | terminal |
| Type of scales | |
| Diagnosis |
Body slender and snout elongate, continuous superior and inferior trunk and tail ridges, a dorsal fin which originates on trunk rings 5-9, and an extremely slender tail without a caudal fin. The trunk is broad in females and the brood pouch in males is on the underside of the tail immediately behind the anal fin. No caudal fin. Body rings: 16-19 + 67-79. |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | |
| Pored lateral line scales | |
| Scales in lateral series | |
| Scale rows above lateral line | |
| Scale rows below lateral line | |
| Scales around caudal peduncle | |
| Barbels | |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | |
| on upper limb | |
| total | |
| Vertebrae | |
| preanal | |
| total |
| Attributes | |
| Fins number | 1 |
| Finlets No. | Dorsal 0 - 0 |
| Ventral 0 - 0 | |
| Spines total | 0 - 0 |
| Soft-rays total | 35 - 47 |
| Adipose fin |
| Attributes | other (see remark) |
| Fins number | 1 |
| Spines total | 0 - 0 |
| Soft-rays total | 4 - 4 |
| Pectoral | Attributes |
| Spines 0 | |
| Soft-rays 11 - 16 | |
| Pelvics | Attributes suppressed/absent |
| Position absent | |
| Spines 0 | |
| Soft-rays 0 - 0 |