| Main Ref. | Carvalho, T.P., P. Lehmann A. and R.E. Reis, 2008 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | always different morphology between mature adults |
| Different colors | |
| Remarks | Males with urogenital papilla just behind the anal opening. Adult males have a fleshy flap along the dorsal margin of the pelvic-fin thickened ray, which is wider basally and progressively narrowing distally. The flap is absent in juveniles and females. |
| 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 |
Gymnotocinclus is distinguished from all other hypoptopomatine genera by the following uniquely derived features: extreme reduction of body dermal plates; absence of the lateral connecting bone; absence of bifid hemal spines on the abdominal vertebrae posterior to the first anal-fin proximal radial; and odontode tips on last dermal plates on the caudal peduncle dorsally or anteriorly curved. Gymnotocinclus is also distinguished by a number of non-exclusive traits: maxillary barbel adnateto the lower lip; lateral ethmoid almost completely encapsulating the nasal organ; ventral margin of preopercle straight, not deflected medially; pectoral girdle exposed and supporting odontodes only in a restricted lateral area near base of pectoral fin; and absence of a pectoral-fin slit (Ref. 79020). |
| 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 | |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | |
| Soft-rays total | |
| Adipose fin |
| Attributes |
| Fins number | |
| Spines total | |
| Soft-rays total |
| Pectoral | Attributes |
| Spines | |
| Soft-rays | |
| Pelvics | Attributes |
| Position | |
| Spines | |
| Soft-rays |