| Main Ref. | Bertaco, V.A. and L.R. Malabarba, 2010 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks | Males possess bony hooks on the dorsal-, pectoral-, anal- and pelvic-fin rays; differs slightly in body depth with females; with slightly concave anal-fin shape (nearly straight in females); and mature males with gill gland on first gill arch, covering the first branchial filaments (Ref. 85819). |
| Striking features | |
| Body shape lateral | elongated |
| Cross section | compressed |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | |
| Type of scales | |
| Diagnosis |
This species is distinguished from its congeners, except H. jelskii, by the size of humeral spot over 7-8 horizontal series of scales (vs. 3-6). H. helleri differs from H. jelskii by the number of branched anal-fin rays (19-23 vs. 25-30), and number of scales along anal-fin base scale sheath (6-12 vs. 13-28). It is rather similar to H. inambari, but can be distinguished by the size of humeral spot (over 7-8 vs. 5-6 horizontal series of scales), number of predorsal scales (16-18 vs. 13-16), and by the total number of vertebrae (41-43 vs. 39-40) (Ref. 85819). |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | 42 - 45 |
| Pored lateral line scales | |
| Scales in lateral series | |
| Scale rows above lateral line | 7 - 8 |
| Scale rows below lateral line | |
| Scales around caudal peduncle | 16 - 18 |
| Barbels | |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | 10 - 11 |
| on upper limb | 6 - 7 |
| total | 16 - 18 |
| Vertebrae | |
| preanal | 19 - 21 |
| total | 41 - 43 |
| Attributes | |
| Fins number | |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | |
| Soft-rays total | 8 - 8 |
| Adipose fin |
| Attributes |
| Fins number | |
| Spines total | |
| Soft-rays total | 19 - 23 |
| Pectoral | Attributes |
| Spines | |
| Soft-rays 10 - 11 | |
| Pelvics | Attributes |
| Position | |
| Spines | |
| Soft-rays 6 - 6 |