| Main Ref. | Vanegas-Ríos, J.A., A. Urbano-Bonilla and M.d.l.M Azpelicueta, 2015 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | other |
| Different appearance | always different morphology between mature adults |
| Different colors | always different colors between mature adults |
| Remarks | Males differ from females by the presence of bony hooks on the caudal-, pelvic- and anal-fin rays; the caudal fin has 5-25 tiny hooks usually paired (typically more than one pair per segment), anterodorsally oriented, and placed on the dorsal margin of the lower rays 12-17; all pelvic-fin rays bear short slender hooks, positioned anteroventrally along almost the entire length of rays; these hooks are grouped in 2 pairs per segment, being more numerous on the middle pelvic-fin rays; the anal fin has 1-12 variable-sized hooks distributed in 1 pair per segment and positioned dorsally or anterodorsally on the posteriormost unbranched ray and anterior branched rays 1-12 (often with 2 tiny paired hooks on the posteriormost branched ray and several robust hooks mainly on the proximal half of the branched rays); the anal-fin hooks are arranged in 2 series on the anterior branched rays 3-7: the 1st series is located on the proximal half of the rays, while the 2nd series is located on the distal half of the rays; the presence of these 2 series leaves an area without hooks between the basal and distal portions of each ray; the lower caudal-fin lobe of males has several scales that form a broadly open pouch; this pouch is mainly formed by a single pouch scale plus at least 2 accessory scales; the pouch scale is relatively small, somewhat elongate, curved, and weakly horizontally folded so that its lateral face forms a laterally concave, open pouch; the accessory scales are differently located regarding the pouch position: a medial accessory scale is curved, elongate, and located under the lateral face of the pouch scale (partially visible in lateral view); and a lateral accessory scale is large and somewhat elongate posterodorsally, forming part of the laterodorsal region of the pouch; the pouch scale and the lateral accessory scale are independent but in contact, both scales are strongly attached to each other dorsally through a well-developed medial mass of connective tissue; the caudal-fin rays 12-15 and the anterolateral surface of the pouch have a diffuse, apparently glandular tissue; males have black chromatophores located along the ventral margin of the preanal region and on the lateral region of body between the urogenital pore and the anal-fin origin; usually, the body chromatophores are more concentrated in males than in females, but both have similar arrangement patterns (Ref. 119432). |
| Striking features | none |
| Body shape lateral | elongated |
| Cross section | |
| Dorsal head profile | more or less straight |
| Type of eyes | more or less normal |
| Type of mouth/snout | more or less normal |
| Position of mouth | superior |
| Type of scales | |
| Diagnosis |
Diagnosis: Chrysobrycon guahibo differs from its congeners by having fewer maxillary teeth (1-3 vs. 6-15 in C. eliasi, 3-11 in C. hesperus, 3-12 in C. myersi, and 9-16 in C. yoliae), the nasal bone longer than the antorbital (vs. nasal as long as or shorter than antorbital), absence of bony lamella between the 2nd and 3rd basibranchials (vs. presence of this lamella), and bony hooks on the 3rd to 7th branched anal-fin rays with discontinuous arrangement, forming 2 separate series along each ray in mature males (vs. bony hooks with continuous arrangement, forming single series along rays, except in C. hesperus); Chrysobrycon guahibo is also distinguished from C. eliasi, C. myersi and C. yoliae by the posterior margin of the ventral process of the quadrate not reaching the vertical through posterior margin of symplectic (vs. reaching the vertical through posterior margin of symplectic, except in C. eliasi) and the possession of teeth on the 3rd pharyngobranchial (vs. absence of those teeth, except in C. yoliae); Chrysobrycon guahibo differs from C. hesperus and C. myersi by the presence of a terminal lateralline tube between caudal-fin rays 10 and 11 (vs. absence of this tube), absence of bony lamella between the 1st and 2nd basibranchials (vs. presence of this lamella), and greater number of neural spines between the posteriormost supraneural and the anteriormost dorsal-fin pterygiophore (4-5 vs. 2-3); Chrysobrycon guahibo is distinguished from C. myersi and C. yoliae by the body depth at dorsal-fin origin (24-32 % SL vs. 31-42) and dorsal-fin to adipose-fin length (20-26 % SL vs. 27-33); furthermore, C. guahibo differs from C. myersi by the snout to dorsal-fin origin length (63-71 % SL vs. 57-63), dorsal-fin to hypural complex length (31-39 % SL vs. 40-47), eye to dorsal-fin origin length (51-58 % SL vs. 46-49), upper jaw length (39-48 % HL vs. 49-55), number of vertebrae located anterior to the 1st proximal pterygiophore (19 vs. 15), and number of circumpeduncular scales (14-16 vs. 17-19); Chrysobrycon guahibo differs from C. yoliae by having a lesser dorsal-fin base length (7-11 % SL vs. 12-14) and fewer dentary teeth (9-14 vs. 20-26) (Ref. 119432). |
| Ease of Identification |
| Lateral Lines | 1 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 | 40 |
| Attributes | no striking attributes |
| Fins number | 1 |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | |
| Soft-rays total | 10 - 11 |
| Adipose fin | present |
| Attributes | forked; more or less normal |
| Fins number | 1 |
| Spines total | |
| Soft-rays total | 27 - 34 |
| Pectoral | Attributes more or less normal |
| Spines | |
| Soft-rays 9 - 12 | |
| Pelvics | Attributes more or less normal |
| Position abdominal before origin of D1 | |
| Spines | |
| Soft-rays 7 - 8 |