Bryconops hexalepis
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| Bryconops hexalepis | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Characiformes |
| Family: | Iguanodectidae |
| Genus: | Bryconops |
| Species: | B. hexalepis |
| Binomial name | |
| Bryconops hexalepis | |
Bryconops hexalepis is a species of freshwater ray-finned fish belonging to the family Iguanodectidae. This species is found in the rivers of Brazil. It is solely found in the drainage of the Rio Tocantins. Rather elongate and quite slender, it is considered one of the smaller species of its genus, with tall scales and large eyes.
The specific name "hexalepis" means "six scales". This is in reference to the number of scales above its lateral line, which is indeed six. In contrast, other members of the genus all have 7-10 scales therein, which offers a good baseline defining trait for identification.
Sexual dimorphism
Most members of the genus Bryconops are between 6 and 8 cm SL (standard length).[1] B. hexalepis is on the small end of average, with the largest of its original specimens measuring 6.67 cm SL.[2] Later specimens measured 7.15-7.67 cm SL.[3] It has a generally elongated body shape, with a spine 40 to 41 vertebrae long, and is rather slender, with the deepest point of its body located at the origin of its dorsal fin. The head is large, but the maxillary itself is somewhat short in comparison to structures seen in other Bryconops.[4]
The scales themselves are cycloid, and taller than they are wide. B. hexalepis possesses a dark lateral stripe, and the body color is a dark silvery in life, turning dark-yellow to slightly brown upon preservation in alcohol. The fins are largely hyaline (clear), with the exception of a dusky caudal-fin margin.[2]
In many members of Bryconops, there are few to no morphometric or coloration differences between male and female specimens. B. hexalepis presents an exception to this; the pelvic fin is shorter in females, not reaching the anal-fin origin, but the pelvic fin reaches or passes this point in males.[2] Like many Bryconops, mature males of B. hexalepis also sport bony hooks on some of the anal- and pelvic-fin rays.[2][5]