Bryconops rheoruber

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Bryconops rheoruber
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Iguanodectidae
Genus: Bryconops
Species:
B. rheoruber
Binomial name
Bryconops rheoruber

Bryconops rheoruber is a species of freshwater fish from the rivers of Brazil. Its back scales are tan-to-cream, and its belly is silvery; the divide between the two colors is marked by a broad iridescent-silver stripe. Its fins are a mixture of pale, clear, and reddish, which contributed to its specific name. "Rheo" means "flow" or "current" in Greek, and "ruber" means "red" in Latin.

Contents

It was first described from the rapids of the Rio Xingu (hence "rheo" in its scientific name), and its range is known to extend into the Rio Iriri, the largest tributary therein. Like many other species of Bryconops, it prefers fast-flowing waters over a rocky or sandy substrate.

Description

Bryconops rheoruber ranges from 4.61 to 5.49 cm in standard length. [1] This makes it smaller than most Bryconops, members of which are largely between 6 and 8 cm long. [2] It is deep-chested, with its deepest body section just before the dorsal fin, and it has 8–9 pre-dorsal scales; the latter is a feature it only shares with B. marabaixo and B. chernoffi . [3] [4] Unlike several other species of Bryconops, B. rheoruber lacks a humeral spot (a mark near either pectoral fin). Many fish in Bryconops have either one humeral spot or two. [5]

Bryconops rheoruber has a broad, iridescent-silver lateral stripe that turns lead-gray when a deceased specimen is preserved in alcohol. The scales themselves are tan-to-cream dorsally and silver ventrally in life, with all scales turning pale-yellow upon preservation. Some specimens may have an isolated blotch of pigment upon the distal portion of the caudal fin's dorsal lobe; this is superficially similar to coloration seen in congener B. florenceae , though in B. florenceae the pigmentation is limited to the base of the dorsal lobe and the distal regions are left pale. [6]

The other fins are somewhat varied in coloration. The dorsal fin may have a diffuse, red crescent arching backwards from the center of the base to the outer fin-rays, which leaves a half-oval patch of hyaline dorsal fin near the base, and the tip is whitish. The adipose fin is red. The dorsal half of the caudal fin has a diffuse red ocellus (eyespot) near the base, terminating about midway down the lobe, and the tip of both lobes therein is dusky, sometimes with a darkly-pigmented dorsal tip. The anal, pelvic, and pectoral fins are mostly hyaline (clear). [3]

Sexual dimorphism

Mature males of B. rheoruber sport bony hooks on the rays of the anal and pelvic fins. These hooks are pointed back towards the body. [3] Many members of Bryconops display similar hooks or spines, though appearance varies based on species. [7]

Taxonomy

There are two subgenera in Bryconops, Bryconops and Creatochanes. B. rheoruber has been considered a member of subgenus Bryconops since its description in 2019, based on the fact that its maxilla ries lack teeth or have a single conical tooth isolated to either side. [3] Members of Creatochanes are partially characterized by having one to three teeth on both sides, and also by factors like jaw length and the bones surrounding the eyes. [5]

Etymology

"Rheo" means "flow" or "current" in Greek, and "ruber" means "red" in Latin (compare the word "ruby"); respectively, these reflect B. rheoruber's preference for waters with a strong current, and the red coloration prominent in various fins. [8]

When originally named, B. rheoruber was named B. rheorubrum. [3] However, this was changed to be "rheoruber" because the genus name "Bryconops" is considered masculine by Latin gender rules, and convention states that the species and genus name match genders. "Rheorubrum" would be spelled "rheoruber" when paired with the masculine genus name. [8]

Habitat and ecology

Bryconops rheoruber was originally collected from the clearwater rapids of the Rio Xingu (pronounced sheen-GOO), and is also native to the Rio Iriri, the largest tributary of the Rio Xingu. [3] Its natural habitat classifies it as "rheophilic", a word meaning "living in flowing water or strong current".

This preference for clearwater rapids is demonstrated by other members of Bryconops, even those that are not found in the Xingu. Examples include B. piracolina , from the Igarape Piracolina; [9] B. tocantinensis , from the Rio Conceição; [10] B. caudomaculatus , from the Orinoco and Amazon River basins; [11] and B. magoi , from the rivers of Venezuela. [12]

Conservation status

Bryconops rheoruber has not been evaluated by the IUCN. Nonetheless, there are various factors affecting its surrounding environment that may both help and hinder its survival as a species. The Rio Xingu has been subjected to various infrastructure projects over the years, the most prominent of which was the construction of the Belo Monte Dam, the world's third-largest hydroelectric dam. This significantly altered the flow of the rapids in regions of the Xingu, threatening the environments therein. [13]

The establishment of the Xingu Indigenous Park, created in 1961, has helped to protect the territory not only of various endemic fish species, but also of various cultures and peoples that have lived in the area dating back to the 1200s. [14] The Nascentes da Serra do Cachimbo Biological Reserve, established in 2005, encompasses a great deal of the Rio Iriri. [15]

Related Research Articles

<i>Baryancistrus</i> Genus of fishes

Baryancistrus is a genus of freshwater Loricariid catfish. They inhabit flowing sections of rivers, especially clearwater, in the basins of the Amazon and Orinoco in Brazil and Venezuela. The largest species reach up to 34 cm (13 in) in total length.

<i>Bryconops</i> Genus of fishes

Bryconops is a genus of freshwater fish in the family Iguanodectidae from South America. It consists of small fish, all under half-a-foot long, with slender bodies and silvery scales, though there is some mild color variation. Several species can be identified by way of a humeral patch, and others have a reddish ocellus, or eyespot, on one or both lobes of the dorsal fin.

<i>Bryconops alburnoides</i> Species of fish

Bryconops alburnoides is a small freshwater fish, approximately 6 inches long at its largest, that lives in the rivers of South America. It has a slender body, with a yellowish dorsal fin and yellow-tinged back scales that fade into silver on its belly. It is largely an insectivore that picks land-dwelling insects from the riverbanks, though it eats much more whenever rain washes prey into the water.

<span class="mw-page-title-main">Tailspot tetra</span> Species of fish

The tailspot tetra is a freshwater fish that lives in the coastal river regions of upper South America. Both its common and scientific names reference the distinct spot of color present on the tail fin, which is one of its defining characteristics. It is a small fish, reaching 4.8 in at its longest. Despite its small size, it is an active swimmer, with a preference for fast-flowing waters.

<i>Bryconops cyrtogaster</i> Species of fish

Bryconops cyrtogaster is a midsize species of freshwater fish found in the Oyapock river in French Guiana and Brazil. It is overall silver, with an indistinct dark patch at the base of the tail fin that spreads onto the fin rays slightly. Originally described in 1926 under a different baisonym, it was the subject of a redescription in June 2020.

Bryconops durbinae, sometimes listed under the name Bryconops durbini, is a small species of freshwater fish in the family Iguanodectidae. It is the smallest species of the genus Bryconops, and is endemic to the Tapajós river basin in Brazil.

<i>Bryconops giacopinii</i> Species of fish

Bryconops giacopinii is a mid-sized species of freshwater fish in the family Iguanodectidae. It is the largest member of the genus Bryconops, and is therefore difficult to confuse with any of its congeners. With a diet that consists largely of land-dwelling insects, it serves as an important link between the terrestrial and aquatic aspects of its native range.

<i>Bryconops gracilis</i> Species of fish

Bryconops gracilis is a small species of freshwater fish from the rivers of South America. It is one of multiple species for which the common name "lambari" is used. Though not well-studied, it has been re-described in recent years in order to differentiate it from Bryconops alburnoides, a congener to which it bears a strong resemblance.

Bryconops humeralis is a small freshwater fish distributed across northern South America. The name "humeralis" means "relating to the shoulder", in reference to the distinct humeral patches that the fish sports. It is slightly longer than average in terms of the genus Bryconops, though still firmly within the standard range, and is slightly more slender than is usual for its congeners.

Bryconops inpai is a small freshwater fish native to the rivers of South America. It only lives in two particular river systems - the Casiquiare and Negro - which means that its range is restricted to the northern half of the continent. It has indistinct humeral spots, and is bluish-silver in life, which is unusual for members of Bryconops; they are more often plain silver or greenish-silver.

Bryconops munduruku is a small freshwater fish of the family Iguanodectidae that lives in the rivers of South America. Its adipose fin is black, with a clear base, and it has two humeral spots, which is a feature it shares with few congeners. Its fins are a variety of yellow, red, black, and clear, and mature males have hooks on select fin-rays.

<i>Bryconops piracolina</i> Species of fish

Bryconops piracolina is a small fish that inhabits the waters of Brazil. It is slender and silvery in color, like many fish in Bryconops, but can be distinguished from other members by way of its dorsal fin, which has a black patch of color extending up from the fin-base; congeners usually have light pigment in the dorsal fin, or a brighter color.

<i>Bryconops tocantinensis</i> Species of fish

Bryconops tocantinensis is a small freshwater fish from the rivers of Brazil. It has yellow-gold scales on its back and white scales on its belly, with a bright-silver stripe marking the divide between the two. It gets the name "tocantinensis" from its endemism to the upper Tocantins basin drainage - specifically, the Conceição River.

Bryconops vibex is a small freshwater fish from the rivers of Venezuela, known solely from the Rio Cataniapo. The body is slender, though with an element of sturdiness, and it has one humeral spot by each pectoral fin. It bears visual similarities to several congeners, but can be differentiated by way of many factors.

Bryconops allisoni is a species of freshwater fish known from the rivers of Brazil. It is a recent addition to the genus (2019), currently considered a member incertae sedis. Its name honors Antonio Machado-Allison, an ichthyologist responsible for a great deal of work on the genus Bryconops.

Bryconops chernoffi is a species of freshwater fish that inhabits the rivers of Brazil. Specifically, it is found in the Rio Maicuru and Rio Ipixuna; the latter is a tributary of the former, which is a tributary of the Amazon river main. B. chernoffi demonstrates a preference for clear-water streams with sandy and rocky bottoms.

<i>Bryconops florenceae</i> Species of fish

Bryconops florenceae is a small freshwater fish that inhabits the rivers of South America. Comprehensive research is lacking due to B. florenceae being the most recently described of the genus, but researchers believe it to be a relatively widespread species. It is found throughout the Maroni, Mana, and Sinnamary river basins, which defines its range within Suriname and French Guiana.

Bryconops hexalepis is a small iguanodectid fish from 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.

Bryconops marabaixo is a small freshwater fish from the lower Amazon basin, native to the Rio Jari. It is small and silvery, with a dark-gray back, and its fins are mostly clear, though the caudal fin has a dark stripe on the lower margin of the dorsal lobe, and a spot of red pigment just above that. Like many other members of Bryconops, it has a humeral spot, which is a mark near each pectoral fin.

Bryconops sapezal is a small freshwater fish native to the Rio Tapajós basin of Brazil. It is one of the more recent additions to its genus, described in 2018, and has a name that means "covered in sapê", or thatching. This originates from the Sapezal municipality of Mato Grosso, Brazil, which is type locality of B. sapezal.

References

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  2. Froese, Rainer and Pauly, Daniel, eds. (2022). Species of Bryconops in FishBase . November 2022 version.
  3. 1 2 3 4 5 6 Silva-Oliveira, Cárlison; Sabaj, Mark Henry; Ota, Rafaela Priscila; Py-Daniel, Lúcia H. Rapp (6 June 2019). "Bryconops rheorubrum (Characiformes: Iguanodectidae), new species from the Rio Xingu Rapids, Brazil". Proceedings of the Academy of Natural Sciences of Philadelphia. 166 (1): 1. doi:10.1635/053.166.0115. S2CID   210640024 . Retrieved 17 November 2022.
  4. Silva‐Oliveira, Cárlison; Moreira, Cristiano R.; Lima, Flávio C. T.; Py‐Daniel, Lúcia Rapp (September 2020). "The true identity of Bryconops cyrtogaster (Norman), and description of a new species of Bryconops Kner (Characiformes: Iguanodectidae) from the Rio Jari, lower Amazon basin". Journal of Fish Biology. 97 (3): 860–868. doi:10.1111/jfb.14445. PMID   32584438. S2CID   220060299.
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  10. "Bryconops tocantinensis, Guedes, Oliveira, & Lucinda, 2016". Plazi TreatmentBank. Plazi. Retrieved 8 November 2022.
  11. Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops caudomaculatus" in FishBase . November 2022 version.
  12. Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops magoi" in FishBase . November 2022 version.
  13. Fitzgerald, Daniel B.; Sabaj Perez, Mark H.; Sousa, Leandro M.; Gonçalves, Alany P.; Rapp Py-Daniel, Lucia; Lujan, Nathan K.; Zuanon, Jansen; Winemiller, Kirk O.; Lundberg, John G. (June 2018). "Diversity and community structure of rapids-dwelling fishes of the Xingu River: Implications for conservation amid large-scale hydroelectric development". Biological Conservation. 222: 104–112. doi: 10.1016/j.biocon.2018.04.002 . S2CID   53625155 . Retrieved 20 November 2022.
  14. Heckenberger, Michael J.; Kuikuro, Afukaka; Kuikuro, Urissapá Tabata; Russell, J. Christian; Schmidt, Morgan; Fausto, Carlos; Franchetto, Bruna (19 September 2003). "Amazonia 1492: Pristine Forest or Cultural Parkland?". Science. 301 (5640): 1710–1714. doi:10.1126/science.1086112. PMID   14500979. S2CID   7962308 . Retrieved 20 November 2022.
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