Bryconops marabaixo

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 marabaixo
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Iguanodectidae
Genus: Bryconops
Species:
B. marabaixo
Binomial name
Bryconops marabaixo
Oliveira, Moreira, Lima, & Py-Daniel, 2020

Bryconops marabaixo was officially named in 2020, though it was the secondary focus of the nominal article. The study that described it had the primary purpose of solidifying a proper description for congener Bryconops cyrtogaster, to which it has some superficial resemblance.

Description

Bryconops marabaixo is a relatively small member of its genus. The holotype, or first collected specimen, measured 6.17cm SL (standard length), and further specimens measured 5.04-6.09 cm SL.[1] Most members of Bryconops are between 6 and 8 cm SL.[2] The body, while compressed, is rather convex, especially in comparison to other members of Bryconops.[3]

The scales are generally silver, with a blue-green tint, and they are darker on B. marabaixo's back; this color changes to a yellowish or pale-brown upon preservation of a dead specimen in alcohol.[3] (A silver-to-greenish color is not uncommon in Bryconops.[4] A bluish tint is only otherwise seen in B. inpai and B. sapezal.)[5][6] In life, the dark coloration from the back extends to the caudal peduncle and somewhat onto the base of the caudal fin. The humeral mark is middlingly conspicuous.[3]

Bryconops marabaixo bears some morphological resemblance to congeners Bryconops chernoffi and Bryconops rheoruber. In all three, there are 8-9 predorsal scales (as opposed to 10-17 in other Bryconops) and a similar position of dorsal-fin origin. In marabaixo and chernoffi, the lateral line reaches the interradial membrane (the fin membrane itself) of the caudal fin, where it does not in any other congeners.[3] Nonetheless, differentiation from B. marabaixo specifically is simple because B. chernoffi and B. rheoruber both lack a humeral spot.[3][7]

Taxonomy

The genus Bryconops has two subgenera, Bryconops and Creatochanes. B. marabaixo is characterized as belonging to Creatochanes by way of its teeth and gill rakers; members of Creatochanes have 1-3 teeth in either side of the maxillae, and the gill rakers are ossified (bony) and well-denticulated.[4][7] Both traits are seen in B. marabaixo, though it has a jaw structure more reminiscent of subgenus Bryconops.[3]

B. marabaixo has no known synonyms, and has retained its original name since discovery.[8][9]

Etymology

The specific epithet "marabaixo" originates from a collection of religious and festive practices, Marabaixo, that originated in Amapá, Brazil, the type locality of B. marabaixo.[3][10] It is strongly associated with the resistance and cultural strength of black Brazilians, who were originally settled in the region as slaves.[10][11] The religious aspect is tied with the saints of the Catholic church.[12]

Distribution and ecology

Bryconops marabaixo is only present in the Rio Jari and the Rio Iratapuru. The latter is a tributary of the former. It is the only species of Bryconops to be found in the rio Jari, though most species of Bryconops are from other regions of the Amazon. The range of B. marabaixo seems to be limited by the Cachoeira de Santo Antônio, a major waterfall in a downstream portion of the Jari.[3]

Conservation status

Though B. marabaixo has not been officially evaluated, a large portion of its native range, the Rio Jari, is within the Nascentes do Lago Jari National Park.[13] This park is one of few left in the region that prioritizes biological diversity and preservation, as opposed to sustainable use of natural resources.[14] Nonetheless, it is under threat of illegal activities that include an unlawful access road that cuts through various protected areas.[15] While this is not an immediate threat to the aquatic environment of the region, it sets a precedent of deliberate anthropogenic hazard that may eventually extend into B. marabaixo's habitat.

References
  1. Silva-Oliveira, Cárlison; Ota, Rafaela P.; Lima, Flávio C. T.; Py-Daniel, Lúcia Rapp (13 December 2021). "Rediscovering species: redescription of Bryconops gracilis (Characiformes: Iguanodectidae), an often-misidentified species". Neotropical Ichthyology. 19 (4). doi:10.1590/1982-0224-2021-0054. S2CID 245251694. Retrieved 18 November 2022.
  2. Froese, Rainer and Pauly, Daniel, eds. (2022). Species of Bryconops in FishBase. November 2022 version.
  3. 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.
  4. Chernoff, Barry; Machado-Allison, Antonio (31 December 2005). "Bryconops". doi:10.5281/zenodo.6265593. {{cite journal}}: Cite journal requires |journal= (help)
  5. Knöppel, Hans-armin; Junk, Wolfgang; Géry, Jacques (January 1968). "Bryconops (Creatochanes) Inpai, A New Characoid Fish From The Central Amazon Region, With A Review Of The Genus Bryconops". Amazoniana. 1 (3): 231–246. Retrieved 16 November 2022.
  6. "Bryconops sapezal, Wingert & Chuctaya & Malabarba, 2018". Plazi TreatmentBank. Plazi. Retrieved 3 November 2022.
  7. 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.
  8. "Bryconops marabaixo Silva". GBIF. Global Biodiversity Information System. Retrieved 18 November 2022.
  9. Bailly, Nicolas. "Bryconops marabaixo Silva‐Oliveira, Moreira, Lima & Rapp Py‐Daniel, 2020". World Register of Marine Species. Flanders Marine Institute. Retrieved 18 November 2022.
  10. Scharpf, Christopher; Lazara, Kenneth J. (15 September 2020). "Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE". The ETYFish Project. Retrieved 18 November 2022.
  11. Tartaglia, Ednaldo (2022). "Processos De Dessubjetivação De Sujeitos Negros Do Marabaixo". Alfa: Revista de Linguística (São José do Rio Preto). 66. doi:10.1590/1981-5794-e14057. S2CID 247903642. Retrieved 19 November 2022.
  12. Congó, Elisa. "Marabaixo Garment". Fruturos. Museu do Amanhã. Retrieved 19 November 2022.
  13. "Parque Nacional Nascentes do Lago Jari". Unidades de Conservação no Brasil. Retrieved 19 November 2022.
  14. Citeli, Nathalie; De-Carvalho, Mariana; Brandão, Reuber (September 2020). "Distribution update, conservation status and color in life of the rare Amazonian snake, Eutrachelophis papilio Zaher and Prudente 2019 (Serpentes: Xenodontini)". Acta Amazonica. 50 (3): 252–255. doi:10.1590/1809-4392202001611. S2CID 225265824. Retrieved 19 November 2022.
  15. Fearnside, Philip M.; Yanai, Aurora M.; Ferrante, Lucas; Júnior, Marcos Antonio Isaac (24 November 2020). "Trans-Purus: Brazil's last intact Amazon forest at immediate risk". Mongabay News. Mongabay. Retrieved 19 November 2022.
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