Monotocheirodon duda, a new characid species with remarkable sexual dimorphism is described from the upper Guayabero River, Orinoco basin, Colombia. Researchers putatively place this new species in Monotocheirodon and discuss in depth the unique sexual dimorphic structures potentially linked to inseminating behaviour.
Open-access – https://onlinelibrary.wiley.com/doi/10.1111/jfb.15738
“Given the uniqueness of this species, we perform a description of these sexual structures observed in males, discuss its phylogenetic position, and make some comments on the hitherto disclosed fish diversity of Colombia.”
Sadly, the authors also note “These current and future anthropic activities are considered a threat to the species existence, given its restricted geographic distribution”. Currently, Monotocheirodon duda is categorized as vulnerable (VU) D2, but the authors recommend the IUCN category should be reviewed.
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A new characid species with remarkable sexual dimorphism (Characiformes: Characidae: Stevardiinae) from the upper Guayabero River, Orinoco basin, Colombia
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P. Carvalho, T., Tonolli Thomaz, A., Urbano-Bonilla, A., & Prada-Pedreros, S. (2024). A new characid species with remarkable sexual dimorphism (Characiformes: Characidae: Stevardiinae) from the upper Guayabero River, Orinoco basin, Colombia. Journal of Fish Biology, 1โ13. https://doi.org/10.1111/jfb.15738
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A new species of characid with remarkable sexual characteristics is described from the upper Guayabero River drainage from the Orinoco basin in Colombia. The new species is included in the genus Monotocheirodon by sharing most of the previously proposed diagnostic features of this genus.
It differs from all Stevardiinae by the combination, in adult males, of an enlarged urogenital papilla in contact with the first anal-fin unbranched ray and a highly modified anal fin with enlarged and distally elongated first and second branched anal-fin rays, forming a gonopodium-like structure. In addition, it differs from congeners by the presence of an adipose fin, an incomplete lateral line, an ascending process of the premaxilla dorsally oriented, and a long snout.
The new species was discovered from a poorly sampled region in Colombia and is an unexpected new record given its disjunct geographic distribution from other species of the genus. ๐๐๐๐๐ก๐๐โ๐๐๐๐๐๐๐ species were previously known from piedmont drainages in Bolivia and Peru. The conservation status of the new species is herein categorized following IUCN criteria.
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Monotocheirodon duda is named after the river where the new species was captured, mostly tributaries to the Duda River or captured in the Duda River itself (type locality). In Spanish, the epithet specific โdudaโ means doubt, which also refers to its presumed placement into the genus Monotocheirodon, an assumption that needs further evaluation.
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Lateral view of live specimens of Monotocheirodon duda showing live colouration. Above a male and below a female specimen. Specimens not catalogued.
Copyright ยฉ 2024 the Author(s). Published in Journal of Fish Biology. This paper is released under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) licence. https://creativecommons.org/licenses/by-nc/4.0/
