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.
𝗥𝗲𝘀𝗲𝗮𝗿𝗰𝗵 𝗧𝗶𝘁𝗹𝗲
A new characid species with remarkable sexual dimorphism (Characiformes: Characidae: Stevardiinae) from the upper Guayabero River, Orinoco basin, Colombia
𝗖𝗶𝘁𝗮𝘁𝗶𝗼𝗻
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, 1–13. https://doi.org/10.1111/jfb.15738
𝗔𝗯𝘀𝘁𝗿𝗮𝗰𝘁
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. 𝑀𝑜𝑛𝑜𝑡𝑜𝑐ℎ𝑒𝑖𝑟𝑜𝑑𝑜𝑛 species were previously known from piedmont drainages in Bolivia and Peru. The conservation status of the new species is herein categorized following IUCN criteria.
𝗘𝘁𝘆𝗺𝗼𝗹𝗼𝗴𝘆
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 “duda” means doubt, which also refers to its presumed placement into the genus Monotocheirodon, an assumption that needs further evaluation.
𝗣𝗵𝗼𝘁𝗼 𝗖𝗿𝗲𝗱𝗶𝘁
Lateral view of live specimens of Monotocheirodon duda showing live colouration. Above a male and below a female specimen. Specimens not catalogued.
Copyright © 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/
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