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| Characidium dumonti Stabile, Reis, Oliveira & Graça, 2025 |
Abstract
A new species of Characidium is described from the Iguaçu National Park, Brazil. The new species can be diagnosed from the congeners by the absence of conspicuous vertical bars, blotches and spots along the sides of the body, the presence of a scaled isthmus and adipose fin, a series of scales below lateral line and the presence of a thin dark midlateral stripe. The reticulated colour pattern of melanophores along the posterior edge of scales found in the new species is similar to that found in C. xanthopterum, with which it presents 4.2% of genetic distance. Morphological and molecular analyses showed that it is a new species, supported by multiple species delimitation methods (Assemble Species by Automatic Partitioning, the General Mixed Yule Coalescent method, and the Poisson Tree Process and its Bayesian implementation). The new species is a sister group of C. itarare, a species that occurs in the Paranapanema river basin (upper Paraná river). Despite being located within a conservation unit, the new species is known from only two creeks, raising concerns about its long-term conservation.
Keywords: COI, conservation unit, freshwater fish, integrative taxonomy, south American darters
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| Live specimens of Characidium dumonti before fixation, sampled in Córrego Carlos Giovanni, tributary of Rio São João, Rio Iguaçu basin, Lower Rio Paraná. Photograph by Natália de Paula Lopes. |
Characidium dumonti, sp. nov.
Diagnosis: Characidium dumonti can be distinguished from its congeners, except Characidium bolivianum Pearson 1924, C. chicoi da Graça, Ota & Domingues 2019, C. iaquira Zanata, Ohara, Oyakawa & Dagosta 2020, C. kamakan Zanata & Camelier 2015, C. lanei Travassos 1967, C. nana Mendonça & Netto-Ferreira 2015, C. samurai Zanata & Camelier 2014, C. summus Zanata & Ohara 2015, C. tapuia Zanata, Ramos & Oliveira-Silva 2018, and C. xanthopterum Silveira, Langeani, da Graça, Pavanelli & Buckup 2008 by the absence of conspicuous dark-brown vertical bars, blotches and spots along the sides of body (vs. presence of conspicuous dark-brown vertical bars, blotches and spots along the sides of body in the remaining congeners). Characidium dumonti can be distinguished from C. bolivianum, C. iaquira, C. kamakan, C. lanei and C. summus by the scaled isthmus (vs. scaleless isthmus). From C. chicoi and C. nana by the presence of adipose fin (vs. absence of adipose fin). From C. xanthopterum by the presence of five scales series below lateral line (vs. four). From C. samurai and C. tapuia by the presence of a thin dark midlateral stripe occupying half scale height in vertical through dorsal-fin origin and one scale height on caudal peduncle (vs. broad lateral stripe occupying at least one scale height). The new species can be further distinguished from all congeners except C. xanthopterum by the presence of a reticulated colour pattern, with melanophores along the posterior edge of the scales (vs. absence of a reticulated colour pattern, without melanophores along the posterior edge of the scales) and from C. xanthopterum by the shorter dorsal and pelvic-fin height, 19.1%–23.7% and 12.1%–18.1% of Ls (vs. 24.9%–32.2% and 21.6%–27.4% of Ls), and shorter predorsal distance 44.5%–48.0% of Ls (vs. 49.2%–56.7% of Ls).
Etymology: The specific name dumonti was chosen in honour of Alberto Santos-Dumont (1873–1932), who is regarded as the father of aviation. In 1916, Dumont visited the area around the Iguaçu Falls and worked to convince the government to create a natural park there. His efforts were essential for the establishment of the Iguaçu National Park, a place that protects the type locality of Characidium dumonti and home of many other species. A genitive.
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| Map of the distribution of Characidium dumonti, inside Iguaçu National Park (INP-orange), Rio Iguaçu, lower Rio Paraná basin, Paraná, Brazil. The yellow circles represent localities of paratypes and the red star represents the type locality. |
Bruno H. M. Stabile, Renan B. dos Reis, Alessandra V. de Oliveira and Weferson J. da Graça. 2025. A New Species of Characidium (Characiformes: Crenuchidae) from the Iguaçu National Park, Rio Iguaçu Basin, Paraná, Brazil. Journal of Fish Biology. DOI: doi.org/10.1111/jfb.70035 [09 April 2025]