Browsing by Autor "F. Gallo-Cardozo"

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A New Cryptic Species of Piranha Serrasalmus (Serrasalmidae) from the Bolivian Amazon, Upper Madeira River System
(Pleiades Publishing, 2025) F. Gallo-Cardozo; M. Careaga; Fernando M. Carvajal‐Vallejos
A new species of piranha in the genus Serrasalmus (Characiformes, Serrasalmidae) is described from tributaries of the upper Madeira River drainage in the Bolivian Amazon Basin. This species shares a similar morphology with S. compressus but showing differences in body depth, body color and shape, and can be morphologically distinguished from its congeners. Genetic analysis of COI sequence data revealed minimal divergence (~1%) from morphologically recognized species, indicating that although S. compressus is the species most similar in appearance, genetically it shows the closest relationship to S. compressus and S. magallanesi.
A New Species of Piranha (Serrasalmus, Serrasalmidae) from the Upper Madeira River System, Amazon Basin, Bolivia
(Pleiades Publishing, 2024) F. Gallo-Cardozo; Mabel Maldonado; M. Careaga; Fernando M. Carvajal‐Vallejos
A new species of piranha, in the genus Serrasalmus (Characiformes, Serrasalmidae), is described from tributaries of the upper Madeira River drainage (Bolivian Amazon Basin). This new species exhibits a similar caudal-fin color like that observed in S. hollandi, and review of the literature suggested that former studies have misidentified these two species. The new species can be diagnosed morphologically from other congeners, but genetic variation of the COI sequence data showed little difference (~1%) from similar, morphologically recognized species. Since Serrasalmus species are widespread and morphologically difficult to identify, a key for identifying Bolivian species of this genus is presented.
Population dynamics of two Andean Trichomycterus (Siluriformes: Trichomycteridae) species from Bolivia
(Sociedade Brasileira de Ictiologia, 2025) F. Gallo-Cardozo; Fernando M. Carvajal‐Vallejos; M. Careaga; Laura Herbas; Edgar Goïtia; Mabel Maldonado
Abstract The species of Trichomycterus (Siluriformes: Trichomycteridae) are small catfish distributed throughout South and Central America, from Patagonia to Costa Rica, at elevations ranging from sea level to over 4,000 m. In Bolivia, 17 species have been recorded, but information about the status of their populations and their relationship with the environment is unknown. This study addressed the population dynamics of two species (T. cf. corduvensis and T. tiraquae) in an Andean river from the Cochabamba Department in Bolivia, over a hydrological cycle. Monthly abundance, size structure, condition factor (K), and the relationship between abundance and environmental factors were calculated using multiple regressions. Results indicated that T. cf. corduvensis is more abundant than T. tiraquae. The temporal variation in the abundance of both species is related to the hydrological cycle and local factors, without showing a clear habitat preference. Juvenile individuals predominate, and the condition factor did not vary significantly.
Redescription of the Сommon but Poorly Known Piranha Dulce Serrasalmus hollandi (Serrasalmidae) from the Upper Madeira River
(Pleiades Publishing, 2023) F. Gallo-Cardozo; M. Careaga; Fernando M. Carvajal‐Vallejos
The piranha Serrasalmus hollandi was described in 1915 by Eigenmann based on a single specimen from the upper Madeira River basin in the southwestern Amazon and the holotype was later lost. Because morphological variation is absent from the description, species identification is somewhat difficult. Misidentification with S. eigenmanni, another poorly known but morphologically similar species, may have been common in ichthyological inventories. This last species was described in 1929 by Norman, based on a single specimen collected from the Essequibo River, which drains the Guyana Shield, northeast of the Amazon Basin. The present study redescribes S. hollandi, a species commonly known in the Iténez basin of Bolivia as piraña dulce, based on morphological and genetic (mtDNA-COI) information. A neotype was designated from the Paraguá River, a tributary of the Itenéz River which is close to the type locality. A diagnosis to differentiate among S. hollandi and species reported in the Bolivian Amazon and La Plata basins, and S. eigenmanni is presented.
Redescription of the Сommon but Poorly Known Piranha Dulce Serrasalmus hollandi (Serrasalmidae) from the Upper Madeira River
(Pleiades Publishing, 2023) F. Gallo-Cardozo; M. Careaga; Fernando M. Carvajal‐Vallejos
The piranha Serrasalmus hollandi was described in 1915 by Eigenmann based on a single specimen from the upper Madeira River basin in the southwestern Amazon and the holotype was later lost. Because morphological variation is absent from the description, species identification is somewhat difficult. Misidentification with S. eigenmanni, another poorly known but morphologically similar species, may have been common in ichthyological inventories. This last species was described in 1929 by Norman, based on a single specimen collected from the Essequibo River, which drains the Guyana Shield, northeast of the Amazon Basin. The present study redescribes S. hollandi, a species commonly known in the Iténez basin of Bolivia as piraña dulce, based on morphological and genetic (mtDNA-COI) information. A neotype was designated from the Paraguá River, a tributary of the Itenéz River which is close to the type locality. A diagnosis to differentiate among S. hollandi and species reported in the Bolivian Amazon and La Plata basins, and S. eigenmanni is presented.
Weight‐Length Ratio of Piranhas Serrasalmus (Characiformes, Serrasalmidae) in Bolivia: Relationships to Molecular Divergence and Maximum Size?
(Wiley, 2025) Fernando M. Carvajal‐Vallejos; F. Gallo-Cardozo; M. Careaga; Melina Campero
Weight-Length Relationships (WLRs) provide a basis for comparing life history strategies and morphological differentiation among fish species, potentially linking slope variations to evolutionary divergences in size and weight. This study presents the WLRs of nine Serrasalmus piranha species from the Amazon and La Plata basins in Bolivia, assessing whether WLRs slopes are influenced by phylogenetic relationships using a phylogenetic mixed model analysis on the mitochondrial DNA COI (barcoding) locus. All species demonstrated an exponential (power-type) growth pattern, with most showing positive allometric growth. The species showing the greatest differentiation in both WLRs and genetic variation was S. elongatus. We detected a strong phylogenetic signal in WLR slopes, though clustering techniques for WLRs slopes and molecular data revealed only partial concordance. We discuss how these concordances and discrepancies between WLRs and genetic data may reflect ancient and intermediate speciation events, shaped by habitat conditions and stochastic evolutionary processes. Such processes appear to influence swimming mechanisms and ecological niche navigation in these closely related Serrasalmus species.