New piranha species discovered in Bolivia

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Live photograph of the Holotype of Serrasalmus magallanesi, Beni River sub-basin
Live photograph of the Holotype of Serrasalmus magallanesi, Beni River sub-basin, Amazon basin / Author: Fernando M. Carvajal-Vallejos

A team of biologists, with the participation of the Universidad Autónoma de Madrid (UAM), has discovered a new species of piranha in the upper Madeira River system in Bolivia. The newly identified Serrasalmus magallanesi adds a new link to the rich biodiversity of the Amazon basin. This finding underscores the importance of continuing research on the region’s ichthyofauna for its proper conservation.

Species of the genera Serrasalmus, Pygocentrus and Pygopristis are commonly known as piranhas or palometas in the regions of the upper Madeira River system in Bolivia. As in many other regions of South America, these piranhas are predators that feed mainly on fish, small invertebrates and even plant materials such as fruits and seeds.

The taxonomy of Serrasalmus species in Bolivia is poorly known. There are few studies that focus on the identification of these species through external morphology or genetic information. The morphological identification of species of the genus Serrasalmus, both in the field and in museums, represents a challenge for ichthyologists and aquatic ecologists due to factors such as the difference in the ontogeny of these species and morphological variation within the same species. Therefore, studies that integrate morphological and genetic techniques are required to adequately characterize and diagnose the species of this genus.

Recent revisions of material from ichthyological collections in Bolivia have evidenced the presence of a new species of piranha of the genus Serrasalmus in the upper Madeira River system. This species had been erroneously identified as Serrasalmus hollandi due to the similarity in the spot at the base of the caudal fin in Bolivian collections. However, S. hollandi has a short, robust snout and an obvious humeral spot, whereas the new species has an elongated snout and the humeral spot is diffuse or absent.

To confirm the existence of this new species, 159 individuals of the eight known species and the possible new species of Serrasalmus present in Bolivia were analyzed. Thirty-three morphological measurements, 17 morphological counts (scale counts, fin rays and teeth) and the analysis of 10 coloration variables were performed. Many of these variables were analyzed in previous studies on species of the genus Serrasalmus. In addition, radiographs were taken to count osteological structures (vertebrae, ribs and fin rays) and to measure some bones. Original descriptions and works related to the 24 species of the genus Serrasalmus not reported in Bolivia were also reviewed to determine comparative diagnoses.

The study included genetic analyses based on the mitochondrial COI (Cytochrome Oxidase I) gene. Sequences of Bolivian species were obtained from the Canadian Center of Barcoding (Guelph, Canada) and deposited in the Barcode of Life Data Systems ( BOLD ), while complementary sequences of other species were obtained from GenBank. Genetic analyses were performed using MEGA 11 and PhyML programs.

Serrasalmus magallanesi: a new species

Serrasalmus magallanesi sp. nov. differs from the rest by a unique combination of characteristics: silvery body in life, anal fin with a striking crescent-shaped spot at the base, deep red anal fin with a dark stripe on the edge. It can reach 20 cm in length and has an elongated snout and a diffuse or absent humeral spot. Once preserved in alcohol, the red coloration of the anal fin and the silver coloration of the body disappear.

Holotype radiograph of Serrasalmus magallanesi, Beni River sub-basin, Amazon basin.

The new species was described by a group of Bolivian biologists from the Limnology and Aquatic Resources Unit (ULRA) of the Universidad Mayor de San Simón (Cochabamba, Bolivia). The type locality of this species is: Laguna 27 de Mayo, sub-basin of the Beni River, Department of Beni, upper Madeira River, Amazon basin, Bolivia.

The discovery of Serrasalmus magallanesi is the ninth species of piranha recorded in Bolivia and the 32nd in South America. This discovery highlights the need to continue research on the ichthyofauna of the Amazon basin, both to discover new species and to conserve them, as they represent an important natural heritage of the planet.

Bibliographic reference:

Gallo-Cardozo, F.; Maldonado, M.; Careaga, M.; Carvajal-Vallejos, F. M. (2024). A New Species of Piranha (Serrasalmus, Serrasalmidae) from the Upper Madeira River System, Amazon Basin, Bolivia. Journal of Ichthyology, 1-24. https://doi.org/10.1134/S0032945­224700036. https://doi.org/10.1134/S003294­5224700036

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