Molecular and morphological evidence revalidates Acrobrycontarijae (Characiformes, Characidae) and shows hidden diversity.
Brinoccoli, Y. F., Bogan, S., Arcila, D., Rosso, J. J., Mabragana, E., Delpiani, S. M., de Astarloa, J. M. D. and Cardoso, Y. P.
Laboratorio de Ictiofisiologia y Acuicultura, Instituto Tecnologico Chascomus, Universidad Nacional de San Martin, Av. Intendente Marino km 8200 CC 164 7130, Chascomus, Buenos Aires, Argentina.
Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires, Godoy Cruz 2290, CABA, Argentina.
Fundacion de Historia Natural "Felix de Azara", Centro de Ciencias Naturales, Ambientales y Antropologicas, Universidad Maimonides, Hidalgo 775 piso 7, C1405BDB, Buenos Aires, Argentina.
Sam Noble Oklahoma Museum of Natural History and Department of Biology, University of Oklahoma, Norman, Oklahoma, 73072, USA.
Grupo de Biotaxonomia Morfologica y Molecular de Peces, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata, Argentina.
Departamento de Biologia, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3250, 7600 Mar del Plata, Argentina.
Laboratorio de Sistematica y Biologia Evolutiva, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata. Paseo del Bosque S/N, B1900FWA, La Plata, Buenos Aires, Argentina.
We conducted a revision of the Neotropical genus Acrobrycon. A previous study synonymized the species, A.ipanquianus, distributed from the western portion of the Amazon River to the north-western region of the La Plata River Basin, and A.tarijae, with type locality in the Lipeo River in Bolivia. We revisited this result by collecting new morphometric, meristic, and genetic data (COI mitochondrial gene) for 24 individuals distributed along La Plata River Basin in Argentina, and discussed our results in the context of multiple biogeographic processes of isolation in that basin. Our results revealed a more complex history of diversification and geographic distribution across Acrobrycon species than previously suspected, probably associated with multiple biogeographic processes of isolation in La Plata River Basin. We present new evidence that led us to reconsider the validity of A.tarijae, which is distinguishable from A.ipanquianus by the number of vertebrae (37-39 vs. 41-42) and pleural ribs (12-13 vs. 14). These results were also supported by our molecular analyses that revealed a genetic divergence >4% between A.ipanquianus and A.tarijae. We also identified two main genetic clusters within A.tarijae: the first cluster consisted of specimens from the Bermejo, Pilcomayo, Itiyuro and Juramento river basins (northern Argentina); and the second cluster included specimens from the southernmost basins, such as the Sali River in Tucuman, Cuarto River in the province of Cordoba and the Quinto River in the province of San Luis. Our results suggest that the genetic structure observed in A.tarijae is the result of the type of drainage (endorheic vs. exorheic) and geographical distance.
Zookeys 1091: 99-117 (2022)