A new genus of Anostomidae (Characiformes) is described to include ten valid extant species previously classified in Leporinus or Hypomasticus and distributed throughout most major river basins in South America: L. brinco, L. conirostris, L. elongatus, H. garmani, L. macrocephalus, L. muyscorum, L. obtusidens, L. piavussu, L. reinhardti, and L. trifasciatus. The monophyly of Megaleporinus is well-supported in a phylogenetic analysis based on two mitochondrial and three nuclear genes, as well as its sister group relationship to Abramites. Megaleporinus is diagnosed by having the exclusive combination of three unicuspid teeth on each premaxillary and dentary bone and a color pattern composed of one to four dark midlateral blotches. Additional distinguishing features and possible synapomorphies include a unique ZZ/ZW sex chromosome system confirmed for six congeners and a drumming apparatus wherein the first rib is elongated and associated with hypertrophied intercostal muscles, which was confirmed for three congeners as exclusive to mature males. Furthermore, our study identified at least four undescribed cryptic species, emphasizing the need for further taxonomic work and genetic analyses. A time-calibrated phylogenetic and biogeographical analysis of the new genus suggests that speciation in the proto-Amazon-Orinoco lineage was primarily driven by paleogeographic processes, such as the formation of the Orinoco and Tocantins basins. Dispersal and diversification of the genus in coastal basins draining the Eastern Brazilian Shield appears to have been facilitated by connections between paleo-basins during low sea level periods and headwater captures between coastal and inland watersheds. The present contribution demonstrates the importance of integrating data from morphology, DNA sequences and cytogenetics to advance the taxonomy and systematics of any complex species group.
Bibliographical noteFunding Information:
This work was supported by the Conselho Nacional de Desenvolvimento Cientifíco e Tecnológico (Universal 473474/2011-5 to P.M.G.J.; Universal 420255/2016-8 to J.L.O.B.), the SISBIOTA-Brazil Program (CNPq, 563299/2010-0; FAPESP, 10/52315-7), and the South American Characiformes Inventory Project (FAPESP 2011/50282-7). The authors received fellowship grants from Fundação de Amparo à Pesquisa do Estado de São Paulo (2011/21836-4, J.L.R.; 10/51250-9, J.L.O.B.). The authors received productivity research grants from Conselho Nacional de Desenvolvimento Cientifíco e Tecnológico (304440/2009-4 to P.M.G.J.) and Fundação Araucária (641/2014 to J.L.O.B.). We are grateful to C. Cramer, C. Doria, D. Carvalho, H. Ortega, J.C. Riofrio, J. Rodriguez-Pulido, M. Carrillo, P. R. Afonso, P. Venere and W. Troy for help obtaining part of the tissue samples and ICMBIO/MMA for sampling fish authorization (32215-1). For loans and assistance during collection visits we thank Mark Sabaj and John Lundberg (ANSP), James Maclaine, Oliver Crimmen, Patrick Campbell and Ralf Britz (BMNH), Tomio Iwamoto and Dave Catania (CAS), Kevin Swagel and Susan Mochel (FMNH), Lucia Rapp Py-Daniel and Renildo Oliveira (INPA), Carlos Alberto Lucena and Roberto E. Reis (MCP), Karsten E. Hartel, Karel F. Liem and Andrew Williston (MCZ), Patrice Pruvost (MNHN), Paulo Buckup and Marcelo Britto (MNRJ), Wolmar Wosiacki, Alberto Akama and André Netto-Ferreira (MPEG), Max Hidalgo and Hernan Ortega (MUSM), Heraldo Britski, Naércio Menezes, Mario de Pinna, Aléssio Datovo and Osvaldo Oyakawa (MZUSP), Helmut Wellendorf and Christian Pollman (NMW), Carla Pavanelli (NUP), Angela Zanata (UFBA), and Larry Page (UF). Comments and suggestions on the MS were provided by Mark Sabaj, supported by the iXingu Project (NSF DEB-1257813). The authors thank Brian Sidlauskas, Nathan K. Lujan and a third anonymous reviewer for suggestions and comments that improved the revised manuscript.
- Cryptic species
- ZW sex chromosomes