Molecular phylogeny and species delimitation of the genus Schizodon (Characiformes, Anostomidae)

Jorge L. Ramirez, Cesar A. Santos, Carolina B. Machado, Alexandre K. Oliveira, Julio C. Garavello, Heraldo A. Britski, Pedro M. Galetti

Research output: Contribution to journalArticlepeer-review

Abstract

The genus Schizodon is part of a group of headstanders and relatives (Family Anostomidae) that are widespread and ecologically important fishes in South American rivers. Schizodon includes 15 nominal species but their taxonomy has been challenging due to paucity of decisive characters to diagnose species. We present new molecular data to assess species boundaries or molecular operational taxonomic units (MOTUs), and to infer phylogenetic relationships among species. Evidence from two mitochondrial and three nuclear genes was used in these analyses. Mitochondrial DNA data for 112 specimens (from 11 nominal species) supported 13 consensus MOTUs, six of which matched valid nominal species (Schizodon borellii, S. fasciatus, S. intermedius, S. isognathus, S. knerii and S. scotorhabdotus). The nominal species Schizodon vittatus, S. nasutus, and S. dissimilis were subdivided into two MOTUs each, revealing either cryptic species or strong population structuring. In contrast, S. platae and S. jacuiensis constituted a single MOTU, indicating a possible case of synonymy. Our phylogenetic analysis subdivided the genus Schizodon into two large clades that are compatible with observed color patterns and biogeographic distribution. The first clade includes species with three to four conspicuous dark vertical bars on the flanks that originated in the Amazonas region (S. borellii, S. dissimilis, S. intermedius, S. fasciatus, S. scotorhabdotus, S. vittatus, and a cryptic species, Schizodon aff. vittatus). The second clade includes species with a conspicuous dark caudal blotch on the caudal peduncle, with vertical bars absent or inconspicuous, with a biogeographic origin in the La Plata drainage (S. isognathus, S. jacuiensis, S. knerii, S. nasutus and S. platae). Our results reinforce the importance of using molecular analyses to accelerate the study of diversity, particularly in groups with a wide distribution, few variable meristic characters, and high morphological plasticity, which may hide still unknown or underestimated diversity.

Original languageEnglish
Article number106959
JournalMolecular Phylogenetics and Evolution
Volume153
DOIs
StatePublished - Dec 2020

Bibliographical note

Funding Information:
This work was supported by the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico, CNPq ( 473474/2011-5 and 405309/2016-3 to P.M.G.J.), the SISBIOTA-Brazil Program (CNPq, 563299/2010-0 ; FAPESP , 10/52315-7 ), the Biota-Fapesp Program (FAPESP, 2011/50213-5 and 2018/04388-7 ), and the Consejo Nacional de Ciencia Tecnología e Innovación Tecnológica, CONCYTEC-FONDECYT (Proyecto Investigación Básica 2019-01 , 431-2019-FONDECYT to J.L.R.). J.L.R had a fellowship from the Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP (2011/21836-4). C.A.S. and C.B.M. had fellowships from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES (financial code 001). P.M.G.J. had a research fellowship from the Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq (303524/2019-7). We are grateful to the following scientific collection curators for providing tissue material: C. Cramer and C. Doria (UFRO-I), C. Lucena (MCP), and C. Oliveira (LBP). We are also grateful to D. Carvalho, E. Feldberg, H. Ortega, J.C. Riofrio, J. Rodriguez-Pulido, L. Carvalho-Costa, M. Carrillo, P. Venere and W. Troy for helping us to obtain a portion of the tissue samples, to ICMBIO/MMA for the sampling fish authorization (32215-1) and to SISGEN (AAA03B9) for the genetic material access authorization. The authors thank B. Sidlauskas and an anonymous reviewer for their helpful suggestions and comments that improved the revised manuscript.

Funding Information:
This work was supported by the Conselho Nacional de Desenvolvimento Cientifico e Tecnol?gico, CNPq (473474/2011-5 and 405309/2016-3 to P.M.G.J.), the SISBIOTA-Brazil Program (CNPq, 563299/2010-0; FAPESP, 10/52315-7), the Biota-Fapesp Program (FAPESP, 2011/50213-5 and 2018/04388-7), and the Consejo Nacional de Ciencia Tecnolog?a e Innovaci?n Tecnol?gica, CONCYTEC-FONDECYT (Proyecto Investigaci?n B?sica 2019-01, 431-2019-FONDECYT to J.L.R.). J.L.R had a fellowship from the Funda??o de Amparo ? Pesquisa do Estado de S?o Paulo, FAPESP (2011/21836-4). C.A.S. and C.B.M. had fellowships from the Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES (financial code 001). P.M.G.J. had a research fellowship from the Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico, CNPq (303524/2019-7). We are grateful to the following scientific collection curators for providing tissue material: C. Cramer and C. Doria (UFRO-I), C. Lucena (MCP), and C. Oliveira (LBP). We are also grateful to D. Carvalho, E. Feldberg, H. Ortega, J.C. Riofrio, J. Rodriguez-Pulido, L. Carvalho-Costa, M. Carrillo, P. Venere and W. Troy for helping us to obtain a portion of the tissue samples, to ICMBIO/MMA for the sampling fish authorization (32215-1) and to SISGEN (AAA03B9) for the genetic material access authorization. The authors thank B. Sidlauskas and an anonymous reviewer for their helpful suggestions and comments that improved the revised manuscript.

Publisher Copyright:
© 2020 Elsevier Inc.

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • Freshwater fishes
  • Hidden diversity
  • Molecular systematic
  • Neotropical
  • Species delimitation

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