Abstract:

In the present work, we conducted an extensive long-lasting inventory of the fishes, using different collection methodologies, covering almost the entire Pindaré River drainage, one of the principal tributaries of the Mearim River basin, an area included in the Amazônia Legal region, northeastern Brazil. We reported 101 species, just three of them being non-native, demonstrating that the composition of this studied fish community is majority composed of native species. We found a predominance of species of the orders Characiformes and Siluriformes, corroborating the pattern usually found for the Neotropical fish fauna. Similar to other studies, this inventory was mainly dominated by small characids, representing 21% of the species herein recorded. When comparing the present survey with other species lists published for this region (including the States of Maranhão and Piaui), we can conclude that the freshwater fish fauna of the State of Maranhão is probably still underestimated. We reported 41 more species, and one more species than Soares (2005SOARES, E.C. 2005. Peixes do Mearim. Instituto Geia, São Luís., 2013)SOARES, E.C. 2013. Peixes do Mearim. Instituto Geia, São Luis. and Abreu et al. (2019)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... recorded for the entire Mearim River basin, respectively. We believe, however, that the number of species presented by Abreu et al. (2019)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... is overestimated. We compared our results with all other freshwater fish species inventories performed for the hydrological units Maranhão and Parnaíba sensu Hubbert & Renno (2006). With these comparisons, we concluded that our results evidenced that a high effort was put in the inventory here presented. The two works including more species recorded from coastal river basins of the hydrological units Maranhão and Parnaíba were the works published by Ramos et al. (2014)RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039. for the Parnaíba River basin, one of the main and larger river basin of Brazil, and the compiled data published by Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202. for the Mearim, Pindaré, Pericumã, and upper Turiaçu River drainages, including 146 and 109 species, respectively. Our survey recorded only 45 less species than Ramos et al. (2014)RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039., and eight less species than Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202.. However, it is essential to emphasize that the number of species presented by Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202. is probably overestimated since they did not update and check the taxonomic status of the species of their compiled data. In several cases, they considered more than one name for the same species.

Keywords:
Amazônia Legal; Endemic species; Ichthyology; Maranhão; Neotropical Region; Species list

Resumo:

No presente trabalho nós conduzimos um inventário de peixes extensivo e de longa duração, utilizando diferentes métodos de coletas, e cobrindo a vasta maioria da drenagem do Rio Pindaré, um dos principais afluentes da bacia do Rio Mearim, uma área incluída na região da Amazônia Legal, nordeste do Brasil. Nós registramos 101 espécies, apenas três delas sendo exóticas, demonstrando que a composição dessa comunidade de peixes estudada é majoritariamente composta por espécies nativas. Nós encontramos uma predominância de espécies das ordens Characiformes e Siluriformes, corroborando com o padrão geralmente encontrado na fauna de peixes Neotropicais. De maneira similar a outros estudos, o presente inventário foi principalmente dominado por espécies de pequenos caracídeos, representando 21% das espécies aqui registradas. Quando comparamos o presente inventário com outros inventários realizados para a região (incluindo os Estados do Maranhão e Piauí), nós podemos concluir que a fauna de peixes de água doce do estado está provavelmente subestimada. Nós registramos 41 mais espécies, e uma espécie a mais do que Soares (2005SOARES, E.C. 2005. Peixes do Mearim. Instituto Geia, São Luís., 2013)SOARES, E.C. 2013. Peixes do Mearim. Instituto Geia, São Luis. e Abreu et al. (2019)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... registraram para a bacia inteira do Rio Mearim, respectivamente. Entretanto, nós acreditamos que o número de espécies apresentados por Abreu et al. (2019)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... está superestimado. Nós comparamos nossos resultados com todos os outros inventários de peixes de água doce realizados nas unidades hidrológicas Maranhão e Parnaíba sensu Hubbert & Renno (2006). Com essas comparações pudemos concluir que nosso resultado evidencia o grande esforço colocado no inventário aqui apresentado. Os dois trabalhos incluindo mais espécies registradas para bacias costeiras nas unidades hidrológicas Maranhão e Parnaíba foram os trabalhos publicados por Ramos et al. (2014)RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039. para a bacia do Rio Parnaíba, uma das principais e maiores bacias hidrográficas do Brasil, e a compilação de dados publicada por Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202. para as drenagens dos Rios Mearim, Pindaré, Pericumã e alto Turiaçu, incluindo 146 e 109 espécies, respectivamente. Nosso inventário registrou 45 espécies a menos do que o trabalho de Ramos et al. (2014)RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039., e oito espécies a menos do que Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202.. Entretanto, é importante enfatizar que o número de espécies apresentadas por Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202. está provavelmente superestimado, pois eles não atualizaram nem checaram o status taxonômico das espécies de seus dados compilados, e em vários casos eles consideraram mais de um nome para a mesma espécie.

Palavras-chave:
Amazônia Legal; Espécies endêmicas; Ictiologia; Lista de espécies; Maranhão; Região Neotropical

Introduction

The South America is the continent with the richest ichthyofauna of the world, with currently estimates of more than 9,100 species, about 27% of all the fishes around the world (including freshwater fishes and nearshore marine waters) (Reis et al. 2016REIS, R.E., ALBERT, J.S., DI DARIO, F., MINCARONE, M.M., PETRY, P. & ROCHA, L.A. 2016. Fish biodiversity and conservation in South America. Journal of Fish Biology. 89 (1): 12-47. https://doi.org/10.1111/jfb.13016
https://doi.org/10.1111/jfb.13016... ). The freshwater ichthyofauna is richer than the marine ichthyofauna in South America: about 5,160 are freshwater fishes, representing about 1/3 of all the freshwater fish species of the world, occurring in about 12% of the total continental surface area of the planet. New estimates, however, suggest that the diversity of freshwater ichthyofauna in the Neotropical region is still underestimated, and may be much greater, on the order of eight to nine thousand species (Albert & Reis 2011ALBERT, J.S. & REIS, R. 2011. Historical Biogeography of Neotropical Freshwater Fishes. University of California Press., Reis et al. 2016REIS, R.E., ALBERT, J.S., DI DARIO, F., MINCARONE, M.M., PETRY, P. & ROCHA, L.A. 2016. Fish biodiversity and conservation in South America. Journal of Fish Biology. 89 (1): 12-47. https://doi.org/10.1111/jfb.13016
https://doi.org/10.1111/jfb.13016... ), a similar estimate already proposed by Schaefer (1998)SCHAEFER, S. A. 1998. Conflict and resolution: impact of new taxa on phylogenetic studies of the Neotropical cascudinhos (Silurioidei: Loricariidae). In Phylogeny and Classification of Neotropical Fishes (L.R. Malabarba et al., eds). EDIPUCRS, Porto Alegre..

The Amazonia biome, which occurs in the Neotropical region, extends across all countries in northern South America (Martins & Oliveira 2011MARTINS, M.B. & OLIVEIRA, T.G. 2011. Amazônia Maranhense: Diversidade e Conservação. MPEG, Belém, PA., Van Der Sleen & Albert 2018VAN DER SLEEN, P. & ALBERT, J.S. 2018. Field Guide to the fishes of the Amazon, Orinoco & Guianas. Princeton University Press, Priceton., Val 2019VAL, A.L. 2019. Fishes of the Amazon: divversity and beyound. Anais da Academia Brasileira de Ciências. 91(3): e20190260.), comprising an area of more than eight million km² (Van Der Sleen & Albert 2018VAN DER SLEEN, P. & ALBERT, J.S. 2018. Field Guide to the fishes of the Amazon, Orinoco & Guianas. Princeton University Press, Priceton.), with more than five million km² belonging to Brazil (Val 2019VAL, A.L. 2019. Fishes of the Amazon: divversity and beyound. Anais da Academia Brasileira de Ciências. 91(3): e20190260.). The biome is covered with dense tropical rainforests, being a large and important center for freshwater fish diversity, having more than 3,000 species (Van Der Sleen & Albert 2018VAN DER SLEEN, P. & ALBERT, J.S. 2018. Field Guide to the fishes of the Amazon, Orinoco & Guianas. Princeton University Press, Priceton.). This high diversity is distributed in several aquatic ecosystems, such as large rivers, lakes, streams, floating vegetation, and beaches (Santos & Ferreira 1999SANTOS, G.M. & FERREIRA, E.J.G. 1999. Peixes da bacia Amazônica. In Estudos ecológicos de 297 comunidades de peixes tropicais (R.H. Lowe-McConnell, ed.). EDUSP, São Paulo. p.349-354.). In addition to the Amazon River basin, the Amazonia biome comprises other river basins and drainages (Van Der Sleen & Albert 2018VAN DER SLEEN, P. & ALBERT, J.S. 2018. Field Guide to the fishes of the Amazon, Orinoco & Guianas. Princeton University Press, Priceton., fig., 1), such as Orinoco River basin and Guiana shield basins, both located to the north of the biome region; and a series of coastal river basins and drainages in its eastern portion, after the mouth of the Amazon River, in the State of Pará, and in the west and center of the State of Maranhão; forming the Amazônia Legal area (Martins & Oliveira 2011MARTINS, M.B. & OLIVEIRA, T.G. 2011. Amazônia Maranhense: Diversidade e Conservação. MPEG, Belém, PA., Van Der Sleen & Albert 2018VAN DER SLEEN, P. & ALBERT, J.S. 2018. Field Guide to the fishes of the Amazon, Orinoco & Guianas. Princeton University Press, Priceton.).

Figure 1
Collecting sites at Pindaré river drainage, Mearim river basin.

The State of Maranhão stands out for presenting few studies related to its freshwater ichthyofauna, especially in the area of taxonomy, causing gaps and lack of information related to the taxonomy and systematics of the species and groups, species composition, geographical distribution and biogeography of the ichthyofauna from the State (Guimarães et al. 2018GUIMARÃES, E.C., BRITO, P.S., FERREIRA, B.R. & OTTONI, F.P. 2018. A new species of Charax (Ostariophysi, Characiformes, Characidae) from northeastern Brazil. Zoosystematics and Evolution 94 (1): 83-93. https://doi.org/10.3897/zse.94.22106
https://doi.org/10.3897/zse.94.22106... ). Biodiversity estimates and inventories of freshwater fishes have been continually published in the last decades for water bodies occurring in the State of Maranhão (e.g. Garavello et al. 1998, Piorski 1998PIORSKI, N.M., CASTRO, A.C.L., PEREIRA, L.G. & MUNIZ, M.E.L. 1998. Ictiofauna do trecho inferior do Rio Itapecuru, nordeste do Brasil. Boletim do Laboratório de Hidrobiologia. 11: 15-24., Castro 2001CASTRO, A.C.L. 2001. Diversidade da assembléia de peixes em igarapés do estuário do Rio Paciência (MA - Brasil). Atlántida (Madrid), Rio Grande, v. 23, p. 39-46., Castro et al. 2002CASTRO, A.C.L., PIORSKI, N.M. & PINHEIRO JUNIOR, J.R. 2002. Avaliação qualitativa da ictiofauna da Lagoa da Jansen, São Luís-MA. Boletim do Laboratório de Hidrobiologia. 15: 39-50., Piorski et al. 2003PIORSKI, N.M., CASTRO, A.C.L. & PINHEIRO, C.U.B. 2003. A prática da pesca entre os grupos indígenas das bacias dos rios Pindaré e Turiaçu, no Estado do Maranhão, Nordeste do Brasil. Boletim do Laboratório de Hidrobiologia. 16:67-74., Soares 2005SOARES, E.C. 2005. Peixes do Mearim. Instituto Geia, São Luís., Piorski et al. 2007PIORSKI, N.M., CASTRO, A.C.L. & SOUSA NETO, A.M. 2007. Peixes do cerrado da região sul maranhense. In Cerrado Norte do Brasil (L.N. Barreto. Org.). São Luís: USEB; 2007. p.177-212, Castro et al. 2010CASTRO, A.C.L., CASTRO, K.D.D. & PORTO, H.L.R. 2010. Distribuição da assembléia de peixes na área de influência de uma indústria de alumínio na ilha de São Luís-MA. Arquivos de Ciências do Mar. 43: 71-78., Barros et al. 2011BARROS, M.C., FRAGA, E.C. & BIRINDELLI, J.L.O. 2011. Fishes from Itapecuru River basin, State of Maranhão, northeast Brazil. Brazilian Journal of Biology. 71 (2): 375-380., Martins & Oliveira 2011MARTINS, M.B. & OLIVEIRA, T.G. 2011. Amazônia Maranhense: Diversidade e Conservação. MPEG, Belém, PA., Sousa et al. 2011SOUSA, M.R.J., CASTRO, A.C.L. & SILVA, M.H.L. 2011. Comunidade de peixes como indicador de qualidade ambiental na área de influência da indústria ALUMAR, ilha de São Luís - MA. Boletim do Laboratório de Hidrobiologia. 24: 1-8., Fraga et al. 2012FRAGA, E., BIRINDELLI, J.L.O., AZEVEDO, C.A.S. & BARROS, M.C.A. 2012. Ictiofauna da Área de Proteção Ambiental Municipal do Inhamum, Caxias/MA. In Biodiversidade na Área de Proteção Ambiental Municipal do Inhamum (M.C. Barros, Org.). UEMA, São Luís, v. 1, p. 107-115., Almeida et al. 2013ALMEIDA, Z.S., SANTOS, L.S., NUNES, J.L.S., SANTOS, N.B., FIGUEIREDO, M.B. & PIORSKI, N.M. 2013. Diversidade e Cadeia Produtiva de Peixes nos Grandes Lagos da área de Proteção Ambiental da Baixada Maranhense. In Diversidade e Cadeia Produtiva de Peixes nos Grandes Lagos da área de Proteção Ambiental da Baixada Maranhense (Z.S. Almeida, Org.). São Luis, v. 1, 100-119., Viana et al. 2014, Ribeiro et al. 201RIBEIRO, M.F.R., PIORSKI, N.M., ALMEIDA, Z.S. & NUNES, J.L.S. 2014. Fish aggregating known as moita, an artisanal fishing technique performed in Munim river, State of Maranhão, Brasil. Boletim do Instituto de Pesca (Impresso). 40 (4): 677-682. http://www.pesca.sp.gov.br/40_4-677-682.pdf
http://www.pesca.sp.gov.br/40_4-677-682.... , Lima et al. 2015LIMA, R.C., NASCIMENTO, M.H.S., BARROS, M.C. & FRAGA, E. 2015. Identificação Molecular via DNA Barcoding dos peixes da APA Municipal do Inhamum, Caxias/MA. In Áreas de Proteção Ambiental no Maranhão: situação atual e estratégias de manejo (R.N.F. Carvalho Neta, Org.). UEMA, São Luís, v. 1, p. 303-315., Matavelli et al. 2015MATAVELLI, R., CAMPOS, A.M., VALE, J., PIORSKI, N.M. & POMPEU, P.S. 2015. Ichthyofauna sampled with tadpoles in northeastern Maranhão state, Brazil. Check List. 11 (1): 1550. DOI: 10.15560/11.1.1550
https://doi.org/10.15560/11.1.1550... , Ramos et al. 201RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039., Melo et al. 2016MELO, F.A.G., BUCKUP, P.A., RAMOS, T.P.A., SOUZA, A.K.N., SILVA, C.M.A., COSTA, T.C. & TORRES, A.R. 2016. Fish fauna of the lower course of the Parnaíba river, northeastern Brazil. Boletim do Museu de Biologia Mello Leitão. 38(4):363-400., Piorski et al. 2017PIORSKI, N.M., FERREIRA, B.R.A., GUIMARÃES, E.C., OTTONI, F.P., NUNES, J.L.S. & BRITO, P.S. 2017. Peixes do Parque Nacional dos Lençóis Maranhenses. EDUFMA, São Luís., Brito et al. 2019BRITO, P.S., GUIMARÃES, E.C., FERREIRA, B.R.A., OTTONI, F.P. & PIORSKI, N.M. 2019. Freshwater fishes of the Parque Nacional dos Lençóis Maranhenses and adjacent areas. Biota Neotropica. 19 (3): e20180660. https://doi.org/10.1590/1676-0611-bn-2018-0660
https://doi.org/10.1590/1676-0611-bn-201... , Lima et al. 2019LIMA, R.C., ALMEIDA, M.S., BARROS, M.C. & FRAGA, E. 2019. Identificação e caracterização molecular de peixes da APA do Inhamum, Leste Maranhense, Brasil. In Conceitos Básicos da Genética (B.R. Silva Neto, Org.), Atena Editora, Ponta Grossa, p. 151-168., Teixeira et al. 2019TEIXEIRA, B.R.S., BARROS, M.C. & FRAGA, E.C. 2019. DNA barcoding confirma a ocorrência de espécies amazônicas na ictiofauna do rio Turiaçu, Maranhão/Brasil. In Conceitos Básicos da Genética. (B.R. Silva Neto, Org.). Atena Editora, Ponta Grossa, p. 98-110.). However, the published information regarding the diversity and composition of fishes from the Mearim River basin is limited to only one book published by Soares (2005)SOARES, E.C. 2005. Peixes do Mearim. Instituto Geia, São Luís. and reprinted by Soares (2013)SOARES, E.C. 2013. Peixes do Mearim. Instituto Geia, São Luis., focusing mainly in commercial importance and large size species, and a book chapter by Martins & Oliveira (2011)MARTINS, M.B. & OLIVEIRA, T.G. 2011. Amazônia Maranhense: Diversidade e Conservação. MPEG, Belém, PA.. This book chapter compiled data based on Soares (2005)SOARES, E.C. 2005. Peixes do Mearim. Instituto Geia, São Luís., on a study about the fishing practice among indigenous groups performed by Piorski et al. (2003)PIORSKI, N.M., CASTRO, A.C.L. & PINHEIRO, C.U.B. 2003. A prática da pesca entre os grupos indígenas das bacias dos rios Pindaré e Turiaçu, no Estado do Maranhão, Nordeste do Brasil. Boletim do Laboratório de Hidrobiologia. 16:67-74., and on non-published data, such as a project report and a graduate course completion work. In addition to these two works, Abreu et al. (2019)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... published a paper on the Historical biogeography of fishes from coastal basins of Maranhão State. Aiming to conduct their biogeographic analysis, they make a matrix of fish species occurring in coastal drainages of the State based on examination of material deposited in CPUFMA (Coleção de Peixes da Universidade Federal do Maranhão) and compiled data from published works (e.g., Reis et al. 2003REIS, R.E., KULLANDER, S.O. & FERRARIS, JR. C.J. 2003. Check list of the freshwater fishes of South and Central America. EDIPUCRS, Porto Alegre., Soares 2005SOARES, E.C. 2005. Peixes do Mearim. Instituto Geia, São Luís., Buckup et al. 2007BUCKUP, P.A., MENEZES, N.A. & GHAZZI, M.S. 2007. Catálogo das espécies de peixes de água doce do Brasil. Museu Nacional, Rio de Janeiro., Lucinda et al. 2007LUCINDA, P.H.F., FREITAS, I.S., SOARES, A.B., MARQUES, E.E., AGOSTINHO, C.S. & OLIVEIRA, R.J. 2007. Fish, Lajeado Reservoir, rio Tocantins drainage, State of Tocantins, Brazil. Check List. 3 (2). https://doi.org/10.15560/3.2.70
https://doi.org/10.15560/3.2.70... , Soares et al. 2009SOARES, A.B., PELICICE, F.M., LUCINDA, P.H.F. & AKAMA, A. 2009. Diversidade de peixes na área de influência da barragem de Peixe Angical, antes e após a formação do reservatório. In Reservatório de Peixe Angical: bases ecológicas para o manejo da ictiofauna (C.S. Agostinho, F.M. Pelicice & E.E. Marques, eds). RIMa, São Carlos. p.15-27., Mérona et al. 2010MÉRONA, B.J.L., JURAS, A.A., SANTOS, G.M. & CINTRA, I.H.A. 2010. Os peixes e a pesca no baixo rio Tocantins: vinte anos depois da UHE Tucuruí. Eletronorte, Belém., Barros et al. 2011BARROS, M.C., FRAGA, E.C. & BIRINDELLI, J.L.O. 2011. Fishes from Itapecuru River basin, State of Maranhão, northeast Brazil. Brazilian Journal of Biology. 71 (2): 375-380., Lima & Caires 2011LIMA, F.C.T. & CAIRES, R.A. 2011. Peixes da Estação Ecológica Serra Geral do Tocantins, bacias dos rios Tocantins e São Francisco, com observações sobre as implicações biogeográficas das “águas emendadas” dos rios Sapão e Galheiros. Biota Neotropica. 11(1):231-50., Claro-García & Shibatta 2013CLARO-GARCÍA, A. & SHIBATTA, O.A. 2013. The fish fauna of streams from the upper rio Tocantins basin, Goiás State, Brazil. Check List. 9 (1): 28-33., Ramos et al. 201RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039., Melo et al. 2016MELO, F.A.G., BUCKUP, P.A., RAMOS, T.P.A., SOUZA, A.K.N., SILVA, C.M.A., COSTA, T.C. & TORRES, A.R. 2016. Fish fauna of the lower course of the Parnaíba river, northeastern Brazil. Boletim do Museu de Biologia Mello Leitão. 38(4):363-400., Bartolette et al. 2017BARTOLETTE, R., VIEIRA, C.S., SANTOS, J.F.L., SANTOS, C.D.C., LUDUVICE, J.S.V., PASSOS, T.S., D’AVILLA, T., NASCIMENTO, B.O., ERNESTO, D., ARGOLO, F.H., AGUIAR, A.J.M., ARGOLO, F., PEREIRA, M.S.A., SANTOS, T.F. & BRITO, M.F.G. 2017. The ichthyofauna in the influence area of the Lajeado reservoir, Tocantins state, Brazil. Check List. 13 (3): 2156. Available from: http://dx.doi.org/10.15560/13.3.2156
http://dx.doi.org/10.15560/13.3.2156... , Dagosta & de Pinna 2017DAGOSTA, F.C.P. & DE PINNA, M. 2017. Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units. Neotropical Ichthyology. 15 (3): e170034. https://doi.org/10.1590/1982-0224-20170034
https://doi.org/10.1590/1982-0224-201700... , Piorski et al. 2017PIORSKI, N.M., FERREIRA, B.R.A., GUIMARÃES, E.C., OTTONI, F.P., NUNES, J.L.S. & BRITO, P.S. 2017. Peixes do Parque Nacional dos Lençóis Maranhenses. EDUFMA, São Luís.), listing 160 fish species for all the coastal river drainages of the State of Maranhão, and 100 species for the Mearim River basin. This recent paper, however, was not a taxonomic revision, neither a species inventory, thus many species had not their taxonomic status revised and updated (see Abreu et al. 2019ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... : S2). A common fact among these three works is that none of them presented voucher numbers for their reported species (not designating testimony material for their identifications). Therefore, the present study aims to present an extensive long-lasting inventory, using different collection methodologies, of the fishes from the Pindaré River drainage, one of the main drainages of the Mearim River basin, a river basin included at the Amazonia Legal area in the State of Maranhão, northeastern Brazil. This inventory focused on the entire ichthyofauna occurring in Pindaré River drainage.

Material and Methods

Study area

This study was carried out in the rivers, streams, and lagoons of the Pindaré River drainage, Mearim River basin, located in the State of Maranhão, Northeastern Brazil (Figure 1). The Pindaré River rises in the Serra do Gurupi (5º 9 'S 46º 54' W), in elevations of approximately 300 meters (Silva et al. 2017SILVA, M.R., SILVA, L.V., BARRETO, L.N.C., RODRIGUES, E.H.C., MIRANDA, R.C.M., BEZERRA, D.S. & PEREIRA, D.C.A. 2017. Quality of the water from the Pindare river Basin, In the facts corresponding to the municipalities of Pindare Mirim, Tufilandia and Alto Alegre In the State of Maranhão. Águas Subterrâneas. 31(4): 347-354.). It travels about 575.59 km until it flows into the Mearim River in the vicinity of its mouth in São Marcos Bay (Silva et al. 2017SILVA, M.R., SILVA, L.V., BARRETO, L.N.C., RODRIGUES, E.H.C., MIRANDA, R.C.M., BEZERRA, D.S. & PEREIRA, D.C.A. 2017. Quality of the water from the Pindare river Basin, In the facts corresponding to the municipalities of Pindare Mirim, Tufilandia and Alto Alegre In the State of Maranhão. Águas Subterrâneas. 31(4): 347-354.). Its main tributaries are the rivers Buriticupu, Negro, Paragominas, Zutiua, Timbira, Água Preta, and Santa Rita (Silva et al. 2017SILVA, M.R., SILVA, L.V., BARRETO, L.N.C., RODRIGUES, E.H.C., MIRANDA, R.C.M., BEZERRA, D.S. & PEREIRA, D.C.A. 2017. Quality of the water from the Pindare river Basin, In the facts corresponding to the municipalities of Pindare Mirim, Tufilandia and Alto Alegre In the State of Maranhão. Águas Subterrâneas. 31(4): 347-354.). The Pindaré River and its tributaries have a simple hydrological regime, with two well-defined seasons: the maximum - full - water that runs from February to May and the minimum - drought or ebb - that last from August to November (IBGE 1997).

Sampling design

The collection of samples was conducted at 28 collecting sites distributed within the boundaries of Pindaré River drainage, Mearim River Basin, comprising rivers, streams, lagoons, and lakes (Table 1, Figures 1, 2). The sampling design of this study based on the establishment of (1) fixed sites for seasonal collection (18 collection sites with 50 meters in size, dry and wet seasons, from 2011 to 2017), (2) five random expeditions performed between 2017 and 2020, during both wet and dry seasons, which covered almost the entire drainage.

Figure 2
Sampled localities in the Pindaré river drainage. Numbers follow Table 1. Photographs by E.C. Guimarães and P.S. Brito.

Collection and identification of specimens

Fishes were collected with manual trail-net (2 m long × 1.8m high; mesh size, 2mm), cast nets (2 m height, mesh size 15 mm), gillnets of various mesh sizes (15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 100 mm), and dip nets (mesh size 5 and 10 mm). The collected ichthyological material was euthanized in a buffered solution of ethyl-3-amino-benzoate-methanesulfonate (MS-222) at a concentration of 250 mg/l until completely ceasing opercular movements, according to animal welfare laws and guidelines (Close et al. 1996CLOSE, B., BANISTER, K., BAUMANS, V., BERNOTH, E.M., BROMAGE, N., BUNYAN, J., ERHARDT, W., FLECKNELL, P., GREGORY, N., HACKBARTH, H., MORTON, D. & WARWICK, C. 1996. Recommendations for euthanasia of experimental animals: Part 1. Laboratory Animals. 30: 293-316. https://doi.org/10.1258/002367796780739871
https://doi.org/10.1258/0023677967807398... , 1997CLOSE, B., BANISTER, K., BAUMANS, V., BERNOTH, E.M., BROMAGE, N., BUNYAN, J., ERHARDT, W., FLECKNELL, P., GREGORY, N., HACKBARTH, H., MORTON, D. & WARWICK, C. 1997. Recommendations for euthanasia of experimental animals: part 2. Laboratory Animals. 31: 1-32. https://doi.org/10.1258/002367797780600297
https://doi.org/10.1258/0023677977806002... ; Leary et al. 2013LEARY, S., UNDERWOOD, W., ANTHONY, R., CARTNER, S., COREY, D. & GRANDIN, T. 2013. AVMA guidelines for the euthanasia of animals: 2013 edition.). Specimens selected for morphological analysis were fixed in formalin and left for ten days, after which they were preserved in 70% ethanol. Specimens selected for future molecular analysis were fixed and preserved in absolute ethanol. Sorting and identification of specimens were carried out at the Laboratório de Sistemática e Ecologia de Organismos Aquáticos of the Universidade Federal do Maranhão using specialized bibliography for each taxonomic group and consulting experts. The ichthyological material was deposited in the Coleção de Peixes da Universidade Federal do Maranhão (CPUFMA) and Coleção Ictiológica do Centro de Ciências Agrárias e Ambientais of the Universidade Federal do Maranhão (CICCAA). The taxonomic classification, the names of species considered as valid, authors and years of species descriptions, and geographic distribution, were based on the compilations made by Fricke et al. (2020aFRICKE, R., ESCHMEYER, W.N., & VAN DER LAAN, R. 2020a. Eschmeyer’s Catalog of fishes: genera, species, references. http://researcharchive.calacademy.org (last access in 10/04/2020)
http://researcharchive.calacademy.org... , bFRICKE, R., ESCHMEYER, W.N., & FONG, J.D. 2020b Species by Family/Subfamily. http://researcharchive.calacademy.org (last access in 10/04/2020)
http://researcharchive.calacademy.org... ), where the authors gather all the most recent classifications for each group of fish. The name of the collections and the acronyms can be consulted in Fricke & Eschmeyer (2020)FRICKE, R. & ESCHMEYER, W.N. 2020. Guide to fish collections. http://researcharchive.calacademy.org/research/ichthyology/catalog/collections.asp (last access in 10/04/2020)
http://researcharchive.calacademy.org/re... .

Figure 3
Ranking of richness by orders in the Pindaré river drainage, Mearim river basin.

Figure 4
Ranking of richness by families in the Pindaré river drainage, Mearim river basin.

Results

This fish survey resulted in 101 species representing eight orders and 32 fish families occurring in the Pindaré river drainage (Table 2, Table S1). Orders comprising the highest percentage of species richness were Characiformes 44 (43%), Siluriformes 37 (37%), Cichliformes 9 (9%), and Gymnotiformes 6 (6%), representing 96% of the total species richness. Cyprinodontiformes (Anablepsoides Huber 1992 and Poecilia Bloch & Schneider 1801), Clupeiformes (Anchovia Jordan & Evermann 1895), Myliobatiformes (Potamotrygon Garman, 1877) and Synbranchiformes (Synbranchus Bloch 1795) complete the list of Orders, with two (Cyprinodontiformes) and one species (other orders). The most species diverse family was Characidae 21 (21% of total species), followed by Loricariidae 12 (12%) and Cichlidae 9 (9%) (Table 2). From these 101 species herein recorded, just three are non-native, while the other 98 are native species.

Discussion

In the present work, we conducted an extensive long-lasting inventory of fishes, using different collection methodologies, covering almost the entire studied drainage (Fig. 1 and Table 1). We found a predominance of species of the Orders Characiformes and Siluriformes, corroborating the pattern usually found for the Neotropical fish fauna (Lowe-McConnell 1999LOWE-MCCONNELL, R. 1999. Estudos ecológicos em comunidades de peixes tropicais. EDUSP, São Paulo., Pelicice et al. 2005PELICICE, F.M., AGOSTINHO, A.A. & THOMAZ, S.M. 2005. Fish assemblages associated with Egeria in a tropical reservoir: investigating the effects of plant biomass and diel period. Acta Oecologica. 27 (1): 9-16., Langeani et al. 2007LANGEANI, F., CASTRO, R.M.C., OYAKAWA, O.T., SHIBATTA, O.A., PAVANELLI, C.S. & CASATTI, L. 2007. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotropica. 7 (3): bn03407032007. https://doi.org/10.1590/S1676-06032007000300020
https://doi.org/10.1590/S1676-0603200700... ; Vari et al. 2009VARI, R.P., FERRARIS, C.J., RADOSAVLJEVIC, A. & FUNK, V.A. 2009. Checklist of the Freshwater Fishes of the Guiana Shield. Bullletin of the Biological Society of Washington. 17 (1): 1-94. https://doi.org/10.2988/0097-0298-17.1.i
https://doi.org/10.2988/0097-0298-17.1.i... , Polaz et al. 2014POLAZ, C.N.M., MELO, B.F., BRITZKE, R., RESENDE, E.K., MACHADO, F., LIMA, J.A.F. & PETRERE, JR. M. 2014. Fishes from the Parque Nacional do Pantanal Matogrossense, upper Paraguai River basin, Brazil. Check List. 10 (1): 122-130. https://doi.org/10.15560/10.1.122
https://doi.org/10.15560/10.1.122... , Reis et al. 2016REIS, R.E., ALBERT, J.S., DI DARIO, F., MINCARONE, M.M., PETRY, P. & ROCHA, L.A. 2016. Fish biodiversity and conservation in South America. Journal of Fish Biology. 89 (1): 12-47. https://doi.org/10.1111/jfb.13016
https://doi.org/10.1111/jfb.13016... , Brito et al., 2019BRITO, P.S., GUIMARÃES, E.C., FERREIRA, B.R.A., OTTONI, F.P. & PIORSKI, N.M. 2019. Freshwater fishes of the Parque Nacional dos Lençóis Maranhenses and adjacent areas. Biota Neotropica. 19 (3): e20180660. https://doi.org/10.1590/1676-0611-bn-2018-0660
https://doi.org/10.1590/1676-0611-bn-201... , Dagosta & de Pinna 2019DAGOSTA, F.C. & DE PINNA, M. 2019. The fishes of the Amazon: Distribution and biogeographical patterns, with a comprehensive list of species. Bulletin of the American Museum of Natural History. 2019(431):1-163). Similar to other studies, this inventory was mainly dominated by small characids (e.g. Ramos et al. 2014RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039., Brito et al. 2019BRITO, P.S., GUIMARÃES, E.C., FERREIRA, B.R.A., OTTONI, F.P. & PIORSKI, N.M. 2019. Freshwater fishes of the Parque Nacional dos Lençóis Maranhenses and adjacent areas. Biota Neotropica. 19 (3): e20180660. https://doi.org/10.1590/1676-0611-bn-2018-0660
https://doi.org/10.1590/1676-0611-bn-201... ), probably due to their ability to obtain oxygen from upper layers of the water column, high trophic plasticity (Abelha et al. 2001ABELHA, M.C.F., AGOSTINHO, A.A. & GOULART, E. 2001. Plasticidade trófica em peixes de água doce. Acta Scientiarum. 23 (2): 425-434.), and exceptional species diversity in the Neotropical region (Dagosta & de Pinna 2019DAGOSTA, F.C. & DE PINNA, M. 2019. The fishes of the Amazon: Distribution and biogeographical patterns, with a comprehensive list of species. Bulletin of the American Museum of Natural History. 2019(431):1-163).

From these 101 species herein recorded, just three are non-native [Megaleporinus macrocephalus (Garavello & Britski, 1988), Oreochromis sp. and Cichla sp.] occurring in the middle-lower Pindaré River drainage region, while the other 98 are native species. This demonstrates that the composition of the studied fish community is majority composed of native species, with rare cases of introduced species.

When comparing the present survey with other inventories published for the hydrological units Maranhão and Parnaíba sensu Hubbert & Renno (2006) (hereafter Mrn and Prn following the acronyms proposed by the same authors), we can conclude that the freshwater fish fauna of the State of Maranhão is probably still underestimated, as argued by Piorski (2010)PIORSKI, N.M. 2010. Diversidade genética das espécies de Hoplias malabaricus (Bloch, 1794) e Prochilodus lacustris Steindachner, 1907 no Nordeste do Brasil. Tese de doutorado, Universidade Federal de São Carlos, São Carlos. and Guimarães et al. (2018)GUIMARÃES, E.C., BRITO, P.S., FERREIRA, B.R. & OTTONI, F.P. 2018. A new species of Charax (Ostariophysi, Characiformes, Characidae) from northeastern Brazil. Zoosystematics and Evolution 94 (1): 83-93. https://doi.org/10.3897/zse.94.22106
https://doi.org/10.3897/zse.94.22106... . Were reported a total of 101 species to only one of the main drainages of the Mearim River basin, the Pindaré River drainage (Table 2), 41 more species, and one more species than Soares (2005SOARES, E.C. 2005. Peixes do Mearim. Instituto Geia, São Luís., 2013)SOARES, E.C. 2013. Peixes do Mearim. Instituto Geia, São Luis. (60 species) and Abreu et al. (2019: S2)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... (100 species) recorded for the entire Mearim River basin, respectively. In addition, we reported only 59 less species than the number of species reported by Abreu et al. (2019: S2)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... (160 species) for all the coastal river systems of the State of Maranhão. We believe, however, that the number of species reported by Abreu et al. (2019)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... overestimated, and we will discuss it in detail below.

The two works including more species recorded from coastal river basins of the Mrn and Prn, were the works published by Ramos et al. (2014)RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039. for the Parnaíba River basin, the major coastal river basin of the Mrn and Prn, and the compiled data published by Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202. for the Mearim, Pindaré, Pericumã, and upper Turiaçu River drainages, including 146 and 109 species, respectively. The first one was an exhaustive inventory of one of the main and larger river basins of Brazil, and the largest of the hydrological units mentioned above (Mrn and Prn). The second one included compiled data from three distinguished river drainages: Mearim and Pindaré from the Mearim river system, the second major river system of the Mrn and Prn, and Turiaçu, one of the main river basins of the Mrn and Prn. Even so, our survey recorded only 45 less species than Ramos et al. (2014)RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039. and eight less species than Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202., which demonstrates the high effort put in the inventory here presented. It is important to emphasize that the number of species presented by Castro & Dourado (2011)CASTRO, A.C.L. & DOURADO, E.C.S. 2011. Ictiofauna da Amazônia Oriental Brasileira - um panorama das regiões maranhenses. In Amazônia Maranhense: diversidade e conservação (M.B. Martins & T.G. Oliveira, eds). MPEG, Belém, p.195-202. is probably overestimated since they did not update and check the taxonomic status of the species of their compiled data. In several cases, they considered more than one name for the same species, for example, two names representing Charax awaGuimarães, Brito, Ferreira & Ottoni 2018GUIMARÃES, E.C., BRITO, P.S., FERREIRA, B.R. & OTTONI, F.P. 2018. A new species of Charax (Ostariophysi, Characiformes, Characidae) from northeastern Brazil. Zoosystematics and Evolution 94 (1): 83-93. https://doi.org/10.3897/zse.94.22106
https://doi.org/10.3897/zse.94.22106... [Charax gibbosus (Linnaeus, 1758) and Charax sp.]; and four names representing Acestrorhynchus [Acestrorhynchus falcatus (Bloch, 1794), Acestrorhynchus lacustris (Lütken, 1875), Acestrorhynchus heterolepis (Cope, 1878), Acestrorhynchus microlepis (Schomburgk, 1841)]. This situation, however, was not restricted to only those two mentioned examples, but also to several other fish species.

Based on the examination of material deposited in CPUFMA, and based on the examination of material collected during our survey, an exhaustive study conducted over nine years of collections (2011 to 2020), we verified some inconsistencies in the 100 species listed for the Mearim River basin by Abreu et al. (2019: S2)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... . Some species were misidentified, some genera had their diversity overestimated, and some species did not have their taxonomic status updated. Examining the material deposited in CPUFMA and CICCAA, we could notice that there were the following identification errors: 1- While conducting this inventory some specimens were provisionally identified as Elachocharax pulcher Myers, 1927, but after a detailed morphological inspection it was verified that, in fact, these specimens were Hoplias malabaricus (Bloch 1794) in the initial juvenile stage. 2 - A similar case occurred with some specimens of Gymnotiformes. While conducting this inventory, some specimens of Gymnotiformes presenting a paler coloration were provisionally identified as Eigenmannia limbata (Schreiner & Miranda Ribeiro, 1903). However, after a detailed morphological inspection, it was verified that these specimens were Sternopygus macrurus (Bloch & Schneider 1801), and this paler coloration occurred due to the fixation process of those specimens. 3 - Poecilia branneri Eigenmann, 1894 is, in fact, Poecilia sarrafaeBragança, Costa, 2011BRAGANÇA, P.H.N. & COSTA, W.J.E.M. 2011. Poecilia sarrafae, a new poeciliid from the Paraíba and Mearim river basins, northeastern Brazil (Cyprinodontiformes: Cyprinodontoidei). Ichthyological Exploration of Freshwaters. 21 (4): 369-376.. 4- Rhamphichthys rostratus (Linnaeus, 1766) is Rhamphichthys atlanticus Triques, 1999TRIQUES, M.L. 1999. Three new species of Rhamphichthys Müller et Troschell [sic], 1846 (Ostariophysi: Gymnotiformes: Rhamphichthyidae). Revue française d’Aquariologie Herpétologie. 26(1-2): 1-6.. 5 - Leporacanthicus galaxias is Pterygoplichthys sp. 6 - Nannostomus unifasciatus Steindachner 1876 is Nannostomus beckfordi Günther 1872. 7- Prochilodus brevis Steindachner, 1875, is Prochilodus lacustris Steindachner, 1907. 8 - Triportheus angulatus (Spix, Agassiz, 1829) is Triportheus signatus (Garman, 1890). And 9 - And Auchenipterus nuchalis (Spix, Agassiz, 1829) is Auchenipterus menezesiFerraris & Vari 1999FERRARIS, C.J. JR. & VARI, R.P. 1999. The South American catfish genus Auchenipterus Valenciennes, 1840 (Ostariophysi: Siluriformes: Auchenipteridae): monophyly and relationships, with a revisionary study. Zoological Journal of the Linnean Society. 126 (4): 387-450. https://doi.org/10.1111/j.1096-3642.1999.tb00156.x
https://doi.org/10.1111/j.1096-3642.1999... (Table 2).

Regarding the overestimation of the species diversity within some genera, we could notice that Abreu et al. (2019: S2)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... recorded the following species for the Mearim River basin: two species of Geophagus Heckel 1840, both species belonging to the G. surinamensis species group [Geophagus parnaibaeStaeck, Schindler, 2006STAECK, W. & SCHINDLER, I. 2006. Geophagus parnaibae sp. n. - a new species of cichlid fish (Teleostei: Perciformes: Cichlidae) from the rio Parnaíba basin, Brazil. Zoologische Abhandlungen, Staatliche Naturhistorische Sammlungen Dresden, Museum für Tierkunde. 55: 69-75. and Geophagus surinamensis (Bloch, 1791)]; three species of Crenicichla Heckel 1840 [(Crenicichla lepidota Heckel, 1840, Crenicichla marmorata Pellegrin, 1904, and Crenicichla brasiliensis (Bloch 1792)]; two species of Poecilia (Poecilia branneri and Poecilia sarrafae); and three species of Hemiodus Müller 1842 [Hemiodus microlepis Kner, 1858, Hemiodus parnaguae Eigenmann, Henn, 1916, and Hemiodus unimaculatus (Bloch, 1794)]. However, based on the examination of the material collected during our exhaustive study (nine years of collections in the Pindaré River drainage) and examination of material from CPUFMA, it was reported the following number of species for those genera mentioned above: 1- Two species of the genus Crenicichla (Crenicichla brasiliensis and Crenicihla sp., this latter species only few specimens were collected from one single locality at the municipality of Pindaré-Mirim). 2- One species of Geophagus not identified at the species level (G. cf. parnaibae) since the need of a taxonomic study for this group along the coastal river basins of the State of Maranhão. 3 - One species of Hemiodus also not identified at the species level (Hemiodus cf. parnaguae) since the need of a taxonomic study for this group along the coastal river basins of the State of Maranhão. 4 - And one species of Poecilia (P. sarrafae), with its type locality in the Prn (Table 2). After this careful inspection and taxonomic update in the compiled data listed by Abreu et al. (2019: S2)ABREU, J.M.S., CRAIG, J.M., ALBERT, J.S. & PIORSKI, N.M. 2019. Historical biogeography of fishes from coastal basins of Maranhão State, northeastern Brazil. Neotropical Ichthyology. 17 (2): e180156. https://doi.org/10.1590/1982-0224-20180156
https://doi.org/10.1590/1982-0224-201801... , we can conclude that the number of species for the Mearim River basin proposed by them was overestimated and included some taxonomically outdated data.

The Preguiças and Periá River basins, two very small coastal river basins when compared to the major coastal river basins of the Mrn and Prn, possess a total of 56 recorded species (Piorski et al. 2017PIORSKI, N.M., FERREIRA, B.R.A., GUIMARÃES, E.C., OTTONI, F.P., NUNES, J.L.S. & BRITO, P.S. 2017. Peixes do Parque Nacional dos Lençóis Maranhenses. EDUFMA, São Luís., Brito et al. 2019BRITO, P.S., GUIMARÃES, E.C., FERREIRA, B.R.A., OTTONI, F.P. & PIORSKI, N.M. 2019. Freshwater fishes of the Parque Nacional dos Lençóis Maranhenses and adjacent areas. Biota Neotropica. 19 (3): e20180660. https://doi.org/10.1590/1676-0611-bn-2018-0660
https://doi.org/10.1590/1676-0611-bn-201... , 2020BRITO, P.S., GUIMARÃES, E.C., FERREIRA, B.R.A., SANTOS, J.P., AMARAL, Y.T. & OTTONI, F.P. 2020. Updated and supplementary data on Brito et al. (2019): Freshwater fishes of the PN dos Lençóis Maranhenses and adjacent areas. Ichthyological Contributions of PecesCriollos. 73: 1-17). This number is about half of the number that we have reported for the Pindaré River basin. This fact, however, was already expected due to the small size of the two basins mentioned above. In relation to the Munin River basin, a medium-size coastal river basin from eastern Maranhão, we reported at least five times more species than the surveys performed by Matavelli et al. (2015)MATAVELLI, R., CAMPOS, A.M., VALE, J., PIORSKI, N.M. & POMPEU, P.S. 2015. Ichthyofauna sampled with tadpoles in northeastern Maranhão state, Brazil. Check List. 11 (1): 1550. DOI: 10.15560/11.1.1550
https://doi.org/10.15560/11.1.1550... (13 species), including in addition to water bodies of the lower Munin, water bodies the other rivers system, such as the lower Parnaíba and other and smaller coastal river basins; and Ribeiro et al. (2014)RIBEIRO, M.F.R., PIORSKI, N.M., ALMEIDA, Z.S. & NUNES, J.L.S. 2014. Fish aggregating known as moita, an artisanal fishing technique performed in Munim river, State of Maranhão, Brasil. Boletim do Instituto de Pesca (Impresso). 40 (4): 677-682. http://www.pesca.sp.gov.br/40_4-677-682.pdf
http://www.pesca.sp.gov.br/40_4-677-682.... (20 species) for an area of the upper Munin River basin. When comparing our study with the surveys published by Barros et al. (2011)BARROS, M.C., FRAGA, E.C. & BIRINDELLI, J.L.O. 2011. Fishes from Itapecuru River basin, State of Maranhão, northeast Brazil. Brazilian Journal of Biology. 71 (2): 375-380. (69 species) and Nascimento et al. (2016)NASCIMENTO, M.H.S., ALMEIDA, M.S., VEIRA, M.N.S., LIMEIRA FILHO, D., LIMA, R.C., BARROS, M.C. & FRAGA, E.C. 2016. DNA barcoding reveals high levels of genetic diversity in the fishes of the Itapecuru Basin in Maranhão, Brazil. Genetics and molecular research. 15 (3): gmr.15038476. https://doi.org/10.4238/gmr.15038476
https://doi.org/10.4238/gmr.15038476... (64 species), both for the Itapecuru River basin, one of the main coastal river basins of the Mrn and Prn, we can notice that we report about a third more species than these both studies. Moreover, finally, we recorded 46 more species than the survey published by Melo et al. (2016)MELO, F.A.G., BUCKUP, P.A., RAMOS, T.P.A., SOUZA, A.K.N., SILVA, C.M.A., COSTA, T.C. & TORRES, A.R. 2016. Fish fauna of the lower course of the Parnaíba river, northeastern Brazil. Boletim do Museu de Biologia Mello Leitão. 38(4):363-400. (65 species) for the lower portion of the Parnaíba River basin. All these numbers and facts pointed out above only emphasize the great sampling force that we carried out in our inventory, as well as the importance of the present work.

From the 98 native species herein reported, it was not possible to identify 32 taxa accurately at the species level (about 31%). The reason that did not allow us to identify these 32 taxa accurately at the species level were: The lack of taxonomic knowledge and information on fish species and groups occurring in the State of Maranhão (Guimarães et al. 2018GUIMARÃES, E.C., BRITO, P.S., FERREIRA, B.R. & OTTONI, F.P. 2018. A new species of Charax (Ostariophysi, Characiformes, Characidae) from northeastern Brazil. Zoosystematics and Evolution 94 (1): 83-93. https://doi.org/10.3897/zse.94.22106
https://doi.org/10.3897/zse.94.22106... ). Some of these species may be part of species complex or groups taxonomically still poorly resolved (e.g., Anablepsoides cf. vieirai, Apistogramma cf. piauiensis, Astyanax cf. bimaculatus, Characidium cf. zebra, Geophagus cf. parnaibae, Hemigrammus aff. ocellifer, Leporinus aff. friderici, Loricaria aff. cataphracta, Phenacogaster cf. pectinata). In this case, we can take as example the species Apistogramma piauiensisKullander 1980KULLANDER, S.O. 1980. A taxonomical study of the genus Apistogramma Regan, with a revision of Brazilian and Peruvian species (Teleostei: Percoidei: Cichlidae). Bonner Zoologische Monographien. 14: 1-152.. This species was described based on three specimens, one subadult female (holotype) and two juveniles (paratypes), from the Parnaíba River basin, in the State of Piaui. Although it is very similar to Apistogramma caeteiKullander 1980KULLANDER, S.O. 1980. A taxonomical study of the genus Apistogramma Regan, with a revision of Brazilian and Peruvian species (Teleostei: Percoidei: Cichlidae). Bonner Zoologische Monographien. 14: 1-152., described based on four species (three types and one additional male) from the Apeu and Caeté River basins, in the eastern State of Pará (Kullander 1980KULLANDER, S.O. 1980. A taxonomical study of the genus Apistogramma Regan, with a revision of Brazilian and Peruvian species (Teleostei: Percoidei: Cichlidae). Bonner Zoologische Monographien. 14: 1-152.). As the Pindaré River is located between the type locality of these two species, these species are very similar and difficult to differentiate from each other, and they were described based on few material and were never redescribed; it is difficult to know exactly which of them occur in the Pindaré River basin, or if the population is an undescribed species. Although some aquarium publications recorded A. piauiensis as the species occurring in the Pindaré River drainage (e.g., Link & Staeck 1995, Schindler 1998SCHINDLER, I. 1998. Apistograma piauiensis Kullander, 1980. DCG-Informationen. 29 (3): 1-4.), we believe that a comprehensive taxonomic study should be carried out in populations of this genus along the coastal river basins of Maranhão, as well as, these two species should be redescribed. Another example is Anablepsoides vieiraiNielsen 2016NIELSEN, D.T. 2016. Description of two new species of Anablepsoides (Cyprinodontiformes: Cynolebiidae) from Rio Madeira, Amazon drainage, Rondônia state and from Rio Itapecurú basin, Maranhão state, Brazil. Aqua International Journal of Ichthyology. 22 (4): 165-176.. This species was described from one single locality in the Parnaíba River basin (Nielsen 2016NIELSEN, D.T. 2016. Description of two new species of Anablepsoides (Cyprinodontiformes: Cynolebiidae) from Rio Madeira, Amazon drainage, Rondônia state and from Rio Itapecurú basin, Maranhão state, Brazil. Aqua International Journal of Ichthyology. 22 (4): 165-176.). Despite this is the closest geographically species of the Anablepsoides urophthalmus species group to the Pindaré River basin, the general color pattern of the specimens collected in the Pindaré River drainage is quite different from the color pattern of the specimens from the type locality of the species. In addition, the type locality of Anablepsoides urophthalmus (Günther 1866) is from Belém, State of Pará (Fricke et al. 2020aFRICKE, R., ESCHMEYER, W.N., & VAN DER LAAN, R. 2020a. Eschmeyer’s Catalog of fishes: genera, species, references. http://researcharchive.calacademy.org (last access in 10/04/2020)
http://researcharchive.calacademy.org... ), a location not so far from the studied drainage. Therefore, a taxonomic study among the populations occurring in the coastal river system from Belém (State of Pará) to the Parnaíba River basin is still necessary to let we know which of these two species occurs in the Pindaré River system, or if it is an undescribed species. A third example is Geophagus parnaibaeStaeck & Schindler 2006STAECK, W. & SCHINDLER, I. 2006. Geophagus parnaibae sp. n. - a new species of cichlid fish (Teleostei: Perciformes: Cichlidae) from the rio Parnaíba basin, Brazil. Zoologische Abhandlungen, Staatliche Naturhistorische Sammlungen Dresden, Museum für Tierkunde. 55: 69-75., which was described from tributaries of the Parnaiba River basin, in the State of Maranhão (Staeck & Schindler 2006STAECK, W. & SCHINDLER, I. 2006. Geophagus parnaibae sp. n. - a new species of cichlid fish (Teleostei: Perciformes: Cichlidae) from the rio Parnaíba basin, Brazil. Zoologische Abhandlungen, Staatliche Naturhistorische Sammlungen Dresden, Museum für Tierkunde. 55: 69-75.). Although our few collected specimens from the Pindaré River drainage morphologically resemble this species, there are aquarium publications that argue that the population of the Pindaré River drainage is, in fact, an undescribed species, known by aquarists as Geophagus sp. “Pindare” (e.g., Grad, 2004GRAD, J. 2004. Geophaugus sp. “Pindare”. DCG-Informationen. 35 (11): 248-251.). In addition, several species of this genus are reported for the Tocantins River Basin, Lower Amazon, and coastal river basin of Guiana Shield (Fricke et al. 2020aFRICKE, R., ESCHMEYER, W.N., & VAN DER LAAN, R. 2020a. Eschmeyer’s Catalog of fishes: genera, species, references. http://researcharchive.calacademy.org (last access in 10/04/2020)
http://researcharchive.calacademy.org... ). Therefore, this is another group that needs to be better taxonomically studied, mainly the populations of the coastal river systems from Belém (State of Pará) to the Parnaíba River basin.

Other species such as, Astyanax bimaculatus (Linnaeus 1758), Characidium zebra Eigenmann 1909, Hemigrammus ocellifer (Steindachner 1882), Leporinus friderici (Bloch 1794), Loricaria cataphracta Linnaeus 1758, Phenacogaster pectinata (Cope 1870) are already known to be species complexes based on several studies (e.g., Isbrucker, 1972, Lucena et al. 2010, Fricke et al. 2020aFRICKE, R., ESCHMEYER, W.N., & VAN DER LAAN, R. 2020a. Eschmeyer’s Catalog of fishes: genera, species, references. http://researcharchive.calacademy.org (last access in 10/04/2020)
http://researcharchive.calacademy.org... ), needing comprehensive taxonomic studies to reveal the hidden diversity under these species names. Some taxa probably correspond to still undescribed species (e.g., Ancistrus sp., Aphyocharax sp., Bryconops aff. caudomaculatus, Hemigrammus sp., Microschemobrycon sp., Loricariichthys sp., Serrapinnus sp., and Sturisoma aff. lyra) that still need a more detailed taxonomic study to make sure that they are new to the science. Besides, some of these species had very few specimens collected (e.g. Microschemobrycon sp. and Sturisoma aff. lyra), which makes taxonomic studies difficult. It is important to emphasize that in the last two decades several new species occurring in the Mearim River basin have been described, what reinforces this possibility that these taxa could be still undescribed species (e.g., Ferraris & Vari 1999FERRARIS, C.J. JR. & VARI, R.P. 1999. The South American catfish genus Auchenipterus Valenciennes, 1840 (Ostariophysi: Siluriformes: Auchenipteridae): monophyly and relationships, with a revisionary study. Zoological Journal of the Linnean Society. 126 (4): 387-450. https://doi.org/10.1111/j.1096-3642.1999.tb00156.x
https://doi.org/10.1111/j.1096-3642.1999... , Triques 1999TRIQUES, M.L. 1999. Three new species of Rhamphichthys Müller et Troschell [sic], 1846 (Ostariophysi: Gymnotiformes: Rhamphichthyidae). Revue française d’Aquariologie Herpétologie. 26(1-2): 1-6., Lucena 2003LUCENA, C.A.S. 2003. Revisão taxonômica e relações filogenéticas das espécies de Roeboides grupo-microlepis (Ostariophysi, Characiformes, Characidae). Iheringia Série Zoologia. 93(3): 283-308. http://dx.doi.org/10.1590/S0073-47212003000300008
http://dx.doi.org/10.1590/S0073-47212003... , 2007LUCENA, C.A.S. 2007. Revisão taxonômica das espécies do gênero Roeboides grupo-affinis (Ostariophysi, Characiformes, Characidae). Iheringia Série Zoologia. 97(2): 117-136. http://dx.doi.org/10.1590/S0073-47212007000200001
http://dx.doi.org/10.1590/S0073-47212007... , Piorski et al. 2008PIORSKI, N.M., GARAVELLO, J.C., ARCE, M.H. & SABAJ PÉREZ, M.H. 2008. Platydoras brachylecis, a new species of thorny catfish (Siluriformes: Doradidae) from northeastern Brazil. Neotropical Ichthyology. 6(3):481-494. http://dx.doi.org/10.1590/S1679-62252008000300021
http://dx.doi.org/10.1590/S1679-62252008... , Bragança & Costa 2011BRAGANÇA, P.H.N. & COSTA, W.J.E.M. 2011. Poecilia sarrafae, a new poeciliid from the Paraíba and Mearim river basins, northeastern Brazil (Cyprinodontiformes: Cyprinodontoidei). Ichthyological Exploration of Freshwaters. 21 (4): 369-376., Ottoni 2011OTTONI, F.P. 2011. Cichlasoma zarskei, a new cichlid fish from northern Brazil (Teleostei: Labroidei: Cichlidae). Vertebrate Zoology. 61(3): 335-342.; Guimarães et al. 2018GUIMARÃES, E.C., BRITO, P.S., FERREIRA, B.R. & OTTONI, F.P. 2018. A new species of Charax (Ostariophysi, Characiformes, Characidae) from northeastern Brazil. Zoosystematics and Evolution 94 (1): 83-93. https://doi.org/10.3897/zse.94.22106
https://doi.org/10.3897/zse.94.22106... , Guimarães et al. 2019GUIMARÃES, E.C., DE BRITO, P.S., FEITOSA, L.M., CARVALHO-COSTA, L.F. & OTTONI, F.P. 2019. A new cryptic species of Hyphessobrycon Durbin, 1908 (Characiformes, Characidae) from the Eastern Amazon, revealed by integrative taxonomy. Zoosystematics and Evolution. 95 (2): 345-360. https://doi.org/10.3897/zse.95.34069
https://doi.org/10.3897/zse.95.34069... , Leão et al. 2019LEÃO, M.DV., CARVALHO, T.P., REIS, R.E. & WOSIACKI, W.B. 2019. A new species of Pseudobunocephalus Friel, 2008 (Siluriformes: Aspredinidae) from the lower Tocantins and Mearim river drainages, North and Northeast of Brazil. Zootaxa. 4586 (1): 109. https://doi.org/10.11646/zootaxa.4586.1.5
https://doi.org/10.11646/zootaxa.4586.1.... , Santana et al. 2019SANTANA, D.C., CRAMPTON, W.G.R., DILLMAN, C.B., ET AL. 2019. Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator. Nature Communications. 10:4000. https://doi.org/10.1038/s41467-019-11690-z
https://doi.org/10.1038/s41467-019-11690... ). From the 98 native species herein recorded, 32 of them were not possible to be accurately identified at the species level. Thus, we will not address these species in our biogeographic comments. From the remaining 66 species, 25 (almost half of the species) did not occur in the Amazon River basin [Auchenipterus menezesiFerraris & Vari, 1999FERRARIS, C.J. JR. & VARI, R.P. 1999. The South American catfish genus Auchenipterus Valenciennes, 1840 (Ostariophysi: Siluriformes: Auchenipteridae): monophyly and relationships, with a revisionary study. Zoological Journal of the Linnean Society. 126 (4): 387-450. https://doi.org/10.1111/j.1096-3642.1999.tb00156.x
https://doi.org/10.1111/j.1096-3642.1999... , Brachychalcinus parnaibae Reis 1989, Charax awa Guimarães, Brito, Ferreira & Ottoni 2018, Cichlasoma zarskeiOttoni 2011OTTONI, F.P. 2011. Cichlasoma zarskei, a new cichlid fish from northern Brazil (Teleostei: Labroidei: Cichlidae). Vertebrate Zoology. 61(3): 335-342., Crenicichla brasiliensis (Bloch 1792), Corydoras vittatus Nijssen 1971, Curimata macrops Eigenmann & Eigenmann, 1889, Hassar affinis (Steindachner 1881), Hyphessobrycon caru Guimarães, Brito, Feitosa, Carvalho-Costa & Ottoni 2019, Knodus victoriae (Steindachner 1907), Myloplus rubripinnis (Müller & Troschel 1844), Pimelodella parnahybae Fowler 1941, Platydoras brachylecis Piorski, Garavello, Arce H. & Sabaj Pérez 2008, Psectrogaster rhomboides Eigenmann & Eigenmann 1889, Poecilia sarrafaeBragança & Costa 2011BRAGANÇA, P.H.N. & COSTA, W.J.E.M. 2011. Poecilia sarrafae, a new poeciliid from the Paraíba and Mearim river basins, northeastern Brazil (Cyprinodontiformes: Cyprinodontoidei). Ichthyological Exploration of Freshwaters. 21 (4): 369-376., Prochilodus lacustris Steindachner 1907, Pterygoplichthys parnaibae (Weber, 1991), Schizodon dissimilis (Garman 1890), Steindachnerina notonota (Miranda Ribeiro 1937), Triportheus signatus (Garman 1890), Rhamphichthys atlanticusTriques 1999TRIQUES, M.L. 1999. Three new species of Rhamphichthys Müller et Troschell [sic], 1846 (Ostariophysi: Gymnotiformes: Rhamphichthyidae). Revue française d’Aquariologie Herpétologie. 26(1-2): 1-6., Roeboides margareteaeLucena 2003LUCENA, C.A.S. 2003. Revisão taxonômica e relações filogenéticas das espécies de Roeboides grupo-microlepis (Ostariophysi, Characiformes, Characidae). Iheringia Série Zoologia. 93(3): 283-308. http://dx.doi.org/10.1590/S0073-47212003000300008
http://dx.doi.org/10.1590/S0073-47212003... , and Roeboides sazimaiLucena 2007LUCENA, C.A.S. 2007. Revisão taxonômica das espécies do gênero Roeboides grupo-affinis (Ostariophysi, Characiformes, Characidae). Iheringia Série Zoologia. 97(2): 117-136. http://dx.doi.org/10.1590/S0073-47212007000200001
http://dx.doi.org/10.1590/S0073-47212007... ]; 18 of them (Auchenipterus menezesi, Brachychalcinus parnaibae, Charax awa, Cichlasoma zarskei, Corydoras vittatus, Curimata macrops, Hassar affinis, Hyphessobrycon caru, Knodus victoriae, Pimelodella parnahybae, Platydoras brachylecis, Poecilia sarrafae, Prochilodus lacustris, Pterygoplichthys parnaibae, Schizodon dissimilis, Rhamphichthys atlanticus, Roeboides margareteae, Roeboides sazimai) being endemic to the Mrn and Prn (see Fricke et al. 2020aFRICKE, R., ESCHMEYER, W.N., & VAN DER LAAN, R. 2020a. Eschmeyer’s Catalog of fishes: genera, species, references. http://researcharchive.calacademy.org (last access in 10/04/2020)
http://researcharchive.calacademy.org... ). All the remaining species herein reported (41 species) have their distribution known to the Amazon River basin (see Fricke et al. 2020aFRICKE, R., ESCHMEYER, W.N., & VAN DER LAAN, R. 2020a. Eschmeyer’s Catalog of fishes: genera, species, references. http://researcharchive.calacademy.org (last access in 10/04/2020)
http://researcharchive.calacademy.org... ), showing a considerable biogeographic influence of the Amazon basin in the Pindaré River drainage. According to Rosa et al. (2003)ROSA, R.S., MENEZES, N.A., BRITSKI, H.A., COSTA, W.J.E. & GROTH, F. 2003. Diversidade, padrões de distribuição e conservação dos peixes da caatinga. In Ecologia e Conservação da Caatinga (I.R. Leal, M. Tabarelli, J.M.C. Da Silva, eds). Editora Universitária da Universidade Federal de Pernambuco, Recife, p.135-180., the fish fauna of the Maranhão-Piaui ecoregion, which includes the Prn and part of Mrn, was historically pointed out as poorly endemic. Otherwise, the low level of endemism recorded during the past decades would be related to few sampling effort on the whole region (Piorski 2010PIORSKI, N.M. 2010. Diversidade genética das espécies de Hoplias malabaricus (Bloch, 1794) e Prochilodus lacustris Steindachner, 1907 no Nordeste do Brasil. Tese de doutorado, Universidade Federal de São Carlos, São Carlos., Ramos et al. 2014RAMOS, T.P.A., RAMOS, R.T.C. & RAMOS, S.A.Q.A. 2014. Ichthyofauna of the Parnaíba River basin, northeastern Brazil. Biota Neotropica 14 (1): e20130039., Guimarães et al. 2018GUIMARÃES, E.C., BRITO, P.S., FERREIRA, B.R. & OTTONI, F.P. 2018. A new species of Charax (Ostariophysi, Characiformes, Characidae) from northeastern Brazil. Zoosystematics and Evolution 94 (1): 83-93. https://doi.org/10.3897/zse.94.22106
https://doi.org/10.3897/zse.94.22106... ). Several species in the Maranhão-Piaui rivers are known to occur along the Amazon basin (including coastal rivers in Suriname and the Guianas), a distribution pattern suggested by Barros et al. (2011)BARROS, M.C., FRAGA, E.C. & BIRINDELLI, J.L.O. 2011. Fishes from Itapecuru River basin, State of Maranhão, northeast Brazil. Brazilian Journal of Biology. 71 (2): 375-380., who observed a predominance of Amazonian species in the Itapecuru basin, as well as corroborated for some putative species by Guimarães et al. (2016GUIMARÃES, E. C., OTTONI, F.P., KATZ, A.M. & BRITO, P.S. 2016. Range extension of Moenkhausia oligolepis (Günther,1864) to the Pindaré river drainage, of Mearim river basin, and Itapecuru river basin of northeastern Brazil (Characiformes: Characidae). International Journal of Aquatic Biology. 4 (3): 202-207. https://doi.org/10.22034/ijab.v4i3.202
https://doi.org/10.22034/ijab.v4i3.202... , 2017aGUIMARÃES, E.C., OTTONI, F.P., BRITO, P.S., PIORSKI, N.M. & NUNES, J.L.S. (2017a) Range extension of Gasteropelecus sternicla (Characiformes) for three coastal river basins of the Eastern Amazon region as well as for the Itacaiunas River drainage of the Tocantins River basin. Cybium. 41 (1): 72-74., b)GUIMARÃES, E.C., OTTONI, F.P. & KATZ, A.M. (2017b) Range extension of Piabucus dentatus (Koelreuter, 1763) for the Pindaré River drainage, Mearim River basin, Brazil (Characiformes: Iguanodectinae). Cybium. 41 (3): 287-289.. Besides, this influence of the Amazon River basin in theses hydrological units (Mrn and Prn) was also advocated by Hubert & Renno (2006)HUBERT, N. & RENNO, J.F. 2006. Historical biogeography of South American freshwater fishes. Jounal of Biogeography. 33: 1414-1436. https://doi.org/10.1111/j.1365-2699.2006.01518.x
https://doi.org/10.1111/j.1365-2699.2006... and Dagosta & de Pinna (2017)DAGOSTA, F.C.P. & DE PINNA, M. 2017. Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units. Neotropical Ichthyology. 15 (3): e170034. https://doi.org/10.1590/1982-0224-20170034
https://doi.org/10.1590/1982-0224-201700... , in their biogeographic studies. However, these same authors also advocated the possibility of the coastal river basin of the State of Maranhão constituting one or more areas of endemism. Both papers, however, suggest that data related to the freshwater ichthyofauna from this region are too scarce to have a more conclusive hypothesis. However, a list of several species endemic to the Mrn and Prn, or also occurring just on neighboring areas, was provided Guimarães et al. (2018)GUIMARÃES, E.C., BRITO, P.S., FERREIRA, B.R. & OTTONI, F.P. 2018. A new species of Charax (Ostariophysi, Characiformes, Characidae) from northeastern Brazil. Zoosystematics and Evolution 94 (1): 83-93. https://doi.org/10.3897/zse.94.22106
https://doi.org/10.3897/zse.94.22106... , reinforcing the hypothesis that the coastal river basins of the State of Maranhão could constitute one or more areas of endemism, as suggested as a possibility by Hubert & Renno (2006)HUBERT, N. & RENNO, J.F. 2006. Historical biogeography of South American freshwater fishes. Jounal of Biogeography. 33: 1414-1436. https://doi.org/10.1111/j.1365-2699.2006.01518.x
https://doi.org/10.1111/j.1365-2699.2006... and Dagosta & de Pinna (2017)DAGOSTA, F.C.P. & DE PINNA, M. 2017. Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units. Neotropical Ichthyology. 15 (3): e170034. https://doi.org/10.1590/1982-0224-20170034
https://doi.org/10.1590/1982-0224-201700... .

Acknowledgements

Thanks are owed to Axel Zarske, Ingo Schindler, Oscar Lasso-Alcalá, Ronald Fricke and Stefan Koerber for providing useful literature; Vale S.A and Amplo Engenharia and Rubem Dornas for the cession of part of the data analysed in this study; CAPES (Coordenação de Aperfeiçoamento de pessoal de nível Superior - Finance Code 001), and FAPEMA (Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão) for providing the scholarship to PSB and ECG under the process 88887.159561/2017-00 and BD-05604/19, and for financing this study (Process UNIVERSAL-00724/17). All material was collected with permits 51540-3 from SISBIO (Brazilian Institute of Environment and Natural Resources) and 02001.007241/2004-37 IBAMA (Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis).

Supplementary Material

The following online material is available for this article:

Table S1 - Examined material

References

Publication Dates

History