2018

• Bragança, P.H.N., Amorim, P.F. & Costa, W.J.E.M. 2018. Pantanodontidae (Teleostei, Cyprinodontiformes), the sister group to all other cyprinodontoid killifishes as inferred by molecular data. Zoosystematics and Evolution 94(1): 137–145. DOI: 10.3897/zse.94.22173 . Reference page. 

• Costa, W.J.E.M. & Amorim, P.F. 2018. A new miniature cryptic species of the seasonal killifish genus Spectrolebias from the Tocantins River basin, central Brazil (Cyprinodontiformes, Aplocheilidae). Zoosystematics and Evolution 94(2): 359–368. DOI: 10.3897/zse.94.28085 Reference page. 

• Costa, W.J.E.M., Amorim, P.F. & Mattos, J.L.O. 2018. Cryptic species diversity in the Hypsolebias magnificus complex, a clade of endangered seasonal killifishes from the São Francisco River basin, Brazilian Caatinga (Cyprinodontiformes, Aplocheilidae). ZooKeys 777: 141–158. DOI: 10.3897/zookeys.777.25058 Reference page. 

• Mattos, J.L.O. & Costa, W.J.E.M. 2018. Three new species of the "'‘Geophagus’'" brasiliensis species group from the northeast Brazil (Cichlidae, Geophagini). Zoosystematics and Evolution 94(2): 325–337. DOI: 10.3897/zse.94.22685 Reference page. 

2017

• Costa, W.J.E.M. 2017. Three new species of the killifish genus Melanorivulus from the central Brazilian Cerrado savanna (Cyprinodontiformes, Aplocheilidae). ZooKeys 645: 51–70. DOI: 10.3897/zookeys.645.10920 . Reference page. 

• Costa, W.J.E.M. 2017. Redescription of Nothobranchius lucius and description of a new species from Mafia Island, eastern Tanzania (Cyprinodontiformes, Aplocheilidae). Zoosystematics and Evolution 93(1): 35–44. DOI: 10.3897/zse.93.11041 Reference page. 

• Costa, W.J.E.M. 2017. Description of two endangered new seasonal killifish species of the genus Cynolebias from the São Francisco River basin, Brazilian Caatinga (Cyprinodontiformes, Aplocheilidae). Zoosystematics and Evolution 93(2): 333–341. DOI: 10.3897/zse.93.20906 Reference page. 

2016

• da Costa, W.J.E.M., de Amorim, P.F. & Mattos, J.L.O. 2016. A new species of inseminating seasonal killifish of the Cynopoecilus melanotaenia complex from southern Brazil (Cyprinodontiformes: Rivulidae). Biodiversity Data Journal 4: e6888. DOI: 10.3897/BDJ.4.e6888 . Reference page. 

2015

• Costa, W.J.E.M. 2015. Taxonomy of the seasonal killifish genus Neofundulus in the Brazilian Pantanal (Cyprinodontiformes: Rivulidae). Vertebrate Zoology 65(1): 15–25. PDF. Reference page. 

• Costa, W.J.E.M., Amorim, P.F. & Mattos, J.L.O. 2015. Molecular phylogeny and evolution of internal fertilization in South American seasonal cynopoeciline killifishes. Molecular Phylogenetics and Evolution, available online November 28, 2015. DOI: 10.1016/j.ympev.2015.11.011 Reference page. 

• Mattos, J.L.O., Costa, W.J.E.M. & Santos, A.C.A. 2015. Geophagus diamantinensis, a new species of the G. brasiliensis species group from Chapada Diamantina, north-eastern Brazil (Cichlidae: Geophagini). Ichthyological Exploration of Freshwaters 26(3): 209–220. Abstract (PDF). Reference page. 

2014

• Costa, W.J.E.M., Amorim, P.F. & Bragança, P.H.N. 2014. Species limits and phylogenetic relationshops of red-finned cryptic species of the seasonal killifish genus Hypsolebias from the Brazilian semi-arid Caatinga (Teleostei: Cyprinodontiformes: Rivulidae). Journal of zoologidal systematics and evolutionary research 52(1): 52–58. DOI: 10.1111/jzs.12041 Reference page. 

• Costa, W.J.E.M. 2014. A new genus of miniature cynolebiasine from the Atlantic Forest and alternative biogeographical explanations for seasonal killifish distribution patterns in South America (Cyprinodontiformes: Rivulidae). Vertebrate zoology 64(1): 23–33. Full article (PDF). Reference page. 

• Costa, W.J.E.M. 2014. Four new species of the genus Atlantirivulus (Cyprinodontiformes: Rivulidae) from the Brazilian Atlantic Forest. Vertebrate zoology 64(1): 9–21. Full article (PDF). Reference page. 

2012

• Costa, W.J.E.M. 2012. Melanorivulus pindorama, a new killifish from the Tocantins River drainage, central Brazilian Cerrado (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 23(1): 57–61. Reference page. 

2011

• Costa, W.J.E.M. 2011. Phylogenetic position and taxonomic status of Anablepsoides, Atlantirivulus, Cynodonichthys, Laimosemion and Melanorivulus (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 22(3): 233–249. Abstract (PDF). Reference page. 

• Costa, W.J.E.M. 2011. Hypsolebias nudiorbitatus, a new seasonal killifish from the Caatinga of northeastern Brazil, Itapicuru River basin (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 22(3): 221–226. (PDF). Reference page. 

• Costa, W.J.E.M. & De Luca, A.C. 2011. Rivularus cajariensis, a new killifish from the Guiana Shield of Brazil, eastern Amazon (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 21(4) [Dec. 2010]: 353–358. Reference page. 

• Costa, W.J.E.M. & Amorim, P.F. 2011. A new annual killifish species of the Hypsolebias flavicaudatus complex from the São Francisco River basin, Brazilian Caatinga (Cyprinodontiformes: Rivulidae). Vertebrate Zoology 61(1): 99–104. PDF. Reference page. 

2010

• Costa, W.J.E.M. 2010. Two new species of the Rivulus urophthalmus group from the Tocantins and Xingu river drainages, eastern Brazilian Amazon (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 21(1): 79–85, 2 figs., 1 tab. Abstract (PDF). Reference page. 

2009

• Costa, W.J.E.M. & Lanés, L.E.K. 2009. Rivulus riograndensis, a new aplocheiloid killifish from southern Brazil (Cyprinodontiformes: Rivulidae). Ichthyological exploration of freshwaters 20(1): 91–95. Abstract (PDF). Reference page. 

• Costa, W.J.E.M. & De Luca, A.C. 2009. Rivulus unaensis, a new aplocheiloid killifish of the subgenus Atlantirivulus from eastern Brazil (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 20(1): 71–74. PDF. Reference page. 

2008

• Costa, W.J.E.M. & Lazzarotto, H. 2008. Rivulus amanan, a new killifish from the Japurá river drainage, Amazonas river basin, Brazil (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 19(2): 129–134. Reference page. 

• Costa, W.J.E.M. 2008. Atlantirivulus, a new subgenus of the killifish genus Rivulus from the eastern Brazilian coastal plains (Teleostei: Cyprinodontiformes: Rivulidae). Vertebrate Zoology 58: 45–48. Reference page. 

• Costa, W.J.E.M. 2008. Rivulus jurubatibensis, a new aplocheiloid killifish from the southeastern Brazilian coastal plains (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 19(2): 135–140. Reference page. 

• Costa, W.J.E.M. 2008. Simpsonichthys longignatus a new seasonal killifish of the S. flammeus group from the Pacoti River basin, northeastern Brazil (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 19(2): 155–159. Reference page. 

2007

• Costa, W.J.E.M., Suzart, R. & Nielsen, D.T.B. 2007. Cynolebias paraguassuensis n. sp. (Teleostei: Cyprinodontiformes: Rivulidae), a new seasonal killifish from the Brazilian Caatinga, Paraguaçu River basin. Aqua, Journal of Ichthyology 12(3): 129–132. Reference page. 

• Costa, W.J.E.M. 2007. Rivulus lazzarotoi n. sp. (Teleostei: Cyprinodontiformes: Rivulidae), a new killifish from the Jurumirim River basin, southeastern Brazil. Aqua, International Journal of Ichthyology 12(3): 123–128. Abstract. Reference page. 

2006

• Costa, W.J.E.M. 2006. Redescription of Kryptolebias ocellatus (Hensel) and K. caudomarginatus (Seegers) (Teleostei: Cyprinodontiformes: Rivulidae), two killifishes from mangroves of south-eastern Brazil. Aqua, Journal of Ichthyology and Aquatic Biology 11(1): 5–12. Reference page. 

• Costa, W.J.E.M. 2006. The South American annual killifish genus Austrolebias (Teleostei: Cyprinodontiformes: Rivulidae): phylogenetic relationships, descriptive morphology and taxonomic revision. Zootaxa No. 1213: 1–162. Reference page. 

• Costa, W.J.E.M. 2006. Taxonomy and phylogenetic relationships among species of the seasonal, internally inseminating, South American killifish genus Campellolebias (Teleostei: Cyprinodontiformes: Rivulidae), with the description of a new species. Zootaxa No. 1227: 31–55. ZooBank Reference page. 

• Costa, W.J.E.M. 2006. Three new species of seasonal killifishes of the Simpsonichthys antenori species group (Teleostei: Cyprinodontiformes: Rivulidae) from the rio São Francisco basin, Brazil. Zootaxa 1306: 25–39. Abstract & excerpt Reference page. 

• Costa, W.J.E.M. & Brasil, G.C. 2006. Three new species of the seasonal killifish genus Simpsonichthys, subgenus Hypsolebias (Teleostei: Cyprinodontiformes: Rivulidae) from the rio Paracatu drainage, rio São Francisco basin, Brazil. Zootaxa 1244: 41–55. Abstract & excerpt (PDF). Reference page. 

2004

• Costa, W.J.E.M., Lima, S.M.Q. & Bizerril, C.R.S.F. 2004. Microcambeva ribeirae sp. n. (Teleostei: Siluriformes: Trichomycteridae): a new sarcoglanidine catfish from the Rio Ribeira do Iguape basin, southeastern Brazil. Zootaxa 563: 1–10. Abstract and excerpt (PDF). Full article (PDF). Reference page. 

• Costa, W.J.E.M. & Brasil, G.C. 2004. Simpsonichthys radiosus sp. n. (Teleostei: Cyprinodontiformes: Rivulidae): a new annual killifish from the upper Rio Tocantins basin, central Brazil. Zootaxa 737: 1–7. DOI: 10.5281/zenodo.158628 Reference page. 

• Costa, W.J.E.M. 2004. Moema apurinan sp. n. and Aphyolebias boticarioi sp. n. (Teleostei: Cyprinodontiformes: Rivulidae): two new annual killifishes from the Rio Purus basin, Brazilian Amazon. Zootaxa 707: 1–12. Abstract (PDF). Reference page. 

• Costa, W.J.E.M. 2004. Rivulus simplicis n. sp. (Cyprinodontiformes: Rivulidae): A new killifish from the coastal plains of south-eastern Brazil. Aqua, International Journal of Ichthyology 8(3): 103–108. Reference page. 

• Costa, W.J.E.M. 2004. A new killifish genus and species from the coastal plains of north-eastern Brazil (Teleostei: Cyprinodontiformes: Rivulidae). Zootaxa 642: 1–10. Abstract & excerpt (PDF). Reference page. 

• Costa, W.J.E.M. & Nielsen, D.T.B. 2004. Simpsonichthys carlettoi (Cyprinodontiformes: Rivulidae) a new annual fish from the Rio São Francisco basin, north-eastern Brazil. Aqua, Journal of Ichthyology 8(3): 125–130. Abstract. Reference page. 

2003

• Costa, W.J.E.M. 2003. Three new annual fishes of the genus Aphyolebias Costa, 1998 (Cyprinodontiformes: Rivulidae) from Bolivian and Peruvian Amazon. Comunicações do Museu de Ciências e Tecnologia da PUCRS, Sér. Zoologia 16(2): 155–166. Reference page. 

• Costa, W.J.E.M. 2003. The Simpsonichthys flavicaudatus species group (Cyprinodontiformes: Rivulidae: Cynolebiatinae): phylogenetic relationships, taxonomic revision and biogeography. Ichthyological Exploration of Freshwaters 14(1): 31–60. Reference page. 

2002

• Costa, W.J.E.M. 2002. The annual fish genus Cynopoecilus (Cyprinodontiformes: Rivulidae): taxonomic revision, with descriptions of four new species. Ichthyological Exploration of Freshwaters 13(1): 11–24.

2001

• Costa, W.J.E.M. 2001. The neotropical annual fish genus Cynolebias (Cyprinodontiformes: Rivulidae): phylogenetic relationships, taxonomic revision and biogeography. Ichthyological Exploration of Freshwaters 12(4): 333–383. Reference page. 

• Costa, W.J.E.M., Nielsen, D.T.B. & de Luca, A.C. 2001. Quatro novos rivulídeos anuais do gênero Simpsonichthys (Cyprinodontiformes) das bacias dos rios São Francisco e Pardo, Brasil. Aquarium (Brasil) 4(26): 24–31. Reference page. 

2000

• Costa, W.J.E.M. 2000. Descrições de quatro novas espécies de peixes anuais do gênero Simpsonichthys (Cyprinodontifomes: Rivulidae) das bacias dos rios São Fransisco e Paraná, nordeste e centro do Brasil. Aquarium (Brasil) 3(25): 8–15. Reference page. 

• Costa, W.J.E.M. & Nielsen, D.T.B. 2000. Simpsonichthys auratus, a new annual fish from the rio Paracatú drainage, São Francisco basin, Brazil (Cyprinodontiformes, Rivulidae). Ichthyological Exploration of Freshwaters 11(1): 7–12. Reference page. 

1998

• Costa, W.J.E.M. 1998. Cynolebias gilbertoi, a new species of annual fish (Cyprinodontiformes: Rivulidae) from the Rio São Francisco basin, northeastern Brazil. Cybium 22(3): 237–243. Reference page. 

1996

• Costa, W.J.E.M., Sarmiento, J. & Barrera, E. 1996. A new species of the annual fish genus Pterolebias (Cyprinodontiformes: Rivulidae) from the Rio Mamoré basin, bolivian Amazon. Ichthyological Exploration of Freshwaters 7(1): 91–95. Reference page. 

• Costa, W.J.E.M., Cyrino, A.L.F. & Nielsen, D.T.B. 1996. Description d'une nouvelle espèce de poisson annuel du genre Simpsonichthys (Cyprinodontiformes: Rivulidae) du bassin du rio São Francisco, Brésil. Revue Française d'Aquariologie et d'Herpétologie 23(1–2): 17–20. Reference page. 

1995

• Costa, W.J.E.M. 1995. Pearl killifishes. The Cynolebiatinae. Systematics and biogeography of the neotropical annual fish subfamily (Cyprinodontiformes: Rivulidae). 128 pages. ISBN 978-0-7938-2089-4. Reference page. 

1994

• Costa, W.J.E.M. 1994. Description of two new species of the genus Moenkhausia (Characiformes: Characidae) from the central Brazil. Zoologischer Anzeiger v. 232 (no. 1–2): 21–29. Reference page. 

• Costa, W.J.E.M. & Bockmann, F.A. 1994. A new genus and species of Sarcoglanidinae (Siluriformes: Trichomycteridae) from southeastern Brazil, with a re-examination of subfamilial phylogeny. Journal of Natural History 28(3): 715–730. Reference page. 

• Costa, W.J.E.M. & Brasil, G.C. 1994. Trois nouveaux poissons annuels du genre Cynolebias (Cyprinodontiformes: Rivulidae) du bassin du rio São Francisco, Brésil. Revue Française d'Aquariologie et d'Herpétologie 21(1–2): 5–10. Reference page. 

1993

• Rosa, R.S. & Costa, W.J.E.M. 1993. Systematic revision of the genus Cnesterodon (Cyprinodontiformes: Poeciliidae) with the description of two new species from Brazil. Copeia 1993(3): 696–708. DOI: 10.2307/1447230 Reference page. 

• Costa, W.J.E.M. & Brasil, G.C. 1993. Two new species of Cynolebias (Cyprinodontiformes: Rivulidae) from the São Francisco basin, Brazil, with notes on phylogeny and biogeography of annual fishes. Ichthyological Exploration of Freshwaters 4(3): 193–200. Reference page. 

1991

• Costa, W.J.E.M. 1991. Description d'une nouvelle espèce du genre Pamphorichthys (Cyprinodontiformes: Poeciliidae) du bassin de l'Araguaia, Brésil. Revue française d'aquariologie et d'herpétologie 18(2): 39–42. Reference page. 

• Costa, W.J.E.M. 1991. Description of two new species of the genus Rivulus (Cyprinodontiformes: Rivulidae) from eastern South American coastal plains. Revue Suisse de Zoologie 98(3): 581–587. Reference page. 

• Costa, W.J.E.M. & Brasil, G.C. 1991. Three new species of Cynolebias (Cyprinodontiformes: Rivulidae) from the São Francisco basin, Brazil. Ichthyological Exploration of Freshwaters 2(1): 55–62. ZooBank Reference page. 

• Costa, W.J.E.M. & Brasil, G.C. 1991. Description of a new species of Rivulus (Cyprinodontiformes: Rivulidae) from the coastal plains of eastern Brazil. Ichthyological Exploration of Freshwaters 1(4): 379–383. Reference page. 

1990

• Costa, W.J.E.M., Lacerda, M.T.C. & Brasil, G.C. 1990. Description de deux nouvelles espèces du genre Cynolebias du bassin du Rio Tocantins (Cyprinodontiformes, Rivulidae). Revue française d'Aquariologie et d'Herpétologie 17(1): 9–14. Reference page. 

• Costa, W.J.E.M. & Brasil, G.C. 1990. Description of two new annual fishes of the genus Cynolebias (Cyprinodontiformes: Rivulidae) from the Sao Francisco basin, Brazil. Ichthyological Exploration of Freshwaters 1(1): 15–22. Reference page. 

1989

• Costa, W.J.E.M. 1989. Descrição de cinco novas espécies de Rivulus das bacias dos rios Paraná e São Francisco (Cyprinodontiformes, Rivulidae). Revista Brasileira de Zoologia 6(3): 523–533. Reference page. 

• Costa, W.J.E.M. 1989. Descrição e relações filogenéticas de dois gêneros novos e três espécies novas de peixes anuais neotropicais (Cyprinodontiformes, Rivulidae). Revista Brasileira de Biologia 49(1): 221–230. Reference page. 

• Costa, W.J.E.M. 1989. Redescrição do gênero Cynolebias (Cyprinodontiformes, Rivulinae), com a descrição de uma nova espéce da Bacia do Rio Tocantins. Comunicações do Museu de Ciências da PUCRS 2(9): 181–190. Reference page. 

• Costa, W.J.E.M., Lacerda, M.T.C. & Brasil, G.C. 1989. Systématique et distribution du genre néotropical Campellolebias (Cyprinodontiformes, Rivulidae), avec description de deux nouvelles espèces. Revue française d'Aquariologie et d'Herpétologie 15(3) (1988): 65–72. Reference page. 

1988

• Costa, W.J.E.M. 1988. A new species of the neotropical annual fish genus Pterolebias (Cyprinodontiformes, Rivulidae), from central Brazil. Journal of Zoology (London) v. 215 (pt 4): 657–662. Reference page. 

2018

• Katz, A.M., Barbosa, M.A., Mattos, J.L. de O. & da Costa, W.J.E.M. 2018. Multigene analysis of the catfish genus Trichomycterus and description of a new South American trichomycterine genus (Siluriformes, Trichomycteridae). Zoosystematics and Evolution 94(2): 557–566. DOI: 10.3897/zse.94.29872 Reference page. 

• Costa, W.J.E.M. 2019. Description of a new species of cynopoeciline killifish (Cyprinodontiformes, Aplocheilidae), possibly extinct, from the Atlantic Forest of south-eastern Brazil. Zookeys, 867: 73–85. DOI: 10.3897/zookeys.867.34034 Reference page.