Ichthyological Contributions of PecesCriollos 53: 1-99 (2017) 1 Checklist of the Fishes of Paraguay (CLOFPY). 1 2 3 Stefan Koerber , Héctor S. Vera-Alcaraz & Roberto E. Reis 1 Friesenstr. 11, 45476 Muelheim, Germany, [email protected] 2 Museo Nacional de Historia Natural del Paraguay, Secretaría del Ambiente. Ruta Mariscal Estigarribia km 10.5, Casilla de Correo 19004, 2169 (Sucursal 1 - Campus UNA). San Lorenzo, Central, Paraguay. [email protected] 3 PUCRS, Laboratory of Vertebrate Systematics. P.O. Box 1429, 90619-900 Porto Alegre, RS, Brazil. [email protected] Abstract A checklist of all freshwater fish species demonstrated to occur in Paraguay is presented with the aim of providing an updated list of all known fishes from Paraguay and to establish a baseline to keep the inventory updated. Species listed herein are only those that appear in published papers based on actual collection records. Type localities are provided for primary types of species originally described from Paraguay. For each species, the current name combination is followed by a list of synonyms, beginning with the original name combination, and followed by a list of literature citations for the Paraguayan territory. A total of 307 fish species were confirmed and listed, four of which are categorized as threatened, and including four introduced exotic species. Two thirds of the species belong to the Characiformes and Siluriformes, among the twelve orders and 39 families listed. A description of the hydrographic systems of Paraguay as well as an overview of the history of the ichthyology in Paraguay are also presented. Introduction Approximately one third of all freshwater fish species worldwide or more than 5,160 species occur in the aquatic habitats of South America. Further on the richest freshwater fish fauna, the highest rate of annual new species description is also recorded in the continent, with an average of 104 new species described every year in the past 15 years (Reis et al., 2016). Of the above total, 307 species (Table 1) are documented to occur in the waterways of Paraguay, representing almost 6% of the total in approximately 2.3% of the continental area. Among those, four species, Coptodon rendalli (Cichlidae, Africa), Poecilia reticulata (Poeciliidae, northern South America), and the two species of Cichla (Cichlidae, Amazon basin), are introduced exotic species. Previous estimates of Paraguayan fish richness based on published papers summarized 129 species (Ramlow, 1981), 189 species (Mandelburger et al., 1996) and 298 species (Bertoni, 1939). However, unpublished estimates vary from 259 (www.fishbase.org) to 395 (www.faunaparaguay.com/fishlist.html), and even up to 451 (guyra.org.py). The conservation status of Paraguayan freshwater fish species has been evaluated based on data generated during an international workshop for assessing extinction risk of fishes in the lower La Plata river basin (Baigún et al., 2012), conducted in August 2008 in Asunción, Paraguay. In that opportunity, 11 species were assessed as threatened in the lower La Plata basin using IUCN criteria (IUCN, 2010), four of which occur in Paraguay (Ancistrus piriformis and Brycon orbignyanus categorized as Vulnerable, and Gymnogeophagus setequedas and Hypostomus dlouhyi categorized as Endangered). Salminus hilarii and Zungaro jahu, two species probably present in Paraguay but still in need of confirmation, were also listed as Vulnerable. As in most of South America, continued habitat loss through land use change, construction and operation of hydroelectric dams, urbanization, poor agricultural practices, water pollution, overfishing, and introduction of alien species (Allan et al., 2005; Barletta et al., 2010; Reis, 2013; Reis et al., 2016) are the main causes of fish population decline in Paraguay. This checklist is a biodiversity inventory of the freshwater fishes of Paraguay, which has two objectives: to provide an updated list of all known taxa for Paraguay based on literature funded in actual collection records, and to establish a baseline to keep the inventory updated. Previous papers dealing with the Paraguayan fish diversity consisted in regional species lists (Chernoff et al., 2001) or national approaches (Bertoni, 1914, 1939; Ramlow, 1981; Mandelburger et al., 1996). Surprisingly, all failed in providing the source of information, even those based on scientific collections (Ramlow, 1981; Mandelburger et al., 1996; © www.pecescriollos.de 2017 - ISSN 1868-3703 Ichthyological Contributions of PecesCriollos 53: 1-99 (2017) 2 Chernoff et al., 2001). For this reason, several hundreds of papers had to be checked to identify the ones cited in here. After the first version of the list was completed, 39 fish taxonomists (see list in Acknowledgements) provided a review of their group of expertise, frequently adding new data and increasing accuracy to the work. All efforts were made to deliver a list free of errors, but as this is mostly improbable, we will be thankful for any correction or addition received. Despite the huge efforts of the reviewers all remaining errors are to be considered ours. For the future, all investigators are urged not only to use Paraguayan specimens in their publications, but to explicitly mention confirmations for doubtful species and first records as such. Table 1. CLOFPY "locality" Overview on the number of species of fishes to which the criterion “locality” could be assigned and which are thus confirmed for Paraguay. Myliobatiformes 7 Clupeiformes 2 Characiformes 123 Siluriformes 110 Gymnotiformes 15 Cyprinodontiformes 18 Beloniformes 2 Synbranchiformes 1 „Perciformes“ 2 Cichliformes 24 Pleuronectiformes 2 Ceratodontiformes 1 307 Hydrographic systems of Paraguay The Republic of Paraguay is located in central South America, it hydrologic systems belonging entirely to the Río de la Plata basin, the fifth largest basin in the world with a total area of about 3.1 million km2. This basin encompasses four major freshwater ecoregions through the Paraguayan territory (Figure 1): Chaco, Paraguay, Upper Paraná, and Lower Paraná (Abell et al., 2008). Paraguay is drained by the Río Paraguay and Río Paraná systems, both rivers forming large alluvial fans (or megafans) in the Paraguayan territory. Megafans occur when mountain captation rivers fill a plain area in a large drainage and deposit sediments by a laterally moving arm of the river (DeCelles & Cavazza, 1999). The alluvial fans on the right margin of the Río Paraguay in the Paraguayan ‘Chaco’ freshwater ecoregion are the Parapetí and the Pilcomayo (Iriondo, 1993). According to that author, the Parapetí fan flows to the Río Madeira regularly, and a little portion to the Timane-Paraguay around Bahía Negra during high flood in the rainy season. Furthermore, the Pilcomayo fan once drained in direction to and formed a swampy area known as the Estero Patiño (Iriondo et al., 2000). However, because of siltation and avulsion it actually drains to the Southeast in Argentina and to the West in Paraguay, flooding tributaries of the Río Paraguay as the Río Confuso and others. On the other hand, the Paraná fan covers the Southern part of Eastern Paraguay and the Northwestern part of Corrientes in Argentina (Iriondo & Paira, 2007), occupying the lowermost part of the freshwater ecoregion ‘Paraguay’ and the upper part of the freshwater ecoregion ‘Lower Paraná’ (Figure 2). The Río Paraguay basin is about 2,500 km long and extends to a total area of about 1 million km2, characterized by a vast plain which ranges from an altitude of 125 m in the Pantanal to 48 m at the confluence with the Río Paraná (Barros et al., 2004). Right margin tributaries to the Río Paraguay are generally intermitent systems draining the Chaco ecoregion in Paraguay as a result of the Pilcomayo alluvial fan (Iriondo et al., 2000). The Western Chaco is characterized by ephemeral channels, and the Eastern Chaco by swamps located in alluvial belts draining to the Río Paraguay (Iriondo, 1993). The most important right margin tributaries in the Paraguayan territory are nested entirely within the Chaco ecoregion and include the rivers Negro, Verde, Montelindo, Aguaray-Guasú, Confuso, and Pilcomayo. Left margin tributaries of the Río Paraguay are nested completely in the freshwater ecoregion ‘Paraguay’ and the most important tributaries on the Paraguayan territory are the rivers Apa, Aquidabán, Ypané, Jejuí-Guazú, Manduvirã, Salado, and Tebicuary (Figure 2). © www.pecescriollos.de 2017 - ISSN 1868-3703 Ichthyological Contributions of PecesCriollos 53: 1-99 (2017) 3 Figure 1. Partial map of South America showing the Río de la Plata Basin and four freshwater ecoregions: 1 Chaco, 2 Paraguay, 3 Upper Paraná, and 4 Lower Paraná. Red lines are ecoregion boundaries. Black lines are political boundaries. Figure 2. Map of Paraguay showing it hydrological systems: Black numbers indicate river: 1 Negro, 2 Verde, 3 Aguaray-Guasú, 4 Confuso, 5 Pilcomayo, 6 Apa, 7 Ypané, 8 Aquidabán, 9 Manduvirã, 10 Tebicuary, 11 Acaray, 12 Monday, and 13 Ñacunday. Red numbers indicate alluvial fans: 1 Parapetí fan, 2 Pilcomayo fan, 3 Paraná fan. Red arrows indicate flow direction. Dashed lines are fan boundaries. © www.pecescriollos.de 2017 - ISSN 1868-3703 Ichthyological Contributions of PecesCriollos 53: 1-99 (2017) 4 The Río Paraná system is approximately 4,695 km long and extends from its source formed by the junction of the Grande and Paranaíba rivers at 20°S, to 34°S at its mouth, near Buenos Aires, Argentina (Stevaux, 1994). The Río Paraná basin is divided into two major ecoregions, extending the ‘Upper Paraná’ from its source to the Itaipú dam near Ciudad del Este (Paraguay) and Foz do Iguaçu (Brazil). The most important right margin tributaries of this ecoregion is the Río Acaray. Below this point, Paraguayan water bodies are embedded entirely in the ‘Lower Paraná’ freshwater ecoregion and the most important right margin tributaries are the rivers Monday, Ñacunday, and Tembey (Figure 2). The Río Paraguay and the Río Paraná, including the whole basin of the Río de La Plata, are considered an area of endemism for Neotropical fishes.