Taxonomic revision of the South American catfish genus Ageneiosus (Siluriformes: Auchenipteridae) with the description of four new species

Abstract

The catfish genus Ageneiosus in the exclusively Neotropical family Auchenipteridae is revised. Species of Ageneiosus are widely distributed in all major South American continental drainages except the São Francisco River basin and small rivers along the Brazilian east coast. The taxonomic revision was based on examination of available type specimens, additional museum material and comparisons of original descriptions. A suite of morphometric, meristic and qualitative characters of internal and external anatomy were used to diagnose valid species and determine synonyms. Thirteen valid species are recognized in the genus Ageneiosus, some of which are widely distributed across South America. Ageneiosus pardalis is the only trans-Andean species in the genus. Ageneiosus polystictus and Ageneiosus uranophthalmus are more widely distributed than previously reported. Ageneiosus marmoratus is a junior synonym of Ageneiosus inermis. Ageneiosus dentatus is a valid species and its name is removed from the synonymy of Ageneiosus ucayalensis. Four new species are described: Ageneiosus akamai, Ageneiosus apiaka, Ageneiosus intrusus and Ageneiosus lineatus, all from the Amazon River basin. A dichotomous key for all 13 valid species of Ageneiosus species is provided.

Ichthyofauna from tributaries of Urubu and Amazonas rivers, Amazonas State, Brazil

“…About 28% of South America's known fauna has been described in the last 11 years, due to the unique environmental aspects of the Amazon basin, which contribute to new species discoveries (Reis et al 2016). We recorded six species described for the Amazonas river basin in the last decade, Moenkhausia mikia, Hemigrammus diagnonicus, Eigenmannia muirapinima, Metynnis melanogrammus, Curimatopsis pallida, and Ageneiosus lineatus (Marinho & Langeani, 2016, Mendonça & Wosiacki 2011, Peixoto et al 2015, Ota et al 2016, Melo & Oliveira 2017, Ribeiro et al 2017, along with a common species that was recently redescribed as Mylossoma albiscopum (Mateussi et al 2017). Still, a new species for science, identified here as Moenkhausia aff.…”

Quantifying shortfalls in the knowledge on Neotropical Auchenipteridae fishes

“…comm. ; see Akama, 2004;Ribeiro et al, 2017). In this sense, revisionary studies are responsible for re-identifying material deposited in the collections, including older and recent specimens sampled, also contributing to updating the database collection and the geographic distribution of species (Lundberg et al, 2000;von Staden, Raimondo, & Dayaram, 2013).…”

“…In Auchenipteridae, the revisionary studies published in the last decade significantly contributed to the description of new species. Around 40% of auchenipterid species described between 2001 and 2018 resulted from taxonomic revisions (e.g Reis & Borges, 2006;Ribeiro, Rapp Py-Daniel, & Walsh, 2017;Sarmento-Soares & Martins-Pinheiro, 2008)…”

First records of freshwater fish species in Colombia: extending the distribution of 17 Amazonian and Orinoco fish species

“…Identification. The specimens were identified by slightly emarginate caudal fin, and dark spots randomly distributed on the flanks (Ribeiro et al 2017). Previously known distribution.…”

“…Previously known distribution. Brazil: rio Negro and middle Amazon basin (Ribeiro et al 2017). Type locality: mouth of rio Negro, Amazon system, Brazil.…”