Microglanis malabarbai

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Neotropical Ichthyology, 3(1):61-67, 2005 Copyright © 2005 Sociedade Brasileira de Ictiologia

A new species of Microglanis (Siluriformes: Pseudopimelodidae) from the rio Uruguay drainage, Brazil

Vinicius A. Bertaco and Alexandre R. Cardoso

A new pseudopimelodid catfish, Microglanis malabarbai, is described from the rio Ijuí drainage, tributary of the middle rio Uruguay, Rio Grande doSul, Brazil. The new species is distinguished from all other Microglanis species by the caudal fin color pattern, almost completely black, with a narrow vertical white band across central portions of the caudal-fin rays. Furthermore, it is distinguished from M. cottoides and M. eurystoma, both from rio Uruguay drainage, by head length, maxillary barbel length, internareal distance, and number oflateral-line pores, and from M. cibelae from the coastal drainages of northern Rio Grande do Sul and southern Santa Catarina states, by head length, maxillary barbel length, and body width. A key is presented for the species of Microglanis occurring in southern Brazil. Uma nova espécie de pseudopimelodídeo, Microglanis malabarbai, é descrita da bacia do rio Ijuí, tributário do médio rio Uruguai,Brasil. A nova espécie distingue-se das demais espécies de Microglanis pelo colorido da nadadeira caudal, quase completamente preta, com uma pequena faixa vertical branca na sua porção central. Além disso, distingue-se de M. cottoides e M. eurystoma, ambas da bacia do rio Uruguai, pelo comprimento da cabeça, comprimento do barbilhão maxilar, distância entre as narinas anteriores e número de poros nalinha lateral, e de M. cibelae, das drenagens costeiras do norte do Rio Grande do Sul e sul de Santa Catarina, pelo comprimento da cabeça, comprimento do barbilhão maxilar e largura do corpo. É apresentada uma chave para as espécies de Microglanis ocorrentes no sul do Brasil. Key words: Neotropical, taxonomy, M. eurystoma, M. cibelae, M. cottoides, rio Ijuí, Southern Brazil.

IntroductionMicroglanis is a genus of Neotropical pseudopimelodid catfishes comprising 12 valid species and distributed throughout most of tropical South America on both sides of the Andes (Shibatta, 2003a). The genus is known from Pacific coast drainage in Ecuador, Lake Maracaibo basin (rio Catatumbo), Orinoco basin, coastal drainages of the Guianas, Amazon basin, Río de la Plata basin, and coastal drainages ofsouthern Brazil from the states of Rio de Janeiro to Rio Grande do Sul (Mees, 1974; Le Bail et al., 2000; Shibatta, 2003a). Recently, Malabarba & Mahler (1998) reviewed the diversity of Microglanis in the rio Uruguay and coastal drainages of southern Brazil, recognizing three species. Microglanis cottoides (Boulenger, 1891) was considered valid, redescribed, and recorded from the rio Uruguay andrio Jacuí drainages, and two new species were described: M. eurystoma Malabarba & Mahler, 1998, from the upper rio Uruguay

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drainage, and M. cibelae Malabarba & Mahler, 1998, from the coastal drainages of northern Rio Grande do Sul and southern Santa Catarina states. During inventory field studies conducted by the authors and related to the construction of two hydroelectric damsin the rio Ijuí, an additional undescribed species of Microglanis was discovered in this tributary of the middle rio Uruguay (Fig. 1), Brazil, which is described herein. Methods and materials Measurements were taken as described in Malabarba & Mahler (1998), including the following additional measurements: caudal peduncle length (measured from the base of the last anal-fin ray to the posteriormargin of the hypural fan), dorsal-fin base, adipose-fin base, horizontal orbital diameter, maxillary barbel length, head depth (measured at a vertical immediately before pectoral fin spines), and

Laboratório de Ictiologia, Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, 90619-900 Porto Alegre, RS, Brazil.

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