PROC. BIOL. SOC. WASH. 101(3), 1988, pp. 509-516 RELATIONSHIPS OF THE NEOTROPICAL CATFISH GENUS NEMUROGLANIS, WITH A DESCRIPTION OF A NEW SPECIES (OSTEICHTHYS: SILURIFORMES: PIMELODIDAE) Carl J. Ferraris, Jr. Abstract.— K new species of the Neotropical catfish genus Nemuwglanis is described from material from the Rio Negro and Rio Orinoco. Osteological characters place the genus within a large, previously recognized but unnamed clade of the Pimelodidae which contains most of the smaller sized members of the family. A more restrictive clade, which contains Nemuwglanis and members of several other pimelodid genera, is defined on characteristics of the fin spines and transverse processes of the anterior vertebrae. Resumen. —Una nueva especie de pez siluriforme (bagre) perteneciente al genero neotropical Nemuwglanis se describe del material procedente de los rios Negro e Orinoco. Los caracteres osteologicos encontrados permiten incluir al genero dentro de un clado grande, previamente reconocido, pero sin nombre, de los Pimelodidae el cual contiene la mayor parte de los miembros de tamaiio pequefio de la familia. Un clado mas restringido, que contiene a Nemuwglanis y a miembros de varios otros generos de pimelodidos se define en base a las caracteristicas de las espinas de las aletas y a los procesos tranversales de las vertebras anteriores. The pimelodid catfish genus Nemuw-glanis has been a taxonomic enigma since it was first described. Eigenmann & Eigen-mann (1889) proposed the name for a new species, A^. lanceolatus, based on a single specimen taken by the Thayer expedition to Brazil. While undoubtedly a new species and a member of the Pimelodidae, as currently construed, the relationships of this fish within the family remained obscure. Until quite recently, our knowledge of the species and genus was based entirely on a single, fragile, 23.5 mm standard length (SL) spec-imen and a brief and inaccurate original de-scription. Eigenmann & Eigenmann (1889) stated firmly, but incorrectly, that Nemuwglanis belonged to a sub-group of pimelodids with toothed vomers, a group that otherwise con-tained only the largest of the Pimelodidae. Gosline (1941), however, included Nemu-wglanis in his study of those pimelodids without a free orbital rim although no other pimelodid with a toothed vomer was in-cluded, and despite his comment that it was impossible to tell from the original descrip-tion whether the genus had a free orbital rim. Recent efforts to elucidate the rela-tionships within the Pimelodidae (e.g., Has-sur 1970, Stewart 1986, and Lundberg & McDade 1986) have, of necessity, had to ignore Nemuwglanis. Fortunately, in this time of active investigation of the relation-ships of Neotropical catfishes, recent col-lecting in the Rio Negro and Rio Orinoco of Venezuela has uncovered a number of specimens of a species which, while not con-specific, are closely related to Nemuwglanis lanceolatus. The new species is described and figured herein, and aspects of the anat-
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