;,::; > INTRODUCTION 



Members of the catfish family Ageneiosidae are widely distributed 

 throughout major freshwater drainages of the neotropics from Panama southward to 

 Paraguay and Argentina. They are small to moderately sized fishes typically found 

 in open-water habitats, such as lakes and large river channels. Some species 

 comprise a significant element of local fisheries harvests, and are thus familiar to 

 many native South Americans by a variety of vernacular names. In spite of their 

 widespread distribution and popularity as food fishes, the taxonomy and 

 phylogenetic relationships of ageneiosids have remained largely obscure to 

 ichthyologists in this century. ,, . 



? The present study was undertaken to address the following objectives: (1) to 

 compile all pertinent literature of the Ageneiosidae; (2) to elucidate the salient 

 features of morphometry, osteology, and soft anatomy of all known species; (3) to 

 provide a comprehensive systematic revision of the family based on morphological 

 criteria; (4) to test the hypothesis that the nominal genersi Ageneiosus, 

 Pseudageneiosus, Tetranematichthys, and Tympanopleura form a monophyletic group; 

 (5) to determine the nomenclatural status of each of these genera and the species 

 included in them; (6) to evaluate the relationships of all included species using 

 phylogenetic methods; (7) to summarize previous studies on higher relationships of 

 ageneiosids to other catfish genera and families; and (8) to compile range maps of 

 all species from museum specimens, and to compare their distributions with those of 

 other neotropical freshwater fishes. ^ 't^ 



' % 



/. 



