Proceedings of 

 the United States 

 National Museum 



SMITHSONIAN INSTITUTION . WASHINGTON, D.C. 



Volume 116 



1964 



Number 3499 



OSTEOLOGY AND RELATIONSHIPS OF 



SOUTH AMERICAN CHARACID FISHES OF 



SUBFAMILIES LEBIASININAE AND ERYTHRININAE 



WITH SPECIAL REFERENCE TO SUBTRIBE NANNOSTOMINA ^ 



By Stanley H. Weitzman 



Introduction 



The present work is the result of an attempt to determine the 

 relationships of two characid genera, Nannostomus and PoecUobrycon, 

 to other members of the cypriniform family Characidae. The two 

 genera include about eight known species of small characids found in 

 forest brooks of South America. These species are here assigned to 

 the subtribe Nannostomina. Although the first known species of 

 this group was described in 1872, adequate investigation of morpho- 

 logical evidence for their relationships has never been undertaken. 

 Previous investigations have been superficial in scope and often 

 inaccurate in fact primarily because of the small size of these fishes. 

 The total cranial length is usually 5-10 mm, and the largest recorded 

 specimen is 44.5 mm. in standard length. In some cases, despite the 

 lack of adequate morphological data, certain ichthyologists have 



' This paper is the second of three parts based on a dissertation submitted to 

 the Department of Biological Sciences, Stanford University, California, in partial 

 fulfillment for the degree of Doctor of Philosophy. See Weitzman (1962) for 

 the first part. 



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