

ageneiosids were included with taxa of four additional families considered to have 

 relatively high counts (presumably of post-Weberian elements; Howes' conclusion 

 based on this count was questioned by Stewart 1986). Species of Diplomystes have 

 on the order of 40-43 total vertebrae (Arratia 1987). Stewart (1986) considered 

 relatively high total vertebral counts of 49-61 in one clade of pimelodids to 

 represent a derived condition. Similarly, Howes (1983) stated that an increase in 

 the number of vertebrae represents a derived state, but it presumably has occurred 

 independently in many catfish Uneages, and therefore is of limited usefulness for 

 determining probable relationships. While data such as these provide much needed 

 information, counts given by various authors are not always directly comparable; 

 variation in the number of fused centra, and failure of some authors to clearly 

 indicate which elements are included, has led to discrepancies in the literature. Few 

 authors have been as meticulous as Lundberg (1982), Stewart (1986) or Roberts 

 (1989a) in explaining how counts are presented. In spite of these limitations, I 

 follow Stewart (1986) in treating the presumably derived state of an increase in 

 vertebrae to be of some use for inferring relationships within a relatively close group 

 of species. - 



Although ageneiosids have relatively high numbers of vertebrae in 

 comparison to many other siluroids, they are not significantly different from many 

 species of auchenipterids. Britski's (1972) vertebral counts, presumably of post- 

 Weberian centra, ranged from 38 to 51 for various auchenipterid genera; not 

 unexpectedly, he found a correlation between body length and vertebral number. 

 Relatively elongate forms, such as Ageneiosus spp., Auchenipterus, and 

 Trachefyoptenchthys have the highest counts. From the limited data available for 

 other doradoid taxa, it appears that the derived condition of an increase in the 

 number of vertebrae has been obtained independently in several clades, considering 

 a lack of corroborative evidence hnking these taxa. Among species oiAgeneiosus, I 



