■;'.„■■■; "-:''■':■■ /.J,. ■ 128 



extremely porous ossifications. These weakly ossified areas may have a hemopoietic 

 function, but their cytology has not been studied. The porous nature of the caudal 

 skeleton, in combination with cancellous neurocranial bones, is unique to 

 ageneiosids among doradoids. 



, The above fusion pattern corresponds to the PH+ 1 + 2 : 3 + 4 :5 designation of 

 Lundberg and Baskin (1969). They found that A. pardalis shares the same hypural 

 fusion pattern as all auchenipterids studied (eight species in five genera), Doras, two 

 species of mochokids, and several pimelodids. Phylogenetic comparisons based on 

 hypural fusion patterns are confounded by ontogenetic changes, intraspecific 

 variation, and homoplasies among the taxa studied by Lundberg and Baskin (1969). 

 Despite these problems, any given fusion pattern is often characteristic of taxa at the 

 species, genus, or even family level. This is the case in ageneiosids, all species of 

 which have an identical fusion pattern (and this pattern may be indicative of 

 relationships at a higher level of universality). ; ' , ^ 



In very large individuals there are laminar ossifications between the 

 uroneural and fifth hypural, and on the anterior vertical edges of the last few hemal 

 spines; this condition reaches an extreme in A. brevifilis, large specimens of which 

 have the entire caudal skeleton heavily ossified, with lamina between the hypural 

 elements and the last four or five hemal spines (Fig. 30a). Increased laminar 

 ossifications are partially correlated with large body size, as well as number of fin 

 rays. Ferraris (1988) observed thickened hemal spines of preural vertebrae in 

 several genera of auchenipterids, all of which have emarginate or truncate caudal 

 fins. The presence of expanded posterior hemal spines is correlated with an 

 emarginate or truncate caudal fin, and is related to support of the lower principal fin 

 rays. In taxa with a tail of this shape, there are ten principal rays in the lower lobe 

 of the fin, compared to nine rays in fork-tailed species. A combination of one 

 additional lower principal ray and an oblique shape has led to an anterior shift in 



