Tetranematichthys are somewhat more robust and strongly serrated than in the large, 

 fork-tailed species. The outgroup taxa generally have a much stronger spine than is 

 found in ageneiosids; nearly all doradids and several auchenipterids have very 

 strong spines that are serrated on both margins. Several genera of auchenipterids 

 {&.%., Auchenipterus, Epapterus) do not have serrae on the anterior face of the spine, 

 a condition that is shared with ageneiosids, but one that Ferraris (1988) suggested 

 has occurred independently in at least three lineages. 



In ageneiosids there are three ossified radials supporting from 7 to 17 

 branched pectoral-fin rays. The third radial is expanded posteriorly and supports 

 several fin rays (Fig. 25). Ferraris (1988) suggested that the expanded third radial 

 was a synapomorphy of the ageneiosid clade. The number of rays varies by three or 

 four within every species, but modal fin-ray counts can be used to separate some 

 species. The fewest rays are found in A. atronasus,A. brevis,A.piperatus, and 

 Tetranematichthys, all with modal counts under 12. The large fork-tailed species 

 have modal counts of 12 to 13. The greatest number of fin rays is found in^. 

 pofystictus,A. brevifilis, and A. marmoratus, all with modal counts of 14 to 15. The 

 number of pectoral-fin rays among outgroup taxa varies widely (Britski 1972); thus, 

 fin-ray number is of limited use in assessing phylogenetic relationships between 

 genera. Nevertheless, an increase in the number of fin rays possibly represents a 

 derived state within the Ageneiosidae, since most auchenipterids have fewer fin rays 

 and lack the expanded third radial. ' r; /^ , ' 



Pelvic Girdle 



'"'■j"'^ ' 



1^ 



•■-^^ -- - - '■•■■■ -^Ov 



tr< 



?. « f 



The ageneiosid pelvic skeleton is a remarkably conservative structure, 

 varying relatively little in morphology among species, and thus is of no systematic 

 value in determining relationships within the family. By virtue of its constancy in 

 form, however, it is of some use as a diagnostic character of the family. 



