perhaps, gill rakers increase in number during growth, at least until a certain body 

 size is reached. Regardless of the intraspecific variation, the ranges and/or mean 

 number of gill rakers was sufficient to separate several species, as detailed in the 

 species accounts. Among catfishes in general, high gill-raker counts are probably 

 derived (Lundberg 1982); thus, I hypothesize that a high gill-raker count is a 

 synapomorphy among some species of ageneiosids. 



Barbels 



The barbels of catfishes are prominent sensory and tactile structures that, 

 although not unique to these fishes, characterize the order because of their 

 conspicuous appearance in most species. All catfishes have at least one pair of 

 maxillary barbels, which are reduced or vestigial in ageneiosids and a few other taxa, 

 including some species of the eastern hemisphere genera Cryptopterus and 

 Pangasimodon (Giinther 1864; Alexander 1964, 1965; Roberts 1973 [who 

 erroneously stated that they were absent in some female ageneiosids]). The 

 majority of catfishes have additional barbels that are variable in number and 

 structure and associated with the mandibular skin or with the external nares. 

 Diplomystids have only a pair of maxillary barbels. In many taxa, some or all of the 

 barbels are elaborately developed and may have fleshy branches or diverticuli, such 

 as in the Loricariidae, Doradidae, and Mochokidae. Siluroid barbels differ from 

 those of other teleosts, including the related cyprinoids, by their histologically 

 distinctive ultrastructure, consisting of an elastin core (Alexander 1965; Roberts 

 1973; Ghiot and Bouchez 1980; Dimmick 1988), and, in the case of the maxillary 

 pair, myological and osteological adaptations that allow for independent adduction 

 and motility of the barbels for increased tactile and gustatory functions (Alexander 

 1965; Gosline 1975). In the context of their study. Fink and Fink (1981) concluded 



