The maximum body size of ageneiosids varies widely among species, and is of 

 some diagnostic value in their taxonomy. The smallest species, A. piperatus, reaches 

 sexual maturity at less than 50 mm SL. At the other extreme,^, brevifilis commonly 

 exceeds 400 mm SI^ and there are unconfirmed reports that A. pardalis may reach 

 lengths exceeding 1.5 meters. Most auchenipterids and doradids are relatively small 

 fishes, although there are some extremely large doradids. Lundberg (1982) 

 speculated that small body size, less than about 100 mm SL, is probably a derived 

 feature among catfishes in general, but he noted that considerable parallel evolution 

 has probably occurred. An extreme condition is found in numerous miniaturized 

 neotropical taxa (Weitzman and Vari 1988; Schaeffer et al. 1989), many of which 

 have independently acquired small size. Presumably among doradoids in general, a 

 relatively moderate body size is the ancestral condition, and the evolution of small 

 body size may represent a derived condition, such as found in some auchenipterid 

 genera (e.g., Centromochlus, Gelanoglanis). If this assumption is correct, then, on 

 the basis of body size d\one,A.piperatm,A. atronasus, and^. brevis are derived 

 relative to other species of the family Ageneiosidae. However, it seems reasonable 

 to me that an opposite argument can be made, and that large body size may in fact 

 represent a derived state in certain lineages. Among neotropical siluroids, some 

 pimelodids and doradids get extremely large, although most of the species of these 

 two families are relatively small to medium-sized. If the ancestral condition was of a 

 moderate body size within any given lineage, it is logical to assume that either 

 smaller or larger body size could represent derived states in terminal taxa. Within 

 the Ageneiosidae, most species are between 100 and about 200 mm SL, but several 

 species reach much larger sizes. Since all of the small species oiAgeneiosus also 

 have the plesiomorphically large, unencapsulated swimbladder, it seems most 

 parsimonious to assume that evolution of larger body size is the derived state within 

 the family. 'Hevextheless, A. piperatus, the most diminutive species of the family, has 



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