'^ ["':,-:■ .A- ,_,. ., . ,, ^. 120 



Anal Fin 



Ageneiosids have a relatively long anal fin. The number of lepidotrichia 

 varies considerably within every species, although the range and mean number of 

 rays differs significantly between some species (Table 3). Ageneiosus atronasus has 

 the shortest anal fin (23-30 rays), and^l. ucayalensis has the longest (41-50 rays). 

 The ranges of rays in the remaining species overlap widely; thus, anal-fin ray counts 

 must be used m combination with other morphological characteristics to separate 

 these species. ^ ' '"-■ 



Lundberg (1982) concluded from a survey of the hterature that the most 

 common anal fin-ray counts among catfishes fall in a range between 16 and 20, and 

 this range is presumably primitive. Elongation of the fin, therefore, is a derived 

 condition, albeit unquestionably acquired independently in a moderate number of 

 unrelated taxa. Britski (1972) gave a range of anal-fin rays for ageneiosids, several 

 auchenipterid genera, and doradids. From those data, Ferraris (1988) concluded 

 that elongation of the anal fin was a synapomorphy of his Auchenipterinae, although 

 homoplasious within the Doradoidea. However, he considered elongation of the 

 anal fin, "with at least 16 rays and usually more than 20" (Ferraris 1988:51) to be the 

 derived condition. If the range presented by Lundberg (1982) is indeed primitive, 

 then taxa with less than 20 rays cannot be considered derived. Among doradoids, 

 this includes members of the Doradidae, Centromochlidae (sensu Ferraris 1988), 

 Pseudauchenipterus, Trachelyopterus,Asterophysus, a.nd Entomocorus, if the counts 

 given by Britski (1972) are accurate. Given the variability and wide range of anal- 

 fin rays among auchenipterids and ageneiosids, this character seems to be of limited 

 use for determining intergeneric relationships. Taxa with relatively few rays are 

 probably primitive for this character, but it appears that a parallel mcrease in the 

 number of anal-fin rays may have occurred in several lineages. Even so, an increase 



