; ; , Among recent studies, Britski (1972) was the first to firmly indicate a close 



relationship between Tetranematichthys SindAgeneiosus. Britski based his 



conclusion on several similarities in morphology, most notably osteological features 



of the cranium, but he did not explicitly present his hypothesis of relationships 



within a strict phylogenetic context. To that end, Ferraris (1988) placed 



ft 

 Tetranematichthys and Ageneiosus in a monophyletic clade, based on shared, derived 



characters of the the skull and pectoral fin, although he classified both as a subgroup 



of the Auchenipteridae. Curran (1989) excluded Tetranematichthys from a cladistic 



analysis of the Auchenipteridae, and suggested the genus was related to ageneiosids 



based on a combination of two putative synapomorphies involving the barbels and 



additional characters thought to be absent in the auchenipterids. 



The historical confusion in the placement of the genus Tetranematichthys as 

 outlined above reflects largely the discrepant classification schemes presented for 

 doradoid catfishes in general. Based on the work of Britski (1972), Ferraris (1988), 

 and the present study, it is clear that Tetranematichthys should be classified together 

 with the remaining ageneiosids. Ferraris (1988) examined more genera and a larger 

 number of characters than any previous study, in a phylogenetic context, and 

 concluded that Tetranematichthys and Ageneiosus were sister taxa that formed a 

 monophyletic group within the Auchenipteridae and should not be accorded family 

 status. He made no recommendation regarding their subfamihal classification 

 beyond placement within the tribe Auchenipterini, together with five additional 

 genera. For reasons detailed elsewhere in the present study, I choose to continue 

 recognizing the family Ageneiosidae, and regard the treatment of Tetranematichthys 

 as a primary nomenclatural question. 



The presence of a single pair of mental barbels in Tetranematichthys has in 

 the past provided the main basis for recognition of this taxon at the generic level. 

 Ageneiosus and aUied nominal genera (Pseudageneiosus and Tympanopleura) have 



