SOUTH AMERICAN CHARACID FISHES — ^WEITZMAN 155 



like any living member or members of the Characinae. There is per- 

 haps more reason to give separate family status to the Erythrininae 

 than to any other subfamily of characids. Also there is some reason 

 to suspect that at least in certain featm-es, the Erythrininae are the 

 most archaic of living characids. In other aspects, however, they 

 are possibly quite specialized. 



What are the relationships of the subfamily Lebiasininae? Super- 

 ficially, members of the tribe Lebiasinini look much like members of 

 the Erythrininae because of their large scales, short-based anal fin, and 

 the overall similar appearance of the body and head. In addition, both 

 groups lack the supraorbital. The last is possibly not too important 

 a character, for loss of an element probably never should be consid- 

 ered as important as the development of a new structure. Except 

 for the fact, however, that these two groups are characids and have 

 similarly shaped cranial bones because of their similar general body 

 and head shape, they have little in common osteologically. In aU the 

 unique respects in which the Erythrininae differ from the Characinae, 

 the Lebiasininae are like the Characinae. As noted above, members 

 of the tribe Lebiasinini and indeed the entire Labiasininae have a 

 few very unique characters that are different from those of both the 

 Characinae and the Erythrininae. The unique lack of a fenestra 

 between the quadrate and metapterygoid appears specialized. Also, 

 the general reduction in the laterosensory canals of the head of the 

 Lebiasininae and the unique laterosensory head canals of the member 

 subtribes of the Pyrrhulinini are very specialized. It seems likely 

 (1) that the Lebiasininae are somewhat more closely related to the 

 Characinae than to the Erythrininae and (2) that the Lebiasininae 

 evolved from a common characid stock that gave rise to Lebiasininae 

 and Characinae but not to the Erythrininae. 



According to several authors, one of the distinguishing characters 

 of the Lebiasinini is the possession of a "cellular" anterior wall of the 

 posterior chamber of the swimbladder. The present investigation 

 indicates that certain species (Piabucina panamensis and P. ery- 

 thrinoides) in this group lack this feature while others (Lebiasinina 

 bimaculata and Piabucina jestae) do have it. Obviously, the group 

 needs revision and, since Bohlke (1958, p. 94) has indicated he is doing 

 this, no revision is attempted here. It should also be noted that, of 

 the Erythrininae, at least Hoplerythrinus unitaeniatus and Erythrinus 

 erythrinus have a cellular anterior wall of the posterior chamber of 

 the swimbladder. Hoplias malabaricus does not. The significance 

 of the similar "cellular" structure of swimbladders of some members 

 of the Erythrininae to that of some of the Lebiasinini is difficult to 

 assess. In view of the distinct osteological differences between the 

 Erythrininae and the Lebiasinini, however, I prefer to believe that 



