63 



Trachefyopterus. Future studies may reveal that dimorphism of the palatine is more 

 widespread than currently known. 



The maxilla is typically a teardrop-shaped bone with an expanded base (Fig. 

 9). As in other catfishes, it supports the maxillary barbel, and articulates as a hinge 

 joint with the anterior facet of the palatine. Posterolaterally, the maxilla extends as 

 a short cartilaginous core into the maxillary barbel. In nuptial males, the maxilla 

 becomes hyperossified, extends into the barbel for its entire length, and develops 

 sharp, recurved odontodes on the dorsal surface, as discussed below in greater 

 detail. 



Suspensorium ; 



The ageneiosid suspensorium is characterized by its relatively large surface 

 area, comprised of obhquely angled, laminar ossifications on the anterodorsal 

 margins of the metapterygoid, quadrate, hyomandibular, and an additional 

 pterygoid bone. The quadrate, in particular, has a dorsomedial lamina that extends 

 between the metapterygoid and hyomandibular and sutures broadly to each bone 

 (Fig. 10). Anterodorsally, it sutures along most of its margin with the 

 metapterygoid. The metapterygoid is laminar and roughly quadrangular, 

 articulating synchondrally with the quadrate near its posteroventral comer. Ferraris 

 (1988) considered this arrangement of suspensorial elements to be uniquely derived 

 in ageneiosids; the primitive condition in doradoids, as in most catfishes (Alexander 

 1965), is one in which the hyomandibular and metapterygoid contact each other 

 dorsal to the quadrate. Dorsally the hyomandibula articulates synchondrally and by 

 a short anterodorsal process with the sphenotic. Posterior to the sphenotic 

 articulation there is a short, broad process contacting a shallow groove in the 

 pterotic. Ventromedially, the hyomandibula sutures along most of its margin with 



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