•^jy-T 



. 205 

 Diagnosis 



A distinctive ageneiosid characterized by the combination of a small adult 

 body size; strongly arched occiput; short and broad snout; moderately stout 

 pectoral-fin spine; large swimbladder; and a short postcleithral process (shared only 

 with Tetranematichthys). Some individuals in life have pronounced spots on the 

 head, dorsum, and upper sides of the body in a configuration unlike any other 

 species, with the exception of A. pofystictus. Ageneiosus brevis, however, is not Ukely 

 to be confused with A. pofystictus, due to many external differences, including 

 maximum body size and shape of the tail. A combination of the small size and the 

 large, unencapsulated swimbladder separates >1. brevis from all congeners except yl. 

 atronasusa.ndA.piperatiis. Distinguished from y4. fitfronasiw by a much longer anal 

 fin (29-42 rays versus 23-30); fewer preanal vertebrae (modally 14 versus 17); fewer 

 pleural ribs (5-6 versus 7-8); longer and more total gill rakers on outside row of first 

 arch (21-32 versus 14-18); and usually an unmistakable difference in pigmentation. 

 Ageneiosus brevis is distinguished from A. piperatus by its larger adult body size; 

 greater number of pectoral fin rays (modally 11 versus 9); fewer preanal vertebrae 

 (modally 14 versus 16); greater number of branchiostegals (modally 9 versus 7); 

 presence of posterior swimbladder caecae; and differences in pigmentation. 



Description 



A small ageneiosid, most specimens not exceeding 125 mm SL; the largest 

 specimen examined measured 160 mm SL. The principal meristic and proportional 

 measurements are summarized in Tables 8-9. 

 <— . Head relatively short (26-32% SL) and broad (19-23% SL). Dorsal contour 



^% of head smoothly sloping upward to eye, acutely angled from rear margin of 



-■ fontanelle to dorsal origin; strongly concave in breeding males. Snout broadly 



