• :. ■' ■■ r'^- N , . 279 



■■ '-■-•'^'■■. ■■', 



Color in Alcohol ;?; ,. 



Dorsum of body slate gray to brown, usually broken into a series of 

 prominent blotches (Fig. 49). Overall background color dusky white to yellow. Top 

 of head with an irregularly mottled pattern consisting of dark brown blotches, 

 normally with a very dark stripe along each margin of the fontanelle, connected 

 anteriorly by a band extending across the top of the mesethmoid. Nape with a 

 number of smaller spots. Areas between blotches on top of head ranging from 

 immaculate to small, diffuse brown specklings. A dark spot at posteroventral 

 margin of eye, but rest of orbit typically without much pigment. Opercular flap with 

 diffuse specks, margin lightly pigmented. 



Mottling on back consisting of large blotches, with a light stripe down 

 midline; blotches not extending much down sides. Side of body with a diffuse band 

 just above lateral line, diminishing abruptly below middle of sides. Sides above 

 pectoral fin with a sublateral band of variably intense speckling, generally 

 disappearing before pelvic fin. Belly, chin, and throat immaculate. 



Dorsal fin pale, generally without much pigment except for scattered brown 

 flecks. Adipose fin with brown specks at base, otherwise immaculate. Caudal fin 

 with a crescent shaped spot at base of upper lobe, extending about a third onto rays, 

 and confluent with stripe on top of cuadal pedimcle. 



Distribution 



Ageneiosus valenciennesi is confined to southern Brazil, Argentina, Paraguay, 

 and Uruguay. It is distributed widely throughout the middle and lower Rio Parana- 

 Paraguay basin, and in the lower reaches of the Rio Uruguay (Fig. 50) Throughout 

 its range the only other species of the genus with which it is sympatric are^. 

 brevifilis andyl. ucayalensis. 



