' ..■■•\. -^ ^■^- -. :.'.,„ 184 



7b. Total vertebrae behind complex centrum 42-45. Absent from Orinoco and 

 Amazon river basins; distribution in the Rio Parand-Paraguay basin, or in the 

 trans-Andean drainages of northwestern Venezuela, Colombia, and southern 

 Panama 9. 



8a (7a). Pigmentation on body consisting of a very distinct, sharply delineated, ;' 

 midlateral brown stripe extending entire length of side, bordered above and 

 below by unpigmented stripes of nearly equal width. Body very compressed 

 behind head. Free vertebrae behind complex centrum and anterior to first anal 

 pterygiophore 9-12. Pairs of pleural ribs 7-8, modally 7. Pectoral rays 12-15, 

 modally 13. Recorded only from the Amazon river and its tributaries, and the 

 Rio Amapd Ageneiosus n. sp. 



8b. Pigmentation highly variable, but always with traces of a thin, black or brown 

 midlateral stripe over anterior portion of lateral line, a similar stripe extending 

 obliquely downward from the top of the operculum to above the pelvic fin, a . . 

 mottled pair of stripes just lateral to the midline of the back, and a large black 

 spot in the middle of each caudal-fin lobe. Free vertebrae behind complex 

 centrum and anterior to first anal pterygiophore 11-14. Pairs of pleural ribs 8-10, 

 modally 9. Pectoral rays 11-13, modally 12. Present in the Orinoco and upper 

 Amazon basins Ageneiosus vittatus. 



9a (7b). Found only in trans-Andean rivers of northwestern Venezuela (in the 

 Maracaibo basin), Colombia (including the Magdalena, Cauca, Atrato, and San 

 Juan rivers), and southern Panama (Rio Tuira and smaller drainages). 

 Pigmentation heavily mottled on head and dorsum, often extending over most of 



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