225 

 Ageneiosus atronasus Eigemnann and Eigenmann 

 Figs. 1, 6-7, 10, 12, 18, 20, 23, 26, 32, 41-42 

 Tables 11-12 



Ageneiosus atronasus Eigenmann and Eigenmann 1888:119,149-150 (original 

 description [type locality unknown, but probably Amazon River basin; 

 collected by L Agassiz or field associates during Thayer expedition]); 1890: 

 300, 302-303 (in key; partial synonymy [after Eigenmann and Eigenmann 

 1888]; description; comparison withal, brevis); 1891:35 (citation). Miranda- 

 Ribeiro 1911:402 (diagnosis). Gosline 1945:24 (citation). Fowler 1951:451 

 (partial synonymy). Britski 1972:105 (citation). Ferraris 1988:124 (citation). 

 Burgess 1989:286 (citation). 



Ageneiosus melanopogon Miranda-Ribeiro 1917:51-52 (original description [type 

 locality unknown]). Gosline 1945:25 (citation). Fowler 1951:453 (partial 

 synonymy; distribution). Britski 1972:99, 108 (citation). Ferraris 1988:126 

 (citation). Burgess 1989:286 (citation). 



Tympanopleura nigricollis Eigenmann and Allen 1942:139; plate 5, figs. 2-3; plate 6, 

 fig. 3 (original description [type locality: Iquitos, Peru]). Fowler 1945:67 

 (citation); 1951:456, fig. 484 4)artial synonymy; distribution). Gosline 

 1945:26 (citation). Ortega and Vari 1986:14 (citation; common name). 

 Burgess 1989:286 (citation). 



Ageneiosus nigricollis: Britski 1972:100, 108 (new combination; citation). Ferraris 

 1988:69, 71-72, 126-128, 151, figs. 5, 45 (citation; diagnosis; morphology of 

 tripus, swimbladder, and elastic spring apparatus; phylogenetic relationships) 



DiagnQsis 



' A small species distinguished from all other ageneiosids by a unique 



combination of the following characters: size small, rarely exceeding 120 mm SL; 

 unusual pigmentation pattern, consisting of a dense semicircular patch of 

 melanophores on the chin, a patch on the flanks above the anal fin, and an elongate 

 stripe radiating from the base of each caudal lobe; relatively low numbers of 

 pectoral fin rays, anal fin rays, and branchiostegals; swimbladder large, 

 unencapsulated, with bilobed anterior chamber and a pair of posterior caecae; snout 

 short, with gape of mouth gently recurved; tooth patches on premaxillae and 



