229 

 Ecology 



Nothing has previously been published about the ecology of A. atronasus. In 

 the moderate amount of material examined, at least 27 prenuptial or nuptial males 

 and 26 gravid females were identified. Based on these specimens, the reproductive 

 period for this species in the middle and upper Amazon basin occurs sometime 

 between mid-to-late October and the end of March. The extended period during 

 which reproductive specimens were available represents temporal and spatial 

 variation in the rainy season. Males exhibited peak nuptial dimorphism in 

 December and January. Reproductive males ranged from 68.7 to 109.9 mm SL (x 

 = 87.1), and ripe females ranged from 60.4 to 115.7 mm SL (x = 89.7). 



■ :■■'' ; .' / ■ . ff . 



Etymology 



From the Latin ater (neuter atrum), meaning black, and nasus, the nose, in 

 reference to the intense black pigmentation on the tip of the snout in live and 

 freshly preserved specimens. ? . 



Material Examined 



Type material . - Holotype : MCZ 27270 (probable male, 72.2), locality 

 unknown, but presumably from the Amazon river basin in Brazil. 



Pern. - Loreto : BMNH 1977.3.10.229 (male, 87.6), Bueno Cano Amazonas, 

 near Iquitos, 30 May 1974, M. Chapman. BMNH 1977.3.10.230 (male, 93.3), Lago 

 Yarinococha, 27 March 1974, M. Chapman. CAS 57940 (ex lU 15788, holotype of 

 T. nigricollis; male, 88.8), Iquitos, W. R. Allen. CAS 57941 (ex lU 15788, paratypes 

 of T. nigricoUis; male, 95.9; 2 females, 52.1-91.5), Iquitos, September 1920. CAS 

 57942 (ex lU 15789, paratype of T. nigricoUis; female ?, 79.2), Rfo Ucayali near 



