CHARACID FISHES — WEITZMAN 



23 



Diagnosis. — This species may be distinguished from all other 

 known species of Nannostomus and Poecilobrycon by the greatly 

 modified anal fin of the males (fig. 6) and an anal fin count of iii,8 in 

 both sexes. In addition, the following combination of characters will 

 distinguish this species from all others: Primary and secondary 

 horizontal stripes well developed; tertiary horizontal stripe absent 

 or only weakly developed; no perforated lateral-line scales; and 

 adipose fin present. 



Description. — Body elongate, rather cylindrical in its anterior 

 half but compressed posteriorly. Greatest depth a short distance 

 anterior to origin of dorsal fin. Standard length of largest specimen 

 with locality data 25.0 mm. (an aquarium specimen measured, SU 

 18471, SL 27.6 mm.). Greatest body depth 4.7 (4.5-5.0); least 

 depth of caudal peduncle 11.1 (10.3-11.5); length of caudal peduncle, 

 males 5.9 (5.6-6.3), females 5.1 (4.9-5.4); snout tip to origin of dorsal 

 fin 1.8 (1.7-1.9); snout tip to origin of anal fin 1.3 (1.29-1.34). 



Figure 5. — Nannostomus digrammus, male, SL 24.5 mm., SU 50248, 



Head conic but somewhat flattened dorsoventrally; snout obtuse 

 in vertical and horizontal profiles. Top of head between eyes rather 

 convex. Head 3.7 (3.5-3.8); eye in head 2.8 (2.5-3.0); snout in eye 

 1.2 (1.1-1.3) ; least width of bony interorbital in greatest eye diameter 

 1.2 (1.05-1.26). 



Premaxillary with 6 teeth in anterior row, all quadricuspid ; posterior 

 1 or 2 teeth of this row quinque- to sexcuspid, cusps being subequal. 

 Central cusps of each tooth largest and longest. Maxillary with 1 

 quinque- to sexcuspid tooth. Dentary with 5 to 6 (usually 6) teeth 

 in outer row, anterior 4 teeth with 6 cusps, posterior 2 teeth with 

 4 to 5 cusps, cusps subequal. Teeth in inner or second tooth row of 



