NO. 3538 CHARACID FISHES — WEITZMAN 31 



absent. Laterodorsal and anterior surface of snout anterior to nostrils 

 bright red. Also single red line in upper part of iris. Remainder of 

 ii'is pale gold except where primary horizontal stripe extends through 

 eye. Distal region of pelvics silvery blue, especially in male. In some 

 specimens this color almost absent. Belly and region below primary 

 horizontal stripe silvery white. 



Remarks. — Poecilobrycon vittatus of Ahl (1933) Avas described very 

 poorly and the type locality is indefinite. Ahl, following Eigenmann, 

 seemed confused about the identity of Steindachner's trifasciatus and 

 eques, even though, for their time, Steindachner's figures and descrip- 

 tions of these two species were excellent. Ahl believed his vittatus was 

 related to Eigenmann's erythrurus, a form which perhaps could be 

 recognized at most as a subspecies of trifasciatus. For the most part, 

 Ahl's description of vittatus seems to fit the characters listed here for 

 trifasciatus, and I concur with Hoedeman (1954) in considering vittatus 

 a synonym of trifasciatus. 



Eigenmann (1909, pp. 44-45) described Poecilobrycon erythrurus 

 and noted that it was most closely allied to his oaati P. marginatus 

 (now considered to be Nannostomus marginatus) and Steindachner's 

 P. trifasciatus. Later Eigenmann (1912, p. 284) considered Poecilo- 

 brycon auratus to be synonymous with Steindachner's Nannostomus 

 trifasciatus. He apparently had mentally transposed Steindachner's 

 trifasciatus and eques. This probably caused Eigenmann to consider 

 that his erythrurus (at most a subspecies of trifasciatus) was not tri- 

 fasciatus and therefore that it was a distinct species. In any event, 

 examination of some of Eigenmann's specimens of erythrurus and of 

 specimens of trifasciatus from near the type locality of the latter 

 indicates that the two forms are closely related and can be considered 

 members of a widespread, somewhat polymorphic species. Adequate 

 study of many samples from populations throughout the range of the 

 species probably will show that there are several distinct races, some 

 of which undoubtedly will be cansidered as subspecies. Schultz in 

 Axelrod and Schultz (1955, p. 248) considered Poecilobrycon auratus 

 Eigenmann a synonym of Nannostomus trifasciatus. Examination of 

 type specimens of auratus shows it to be a synonym of Poecilobrycon 

 eques (Steindachner) (p. 50). 



Specimens examined.— Three, SU 36900 (SL 24.5 mm.), SU 36999 (SL 27.0 

 mm.), SU 50221 (SL 27.0 mm.), Peru, Shansho Cano, Pevas [Pebas] District, July 

 28, Oct. 20, 1936 (date for third specimen unknown), W. G. Scherer. — One, SU 

 50222, SL 33.0 mm., Peru, Ri'o Ampiyacu, Pevas [P6bas] District, July 23, 1944, 

 W. G. Scherer. — Two (paratj^pes of Poecilobrycon erythrurus Eigenmann), CNHM 

 52974, SL 26.5-28.2 mm., British Guiana, Rockstone River, 1908, Carl H. Eigen- 

 mann.— Two (paratypes of P. erythrurus), CAS(IUM) 11693, SL 23.0-28.6 mm., 

 British Guiana, Rockstone sandbank, Essequibo River, 1908, Carl H. Eigen- 

 mann.— One (paratype of P. erythrurus), CAS(IUM) 11694, SL 24.0 mm., British 



